460 lines
13 KiB
C
460 lines
13 KiB
C
/* Target-dependent code for OpenBSD/amd64.
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Copyright (C) 2003-2018 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "frame.h"
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#include "frame-unwind.h"
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#include "gdbcore.h"
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#include "symtab.h"
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#include "objfiles.h"
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#include "osabi.h"
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#include "regcache.h"
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#include "regset.h"
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#include "target.h"
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#include "trad-frame.h"
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#include "obsd-tdep.h"
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#include "amd64-tdep.h"
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#include "i387-tdep.h"
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#include "x86-xstate.h"
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#include "solib-svr4.h"
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#include "bsd-uthread.h"
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/* Support for signal handlers. */
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/* Default page size. */
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static const int amd64obsd_page_size = 4096;
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/* Return whether THIS_FRAME corresponds to an OpenBSD sigtramp
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routine. */
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static int
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amd64obsd_sigtramp_p (struct frame_info *this_frame)
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{
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CORE_ADDR pc = get_frame_pc (this_frame);
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CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));
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const gdb_byte osigreturn[] =
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{
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0x48, 0xc7, 0xc0,
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0x67, 0x00, 0x00, 0x00, /* movq $SYS_sigreturn, %rax */
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0xcd, 0x80 /* int $0x80 */
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};
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const gdb_byte sigreturn[] =
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{
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0x48, 0xc7, 0xc0,
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0x67, 0x00, 0x00, 0x00, /* movq $SYS_sigreturn, %rax */
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0x0f, 0x05 /* syscall */
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};
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size_t buflen = (sizeof sigreturn) + 1;
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gdb_byte *buf;
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const char *name;
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/* If the function has a valid symbol name, it isn't a
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trampoline. */
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find_pc_partial_function (pc, &name, NULL, NULL);
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if (name != NULL)
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return 0;
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/* If the function lives in a valid section (even without a starting
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point) it isn't a trampoline. */
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if (find_pc_section (pc) != NULL)
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return 0;
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/* If we can't read the instructions at START_PC, return zero. */
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buf = (gdb_byte *) alloca ((sizeof sigreturn) + 1);
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if (!safe_frame_unwind_memory (this_frame, start_pc + 6, buf, buflen))
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return 0;
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/* Check for sigreturn(2). Depending on how the assembler encoded
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the `movq %rsp, %rdi' instruction, the code starts at offset 6 or
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7. OpenBSD 5.0 and later use the `syscall' instruction. Older
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versions use `int $0x80'. Check for both. */
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if (memcmp (buf, sigreturn, sizeof sigreturn)
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&& memcmp (buf + 1, sigreturn, sizeof sigreturn)
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&& memcmp (buf, osigreturn, sizeof osigreturn)
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&& memcmp (buf + 1, osigreturn, sizeof osigreturn))
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return 0;
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return 1;
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}
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/* Assuming THIS_FRAME is for a BSD sigtramp routine, return the
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address of the associated sigcontext structure. */
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static CORE_ADDR
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amd64obsd_sigcontext_addr (struct frame_info *this_frame)
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{
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CORE_ADDR pc = get_frame_pc (this_frame);
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ULONGEST offset = (pc & (amd64obsd_page_size - 1));
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/* The %rsp register points at `struct sigcontext' upon entry of a
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signal trampoline. The relevant part of the trampoline is
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call *%rax
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movq %rsp, %rdi
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pushq %rdi
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movq $SYS_sigreturn,%rax
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int $0x80
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(see /usr/src/sys/arch/amd64/amd64/locore.S). The `pushq'
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instruction clobbers %rsp, but its value is saved in `%rdi'. */
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if (offset > 5)
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return get_frame_register_unsigned (this_frame, AMD64_RDI_REGNUM);
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else
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return get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
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}
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/* OpenBSD 3.5 or later. */
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/* Mapping between the general-purpose registers in `struct reg'
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format and GDB's register cache layout. */
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/* From <machine/reg.h>. */
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int amd64obsd_r_reg_offset[] =
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{
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14 * 8, /* %rax */
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13 * 8, /* %rbx */
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3 * 8, /* %rcx */
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2 * 8, /* %rdx */
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1 * 8, /* %rsi */
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0 * 8, /* %rdi */
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12 * 8, /* %rbp */
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15 * 8, /* %rsp */
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4 * 8, /* %r8 .. */
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5 * 8,
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6 * 8,
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7 * 8,
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8 * 8,
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9 * 8,
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10 * 8,
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11 * 8, /* ... %r15 */
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16 * 8, /* %rip */
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17 * 8, /* %eflags */
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18 * 8, /* %cs */
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19 * 8, /* %ss */
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20 * 8, /* %ds */
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21 * 8, /* %es */
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22 * 8, /* %fs */
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23 * 8 /* %gs */
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};
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/* From <machine/signal.h>. */
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static int amd64obsd_sc_reg_offset[] =
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{
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14 * 8, /* %rax */
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13 * 8, /* %rbx */
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3 * 8, /* %rcx */
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2 * 8, /* %rdx */
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1 * 8, /* %rsi */
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0 * 8, /* %rdi */
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12 * 8, /* %rbp */
