/* Cache and manage frames for GDB, the GNU debugger. Copyright 1986, 1987, 1989, 1991, 1994, 1995, 1996, 1998, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc. This file is part of GDB. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include "defs.h" #include "frame.h" #include "target.h" #include "value.h" #include "inferior.h" /* for inferior_ptid */ #include "regcache.h" #include "gdb_assert.h" #include "gdb_string.h" #include "user-regs.h" #include "gdb_obstack.h" #include "dummy-frame.h" #include "sentinel-frame.h" #include "gdbcore.h" #include "annotate.h" #include "language.h" #include "frame-unwind.h" #include "frame-base.h" #include "command.h" #include "gdbcmd.h" #include "observer.h" static struct frame_info *get_prev_frame_1 (struct frame_info *this_frame); /* We keep a cache of stack frames, each of which is a "struct frame_info". The innermost one gets allocated (in wait_for_inferior) each time the inferior stops; current_frame points to it. Additional frames get allocated (in get_prev_frame) as needed, and are chained through the next and prev fields. Any time that the frame cache becomes invalid (most notably when we execute something, but also if we change how we interpret the frames (e.g. "set heuristic-fence-post" in mips-tdep.c, or anything which reads new symbols)), we should call reinit_frame_cache. */ struct frame_info { /* Level of this frame. The inner-most (youngest) frame is at level 0. As you move towards the outer-most (oldest) frame, the level increases. This is a cached value. It could just as easily be computed by counting back from the selected frame to the inner most frame. */ /* NOTE: cagney/2002-04-05: Perhaps a level of ``-1'' should be reserved to indicate a bogus frame - one that has been created just to keep GDB happy (GDB always needs a frame). For the moment leave this as speculation. */ int level; /* The frame's type. */ /* FIXME: cagney/2004-05-01: Should instead just use ->unwind->type. Unfortunately, legacy_get_prev_frame is still explicitly setting the type. Eliminate that method and this field can be eliminated. */ enum frame_type type; /* For each register, address of where it was saved on entry to the frame, or zero if it was not saved on entry to this frame. This includes special registers such as pc and fp saved in special ways in the stack frame. The SP_REGNUM is even more special, the address here is the sp for the previous frame, not the address where the sp was saved. */ /* Allocated by frame_saved_regs_zalloc () which is called / initialized by DEPRECATED_FRAME_INIT_SAVED_REGS(). */ CORE_ADDR *saved_regs; /*NUM_REGS + NUM_PSEUDO_REGS*/ /* Anything extra for this structure that may have been defined in the machine dependent files. */ /* Allocated by frame_extra_info_zalloc () which is called / initialized by DEPRECATED_INIT_EXTRA_FRAME_INFO */ struct frame_extra_info *extra_info; /* The frame's low-level unwinder and corresponding cache. The low-level unwinder is responsible for unwinding register values for the previous frame. The low-level unwind methods are selected based on the presence, or otherwise, of register unwind information such as CFI. */ void *prologue_cache; const struct frame_unwind *unwind; /* Cached copy of the previous frame's resume address. */ struct { int p; CORE_ADDR value; } prev_pc; /* Cached copy of the previous frame's function address. */ struct { CORE_ADDR addr; int p; } prev_func; /* This frame's ID. */ struct { int p; struct frame_id value; } this_id; /* The frame's high-level base methods, and corresponding cache. The high level base methods are selected based on the frame's debug info. */ const struct frame_base *base; void *base_cache; /* Pointers to the next (down, inner, younger) and previous (up, outer, older) frame_info's in the frame cache. */ struct frame_info *next; /* down, inner, younger */ int prev_p; struct frame_info *prev; /* up, outer, older */ }; /* Flag to control debugging. */ static int frame_debug; /* Flag to indicate whether backtraces should stop at main et.al. */ static int backtrace_past_main; static unsigned int backtrace_limit = UINT_MAX; void fprint_frame_id (struct ui_file *file, struct frame_id id) { fprintf_unfiltered (file, "{stack=0x%s,code=0x%s,special=0x%s}", paddr_nz (id.stack_addr), paddr_nz (id.code_addr), paddr_nz (id.special_addr)); } static void fprint_frame_type (struct ui_file *file, enum frame_type type) { switch (type) { case UNKNOWN_FRAME: fprintf_unfiltered (file, "UNKNOWN_FRAME"); return; case NORMAL_FRAME: fprintf_unfiltered (file, "NORMAL_FRAME"); return; case DUMMY_FRAME: fprintf_unfiltered (file, "DUMMY_FRAME"); return; case SIGTRAMP_FRAME: fprintf_unfiltered (file, "SIGTRAMP_FRAME"); return; default: fprintf_unfiltered (file, ""); return; }; } static void fprint_frame (struct ui_file *file, struct frame_info *fi) { if (fi == NULL) { fprintf_unfiltered (file, ""); return; } fprintf_unfiltered (file, "{"); fprintf_unfiltered (file, "level=%d", fi->level); fprintf_unfiltered (file, ","); fprintf_unfiltered (file, "type="); fprint_frame_type (file, fi->type); fprintf_unfiltered (file, ","); fprintf_unfiltered (file, "unwind="); if (fi->unwind != NULL) gdb_print_host_address (fi->unwind, file); else fprintf_unfiltered (file, ""); fprintf_unfiltered (file, ","); fprintf_unfiltered (file, "pc="); if (fi->next != NULL && fi->next->prev_pc.p) fprintf_unfiltered (file, "0x%s", paddr_nz (fi->next->prev_pc.value)); else fprintf_unfiltered (file, ""); fprintf_unfiltered (file, ","); fprintf_unfiltered (file, "id="); if (fi->this_id.p) fprint_frame_id (file, fi->this_id.value); else fprintf_unfiltered (file, ""); fprintf_unfiltered (file, ","); fprintf_unfiltered (file, "func="); if (fi->next != NULL && fi->next->prev_func.p) fprintf_unfiltered (file, "0x%s", paddr_nz (fi->next->prev_func.addr)); else fprintf_unfiltered (file, ""); fprintf_unfiltered (file, "}"); } /* Return a frame uniq ID that can be used to, later, re-find the frame. */ struct frame_id get_frame_id (struct frame_info *fi) { if (fi == NULL) { return null_frame_id; } if (!fi->this_id.p) { gdb_assert (!legacy_frame_p (current_gdbarch)); if (frame_debug) fprintf_unfiltered (gdb_stdlog, "{ get_frame_id (fi=%d) ", fi->level); /* Find the unwinder. */ if (fi->unwind == NULL) { fi->unwind = frame_unwind_find_by_frame (fi->next, &fi->prologue_cache); /* FIXME: cagney/2004-05-01: Should instead just use ->unwind->type. Unfortunately, legacy_get_prev_frame is still explicitly setting the type. Eliminate that method and this field can be eliminated. */ fi->type = fi->unwind->type; } /* Find THIS frame's ID. */ fi->unwind->this_id (fi->next, &fi->prologue_cache, &fi->this_id.value); fi->this_id.p = 1; if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame_id (gdb_stdlog, fi->this_id.value); fprintf_unfiltered (gdb_stdlog, " }\n"); } } return fi->this_id.value; } struct frame_id frame_unwind_id (struct frame_info *next_frame) { /* Use prev_frame, and not get_prev_frame. The latter will truncate the frame chain, leading to this function unintentionally returning a null_frame_id (e.g., when a caller requests the frame ID of "main()"s caller. */ return get_frame_id (get_prev_frame_1 (next_frame)); } const struct frame_id null_frame_id; /* All zeros. */ struct frame_id frame_id_build_special (CORE_ADDR stack_addr, CORE_ADDR code_addr, CORE_ADDR special_addr) { struct frame_id id; id.stack_addr = stack_addr; id.code_addr = code_addr; id.special_addr = special_addr; return id; } struct frame_id frame_id_build (CORE_ADDR stack_addr, CORE_ADDR code_addr) { return frame_id_build_special (stack_addr, code_addr, 0); } int frame_id_p (struct frame_id l) { int p; /* The .code can be NULL but the .stack cannot. */ p = (l.stack_addr != 0); if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "{ frame_id_p (l="); fprint_frame_id (gdb_stdlog, l); fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", p); } return p; } int frame_id_eq (struct frame_id l, struct frame_id r) { int eq; if (l.stack_addr == 0 || r.stack_addr == 0) /* Like a NaN, if either ID is invalid, the result is false. */ eq = 0; else if (l.stack_addr != r.stack_addr) /* If .stack addresses are different, the frames are different. */ eq = 0; else if (l.code_addr == 0 || r.code_addr == 0) /* A zero code addr is a wild card, always succeed. */ eq = 1; else if (l.code_addr != r.code_addr) /* If .code addresses are different, the frames are different. */ eq = 0; else if (l.special_addr == 0 || r.special_addr == 0) /* A zero special addr is a wild card (or unused), always succeed. */ eq = 1; else if (l.special_addr == r.special_addr) /* Frames are equal. */ eq = 1; else /* No luck. */ eq = 0; if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "{ frame_id_eq (l="); fprint_frame_id (gdb_stdlog, l); fprintf_unfiltered (gdb_stdlog, ",r="); fprint_frame_id (gdb_stdlog, r); fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", eq); } return eq; } int frame_id_inner (struct frame_id l, struct frame_id r) { int inner; if (l.stack_addr == 0 || r.stack_addr == 0) /* Like NaN, any operation involving an invalid ID always fails. */ inner = 0; else /* Only return non-zero when strictly inner than. Note that, per comment in "frame.h", there is some fuzz here. Frameless functions are not strictly inner than (same .stack but different .code and/or .special address). */ inner = INNER_THAN (l.stack_addr, r.stack_addr); if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "{ frame_id_inner (l="); fprint_frame_id (gdb_stdlog, l); fprintf_unfiltered (gdb_stdlog, ",r="); fprint_frame_id (gdb_stdlog, r); fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", inner); } return inner; } struct frame_info * frame_find_by_id (struct frame_id id) { struct frame_info *frame; /* ZERO denotes the null frame, let the caller decide what to do about it. Should it instead return get_current_frame()? */ if (!frame_id_p (id)) return NULL; for (frame = get_current_frame (); frame != NULL; frame = get_prev_frame (frame)) { struct frame_id this = get_frame_id (frame); if (frame_id_eq (id, this)) /* An exact match. */ return frame; if (frame_id_inner (id, this)) /* Gone to far. */ return NULL; /* Either we're not yet gone far enough out along the frame chain (inner(this,id)), or we're comparing frameless functions (same .base, different .func, no test available). Struggle on until we've definitly gone to far. */ } return NULL; } CORE_ADDR frame_pc_unwind (struct frame_info *this_frame) { if (!this_frame->prev_pc.p) { CORE_ADDR pc; if (gdbarch_unwind_pc_p (current_gdbarch)) { /* The right way. The `pure' way. The one true way. This method depends solely on the register-unwind code to determine the value of registers in THIS frame, and hence the value of this frame's PC (resume address). A typical implementation is no more than: frame_unwind_register (this_frame, ISA_PC_REGNUM, buf); return extract_unsigned_integer (buf, size of ISA_PC_REGNUM); Note: this method is very heavily dependent on a correct register-unwind implementation, it pays to fix that method first; this method is frame type agnostic, since it only deals with register values, it works with any frame. This is all in stark contrast to the old FRAME_SAVED_PC which would try to directly handle all the different ways that a PC could be unwound. */ pc = gdbarch_unwind_pc (current_gdbarch, this_frame); } else if (this_frame->level < 0) { /* FIXME: cagney/2003-03-06: Old code and a sentinel frame. Do like was always done. Fetch the PC's value directly from the global registers array (via read_pc). This assumes that this frame belongs to the current global register cache. The assumption is dangerous. */ pc = read_pc (); } else if (DEPRECATED_FRAME_SAVED_PC_P ()) { /* FIXME: cagney/2003-03-06: Old code, but not a sentinel frame. Do like was always done. Note that this method, unlike unwind_pc(), tries to handle all the different frame cases directly. It fails. */ pc = DEPRECATED_FRAME_SAVED_PC (this_frame); } else internal_error (__FILE__, __LINE__, "No gdbarch_unwind_pc method"); this_frame->prev_pc.value = pc; this_frame->prev_pc.p = 1; if (frame_debug) fprintf_unfiltered (gdb_stdlog, "{ frame_pc_unwind (this_frame=%d) -> 0x%s }\n", this_frame->level, paddr_nz (this_frame->prev_pc.value)); } return this_frame->prev_pc.value; } CORE_ADDR frame_func_unwind (struct frame_info *fi) { if (!fi->prev_func.p) { /* Make certain that this, and not the adjacent, function is found. */ CORE_ADDR addr_in_block = frame_unwind_address_in_block (fi); fi->prev_func.p = 1; fi->prev_func.addr = get_pc_function_start (addr_in_block); if (frame_debug) fprintf_unfiltered (gdb_stdlog, "{ frame_func_unwind (fi=%d) -> 0x%s }\n", fi->level, paddr_nz (fi->prev_func.addr)); } return fi->prev_func.addr; } CORE_ADDR get_frame_func (struct frame_info *fi) { return frame_func_unwind (fi->next); } static int do_frame_unwind_register (void *src, int regnum, void *buf) { frame_unwind_register (src, regnum, buf); return 1; } void frame_pop (struct frame_info *this_frame) { struct regcache *scratch_regcache; struct cleanup *cleanups; if (DEPRECATED_POP_FRAME_P ()) { /* A legacy architecture that has implemented a custom pop function. All new architectures should instead be using the generic code below. */ DEPRECATED_POP_FRAME; } else { /* Make a copy of all the register values unwound from this frame. Save them in a scratch buffer so that there isn't a race between trying to extract the old values from the current_regcache while at the same time writing new values into that same cache. */ struct regcache *scratch = regcache_xmalloc (current_gdbarch); struct cleanup *cleanups = make_cleanup_regcache_xfree (scratch); regcache_save (scratch, do_frame_unwind_register, this_frame); /* FIXME: cagney/2003-03-16: It should be possible to tell the target's register cache that it is about to be hit with a burst register transfer and that the sequence of register writes should be batched. The pair target_prepare_to_store() and target_store_registers() kind of suggest this functionality. Unfortunately, they don't implement it. Their lack of a formal definition can lead to targets writing back bogus values (arguably a bug in the target code mind). */ /* Now copy those saved registers into the current regcache. Here, regcache_cpy() calls regcache_restore(). */ regcache_cpy (current_regcache, scratch); do_cleanups (cleanups); } /* We've made right mess of GDB's local state, just discard everything. */ flush_cached_frames (); } void frame_register_unwind (struct frame_info *frame, int regnum, int *optimizedp, enum lval_type *lvalp, CORE_ADDR *addrp, int *realnump, void *bufferp) { struct frame_unwind_cache *cache; if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "\ { frame_register_unwind (frame=%d,regnum=%d(%s),...) ", frame->level, regnum, frame_map_regnum_to_name (frame, regnum)); } /* Require all but BUFFERP to be valid. A NULL BUFFERP indicates that the value proper does not need to be fetched. */ gdb_assert (optimizedp != NULL); gdb_assert (lvalp != NULL); gdb_assert (addrp != NULL); gdb_assert (realnump != NULL); /* gdb_assert (bufferp != NULL); */ /* NOTE: cagney/2002-11-27: A program trying to unwind a NULL frame is broken. There is always a frame. If there, for some reason, isn't a frame, there is some pretty busted code as it should have detected the problem before calling here. */ gdb_assert (frame != NULL); /* Find the unwinder. */ if (frame->unwind == NULL) { frame->unwind = frame_unwind_find_by_frame (frame->next, &frame->prologue_cache); /* FIXME: cagney/2004-05-01: Should instead just use ->unwind->type. Unfortunately, legacy_get_prev_frame is still explicitly setting the type. Eliminate that method and this field can be eliminated. */ frame->type = frame->unwind->type; } /* Ask this frame to unwind its register. See comment in "frame-unwind.h" for why NEXT frame and this unwind cache are passed in. */ frame->unwind->prev_register (frame->next, &frame->prologue_cache, regnum, optimizedp, lvalp, addrp, realnump, bufferp); if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "->"); fprintf_unfiltered (gdb_stdlog, " *optimizedp=%d", (*optimizedp)); fprintf_unfiltered (gdb_stdlog, " *lvalp=%d", (int) (*lvalp)); fprintf_unfiltered (gdb_stdlog, " *addrp=0x%s", paddr_nz ((*addrp))); fprintf_unfiltered (gdb_stdlog, " *bufferp="); if (bufferp == NULL) fprintf_unfiltered (gdb_stdlog, ""); else { int i; const unsigned char *buf = bufferp; fprintf_unfiltered (gdb_stdlog, "["); for (i = 0; i < register_size (current_gdbarch, regnum); i++) fprintf_unfiltered (gdb_stdlog, "%02x", buf[i]); fprintf_unfiltered (gdb_stdlog, "]"); } fprintf_unfiltered (gdb_stdlog, " }\n"); } } void frame_register (struct frame_info *frame, int regnum, int *optimizedp, enum lval_type *lvalp, CORE_ADDR *addrp, int *realnump, void *bufferp) { /* Require all but BUFFERP to be valid. A NULL BUFFERP indicates that the value proper does not need to be fetched. */ gdb_assert (optimizedp != NULL); gdb_assert (lvalp != NULL); gdb_assert (addrp != NULL); gdb_assert (realnump != NULL); /* gdb_assert (bufferp != NULL); */ /* Ulgh! Old code that, for lval_register, sets ADDRP to the offset of the register in the register cache. It should instead return the REGNUM corresponding to that register. Translate the . */ if (DEPRECATED_GET_SAVED_REGISTER_P ()) { DEPRECATED_GET_SAVED_REGISTER (bufferp, optimizedp, addrp, frame, regnum, lvalp); /* Compute the REALNUM if the caller wants it. */ if (*lvalp == lval_register) { int regnum; for (regnum = 0; regnum < NUM_REGS + NUM_PSEUDO_REGS; regnum++) { if (*addrp == register_offset_hack (current_gdbarch, regnum)) { *realnump = regnum; return; } } internal_error (__FILE__, __LINE__, "Failed to compute the register number corresponding" " to 0x%s", paddr_d (*addrp)); } *realnump = -1; return; } /* Obtain the register value by unwinding the register from the next (more inner frame). */ gdb_assert (frame != NULL && frame->next != NULL); frame_register_unwind (frame->next, regnum, optimizedp, lvalp, addrp, realnump, bufferp); } void frame_unwind_register (struct frame_info *frame, int regnum, void *buf) { int optimized; CORE_ADDR addr; int realnum; enum lval_type lval; frame_register_unwind (frame, regnum, &optimized, &lval, &addr, &realnum, buf); } void get_frame_register (struct frame_info *frame, int regnum, void *buf) { frame_unwind_register (frame->next, regnum, buf); } LONGEST frame_unwind_register_signed (struct frame_info *frame, int regnum) { char buf[MAX_REGISTER_SIZE]; frame_unwind_register (frame, regnum, buf); return extract_signed_integer (buf, DEPRECATED_REGISTER_VIRTUAL_SIZE (regnum)); } LONGEST get_frame_register_signed (struct frame_info *frame, int regnum) { return frame_unwind_register_signed (frame->next, regnum); } ULONGEST frame_unwind_register_unsigned (struct frame_info *frame, int regnum) { char buf[MAX_REGISTER_SIZE]; frame_unwind_register (frame, regnum, buf); return extract_unsigned_integer (buf, DEPRECATED_REGISTER_VIRTUAL_SIZE (regnum)); } ULONGEST get_frame_register_unsigned (struct frame_info *frame, int regnum) { return frame_unwind_register_unsigned (frame->next, regnum); } void frame_unwind_unsigned_register (struct frame_info *frame, int regnum, ULONGEST *val) { char buf[MAX_REGISTER_SIZE]; frame_unwind_register (frame, regnum, buf); (*val) = extract_unsigned_integer (buf, DEPRECATED_REGISTER_VIRTUAL_SIZE (regnum)); } void put_frame_register (struct frame_info *frame, int regnum, const void *buf) { struct gdbarch *gdbarch = get_frame_arch (frame); int realnum; int optim; enum lval_type lval; CORE_ADDR addr; frame_register (frame, regnum, &optim, &lval, &addr, &realnum, NULL); if (optim) error ("Attempt to assign to a value that was optimized out."); switch (lval) { case lval_memory: { /* FIXME: write_memory doesn't yet take constant buffers. Arrrg! */ char tmp[MAX_REGISTER_SIZE]; memcpy (tmp, buf, register_size (gdbarch, regnum)); write_memory (addr, tmp, register_size (gdbarch, regnum)); break; } case lval_register: regcache_cooked_write (current_regcache, realnum, buf); break; default: error ("Attempt to assign to an unmodifiable value."); } } /* frame_register_read () Find and return the value of REGNUM for the specified stack frame. The number of bytes copied is DEPRECATED_REGISTER_RAW_SIZE (REGNUM). Returns 0 if the register value could not be found. */ int frame_register_read (struct frame_info *frame, int regnum, void *myaddr) { int optimized; enum lval_type lval; CORE_ADDR addr; int realnum; frame_register (frame, regnum, &optimized, &lval, &addr, &realnum, myaddr); /* FIXME: cagney/2002-05-15: This test is just bogus. It indicates that the target failed to supply a value for a register because it was "not available" at this time. Problem is, the target still has the register and so get saved_register() may be returning a value saved on the stack. */ if (register_cached (regnum) < 0) return 0; /* register value not available */ return !optimized; } /* Map between a frame register number and its name. A frame register space is a superset of the cooked register space --- it also includes builtin registers. */ int frame_map_name_to_regnum (struct frame_info *frame, const char *name, int len) { return user_reg_map_name_to_regnum (get_frame_arch (frame), name, len); } const char * frame_map_regnum_to_name (struct frame_info *frame, int regnum) { return user_reg_map_regnum_to_name (get_frame_arch (frame), regnum); } /* Create a sentinel frame. */ static struct frame_info * create_sentinel_frame (struct regcache *regcache) { struct frame_info *frame = FRAME_OBSTACK_ZALLOC (struct frame_info); frame->type = SENTINEL_FRAME; frame->level = -1; /* Explicitly initialize the sentinel frame's cache. Provide it with the underlying regcache. In the future additional information, such as the frame's thread will be added. */ frame->prologue_cache = sentinel_frame_cache (regcache); /* For the moment there is only one sentinel frame implementation. */ frame->unwind = sentinel_frame_unwind; /* Link this frame back to itself. The frame is self referential (the unwound PC is the same as the pc), so make it so. */ frame->next = frame; /* Make the sentinel frame's ID valid, but invalid. That way all comparisons with it should fail. */ frame->this_id.p = 1; frame->this_id.value = null_frame_id; if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "{ create_sentinel_frame (...) -> "); fprint_frame (gdb_stdlog, frame); fprintf_unfiltered (gdb_stdlog, " }\n"); } return frame; } /* Info about the innermost stack frame (contents of FP register) */ static struct frame_info *current_frame; /* Cache for frame addresses already read by gdb. Valid only while inferior is stopped. Control variables for the frame cache should be local to this module. */ static struct obstack frame_cache_obstack; void * frame_obstack_zalloc (unsigned long size) { void *data = obstack_alloc (&frame_cache_obstack, size); memset (data, 0, size); return data; } CORE_ADDR * frame_saved_regs_zalloc (struct frame_info *fi) { fi->saved_regs = (CORE_ADDR *) frame_obstack_zalloc (SIZEOF_FRAME_SAVED_REGS); return fi->saved_regs; } CORE_ADDR * deprecated_get_frame_saved_regs (struct frame_info *fi) { return fi->saved_regs; } /* Return the innermost (currently executing) stack frame. This is split into two functions. The function unwind_to_current_frame() is wrapped in catch exceptions so that, even when the unwind of the sentinel frame fails, the function still returns a stack frame. */ static int unwind_to_current_frame (struct ui_out *ui_out, void *args) { struct frame_info *frame = get_prev_frame (args); /* A sentinel frame can fail to unwind, e.g., because its PC value lands in somewhere like start. */ if (frame == NULL) return 1; current_frame = frame; return 0; } struct frame_info * get_current_frame (void) { /* First check, and report, the lack of registers. Having GDB report "No stack!" or "No memory" when the target doesn't even have registers is very confusing. Besides, "printcmd.exp" explicitly checks that ``print $pc'' with no registers prints "No registers". */ if (!target_has_registers) error ("No registers."); if (!target_has_stack) error ("No stack."); if (!target_has_memory) error ("No memory."); if (current_frame == NULL) { struct frame_info *sentinel_frame = create_sentinel_frame (current_regcache); if (catch_exceptions (uiout, unwind_to_current_frame, sentinel_frame, NULL, RETURN_MASK_ERROR) != 0) { /* Oops! Fake a current frame? Is this useful? It has a PC of zero, for instance. */ current_frame = sentinel_frame; } } return current_frame; } /* The "selected" stack frame is used by default for local and arg access. May be zero, for no selected frame. */ struct frame_info *deprecated_selected_frame; /* Return the selected frame. Always non-NULL (unless there isn't an inferior sufficient for creating a frame) in which case an error is thrown. */ struct frame_info * get_selected_frame (void) { if (deprecated_selected_frame == NULL) /* Hey! Don't trust this. It should really be re-finding the last selected frame of the currently selected thread. This, though, is better than nothing. */ select_frame (get_current_frame ()); /* There is always a frame. */ gdb_assert (deprecated_selected_frame != NULL); return deprecated_selected_frame; } /* This is a variant of get_selected_frame() which can be called when the inferior does not have a frame; in that case it will return NULL instead of calling error(). */ struct frame_info * deprecated_safe_get_selected_frame (void) { if (!target_has_registers || !target_has_stack || !target_has_memory) return NULL; return get_selected_frame (); } /* Select frame FI (or NULL - to invalidate the current frame). */ void select_frame (struct frame_info *fi) { struct symtab *s; deprecated_selected_frame = fi; /* NOTE: cagney/2002-05-04: FI can be NULL. This occurs when the frame is being invalidated. */ if (deprecated_selected_frame_level_changed_hook) deprecated_selected_frame_level_changed_hook (frame_relative_level (fi)); /* FIXME: kseitz/2002-08-28: It would be nice to call selected_frame_level_changed_event() right here, but due to limitations in the current interfaces, we would end up flooding UIs with events because select_frame() is used extensively internally. Once we have frame-parameterized frame (and frame-related) commands, the event notification can be moved here, since this function will only be called when the user's selected frame is being changed. */ /* Ensure that symbols for this frame are read in. Also, determine the source language of this frame, and switch to it if desired. */ if (fi) { /* We retrieve the frame's symtab by using the frame PC. However we cannot use the frame PC as-is, because it usually points to the instruction following the "call", which is sometimes the first instruction of another function. So we rely on get_frame_address_in_block() which