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Diffstat (limited to 'gdb/i386-obsd-tdep.c')
| -rw-r--r-- | gdb/i386-obsd-tdep.c | 520 |
1 files changed, 520 insertions, 0 deletions
diff --git a/gdb/i386-obsd-tdep.c b/gdb/i386-obsd-tdep.c new file mode 100644 index 0000000..08becfa --- /dev/null +++ b/gdb/i386-obsd-tdep.c @@ -0,0 +1,520 @@ +/* Target-dependent code for OpenBSD/i386. + + Copyright (C) 1988-2016 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 3 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, see <http://www.gnu.org/licenses/>. */ + +#include "defs.h" +#include "arch-utils.h" +#include "frame.h" +#include "frame-unwind.h" +#include "gdbcore.h" +#include "regcache.h" +#include "regset.h" +#include "symtab.h" +#include "objfiles.h" +#include "osabi.h" +#include "target.h" +#include "trad-frame.h" + +#include "obsd-tdep.h" +#include "i386-tdep.h" +#include "i387-tdep.h" +#include "solib-svr4.h" +#include "bsd-uthread.h" + +/* Support for signal handlers. */ + +/* Since OpenBSD 3.2, the sigtramp routine is mapped at a random page + in virtual memory. The randomness makes it somewhat tricky to + detect it, but fortunately we can rely on the fact that the start + of the sigtramp routine is page-aligned. We recognize the + trampoline by looking for the code that invokes the sigreturn + system call. The offset where we can find that code varies from + release to release. + + By the way, the mapping mentioned above is read-only, so you cannot + place a breakpoint in the signal trampoline. */ + +/* Default page size. */ +static const int i386obsd_page_size = 4096; + +/* Offset for sigreturn(2). */ +static const int i386obsd_sigreturn_offset[] = { + 0x0a, /* OpenBSD 3.2 */ + 0x14, /* OpenBSD 3.6 */ + 0x3a, /* OpenBSD 3.8 */ + -1 +}; + +/* Return whether THIS_FRAME corresponds to an OpenBSD sigtramp + routine. */ + +static int +i386obsd_sigtramp_p (struct frame_info *this_frame) +{ + CORE_ADDR pc = get_frame_pc (this_frame); + CORE_ADDR start_pc = (pc & ~(i386obsd_page_size - 1)); + /* The call sequence invoking sigreturn(2). */ + const gdb_byte sigreturn[] = + { + 0xb8, + 0x67, 0x00, 0x00, 0x00, /* movl $SYS_sigreturn, %eax */ + 0xcd, 0x80 /* int $0x80 */ + }; + size_t buflen = sizeof sigreturn; + const int *offset; + gdb_byte *buf; + const char *name; + + /* If the function has a valid symbol name, it isn't a + trampoline. */ + find_pc_partial_function (pc, &name, NULL, NULL); + if (name != NULL) + return 0; + + /* If the function lives in a valid section (even without a starting + point) it isn't a trampoline. */ + if (find_pc_section (pc) != NULL) + return 0; + + /* Allocate buffer. */ + buf = (gdb_byte *) alloca (buflen); + + /* Loop over all offsets. */ + for (offset = i386obsd_sigreturn_offset; *offset != -1; offset++) + { + /* If we can't read the instructions, return zero. */ + if (!safe_frame_unwind_memory (this_frame, start_pc + *offset, + buf, buflen)) + return 0; + + /* Check for sigreturn(2). */ + if (memcmp (buf, sigreturn, buflen) == 0) + return 1; + } + + return 0; +} + +/* Mapping between the general-purpose registers in `struct reg' + format and GDB's register cache layout. */ + +/* From <machine/reg.h>. */ +static int i386obsd_r_reg_offset[] = +{ + 0 * 4, /* %eax */ + 1 * 4, /* %ecx */ + 2 * 4, /* %edx */ + 3 * 4, /* %ebx */ + 4 * 4, /* %esp */ + 5 * 4, /* %ebp */ + 6 * 4, /* %esi */ + 7 * 4, /* %edi */ + 8 * 4, /* %eip */ + 9 * 4, /* %eflags */ + 10 * 4, /* %cs */ + 11 * 4, /* %ss */ + 12 * 4, /* %ds */ + 13 * 4, /* %es */ + 14 * 4, /* %fs */ + 15 * 4 /* %gs */ +}; + +static void +i386obsd_aout_supply_regset (const struct regset *regset, + struct regcache *regcache, int regnum, + const void *regs, size_t len) +{ + struct gdbarch *gdbarch = get_regcache_arch (regcache); + const struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); + const gdb_byte *gregs = (const gdb_byte *) regs; + + gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FSAVE); + + i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset); + i387_supply_fsave (regcache, regnum, gregs + tdep->sizeof_gregset); +} + +static const struct regset i386obsd_aout_gregset = + { + NULL, i386obsd_aout_supply_regset, NULL + }; + +static void +i386obsd_aout_iterate_over_regset_sections (struct gdbarch *gdbarch, + iterate_over_regset_sections_cb *cb, + void *cb_data, + const struct regcache *regcache) +{ + struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); + + /* OpenBSD a.out core dumps don't use seperate register sets for the + general-purpose and floating-point registers. */ + + cb (".reg", tdep->sizeof_gregset + I387_SIZEOF_FSAVE, + &i386obsd_aout_gregset, NULL, cb_data); +} + + +/* Sigtramp routine location for OpenBSD 3.1 and earlier releases. */ +CORE_ADDR i386obsd_sigtramp_start_addr = 0xbfbfdf20; +CORE_ADDR i386obsd_sigtramp_end_addr = 0xbfbfdff0; + +/* From <machine/signal.h>. */ +int i386obsd_sc_reg_offset[I386_NUM_GREGS] = +{ + 10 * 4, /* %eax */ + 9 * 4, /* %ecx */ + 8 * 4, /* %edx */ + 7 * 4, /* %ebx */ + 14 * 4, /* %esp */ + 6 * 4, /* %ebp */ + 5 * 4, /* %esi */ + 4 * 4, /* %edi */ + 11 * 4, /* %eip */ + 13 * 4, /* %eflags */ + 12 * 4, /* %cs */ + 15 * 4, /* %ss */ + 3 * 4, /* %ds */ + 2 * 4, /* %es */ + 1 * 4, /* %fs */ + 0 * 4 /* %gs */ +}; + +/* From /usr/src/lib/libpthread/arch/i386/uthread_machdep.c. */ +static int i386obsd_uthread_reg_offset[] = +{ + 11 * 4, /* %eax */ + 10 * 4, /* %ecx */ + 9 * 4, /* %edx */ + 8 * 4, /* %ebx */ + -1, /* %esp */ + 6 * 4, /* %ebp */ + 5 * 4, /* %esi */ + 4 * 4, /* %edi */ + 12 * 4, /* %eip */ + -1, /* %eflags */ + 13 * 4, /* %cs */ + -1, /* %ss */ + 3 * 4, /* %ds */ + 2 * 4, /* %es */ + 1 * 4, /* %fs */ + 0 * 4 /* %gs */ +}; + +/* Offset within the thread structure where we can find the saved + stack pointer (%esp). */ +#define I386OBSD_UTHREAD_ESP_OFFSET 176 + +static void +i386obsd_supply_uthread (struct regcache *regcache, + int regnum, CORE_ADDR addr) +{ + struct gdbarch *gdbarch = get_regcache_arch (regcache); + enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); + CORE_ADDR sp_addr = addr + I386OBSD_UTHREAD_ESP_OFFSET; + CORE_ADDR sp = 0; + gdb_byte buf[4]; + int i; + + gdb_assert (regnum >= -1); + + if (regnum == -1 || regnum == I386_ESP_REGNUM) + { + int offset; + + /* Fetch stack pointer from thread structure. */ + sp = read_memory_unsigned_integer (sp_addr, 4, byte_order); + + /* Adjust the stack pointer such that it looks as if we just + returned from _thread_machdep_switch. */ + offset = i386obsd_uthread_reg_offset[I386_EIP_REGNUM] + 4; + store_unsigned_integer (buf, 4, byte_order, sp + offset); + regcache_raw_supply (regcache, I386_ESP_REGNUM, buf); + } + + for (i = 0; i < ARRAY_SIZE (i386obsd_uthread_reg_offset); i++) + { + if (i386obsd_uthread_reg_offset[i] != -1 + && (regnum == -1 || regnum == i)) + { + /* Fetch stack pointer from thread structure (if we didn't + do so already). */ + if (sp == 0) + sp = read_memory_unsigned_integer (sp_addr, 4, byte_order); + + /* Read the saved register from the stack frame. */ + read_memory (sp + i386obsd_uthread_reg_offset[i], buf, 4); + regcache_raw_supply (regcache, i, buf); + } + } +} + +static void +i386obsd_collect_uthread (const struct regcache *regcache, + int regnum, CORE_ADDR addr) +{ + struct gdbarch *gdbarch = get_regcache_arch (regcache); + enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); + CORE_ADDR sp_addr = addr + I386OBSD_UTHREAD_ESP_OFFSET; + CORE_ADDR sp = 0; + gdb_byte buf[4]; + int i; + + gdb_assert (regnum >= -1); + + if (regnum == -1 || regnum == I386_ESP_REGNUM) + { + int offset; + + /* Calculate the stack pointer (frame pointer) that will be + stored into the thread structure. */ + offset = i386obsd_uthread_reg_offset[I386_EIP_REGNUM] + 4; + regcache_raw_collect (regcache, I386_ESP_REGNUM, buf); + sp = extract_unsigned_integer (buf, 4, byte_order) - offset; + + /* Store the stack pointer. */ + write_memory_unsigned_integer (sp_addr, 4, byte_order, sp); + + /* The stack pointer was (potentially) modified. Make sure we + build a proper stack frame. */ + regnum = -1; + } + + for (i = 0; i < ARRAY_SIZE (i386obsd_uthread_reg_offset); i++) + { + if (i386obsd_uthread_reg_offset[i] != -1 + && (regnum == -1 || regnum == i)) + { + /* Fetch stack pointer from thread structure (if we didn't + calculate it already). */ + if (sp == 0) + sp = read_memory_unsigned_integer (sp_addr, 4, byte_order); + + /* Write the register into the stack frame. */ + regcache_raw_collect (regcache, i, buf); + write_memory (sp + i386obsd_uthread_reg_offset[i], buf, 4); + } + } +} + +/* Kernel debugging support. */ + +/* From <machine/frame.h>. Note that %esp and %ess are only saved in + a trap frame when entering the kernel from user space. */ +static int i386obsd_tf_reg_offset[] = +{ + 10 * 4, /* %eax */ + 9 * 4, /* %ecx */ + 8 * 4, /* %edx */ + 7 * 4, /* %ebx */ + -1, /* %esp */ + 6 * 4, /* %ebp */ + 5 * 4, /* %esi */ + 4 * 4, /* %edi */ + 13 * 4, /* %eip */ + 15 * 4, /* %eflags */ + 14 * 4, /* %cs */ + -1, /* %ss */ + 3 * 4, /* %ds */ + 2 * 4, /* %es */ + 0 * 4, /* %fs */ + 1 * 4 /* %gs */ +}; + +static struct trad_frame_cache * +i386obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache) +{ + struct gdbarch *gdbarch = get_frame_arch (this_frame); + enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); + struct trad_frame_cache *cache; + CORE_ADDR func, sp, addr; + ULONGEST cs; + const char *name; + int i; + + if (*this_cache) + return (struct trad_frame_cache *) *this_cache; + + cache = trad_frame_cache_zalloc (this_frame); + *this_cache = cache; + + func = get_frame_func (this_frame); + sp = get_frame_register_unsigned (this_frame, I386_ESP_REGNUM); + + find_pc_partial_function (func, &name, NULL, NULL); + if (name && startswith (name, "Xintr")) + addr = sp + 8; /* It's an interrupt frame. */ + else + addr = sp; + + for (i = 0; i < ARRAY_SIZE (i386obsd_tf_reg_offset); i++) + if (i386obsd_tf_reg_offset[i] != -1) + trad_frame_set_reg_addr (cache, i, addr + i386obsd_tf_reg_offset[i]); + + /* Read %cs from trap frame. */ + addr += i386obsd_tf_reg_offset[I386_CS_REGNUM]; + cs = read_memory_unsigned_integer (addr, 4, byte_order); + if ((cs & I386_SEL_RPL) == I386_SEL_UPL) + { + /* Trap from user space; terminate backtrace. */ + trad_frame_set_id (cache, outer_frame_id); + } + else + { + /* Construct the frame ID using the function start. */ + trad_frame_set_id (cache, frame_id_build (sp + 8, func)); + } + + return cache; +} + +static void +i386obsd_trapframe_this_id (struct frame_info *this_frame, + void **this_cache, struct frame_id *this_id) +{ + struct trad_frame_cache *cache = + i386obsd_trapframe_cache (this_frame, this_cache); + + trad_frame_get_id (cache, this_id); +} + +static struct value * +i386obsd_trapframe_prev_register (struct frame_info *this_frame, + void **this_cache, int regnum) +{ + struct trad_frame_cache *cache = + i386obsd_trapframe_cache (this_frame, this_cache); + + return