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24 * 8, /* %rsp */
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4 * 8, /* %r8 ... */
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5 * 8,
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6 * 8,
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7 * 8,
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8 * 8,
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9 * 8,
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10 * 8,
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11 * 8, /* ... %r15 */
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21 * 8, /* %rip */
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23 * 8, /* %eflags */
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22 * 8, /* %cs */
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25 * 8, /* %ss */
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18 * 8, /* %ds */
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17 * 8, /* %es */
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16 * 8, /* %fs */
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15 * 8 /* %gs */
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};
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/* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c. */
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static int amd64obsd_uthread_reg_offset[] =
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{
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19 * 8, /* %rax */
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16 * 8, /* %rbx */
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18 * 8, /* %rcx */
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17 * 8, /* %rdx */
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14 * 8, /* %rsi */
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13 * 8, /* %rdi */
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15 * 8, /* %rbp */
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-1, /* %rsp */
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12 * 8, /* %r8 ... */
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11 * 8,
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10 * 8,
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9 * 8,
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8 * 8,
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7 * 8,
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6 * 8,
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5 * 8, /* ... %r15 */
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20 * 8, /* %rip */
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4 * 8, /* %eflags */
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21 * 8, /* %cs */
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-1, /* %ss */
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3 * 8, /* %ds */
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2 * 8, /* %es */
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1 * 8, /* %fs */
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0 * 8 /* %gs */
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};
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/* Offset within the thread structure where we can find the saved
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stack pointer (%esp). */
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#define AMD64OBSD_UTHREAD_RSP_OFFSET 400
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static void
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amd64obsd_supply_uthread (struct regcache *regcache,
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int regnum, CORE_ADDR addr)
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{
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struct gdbarch *gdbarch = regcache->arch ();
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enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
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CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
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CORE_ADDR sp = 0;
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gdb_byte buf[8];
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int i;
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gdb_assert (regnum >= -1);
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if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
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{
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int offset;
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/* Fetch stack pointer from thread structure. */
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sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
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/* Adjust the stack pointer such that it looks as if we just
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returned from _thread_machdep_switch. */
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offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
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store_unsigned_integer (buf, 8, byte_order, sp + offset);
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regcache_raw_supply (regcache, AMD64_RSP_REGNUM, buf);
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}
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for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
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{
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if (amd64obsd_uthread_reg_offset[i] != -1
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&& (regnum == -1 || regnum == i))
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{
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/* Fetch stack pointer from thread structure (if we didn't
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do so already). */
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if (sp == 0)
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sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
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/* Read the saved register from the stack frame. */
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read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
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regcache_raw_supply (regcache, i, buf);
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}
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}
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}
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static void
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amd64obsd_collect_uthread (const struct regcache *regcache,
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int regnum, CORE_ADDR addr)
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{
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struct gdbarch *gdbarch = regcache->arch ();
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enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
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CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
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CORE_ADDR sp = 0;
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gdb_byte buf[8];
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int i;
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gdb_assert (regnum >= -1);
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if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
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{
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int offset;
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/* Calculate the stack pointer (frame pointer) that will be
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stored into the thread structure. */
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offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
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regcache_raw_collect (regcache, AMD64_RSP_REGNUM, buf);
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sp = extract_unsigned_integer (buf, 8, byte_order) - offset;
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/* Store the stack pointer. */
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write_memory_unsigned_integer (sp_addr, 8, byte_order, sp);
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/* The stack pointer was (potentially) modified. Make sure we
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build a proper stack frame. */
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regnum = -1;
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}
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for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
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{
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if (amd64obsd_uthread_reg_offset[i] != -1
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&& (regnum == -1 || regnum == i))
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{
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/* Fetch stack pointer from thread structure (if we didn't
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calculate it already). */
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if (sp == 0)
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sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);
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/* Write the register into the stack frame. */
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regcache_raw_collect (regcache, i, buf);
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write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
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}
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}
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}
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/* Kernel debugging support. */
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/* From <machine/frame.h>. Easy since `struct trapframe' matches
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`struct sigcontext'. */
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#define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset
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static struct trad_frame_cache *
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amd64obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache)
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{
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struct gdbarch *gdbarch = get_frame_arch (this_frame);
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enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
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struct trad_frame_cache *cache;
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CORE_ADDR func, sp, addr;
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ULONGEST cs;
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const char *name;
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int i;
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if (*this_cache)
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return (struct trad_frame_cache *) *this_cache;
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cache = trad_frame_cache_zalloc (this_frame);
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*this_cache = cache;
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func = get_frame_func (this_frame);
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sp = get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
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find_pc_partial_function (func, &name, NULL, NULL);
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if (name && startswith (name, "Xintr"))
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addr = sp + 8; /* It's an interrupt frame. */
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else
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addr = sp;
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for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++)
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if (amd64obsd_tf_reg_offset[i] != -1)
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trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]);
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/* Read %cs from trap frame. */
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addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM];
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cs = read_memory_unsigned_integer (addr, 8, byte_order);
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if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
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{
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/* Trap from user space; terminate backtrace. */
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trad_frame_set_id (cache, outer_frame_id);
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}
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else
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{
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/* Construct the frame ID using the function start. */
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trad_frame_set_id (cache, frame_id_build (sp + 16, func));
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}
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return cache;
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}
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static void
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amd64obsd_trapframe_this_id (struct frame_info *this_frame,
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void **this_cache, struct frame_id *this_id)
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{
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struct trad_frame_cache *cache =
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amd64obsd_trapframe_cache (this_frame, this_cache);
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trad_frame_get_id (cache, this_id);
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}
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static struct value *
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amd64obsd_trapframe_prev_register (struct frame_info *this_frame,
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void **this_cache, int regnum)
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{
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struct trad_frame_cache *cache =
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amd64obsd_trapframe_cache (this_frame, this_cache);
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return trad_frame_get_register (cache, this_frame, regnum);
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}
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static int
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amd64obsd_trapframe_sniffer (const struct frame_unwind *self,
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struct frame_info *this_frame,
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void **this_prologue_cache)
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{
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ULONGEST cs;
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const char *name;
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/* Check Current Privilege Level and bail out if we're not executing
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in kernel space. */
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cs = get_frame_register_unsigned (this_frame, AMD64_CS_REGNUM);
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if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
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return 0;
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find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL);
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return (name && ((strcmp (name, "calltrap") == 0)
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|| (strcmp (name, "osyscall1") == 0)
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|| (strcmp (name, "Xsyscall") == 0)
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|| (startswith (name, "Xintr"))));
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}
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static const struct frame_unwind amd64obsd_trapframe_unwind = {
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/* FIXME: kettenis/20051219: This really is more like an interrupt
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frame, but SIGTRAMP_FRAME would print <signal handler called>,
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which really is not what we want here. */
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NORMAL_FRAME,
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default_frame_unwind_stop_reason,
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amd64obsd_trapframe_this_id,
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amd64obsd_trapframe_prev_register,
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NULL,
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amd64obsd_trapframe_sniffer
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};
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static void
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amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
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{
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struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
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amd64_init_abi (info, gdbarch,
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amd64_target_description (X86_XSTATE_SSE_MASK));
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obsd_init_abi (info, gdbarch);
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/* Initialize general-purpose register set details. */
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tdep->gregset_reg_offset = amd64obsd_r_reg_offset;
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tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
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tdep->sizeof_gregset = 24 * 8;
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tdep->jb_pc_offset = 7 * 8;
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tdep->sigtramp_p = amd64obsd_sigtramp_p;
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tdep->sigcontext_addr = amd64obsd_sigcontext_addr;
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tdep->sc_reg_offset = amd64obsd_sc_reg_offset;
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tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);
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/* OpenBSD provides a user-level threads implementation. */
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bsd_uthread_set_supply_uthread (gdbarch, amd64obsd_supply_uthread);
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bsd_uthread_set_collect_uthread (gdbarch, amd64obsd_collect_uthread);
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/* OpenBSD uses SVR4-style shared libraries. */
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set_solib_svr4_fetch_link_map_offsets
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(gdbarch, svr4_lp64_fetch_link_map_offsets);
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/* Unwind kernel trap frames correctly. */
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frame_unwind_prepend_unwinder (gdbarch, &amd64obsd_trapframe_unwind);
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}
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void
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_initialize_amd64obsd_tdep (void)
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{
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/* The OpenBSD/amd64 native dependent code makes this assumption. */
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gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);
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gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
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GDB_OSABI_OPENBSD, amd64obsd_init_abi);
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}
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