provides us with a PC which is guaranteed to be inside the frame's code block. */ s = find_pc_symtab (get_frame_address_in_block (fi)); if (s && s->language != current_language->la_language && s->language != language_unknown && language_mode == language_mode_auto) { set_language (s->language); } } } /* Return the register saved in the simplistic ``saved_regs'' cache. If the value isn't here AND a value is needed, try the next inner most frame. */ static void legacy_saved_regs_prev_register (struct frame_info *next_frame, void **this_prologue_cache, int regnum, int *optimizedp, enum lval_type *lvalp, CORE_ADDR *addrp, int *realnump, void *bufferp) { /* HACK: New code is passed the next frame and this cache. Unfortunately, old code expects this frame. Since this is a backward compatibility hack, cheat by walking one level along the prologue chain to the frame the old code expects. Do not try this at home. Professional driver, closed course. */ struct frame_info *frame = next_frame->prev; gdb_assert (frame != NULL); if (deprecated_get_frame_saved_regs (frame) == NULL) { /* If nothing has initialized the saved regs, do it now. */ gdb_assert (DEPRECATED_FRAME_INIT_SAVED_REGS_P ()); DEPRECATED_FRAME_INIT_SAVED_REGS (frame); gdb_assert (deprecated_get_frame_saved_regs (frame) != NULL); } if (deprecated_get_frame_saved_regs (frame) != NULL && deprecated_get_frame_saved_regs (frame)[regnum] != 0) { if (regnum == SP_REGNUM) { /* SP register treated specially. */ *optimizedp = 0; *lvalp = not_lval; *addrp = 0; *realnump = -1; if (bufferp != NULL) /* NOTE: cagney/2003-05-09: In-lined store_address() with it's body - store_unsigned_integer(). */ store_unsigned_integer (bufferp, DEPRECATED_REGISTER_RAW_SIZE (regnum), deprecated_get_frame_saved_regs (frame)[regnum]); } else { /* Any other register is saved in memory, fetch it but cache a local copy of its value. */ *optimizedp = 0; *lvalp = lval_memory; *addrp = deprecated_get_frame_saved_regs (frame)[regnum]; *realnump = -1; if (bufferp != NULL) { #if 1 /* Save each register value, as it is read in, in a frame based cache. */ void **regs = (*this_prologue_cache); if (regs == NULL) { int sizeof_cache = ((NUM_REGS + NUM_PSEUDO_REGS) * sizeof (void *)); regs = frame_obstack_zalloc (sizeof_cache); (*this_prologue_cache) = regs; } if (regs[regnum] == NULL) { regs[regnum] = frame_obstack_zalloc (DEPRECATED_REGISTER_RAW_SIZE (regnum)); read_memory (deprecated_get_frame_saved_regs (frame)[regnum], regs[regnum], DEPRECATED_REGISTER_RAW_SIZE (regnum)); } memcpy (bufferp, regs[regnum], DEPRECATED_REGISTER_RAW_SIZE (regnum)); #else /* Read the value in from memory. */ read_memory (deprecated_get_frame_saved_regs (frame)[regnum], bufferp, DEPRECATED_REGISTER_RAW_SIZE (regnum)); #endif } } return; } /* No luck. Assume this and the next frame have the same register value. Pass the unwind request down the frame chain to the next frame. Hopefully that frame will find the register's location. */ frame_register_unwind (next_frame, regnum, optimizedp, lvalp, addrp, realnump, bufferp); } static void legacy_saved_regs_this_id (struct frame_info *next_frame, void **this_prologue_cache, struct frame_id *id) { /* A developer is trying to bring up a new architecture, help them by providing a default unwinder that refuses to unwind anything (the ID is always NULL). In the case of legacy code, legacy_get_prev_frame() will have previously set ->this_id.p, so this code won't be called. */ (*id) = null_frame_id; } const struct frame_unwind legacy_saved_regs_unwinder = { /* Not really. It gets overridden by legacy_get_prev_frame(). */ UNKNOWN_FRAME, legacy_saved_regs_this_id, legacy_saved_regs_prev_register }; const struct frame_unwind *legacy_saved_regs_unwind = &legacy_saved_regs_unwinder; /* Function: deprecated_generic_get_saved_register Find register number REGNUM relative to FRAME and put its (raw, target format) contents in *RAW_BUFFER. Set *OPTIMIZED if the variable was optimized out (and thus can't be fetched). Note that this is never set to anything other than zero in this implementation. Set *LVAL to lval_memory, lval_register, or not_lval, depending on whether the value was fetched from memory, from a register, or in a strange and non-modifiable way (e.g. a frame pointer which was calculated rather than fetched). We will use not_lval for values fetched from generic dummy frames. Set *ADDRP to the address, either in memory or as a DEPRECATED_REGISTER_BYTE offset into the registers array. If the value is stored in a dummy frame, set *ADDRP to zero. The argument RAW_BUFFER must point to aligned memory. */ void deprecated_generic_get_saved_register (char *raw_buffer, int *optimized, CORE_ADDR *addrp, struct frame_info *frame, int regnum, enum lval_type *lval) { if (!target_has_registers) error ("No registers."); /* Normal systems don't optimize out things with register numbers. */ if (optimized != NULL) *optimized = 0; if (addrp) /* default assumption: not found in memory */ *addrp = 0; /* Note: since the current frame's registers could only have been saved by frames INTERIOR TO the current frame, we skip examining the current frame itself: otherwise, we would be getting the previous frame's registers which were saved by the current frame. */ if (frame != NULL) { for (frame = get_next_frame (frame); frame_relative_level (frame) >= 0; frame = get_next_frame (frame)) { if (get_frame_type (frame) == DUMMY_FRAME) { if (lval) /* found it in a CALL_DUMMY frame */ *lval = not_lval; if (raw_buffer) /* FIXME: cagney/2002-06-26: This should be via the gdbarch_register_read() method so that it, on the fly, constructs either a raw or pseudo register from the raw register cache. */ regcache_raw_read (deprecated_find_dummy_frame_regcache (get_frame_pc (frame), get_frame_base (frame)), regnum, raw_buffer); return; } DEPRECATED_FRAME_INIT_SAVED_REGS (frame); if (deprecated_get_frame_saved_regs (frame) != NULL && deprecated_get_frame_saved_regs (frame)[regnum] != 0) { if (lval) /* found it saved on the stack */ *lval = lval_memory; if (regnum == SP_REGNUM) { if (raw_buffer) /* SP register treated specially */ /* NOTE: cagney/2003-05-09: In-line store_address() with it's body - store_unsigned_integer(). */ store_unsigned_integer (raw_buffer, DEPRECATED_REGISTER_RAW_SIZE (regnum), deprecated_get_frame_saved_regs (frame)[regnum]); } else { if (addrp) /* any other register */ *addrp = deprecated_get_frame_saved_regs (frame)[regnum]; if (raw_buffer) read_memory (deprecated_get_frame_saved_regs (frame)[regnum], raw_buffer, DEPRECATED_REGISTER_RAW_SIZE (regnum)); } return; } } } /* If we get thru the loop to this point, it means the register was not saved in any frame. Return the actual live-register value. */ if (lval) /* found it in a live register */ *lval = lval_register; if (addrp) *addrp = DEPRECATED_REGISTER_BYTE (regnum); if (raw_buffer) deprecated_read_register_gen (regnum, raw_buffer); } /* Determine the frame's type based on its PC. */ static enum frame_type frame_type_from_pc (CORE_ADDR pc) { if (DEPRECATED_USE_GENERIC_DUMMY_FRAMES && deprecated_pc_in_call_dummy (pc, 0, 0)) return DUMMY_FRAME; else return NORMAL_FRAME; } /* Create an arbitrary (i.e. address specified by user) or innermost frame. Always returns a non-NULL value. */ struct frame_info * create_new_frame (CORE_ADDR addr, CORE_ADDR pc) { struct frame_info *fi; if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "{ create_new_frame (addr=0x%s, pc=0x%s) ", paddr_nz (addr), paddr_nz (pc)); } fi = frame_obstack_zalloc (sizeof (struct frame_info)); fi->next = create_sentinel_frame (current_regcache); /* Select/initialize both the unwind function and the frame's type based on the PC. */ fi->unwind = frame_unwind_find_by_frame (fi->next, &fi->prologue_cache); if (fi->unwind->type != UNKNOWN_FRAME) fi->type = fi->unwind->type; else fi->type = frame_type_from_pc (pc); fi->this_id.p = 1; deprecated_update_frame_base_hack (fi, addr); deprecated_update_frame_pc_hack (fi, pc); if (DEPRECATED_INIT_EXTRA_FRAME_INFO_P ()) DEPRECATED_INIT_EXTRA_FRAME_INFO (0, fi); if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, fi); fprintf_unfiltered (gdb_stdlog, " }\n"); } return fi; } /* Return the frame that THIS_FRAME calls (NULL if THIS_FRAME is the innermost frame). Be careful to not fall off the bottom of the frame chain and onto the sentinel frame. */ struct frame_info * get_next_frame (struct frame_info *this_frame) { if (this_frame->level > 0) return this_frame->next; else return NULL; } /* Observer for the target_changed event. */ void frame_observer_target_changed (struct target_ops *target) { flush_cached_frames (); } /* Flush the entire frame cache. */ void flush_cached_frames (void) { /* Since we can't really be sure what the first object allocated was */ obstack_free (&frame_cache_obstack, 0); obstack_init (&frame_cache_obstack); current_frame = NULL; /* Invalidate cache */ select_frame (NULL); annotate_frames_invalid (); if (frame_debug) fprintf_unfiltered (gdb_stdlog, "{ flush_cached_frames () }\n"); } /* Flush the frame cache, and start a new one if necessary. */ void reinit_frame_cache (void) { flush_cached_frames (); /* FIXME: The inferior_ptid test is wrong if there is a corefile. */ if (PIDGET (inferior_ptid) != 0) { select_frame (get_current_frame ()); } } /* Create the previous frame using the deprecated methods INIT_EXTRA_INFO, and INIT_FRAME_PC. */ static struct frame_info * legacy_get_prev_frame (struct frame_info *this_frame) { CORE_ADDR address = 0; struct frame_info *prev; int fromleaf; /* Don't frame_debug print legacy_get_prev_frame() here, just confuses the output. */ /* Allocate the new frame. There is no reason to worry about memory leaks, should the remainder of the function fail. The allocated memory will be quickly reclaimed when the frame cache is flushed, and the `we've been here before' check, in get_prev_frame() will stop repeated memory allocation calls. */ prev = FRAME_OBSTACK_ZALLOC (struct frame_info); prev->level = this_frame->level + 1; /* Do not completely wire it in to the frame chain. Some (bad) code in INIT_FRAME_EXTRA_INFO tries to look along frame->prev to pull some fancy tricks (of course such code is, by definition, recursive). On the other hand, methods, such as get_frame_pc() and get_frame_base() rely on being able to walk along the frame chain. Make certain that at least they work by providing that link. Of course things manipulating prev can't go back. */ prev->next = this_frame; /* NOTE: cagney/2002-11-18: Should have been correctly setting the frame's type here, before anything else, and not last, at the bottom of this function. The various DEPRECATED_INIT_EXTRA_FRAME_INFO, DEPRECATED_INIT_FRAME_PC, and DEPRECATED_FRAME_INIT_SAVED_REGS methods are full of work-arounds that handle the frame not being correctly set from the start. Unfortunately those same work-arounds rely on the type defaulting to NORMAL_FRAME. Ulgh! The new frame code does not have this problem. */ prev->type = UNKNOWN_FRAME; /* A legacy frame's ID is always computed here. Mark it as valid. */ prev->this_id.p = 1; /* Handle sentinel frame unwind as a special case. */ if (this_frame->level < 0) { /* Try to unwind the PC. If that doesn't work, assume we've reached the oldest frame and simply return. Is there a better sentinal value? The unwound PC value is then used to initialize the new previous frame's type. Note that the pc-unwind is intentionally performed before the frame chain. This is ok since, for old targets, both frame_pc_unwind() (nee, DEPRECATED_FRAME_SAVED_PC) and DEPRECATED_FRAME_CHAIN()) assume THIS_FRAME's data structures have already been initialized (using DEPRECATED_INIT_EXTRA_FRAME_INFO) and hence the call order doesn't matter. By unwinding the PC first, it becomes possible to, in the case of a dummy frame, avoid also unwinding the frame ID. This is because (well ignoring the PPC) a dummy frame can be located using THIS_FRAME's frame ID. */ deprecated_update_frame_pc_hack (prev, frame_pc_unwind (this_frame)); if (get_frame_pc (prev) == 0) { /* The allocated PREV_FRAME will be reclaimed when the frame obstack is next purged. */ if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, NULL); fprintf_unfiltered (gdb_stdlog, " // unwound legacy PC zero }\n"); } return NULL; } /* Set the unwind functions based on that identified PC. Ditto for the "type" but strongly prefer the unwinder's frame type. */ prev->unwind = frame_unwind_find_by_frame (prev->next, &prev->prologue_cache); if (prev->unwind->type == UNKNOWN_FRAME) prev->type = frame_type_from_pc (get_frame_pc (prev)); else prev->type = prev->unwind->type; /* Find the prev's frame's ID. */ if (prev->type == DUMMY_FRAME && gdbarch_unwind_dummy_id_p (current_gdbarch)) { /* When unwinding a normal frame, the stack structure is determined by analyzing the frame's function's code (be it using brute force prologue analysis, or the dwarf2 CFI). In the case of a dummy frame, that simply isn't possible. The The PC is either the program entry point, or some random address on the stack. Trying to use that PC to apply standard frame ID unwind techniques is just asking for trouble. */ /* Use an architecture specific method to extract the prev's dummy ID from the next frame. Note that this method uses frame_register_unwind to obtain the register values needed to determine the dummy frame's ID. */ prev->this_id.value = gdbarch_unwind_dummy_id (current_gdbarch, this_frame); } else { /* We're unwinding a sentinel frame, the PC of which is pointing at a stack dummy. Fake up the dummy frame's ID using the same sequence as is found a traditional unwinder. Once all architectures supply the unwind_dummy_id method, this code can go away. */ prev->this_id.value = frame_id_build (deprecated_read_fp (), read_pc ()); } /* Check that the unwound ID is valid. */ if (!frame_id_p (prev->this_id.value)) { if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, NULL); fprintf_unfiltered (gdb_stdlog, " // unwound legacy ID invalid }\n"); } return NULL; } /* Check that the new frame isn't inner to (younger, below, next) the old frame. If that happens the frame unwind is going backwards. */ /* FIXME: cagney/2003-02-25: Ignore the sentinel frame since that doesn't have a valid frame ID. Should instead set the sentinel frame's frame ID to a `sentinel'. Leave it until after the switch to storing the frame ID, instead of the frame base, in the frame object. */ /* Link it in. */ this_frame->prev = prev; /* FIXME: cagney/2002-01-19: This call will go away. Instead of initializing extra info, all frames will use the frame_cache (passed to the unwind functions) to store additional frame info. Unfortunately legacy targets can't use legacy_get_prev_frame() to unwind the sentinel frame and, consequently, are forced to take this code path and rely on the below call to DEPRECATED_INIT_EXTRA_FRAME_INFO to initialize the inner-most frame. */ if (DEPRECATED_INIT_EXTRA_FRAME_INFO_P ()) { DEPRECATED_INIT_EXTRA_FRAME_INFO (0, prev); } if (prev->type == NORMAL_FRAME) prev->this_id.value.code_addr = get_pc_function_start (prev->this_id.value.code_addr); if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, prev); fprintf_unfiltered (gdb_stdlog, " } // legacy innermost frame\n"); } return prev; } /* This code only works on normal frames. A sentinel frame, where the level is -1, should never reach this code. */ gdb_assert (this_frame->level >= 0); /* On some machines it is possible to call a function without setting up a stack frame for it. On these machines, we define this macro to take two args; a frameinfo pointer identifying a frame and a variable to set or clear if it is or isn't leafless. */ /* Still don't want to worry about this except on the innermost frame. This macro will set FROMLEAF if THIS_FRAME is a frameless function invocation. */ if (this_frame->level == 0) /* FIXME: 2002-11-09: Frameless functions can occur anywhere in the frame chain, not just the inner most frame! The generic, per-architecture, frame code should handle this and the below should simply be removed. */ fromleaf = (DEPRECATED_FRAMELESS_FUNCTION_INVOCATION_P () && DEPRECATED_FRAMELESS_FUNCTION_INVOCATION (this_frame)); else fromleaf = 0; if (fromleaf) /* A frameless inner-most frame. The `FP' (which isn't an architecture frame-pointer register!) of the caller is the same as the callee. */ /* FIXME: 2002-11-09: There isn't any reason to special case this edge condition. Instead the per-architecture code should handle it locally. */ /* FIXME: cagney/2003-06-16: This returns the inner most stack address for the previous frame, that, however, is wrong. It should be the inner most stack address for the previous to previous frame. This is because it is the previous to previous frame's innermost stack address that is constant through out the lifetime of the previous frame (trust me :-). */ address = get_frame_base (this_frame); else { /* Two macros defined in tm.h specify the machine-dependent actions to be performed here. First, get the frame's chain-pointer. If that is zero, the frame is the outermost frame or a leaf called by the outermost frame. This means that if start calls main without a frame, we'll return 0 (which is fine anyway). Nope; there's a problem. This also returns when the current routine is a leaf of main. This is unacceptable. We move this to after the ffi test; I'd rather have backtraces from start go curfluy than have an abort called from main not show main. */ if (DEPRECATED_FRAME_CHAIN_P ()) address = DEPRECATED_FRAME_CHAIN (this_frame); else { /* Someone is part way through coverting an old architecture to the new frame code. Implement FRAME_CHAIN the way the new frame will. */ /* Find PREV frame's unwinder. */ prev->unwind = frame_unwind_find_by_frame (this_frame, &prev->prologue_cache); /* FIXME: cagney/2004-05-01: Should instead just use ->unwind->type. Unfortunately, legacy_get_prev_frame is still