trad_frame_get_register (cache, this_frame, regnum); +} + +static int +i386obsd_trapframe_sniffer (const struct frame_unwind *self, + struct frame_info *this_frame, + void **this_prologue_cache) +{ + ULONGEST cs; + const char *name; + + /* Check Current Privilege Level and bail out if we're not executing + in kernel space. */ + cs = get_frame_register_unsigned (this_frame, I386_CS_REGNUM); + if ((cs & I386_SEL_RPL) == I386_SEL_UPL) + return 0; + + find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL); + return (name && (strcmp (name, "calltrap") == 0 + || strcmp (name, "syscall1") == 0 + || startswith (name, "Xintr") + || startswith (name, "Xsoft"))); +} + +static const struct frame_unwind i386obsd_trapframe_unwind = { + /* FIXME: kettenis/20051219: This really is more like an interrupt + frame, but SIGTRAMP_FRAME would print <signal handler called>, + which really is not what we want here. */ + NORMAL_FRAME, + default_frame_unwind_stop_reason, + i386obsd_trapframe_this_id, + i386obsd_trapframe_prev_register, + NULL, + i386obsd_trapframe_sniffer +}; + + +static void +i386obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) +{ + struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); + + /* Obviously OpenBSD is BSD-based. */ + i386bsd_init_abi (info, gdbarch); + obsd_init_abi (info, gdbarch); + + /* OpenBSD has a different `struct reg'. */ + tdep->gregset_reg_offset = i386obsd_r_reg_offset; + tdep->gregset_num_regs = ARRAY_SIZE (i386obsd_r_reg_offset); + tdep->sizeof_gregset = 16 * 4; + + /* OpenBSD uses -freg-struct-return by default. */ + tdep->struct_return = reg_struct_return; + + /* OpenBSD uses a different memory layout. */ + tdep->sigtramp_start = i386obsd_sigtramp_start_addr; + tdep->sigtramp_end = i386obsd_sigtramp_end_addr; + tdep->sigtramp_p = i386obsd_sigtramp_p; + + /* OpenBSD has a `struct sigcontext' that's different from the + original 4.3 BSD. */ + tdep->sc_reg_offset = i386obsd_sc_reg_offset; + tdep->sc_num_regs = ARRAY_SIZE (i386obsd_sc_reg_offset); + + /* OpenBSD provides a user-level threads implementation. */ + bsd_uthread_set_supply_uthread (gdbarch, i386obsd_supply_uthread); + bsd_uthread_set_collect_uthread (gdbarch, i386obsd_collect_uthread); + + /* Unwind kernel trap frames correctly. */ + frame_unwind_prepend_unwinder (gdbarch, &i386obsd_trapframe_unwind); +} + +/* OpenBSD a.out. */ + +static void +i386obsd_aout_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) +{ + i386obsd_init_abi (info, gdbarch); + + /* OpenBSD a.out has a single register set. */ + set_gdbarch_iterate_over_regset_sections + (gdbarch, i386obsd_aout_iterate_over_regset_sections); +} + +/* OpenBSD ELF. */ + +static void +i386obsd_elf_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) +{ + /* It's still OpenBSD. */ + i386obsd_init_abi (info, gdbarch); + + /* But ELF-based. */ + i386_elf_init_abi (info, gdbarch); + + /* OpenBSD ELF uses SVR4-style shared libraries. */ + set_solib_svr4_fetch_link_map_offsets + (gdbarch, svr4_ilp32_fetch_link_map_offsets); +} + + +/* Provide a prototype to silence -Wmissing-prototypes. */ +void _initialize_i386obsd_tdep (void); + +void +_initialize_i386obsd_tdep (void) +{ + /* FIXME: kettenis/20021020: Since OpenBSD/i386 binaries are + indistingushable from NetBSD/i386 a.out binaries, building a GDB + that should support both these targets will probably not work as + expected. */ +#define GDB_OSABI_OPENBSD_AOUT GDB_OSABI_NETBSD_AOUT + + gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_OPENBSD_AOUT, + i386obsd_aout_init_abi); + gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_OPENBSD_ELF, + i386obsd_elf_init_abi); +} |