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Diffstat (limited to 'gdb/i386-linux-tdep.c')
| -rw-r--r-- | gdb/i386-linux-tdep.c | 465 |
1 files changed, 0 insertions, 465 deletions
diff --git a/gdb/i386-linux-tdep.c b/gdb/i386-linux-tdep.c deleted file mode 100644 index a833fb5..0000000 --- a/gdb/i386-linux-tdep.c +++ /dev/null @@ -1,465 +0,0 @@ -/* Target-dependent code for GNU/Linux running on i386's, for GDB. - - Copyright 2000, 2001, 2002 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 "gdbcore.h" -#include "frame.h" -#include "value.h" -#include "regcache.h" -#include "inferior.h" - -/* For i386_linux_skip_solib_resolver. */ -#include "symtab.h" -#include "symfile.h" -#include "objfiles.h" - -#include "solib-svr4.h" /* For struct link_map_offsets. */ - -#include "i386-tdep.h" -#include "i386-linux-tdep.h" - -/* Return the name of register REG. */ - -static const char * -i386_linux_register_name (int reg) -{ - /* Deal with the extra "orig_eax" pseudo register. */ - if (reg == I386_LINUX_ORIG_EAX_REGNUM) - return "orig_eax"; - - return i386_register_name (reg); -} - -/* Recognizing signal handler frames. */ - -/* GNU/Linux has two flavors of signals. Normal signal handlers, and - "realtime" (RT) signals. The RT signals can provide additional - information to the signal handler if the SA_SIGINFO flag is set - when establishing a signal handler using `sigaction'. It is not - unlikely that future versions of GNU/Linux will support SA_SIGINFO - for normal signals too. */ - -/* When the i386 Linux kernel calls a signal handler and the - SA_RESTORER flag isn't set, the return address points to a bit of - code on the stack. This function returns whether the PC appears to - be within this bit of code. - - The instruction sequence for normal signals is - pop %eax - mov $0x77,%eax - int $0x80 - or 0x58 0xb8 0x77 0x00 0x00 0x00 0xcd 0x80. - - Checking for the code sequence should be somewhat reliable, because - the effect is to call the system call sigreturn. This is unlikely - to occur anywhere other than a signal trampoline. - - It kind of sucks that we have to read memory from the process in - order to identify a signal trampoline, but there doesn't seem to be - any other way. The PC_IN_SIGTRAMP macro in tm-linux.h arranges to - only call us if no function name could be identified, which should - be the case since the code is on the stack. - - Detection of signal trampolines for handlers that set the - SA_RESTORER flag is in general not possible. Unfortunately this is - what the GNU C Library has been doing for quite some time now. - However, as of version 2.1.2, the GNU C Library uses signal - trampolines (named __restore and __restore_rt) that are identical - to the ones used by the kernel. Therefore, these trampolines are - supported too. */ - -#define LINUX_SIGTRAMP_INSN0 (0x58) /* pop %eax */ -#define LINUX_SIGTRAMP_OFFSET0 (0) -#define LINUX_SIGTRAMP_INSN1 (0xb8) /* mov $NNNN,%eax */ -#define LINUX_SIGTRAMP_OFFSET1 (1) -#define LINUX_SIGTRAMP_INSN2 (0xcd) /* int */ -#define LINUX_SIGTRAMP_OFFSET2 (6) - -static const unsigned char linux_sigtramp_code[] = -{ - LINUX_SIGTRAMP_INSN0, /* pop %eax */ - LINUX_SIGTRAMP_INSN1, 0x77, 0x00, 0x00, 0x00, /* mov $0x77,%eax */ - LINUX_SIGTRAMP_INSN2, 0x80 /* int $0x80 */ -}; - -#define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code) - -/* If PC is in a sigtramp routine, return the address of the start of - the routine. Otherwise, return 0. */ - -static CORE_ADDR -i386_linux_sigtramp_start (CORE_ADDR