explicitly setting the type. Eliminate that method and this field can be eliminated. */ prev->type = prev->unwind->type; /* Find PREV frame's ID. */ prev->unwind->this_id (this_frame, &prev->prologue_cache, &prev->this_id.value); prev->this_id.p = 1; address = prev->this_id.value.stack_addr; } if (!legacy_frame_chain_valid (address, this_frame)) { if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, NULL); fprintf_unfiltered (gdb_stdlog, " // legacy frame chain invalid }\n"); } return NULL; } } if (address == 0) { if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, NULL); fprintf_unfiltered (gdb_stdlog, " // legacy frame chain NULL }\n"); } return NULL; } /* Link in the already allocated prev frame. */ this_frame->prev = prev; deprecated_update_frame_base_hack (prev, address); /* This change should not be needed, FIXME! We should determine whether any targets *need* DEPRECATED_INIT_FRAME_PC to happen after DEPRECATED_INIT_EXTRA_FRAME_INFO and come up with a simple way to express what goes on here. DEPRECATED_INIT_EXTRA_FRAME_INFO is called from two places: create_new_frame (where the PC is already set up) and here (where it isn't). DEPRECATED_INIT_FRAME_PC is only called from here, always after DEPRECATED_INIT_EXTRA_FRAME_INFO. The catch is the MIPS, where DEPRECATED_INIT_EXTRA_FRAME_INFO requires the PC value (which hasn't been set yet). Some other machines appear to require DEPRECATED_INIT_EXTRA_FRAME_INFO before they can do DEPRECATED_INIT_FRAME_PC. Phoo. Assuming that some machines need DEPRECATED_INIT_FRAME_PC after DEPRECATED_INIT_EXTRA_FRAME_INFO, one possible scheme: SETUP_INNERMOST_FRAME(): Default version is just create_new_frame (deprecated_read_fp ()), read_pc ()). Machines with extra frame info would do that (or the local equivalent) and then set the extra fields. SETUP_ARBITRARY_FRAME(argc, argv): Only change here is that create_new_frame would no longer init extra frame info; SETUP_ARBITRARY_FRAME would have to do that. INIT_PREV_FRAME(fromleaf, prev) Replace DEPRECATED_INIT_EXTRA_FRAME_INFO and DEPRECATED_INIT_FRAME_PC. This should also return a flag saying whether to keep the new frame, or whether to discard it, because on some machines (e.g. mips) it is really awkward to have DEPRECATED_FRAME_CHAIN_VALID called BEFORE DEPRECATED_INIT_EXTRA_FRAME_INFO (there is no good way to get information deduced in DEPRECATED_FRAME_CHAIN_VALID into the extra fields of the new frame). std_frame_pc(fromleaf, prev) This is the default setting for INIT_PREV_FRAME. It just does what the default DEPRECATED_INIT_FRAME_PC does. Some machines will call it from INIT_PREV_FRAME (either at the beginning, the end, or in the middle). Some machines won't use it. kingdon@cygnus.com, 13Apr93, 31Jan94, 14Dec94. */ /* NOTE: cagney/2002-11-09: Just ignore the above! There is no reason for things to be this complicated. The trick is to assume that there is always a frame. Instead of special casing the inner-most frame, create a fake frame (containing the hardware registers) that is inner to the user-visible inner-most frame (...) and then unwind from that. That way architecture code can use the standard frame_XX_unwind() functions and not differentiate between the inner most and any other case. Since there is always a frame to unwind from, there is always somewhere (THIS_FRAME) to store all the info needed to construct a new (previous) frame without having to first create it. This means that the convolution below - needing to carefully order a frame's initialization - isn't needed. The irony here though, is that DEPRECATED_FRAME_CHAIN(), at least for a more up-to-date architecture, always calls FRAME_SAVED_PC(), and FRAME_SAVED_PC() computes the PC but without first needing the frame! Instead of the convolution below, we could have simply called FRAME_SAVED_PC() and been done with it! Note that FRAME_SAVED_PC() is being superseded by frame_pc_unwind() and that function does have somewhere to cache that PC value. */ if (DEPRECATED_INIT_EXTRA_FRAME_INFO_P ()) DEPRECATED_INIT_EXTRA_FRAME_INFO (fromleaf, prev); /* This entry is in the frame queue now, which is good since FRAME_SAVED_PC may use that queue to figure out its value (see tm-sparc.h). We want the PC saved in the inferior frame. */ if (DEPRECATED_INIT_FRAME_PC_P ()) deprecated_update_frame_pc_hack (prev, DEPRECATED_INIT_FRAME_PC (fromleaf, prev)); /* If ->frame and ->pc are unchanged, we are in the process of getting ourselves into an infinite backtrace. Some architectures check this in DEPRECATED_FRAME_CHAIN or thereabouts, but it seems like there is no reason this can't be an architecture-independent check. */ if (get_frame_base (prev) == get_frame_base (this_frame) && get_frame_pc (prev) == get_frame_pc (this_frame)) { this_frame->prev = NULL; obstack_free (&frame_cache_obstack, prev); if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, NULL); fprintf_unfiltered (gdb_stdlog, " // legacy this.id == prev.id }\n"); } return NULL; } /* Initialize the code used to unwind the frame PREV based on the PC (and probably other architectural information). The PC lets you check things like the debug info at that point (dwarf2cfi?) and use that to decide how the frame should be unwound. If there isn't a FRAME_CHAIN, the code above will have already done this. */ if (prev->unwind == NULL) prev->unwind = frame_unwind_find_by_frame (prev->next, &prev->prologue_cache); /* If the unwinder provides a frame type, use it. Otherwise continue on to that heuristic mess. */ if (prev->unwind->type != UNKNOWN_FRAME) { prev->type = prev->unwind->type; if (prev->type == NORMAL_FRAME) /* FIXME: cagney/2003-06-16: would get_frame_pc() be better? */ prev->this_id.value.code_addr = get_pc_function_start (prev->this_id.value.code_addr); if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, prev); fprintf_unfiltered (gdb_stdlog, " } // legacy with unwound type\n"); } return prev; } /* NOTE: cagney/2002-11-18: The code segments, found in create_new_frame() and get_prev_frame(), that initialize the frame's type is subtly different. The latter only updates ->type when it encounters a SIGTRAMP_FRAME or DUMMY_FRAME. This stops get_prev_frame() overriding the frame's type when the INIT code has previously set it. This is really somewhat bogus. The initialization, as seen in create_new_frame(), should occur before the INIT function has been called. */ if (DEPRECATED_USE_GENERIC_DUMMY_FRAMES && deprecated_pc_in_call_dummy (get_frame_pc (prev), 0, 0)) prev->type = DUMMY_FRAME; if (prev->type == NORMAL_FRAME) prev->this_id.value.code_addr = get_pc_function_start (prev->this_id.value.code_addr); if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, prev); fprintf_unfiltered (gdb_stdlog, " } // legacy with confused type\n"); } return prev; } /* Return a "struct frame_info" corresponding to the frame that called THIS_FRAME. Returns NULL if there is no such frame. Unlike get_prev_frame, this function always tries to unwind the frame. */ static struct frame_info * get_prev_frame_1 (struct frame_info *this_frame) { struct frame_info *prev_frame; gdb_assert (this_frame != NULL); if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "{ get_prev_frame_1 (this_frame="); if (this_frame != NULL) fprintf_unfiltered (gdb_stdlog, "%d", this_frame->level); else fprintf_unfiltered (gdb_stdlog, ""); fprintf_unfiltered (gdb_stdlog, ") "); } /* Only try to do the unwind once. */ if (this_frame->prev_p) { if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, this_frame->prev); fprintf_unfiltered (gdb_stdlog, " // cached \n"); } return this_frame->prev; } this_frame->prev_p = 1; /* If any of the old frame initialization methods are around, use the legacy get_prev_frame() method. */ if (legacy_frame_p (current_gdbarch)) { prev_frame = legacy_get_prev_frame (this_frame); return prev_frame; } /* Check that this frame's ID was valid. If it wasn't, don't try to unwind to the prev frame. Be careful to not apply this test to the sentinel frame. */ if (this_frame->level >= 0 && !frame_id_p (get_frame_id (this_frame))) { if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, NULL); fprintf_unfiltered (gdb_stdlog, " // this ID is NULL }\n"); } return NULL; } /* Check that this frame's ID isn't inner to (younger, below, next) the next frame. This happens when a frame unwind goes backwards. Exclude signal trampolines (due to sigaltstack the frame ID can go backwards) and sentinel frames (the test is meaningless). */ if (this_frame->next->level >= 0 && this_frame->next->type != SIGTRAMP_FRAME && frame_id_inner (get_frame_id (this_frame), get_frame_id (this_frame->next))) error ("Previous frame inner to this frame (corrupt stack?)"); /* Check that this and the next frame are not identical. If they are, there is most likely a stack cycle. As with the inner-than test above, avoid comparing the inner-most and sentinel frames. */ if (this_frame->level > 0 && frame_id_eq (get_frame_id (this_frame), get_frame_id (this_frame->next))) error ("Previous frame identical to this frame (corrupt stack?)"); /* Allocate the new frame but do not wire it in to the frame chain. Some (bad) code in INIT_FRAME_EXTRA_INFO tries to look along frame->next to pull some fancy tricks (of course such code is, by definition, recursive). Try to prevent it. There is no reason to worry about memory leaks, should the remainder of the function fail. The allocated memory will be quickly reclaimed when the frame cache is flushed, and the `we've been here before' check above will stop repeated memory allocation calls. */ prev_frame = FRAME_OBSTACK_ZALLOC (struct frame_info); prev_frame->level = this_frame->level + 1; /* Don't yet compute ->unwind (and hence ->type). It is computed on-demand in get_frame_type, frame_register_unwind, and get_frame_id. */ /* Don't yet compute the frame's ID. It is computed on-demand by get_frame_id(). */ /* The unwound frame ID is validate at the start of this function, as part of the logic to decide if that frame should be further unwound, and not here while the prev frame is being created. Doing this makes it possible for the user to examine a frame that has an invalid frame ID. Some very old VAX code noted: [...] For the sake of argument, suppose that the stack is somewhat trashed (which is one reason that "info frame" exists). So, return 0 (indicating we don't know the address of the arglist) if we don't know what frame this frame calls. */ /* Link it in. */ this_frame->prev = prev_frame; prev_frame->next = this_frame; if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, prev_frame); fprintf_unfiltered (gdb_stdlog, " }\n"); } return prev_frame; } /* Debug routine to print a NULL frame being returned. */ static void frame_debug_got_null_frame (struct ui_file *file, struct frame_info *this_frame, const char *reason) { if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "{ get_prev_frame (this_frame="); if (this_frame != NULL) fprintf_unfiltered (gdb_stdlog, "%d", this_frame->level); else fprintf_unfiltered (gdb_stdlog, ""); fprintf_unfiltered (gdb_stdlog, ") -> // %s}\n", reason); } } /* Return a structure containing various interesting information about the frame that called THIS_FRAME. Returns NULL if there is entier no such frame or the frame fails any of a set of target-independent condition that should terminate the frame chain (e.g., as unwinding past main()). This function should not contain target-dependent tests, such as checking whether the program-counter is zero. */ struct frame_info * get_prev_frame (struct frame_info *this_frame) { struct frame_info *prev_frame; /* Return the inner-most frame, when the caller passes in NULL. */ /* NOTE: cagney/2002-11-09: Not sure how this would happen. The caller should have previously obtained a valid frame using get_selected_frame() and then called this code - only possibility I can think of is code behaving badly. NOTE: cagney/2003-01-10: Talk about code behaving badly. Check block_innermost_frame(). It does the sequence: frame = NULL; while (1) { frame = get_prev_frame (frame); .... }. Ulgh! Why it couldn't be written better, I don't know. NOTE: cagney/2003-01-11: I suspect what is happening in block_innermost_frame() is, when the target has no state (registers, memory, ...), it is still calling this function. The assumption being that this function will return NULL indicating that a frame isn't possible, rather than checking that the target has state and then calling get_current_frame() and get_prev_frame(). This is a guess mind. */ if (this_frame == NULL) { /* NOTE: cagney/2002-11-09: There was a code segment here that would error out when CURRENT_FRAME was NULL. The comment that went with it made the claim ... ``This screws value_of_variable, which just wants a nice clean NULL return from block_innermost_frame if there are no frames. I don't think I've ever seen this message happen otherwise. And returning NULL here is a perfectly legitimate thing to do.'' Per the above, this code shouldn't even be called with a NULL THIS_FRAME. */ frame_debug_got_null_frame (gdb_stdlog, this_frame, "this_frame NULL"); return current_frame; } /* There is always a frame. If this assertion fails, suspect that something should be calling get_selected_frame() or get_current_frame(). */ gdb_assert (this_frame != NULL); /* Make sure we pass an address within THIS_FRAME's code block to inside_main_func(). Otherwise, we might stop unwinding at a function which has a call instruction as its last instruction if that function immediately precedes main(). */ if (this_frame->level >= 0 && !backtrace_past_main && inside_main_func (get_frame_address_in_block (this_frame))) /* Don't unwind past main(), but always unwind the sentinel frame. Note, this is done _before_ the frame has been marked as previously unwound. That way if the user later decides to allow unwinds past main(), that just happens. */ { frame_debug_got_null_frame (gdb_stdlog, this_frame, "inside main func"); return NULL; } if (this_frame->level > backtrace_limit) { error ("Backtrace limit of %d exceeded", backtrace_limit); } /* If we're already inside the entry function for the main objfile, then it isn't valid. Don't apply this test to a dummy frame - dummy frame PCs typically land in the entry func. Don't apply this test to the sentinel frame. Sentinel frames should always be allowed to unwind. */ /* NOTE: cagney/2003-02-25: Don't enable until someone has found hard evidence that this is needed. */ /* NOTE: cagney/2003-07-07: Fixed a bug in inside_main_func() - wasn't checking for "main" in the minimal symbols. With that fixed asm-source tests now stop in "main" instead of halting the backtrace in weird and wonderful ways somewhere inside the entry file. Suspect that tests for inside the entry file/func were added to work around that (now fixed) case. */ /* NOTE: cagney/2003-07-15: danielj (if I'm reading it right) suggested having the inside_entry_func test use the inside_main_func() msymbol trick (along with entry_point_address() I guess) to determine the address range of the start function. That should provide a far better stopper than the current heuristics. */ /* NOTE: cagney/2003-07-15: Need to add a "set backtrace beyond-entry-func" command so that this can be selectively disabled. */ if (0 #if 0 && backtrace_beyond_entry_func #endif && this_frame->type != DUMMY_FRAME && this_frame->level >= 0 && inside_entry_func (this_frame)) { frame_debug_got_null_frame (gdb_stdlog, this_frame, "inside entry func"); return NULL; } return get_prev_frame_1 (this_frame); } CORE_ADDR get_frame_pc (struct frame_info *frame) { gdb_assert (frame->next != NULL); return frame_pc_unwind (frame->next); } /* Return an address of that falls within the frame's code block. */ CORE_ADDR frame_unwind_address_in_block (struct frame_info *next_frame) { /* A draft address. */ CORE_ADDR pc = frame_pc_unwind (next_frame); /* If THIS frame is not inner most (i.e., NEXT isn't the sentinel), and NEXT is `normal' (i.e., not a sigtramp, dummy, ....) THIS frame's PC ends up pointing at the instruction fallowing the "call". Adjust that PC value so that it falls on the call instruction (which, hopefully, falls within THIS frame's code block. So far it's proved to be a very good approximation. See get_frame_type() for why ->type can't be used. */ if (next_frame->level >= 0 && get_frame_type (next_frame) == NORMAL_FRAME) --pc; return pc; } CORE_ADDR get_frame_address_in_block (struct frame_info *this_frame) { return frame_unwind_address_in_block (this_frame->next); } static int pc_notcurrent (struct frame_info *frame) { /* If FRAME is not the innermost frame, that normally means that FRAME->pc points at the return instruction (which is *after* the call instruction), and we want to get the line containing the call (because the call is where the user thinks the program is). However, if the next frame is either a SIGTRAMP_FRAME or a DUMMY_FRAME, then the next frame will contain a saved interrupt PC and such a PC indicates the current (rather than next) instruction/line, consequently, for such cases, want to get the line containing fi->pc. */ struct frame_info *next = get_next_frame (frame); int notcurrent = (next != NULL && get_frame_type (next) == NORMAL_FRAME); return notcurrent; } void find_frame_sal (struct frame_info *frame, struct symtab_and_line *sal) { (*sal) = find_pc_line (get_frame_pc (frame), pc_notcurrent (frame)); } /* Per "frame.h", return the ``address'' of the frame. Code should really be using get_frame_id(). */ CORE_ADDR get_frame_base (struct frame_info *fi) { return get_frame_id (fi).stack_addr; } /* High-level offsets into the frame. Used by the debug info. */ CORE_ADDR get_frame_base_address (struct frame_info *fi) { if (get_frame_type (fi) != NORMAL_FRAME) return 0; if (fi->base == NULL) fi->base = frame_base_find_by_frame (fi->next); /* Sneaky: If the low-level unwind and high-level base code share a common unwinder, let them share the prologue