pc) -{ - unsigned char buf[LINUX_SIGTRAMP_LEN]; - - /* We only recognize a signal trampoline if PC is at the start of - one of the three instructions. We optimize for finding the PC at - the start, as will be the case when the trampoline is not the - first frame on the stack. We assume that in the case where the - PC is not at the start of the instruction sequence, there will be - a few trailing readable bytes on the stack. */ - - if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0) - return 0; - - if (buf[0] != LINUX_SIGTRAMP_INSN0) - { - int adjust; - - switch (buf[0]) - { - case LINUX_SIGTRAMP_INSN1: - adjust = LINUX_SIGTRAMP_OFFSET1; - break; - case LINUX_SIGTRAMP_INSN2: - adjust = LINUX_SIGTRAMP_OFFSET2; - break; - default: - return 0; - } - - pc -= adjust; - - if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0) - return 0; - } - - if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0) - return 0; - - return pc; -} - -/* This function does the same for RT signals. Here the instruction - sequence is - mov $0xad,%eax - int $0x80 - or 0xb8 0xad 0x00 0x00 0x00 0xcd 0x80. - - The effect is to call the system call rt_sigreturn. */ - -#define LINUX_RT_SIGTRAMP_INSN0 (0xb8) /* mov $NNNN,%eax */ -#define LINUX_RT_SIGTRAMP_OFFSET0 (0) -#define LINUX_RT_SIGTRAMP_INSN1 (0xcd) /* int */ -#define LINUX_RT_SIGTRAMP_OFFSET1 (5) - -static const unsigned char linux_rt_sigtramp_code[] = -{ - LINUX_RT_SIGTRAMP_INSN0, 0xad, 0x00, 0x00, 0x00, /* mov $0xad,%eax */ - LINUX_RT_SIGTRAMP_INSN1, 0x80 /* int $0x80 */ -}; - -#define LINUX_RT_SIGTRAMP_LEN (sizeof linux_rt_sigtramp_code) - -/* If PC is in a RT sigtramp routine, return the address of the start - of the routine. Otherwise, return 0. */ - -static CORE_ADDR -i386_linux_rt_sigtramp_start (CORE_ADDR pc) -{ - unsigned char buf[LINUX_RT_SIGTRAMP_LEN]; - - /* We only recognize a signal trampoline if PC is at the start of - one of the two instructions. We optimize for finding the PC at - the start, as will be the case when the trampoline is not the - first frame on the stack. We assume that in the case where the - PC is not at the start of the instruction sequence, there will be - a few trailing readable bytes on the stack. */ - - if (read_memory_nobpt (pc, (char *) buf, LINUX_RT_SIGTRAMP_LEN) != 0) - return 0; - - if (buf[0] != LINUX_RT_SIGTRAMP_INSN0) - { - if (buf[0] != LINUX_RT_SIGTRAMP_INSN1) - return 0; - - pc -= LINUX_RT_SIGTRAMP_OFFSET1; - - if (read_memory_nobpt (pc, (char *) buf, LINUX_RT_SIGTRAMP_LEN) != 0) - return 0; - } - - if (memcmp (buf, linux_rt_sigtramp_code, LINUX_RT_SIGTRAMP_LEN) != 0) - return 0; - - return pc; -} - -/* Return whether PC is in a GNU/Linux sigtramp routine. */ - -static int -i386_linux_pc_in_sigtramp (CORE_ADDR pc, char *name) -{ - if (name) - return STREQ ("__restore", name) || STREQ ("__restore_rt", name); - - return (i386_linux_sigtramp_start (pc) != 0 - || i386_linux_rt_sigtramp_start (pc) != 0); -} - -/* Assuming FRAME is for a GNU/Linux sigtramp routine, return the - address of the associated sigcontext structure. */ - -static CORE_ADDR -i386_linux_sigcontext_addr (struct frame_info *frame) -{ - CORE_ADDR pc; - - pc = i386_linux_sigtramp_start (frame->pc); - if (pc) - { - CORE_ADDR sp; - - if (frame->next) - /* If this isn't the top frame, the next frame must be for the - signal handler itself. The sigcontext structure lives on - the stack, right after the signum argument. */ - return frame->next->frame + 12; - - /* This is the top frame. We'll have to find the address of the - sigcontext structure by looking at the stack pointer. Keep - in mind that the first instruction of the sigtramp code is - "pop %eax". If the PC is at this instruction, adjust the - returned value accordingly. */ - sp = read_register (SP_REGNUM); - if (pc == frame->pc) - return sp + 4; - return sp; - } - - pc = i386_linux_rt_sigtramp_start (frame->pc); - if (pc) - { - if (frame->next) - /* If this isn't the top frame, the next frame must be for the - signal handler itself. The sigcontext structure is part of - the user context. A pointer to the user context is passed - as the third argument to the signal handler. */ - return read_memory_integer (frame->next->frame + 16, 4) + 20; - - /* This is the top frame. Again, use the stack pointer to find - the address of the sigcontext structure. */ - return read_memory_integer (read_register (SP_REGNUM) + 8, 4) + 20; - } - - error ("Couldn't recognize signal trampoline."); - return 0; -} - -/* Set the program counter for process PTID to PC. */ - -static void -i386_linux_write_pc (CORE_ADDR pc, ptid_t ptid) -{ - write_register_pid (PC_REGNUM, pc, ptid); - - /* We must be careful with modifying the program counter. If we - just interrupted a system call, the kernel might try to restart - it when we resume the inferior. On restarting the system call, - the kernel will try backing up the program counter even though it - no longer points at the system call. This typically results in a - SIGSEGV or SIGILL. We can prevent this by writing `-1' in the - "orig_eax" pseudo-register. - - Note that "orig_eax" is saved when setting up a dummy call frame. - This means that it is properly restored when that frame is - popped, and that the interrupted system call will be restarted - when we resume the inferior on return from a function call from - within GDB. In all other cases the system call will not be - restarted. */ - write_register_pid (I386_LINUX_ORIG_EAX_REGNUM, -1, ptid); -} - -/* Calling functions in shared libraries. */ - -/* Find the minimal symbol named NAME, and return both the minsym - struct and its objfile. This probably ought to be in minsym.c, but - everything there is trying to deal with things like C++ and - SOFUN_ADDRESS_MAYBE_TURQUOISE, ... Since this is so simple, it may - be considered too special-purpose for general consumption. */ - -static struct minimal_symbol * -find_minsym_and_objfile (char *name, struct objfile **objfile_p) -{ - struct objfile *objfile; - - ALL_OBJFILES (objfile) - { - struct minimal_symbol *msym; - - ALL_OBJFILE_MSYMBOLS (objfile, msym) - { - if (SYMBOL_NAME (msym) - && STREQ (SYMBOL_NAME (msym), name)) - { - *objfile_p = objfile; - return msym; - } - } - } - - return 0; -} - -static CORE_ADDR -skip_hurd_resolver (CORE_ADDR pc) -{ - /* The HURD dynamic linker is part of the GNU C library, so many - GNU/Linux distributions use it. (All ELF versions, as far as I - know.) An unresolved PLT entry points to "_dl_runtime_resolve", - which calls "fixup" to patch the PLT, and then passes control to - the function. - - We look for the symbol `_dl_runtime_resolve', and find `fixup' in - the same objfile. If we are at the entry point of `fixup', then - we set a breakpoint at the return address (at the top of the - stack), and continue. - - It's kind of gross to do all these checks every time we're - called, since they don't change once the executable has gotten - started. But this is only a temporary hack --- upcoming versions - of GNU/Linux will provide a portable, efficient interface for - debugging