cache. */ if (fi->base->unwind == fi->unwind) return fi->base->this_base (fi->next, &fi->prologue_cache); return fi->base->this_base (fi->next, &fi->base_cache); } CORE_ADDR get_frame_locals_address (struct frame_info *fi) { void **cache; if (get_frame_type (fi) != NORMAL_FRAME) return 0; /* If there isn't a frame address method, find it. */ if (fi->base == NULL) fi->base = frame_base_find_by_frame (fi->next); /* Sneaky: If the low-level unwind and high-level base code share a common unwinder, let them share the prologue cache. */ if (fi->base->unwind == fi->unwind) cache = &fi->prologue_cache; else cache = &fi->base_cache; return fi->base->this_locals (fi->next, cache); } CORE_ADDR get_frame_args_address (struct frame_info *fi) { void **cache; if (get_frame_type (fi) != NORMAL_FRAME) return 0; /* If there isn't a frame address method, find it. */ if (fi->base == NULL) fi->base = frame_base_find_by_frame (fi->next); /* Sneaky: If the low-level unwind and high-level base code share a common unwinder, let them share the prologue cache. */ if (fi->base->unwind == fi->unwind) cache = &fi->prologue_cache; else cache = &fi->base_cache; return fi->base->this_args (fi->next, cache); } /* Level of the selected frame: 0 for innermost, 1 for its caller, ... or -1 for a NULL frame. */ int frame_relative_level (struct frame_info *fi) { if (fi == NULL) return -1; else return fi->level; } enum frame_type get_frame_type (struct frame_info *frame) { /* Some targets still don't use [generic] dummy frames. Catch them here. */ if (!DEPRECATED_USE_GENERIC_DUMMY_FRAMES && deprecated_frame_in_dummy (frame)) return DUMMY_FRAME; /* Some legacy code, e.g, mips_init_extra_frame_info() wants to determine the frame's type prior to it being completely initialized. Don't attempt to lazily initialize ->unwind for legacy code. It will be initialized in legacy_get_prev_frame(). */ if (frame->unwind == NULL && !legacy_frame_p (current_gdbarch)) { /* Initialize the frame's unwinder because that's what provides the frame's type. */ frame->unwind = frame_unwind_find_by_frame (frame->next, &frame->prologue_cache); /* FIXME: cagney/2004-05-01: Should instead just use ->unwind->type. Unfortunately, legacy_get_prev_frame is still explicitly setting the type. Eliminate that method and this field can be eliminated. */ frame->type = frame->unwind->type; } if (frame->type == UNKNOWN_FRAME) return NORMAL_FRAME; else return frame->type; } struct frame_extra_info * get_frame_extra_info (struct frame_info *fi) { return fi->extra_info; } struct frame_extra_info * frame_extra_info_zalloc (struct frame_info *fi, long size) { fi->extra_info = frame_obstack_zalloc (size); return fi->extra_info; } void deprecated_update_frame_pc_hack (struct frame_info *frame, CORE_ADDR pc) { if (frame_debug) fprintf_unfiltered (gdb_stdlog, "{ deprecated_update_frame_pc_hack (frame=%d,pc=0x%s) }\n", frame->level, paddr_nz (pc)); /* NOTE: cagney/2003-03-11: Some architectures (e.g., Arm) are maintaining a locally allocated frame object. Since such frames are not in the frame chain, it isn't possible to assume that the frame has a next. Sigh. */ if (frame->next != NULL) { /* While we're at it, update this frame's cached PC value, found in the next frame. Oh for the day when "struct frame_info" is opaque and this hack on hack can just go away. */ frame->next->prev_pc.value = pc; frame->next->prev_pc.p = 1; } } void deprecated_update_frame_base_hack (struct frame_info *frame, CORE_ADDR base) { if (frame_debug) fprintf_unfiltered (gdb_stdlog, "{ deprecated_update_frame_base_hack (frame=%d,base=0x%s) }\n", frame->level, paddr_nz (base)); /* See comment in "frame.h". */ frame->this_id.value.stack_addr = base; } struct frame_info * deprecated_frame_xmalloc_with_cleanup (long sizeof_saved_regs, long sizeof_extra_info) { struct frame_info *frame = XMALLOC (struct frame_info); memset (frame, 0, sizeof (*frame)); frame->this_id.p = 1; make_cleanup (xfree, frame); if (sizeof_saved_regs > 0) { frame->saved_regs = xcalloc (1, sizeof_saved_regs); make_cleanup (xfree, frame->saved_regs); } if (sizeof_extra_info > 0) { frame->extra_info = xcalloc (1, sizeof_extra_info); make_cleanup (xfree, frame->extra_info); } return frame; } /* Memory access methods. */ void get_frame_memory (struct frame_info *this_frame, CORE_ADDR addr, void *buf, int len) { read_memory (addr, buf, len); } LONGEST get_frame_memory_signed (struct frame_info *this_frame, CORE_ADDR addr, int len) { return read_memory_integer (addr, len); } ULONGEST get_frame_memory_unsigned (struct frame_info *this_frame, CORE_ADDR addr, int len) { return read_memory_unsigned_integer (addr, len); } int safe_frame_unwind_memory (struct frame_info *this_frame, CORE_ADDR addr, void *buf, int len) { /* NOTE: read_memory_nobpt returns zero on success! */ return !read_memory_nobpt (addr, buf, len); } /* Architecture method. */ struct gdbarch * get_frame_arch (struct frame_info *this_frame) { return current_gdbarch; } /* Stack pointer methods. */ CORE_ADDR get_frame_sp (struct frame_info *this_frame) { return frame_sp_unwind (this_frame->next); } CORE_ADDR frame_sp_unwind (struct frame_info *next_frame) { /* Normality - an architecture that provides a way of obtaining any frame inner-most address. */ if (gdbarch_unwind_sp_p (current_gdbarch)) return gdbarch_unwind_sp (current_gdbarch, next_frame); /* Things are looking grim. If it's the inner-most frame and there is a TARGET_READ_SP, then that can be used. */ if (next_frame->level < 0 && TARGET_READ_SP_P ()) return TARGET_READ_SP (); /* Now things are really are grim. Hope that the value returned by the SP_REGNUM register is meaningful. */ if (SP_REGNUM >= 0) { ULONGEST sp; frame_unwind_unsigned_register (next_frame, SP_REGNUM, &sp); return sp; } internal_error (__FILE__, __LINE__, "Missing unwind SP method"); } int legacy_frame_p (struct gdbarch *current_gdbarch) { if (DEPRECATED_INIT_FRAME_PC_P () || DEPRECATED_INIT_EXTRA_FRAME_INFO_P () || DEPRECATED_FRAME_CHAIN_P ()) /* No question, it's a legacy frame. */ return 1; if (gdbarch_unwind_dummy_id_p (current_gdbarch)) /* No question, it's not a legacy frame (provided none of the deprecated methods checked above are present that is). */ return 0; if (DEPRECATED_TARGET_READ_FP_P () || DEPRECATED_FP_REGNUM >= 0) /* Assume it's legacy. If you're trying to convert a legacy frame target to the new mechanism, get rid of these. legacy get_prev_frame() requires these when unwind_frame_id() isn't available. */ return 1; /* Default to assuming that it's brand new code, and hence not legacy. Force it down the non-legacy path so that the new code uses the new frame mechanism from day one. Dummy frames won't work very well but we can live with that. */ return 0; } extern initialize_file_ftype _initialize_frame; /* -Wmissing-prototypes */ static struct cmd_list_element *set_backtrace_cmdlist; static struct cmd_list_element *show_backtrace_cmdlist; static void set_backtrace_cmd (char *args, int from_tty) { help_list (set_backtrace_cmdlist, "set backtrace ", -1, gdb_stdout); } static void show_backtrace_cmd (char *args, int from_tty) { cmd_show_list (show_backtrace_cmdlist, from_tty, ""); } void _initialize_frame (void) { obstack_init (&frame_cache_obstack); observer_attach_target_changed (frame_observer_target_changed); add_prefix_cmd ("backtrace", class_maintenance, set_backtrace_cmd, "\ Set backtrace specific variables.\n\ Configure backtrace variables such as the backtrace limit", &set_backtrace_cmdlist, "set backtrace ", 0/*allow-unknown*/, &setlist); add_prefix_cmd ("backtrace", class_maintenance, show_backtrace_cmd, "\ Show backtrace specific variables\n\ Show backtrace variables such as the backtrace limit", &show_backtrace_cmdlist, "show backtrace ", 0/*allow-unknown*/, &showlist); add_setshow_boolean_cmd ("past-main", class_obscure, &backtrace_past_main, "\ Set whether backtraces should continue past \"main\".\n\ Normally the caller of \"main\" is not of interest, so GDB will terminate\n\ the backtrace at \"main\". Set this variable if you need to see the rest\n\ of the stack trace.", "\ Show whether backtraces should continue past \"main\".\n\ Normally the caller of \"main\" is not of interest, so GDB will terminate\n\ the backtrace at \"main\". Set this variable if you need to see the rest\n\ of the stack trace.", NULL, NULL, &set_backtrace_cmdlist, &show_backtrace_cmdlist); add_setshow_uinteger_cmd ("limit", class_obscure, &backtrace_limit, "\ Set an upper bound on the number of backtrace levels.\n\ No more than the specified number of frames can be displayed or examined.\n\ Zero is unlimited.", "\ Show the upper bound on the number of backtrace levels.", NULL, NULL, &set_backtrace_cmdlist, &show_backtrace_cmdlist); /* Debug this files internals. */ add_show_from_set (add_set_cmd ("frame", class_maintenance, var_zinteger, &frame_debug, "Set frame debugging.\n\ When non-zero, frame specific internal debugging is enabled.", &setdebuglist), &showdebuglist); }