programs that use shared libraries. */ - - struct objfile *objfile; - struct minimal_symbol *resolver - = find_minsym_and_objfile ("_dl_runtime_resolve", &objfile); - - if (resolver) - { - struct minimal_symbol *fixup - = lookup_minimal_symbol ("fixup", NULL, objfile); - - if (fixup && SYMBOL_VALUE_ADDRESS (fixup) == pc) - return (SAVED_PC_AFTER_CALL (get_current_frame ())); - } - - return 0; -} - -/* See the comments for SKIP_SOLIB_RESOLVER at the top of infrun.c. - This function: - 1) decides whether a PLT has sent us into the linker to resolve - a function reference, and - 2) if so, tells us where to set a temporary breakpoint that will - trigger when the dynamic linker is done. */ - -CORE_ADDR -i386_linux_skip_solib_resolver (CORE_ADDR pc) -{ - CORE_ADDR result; - - /* Plug in functions for other kinds of resolvers here. */ - result = skip_hurd_resolver (pc); - if (result) - return result; - - return 0; -} - -/* Fetch (and possibly build) an appropriate link_map_offsets - structure for native GNU/Linux x86 targets using the struct offsets - defined in link.h (but without actual reference to that file). - - This makes it possible to access GNU/Linux x86 shared libraries - from a GDB that was not built on an GNU/Linux x86 host (for cross - debugging). */ - -static struct link_map_offsets * -i386_linux_svr4_fetch_link_map_offsets (void) -{ - static struct link_map_offsets lmo; - static struct link_map_offsets *lmp = NULL; - - if (lmp == NULL) - { - lmp = &lmo; - - lmo.r_debug_size = 8; /* The actual size is 20 bytes, but - this is all we need. */ - lmo.r_map_offset = 4; - lmo.r_map_size = 4; - - lmo.link_map_size = 20; /* The actual size is 552 bytes, but - this is all we need. */ - lmo.l_addr_offset = 0; - lmo.l_addr_size = 4; - - lmo.l_name_offset = 4; - lmo.l_name_size = 4; - - lmo.l_next_offset = 12; - lmo.l_next_size = 4; - - lmo.l_prev_offset = 16; - lmo.l_prev_size = 4; - } - - return lmp; -} - - -static void -i386_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) -{ - struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); - - /* GNU/Linux uses ELF. */ - i386_elf_init_abi (info, gdbarch); - - /* We support the SSE registers on GNU/Linux. */ - tdep->num_xmm_regs = I386_NUM_XREGS - 1; - /* set_gdbarch_num_regs (gdbarch, I386_SSE_NUM_REGS); */ - - /* Since we have the extra "orig_eax" register on GNU/Linux, we have - to adjust a few things. */ - - set_gdbarch_write_pc (gdbarch, i386_linux_write_pc); - set_gdbarch_num_regs (gdbarch, I386_SSE_NUM_REGS + 1); - set_gdbarch_register_name (gdbarch, i386_linux_register_name); - set_gdbarch_register_bytes (gdbarch, I386_SSE_SIZEOF_REGS + 4); - - tdep->jb_pc_offset = 20; /* From <bits/setjmp.h>. */ - - tdep->sigcontext_addr = i386_linux_sigcontext_addr; - tdep->sc_pc_offset = 14 * 4; /* From <asm/sigcontext.h>. */ - tdep->sc_sp_offset = 7 * 4; - - /* When the i386 Linux kernel calls a signal handler, the return - address points to a bit of code on the stack. This function is - used to identify this bit of code as a signal trampoline in order - to support backtracing through calls to signal handlers. */ - set_gdbarch_pc_in_sigtramp (gdbarch, i386_linux_pc_in_sigtramp); - - set_solib_svr4_fetch_link_map_offsets (gdbarch, - i386_linux_svr4_fetch_link_map_offsets); -} - -/* Provide a prototype to silence -Wmissing-prototypes. */ -extern void _initialize_i386_linux_tdep (void); - -void -_initialize_i386_linux_tdep (void) -{ - gdbarch_register_osabi (bfd_arch_i386, GDB_OSABI_LINUX, - i386_linux_init_abi); -} |