gdb/amd64obsd-tdep.c - gdb

Global variables defined

Functions defined

Macros defined

Source code

  1. /* Target-dependent code for OpenBSD/amd64.

  3.    Copyright (C) 2003-2015 Free Software Foundation, Inc.

  5.    This file is part of GDB.

  7.    This program is free software; you can redistribute it and/or modify
  8.    it under the terms of the GNU General Public License as published by
  9.    the Free Software Foundation; either version 3 of the License, or
  10.    (at your option) any later version.

  12.    This program is distributed in the hope that it will be useful,
  13.    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15.    GNU General Public License for more details.

  17.    You should have received a copy of the GNU General Public License
  18.    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

  20. #include "defs.h"
  21. #include "frame.h"
  22. #include "frame-unwind.h"
  23. #include "gdbcore.h"
  24. #include "symtab.h"
  25. #include "objfiles.h"
  26. #include "osabi.h"
  27. #include "regcache.h"
  28. #include "regset.h"
  29. #include "target.h"
  30. #include "trad-frame.h"

  32. #include "obsd-tdep.h"
  33. #include "amd64-tdep.h"
  34. #include "i387-tdep.h"
  35. #include "solib-svr4.h"
  36. #include "bsd-uthread.h"

  38. /* Support for core dumps.  */

  40. static void
  41. ‌amd64obsd_supply_regset (const struct regset *regset,
  42.                          struct regcache *regcache, int regnum,
  43.                          const void *regs, size_t len)
  44. {
  45.   struct gdbarch *gdbarch = get_regcache_arch (regcache);
  46.   const struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  48.   gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE);

  50.   i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
  51.   amd64_supply_fxsave (regcache, regnum,
  52.                        ((const gdb_byte *)regs) + tdep->sizeof_gregset);
  53. }

  55. ‌static const struct regset amd64obsd_combined_regset =
  56.   {
  57.     NULL, amd64obsd_supply_regset, NULL
  58.   };

  60. static void
  61. ‌amd64obsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
  62.                                         iterate_over_regset_sections_cb *cb,
  63.                                         void *cb_data,
  64.                                         const struct regcache *regcache)
  65. {
  66.   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  68.   /* OpenBSD core dumps don't use seperate register sets for the
  69.      general-purpose and floating-point registers.  */

  71.   cb (".reg", tdep->sizeof_gregset + I387_SIZEOF_FXSAVE,
  72.       &amd64obsd_combined_regset, NULL, cb_data);
  73. }


  76. /* Support for signal handlers.  */

  78. /* Default page size.  */
  79. ‌static const int amd64obsd_page_size = 4096;

  81. /* Return whether THIS_FRAME corresponds to an OpenBSD sigtramp
  82.    routine.  */

  84. static int
  85. ‌amd64obsd_sigtramp_p (struct frame_info *this_frame)
  86. {
  87.   CORE_ADDR pc = get_frame_pc (this_frame);
  88.   CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));
  89.   const gdb_byte osigreturn[] =
  90.   {
  91.     0x48, 0xc7, 0xc0,
  92.     0x67, 0x00, 0x00, 0x00,        /* movq $SYS_sigreturn, %rax */
  93.     0xcd, 0x80                        /* int $0x80 */
  94.   };
  95.   const gdb_byte sigreturn[] =
  96.   {
  97.     0x48, 0xc7, 0xc0,
  98.     0x67, 0x00, 0x00, 0x00,        /* movq $SYS_sigreturn, %rax */
  99.     0x0f, 0x05                        /* syscall */
  100.   };
  101.   size_t buflen = (sizeof sigreturn) + 1;
  102.   gdb_byte *buf;
  103.   const char *name;

  105.   /* If the function has a valid symbol name, it isn't a
  106.      trampoline.  */
  107.   find_pc_partial_function (pc, &name, NULL, NULL);
  108.   if (name != NULL)
  109.     return 0;

  111.   /* If the function lives in a valid section (even without a starting
  112.      point) it isn't a trampoline.  */
  113.   if (find_pc_section (pc) != NULL)
  114.     return 0;

  116.   /* If we can't read the instructions at START_PC, return zero.  */
  117.   buf = alloca ((sizeof sigreturn) + 1);
  118.   if (!safe_frame_unwind_memory (this_frame, start_pc + 6, buf, buflen))
  119.     return 0;

  121.   /* Check for sigreturn(2).  Depending on how the assembler encoded
  122.      the `movq %rsp, %rdi' instruction, the code starts at offset 6 or
  123.      7.  OpenBSD 5.0 and later use the `syscall' instruction.  Older
  124.      versions use `int $0x80'.  Check for both.  */
  125.   if (memcmp (buf, sigreturn, sizeof sigreturn)
  126.       && memcmp (buf + 1, sigreturn, sizeof sigreturn)
  127.       && memcmp (buf, osigreturn, sizeof osigreturn)
  128.       && memcmp (buf + 1, osigreturn, sizeof osigreturn))
  129.     return 0;

  131.   return 1;
  132. }

  134. /* Assuming THIS_FRAME is for a BSD sigtramp routine, return the
  135.    address of the associated sigcontext structure.  */

  137. static CORE_ADDR
  138. ‌amd64obsd_sigcontext_addr (struct frame_info *this_frame)
  139. {
  140.   CORE_ADDR pc = get_frame_pc (this_frame);
  141.   ULONGEST offset = (pc & (amd64obsd_page_size - 1));

  143.   /* The %rsp register points at `struct sigcontext' upon entry of a
  144.      signal trampoline.  The relevant part of the trampoline is

  146.         call    *%rax
  147.         movq    %rsp, %rdi
  148.         pushq   %rdi
  149.         movq    $SYS_sigreturn,%rax
  150.         int     $0x80

  152.      (see /usr/src/sys/arch/amd64/amd64/locore.S).  The `pushq'
  153.      instruction clobbers %rsp, but its value is saved in `%rdi'.  */

  155.   if (offset > 5)
  156.     return get_frame_register_unsigned (this_frame, AMD64_RDI_REGNUM);
  157.   else
  158.     return get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
  159. }

  161. /* OpenBSD 3.5 or later.  */

  163. /* Mapping between the general-purpose registers in `struct reg'
  164.    format and GDB's register cache layout.  */

  166. /* From <machine/reg.h>.  */
  167. ‌int amd64obsd_r_reg_offset[] =
  168. {
  169.   14 * 8,                        /* %rax */
  170.   13 * 8,                        /* %rbx */
  171.   3 * 8,                        /* %rcx */
  172.   2 * 8,                        /* %rdx */
  173.   1 * 8,                        /* %rsi */
  174.   0 * 8,                        /* %rdi */
  175.   12 * 8,                        /* %rbp */
  176.   15 * 8,                        /* %rsp */
  177.   4 * 8,                        /* %r8 ..  */
  178.   5 * 8,
  179.   6 * 8,
  180.   7 * 8,
  181.   8 * 8,
  182.   9 * 8,
  183.   10 * 8,
  184.   11 * 8,                        /* ... %r15 */
  185.   16 * 8,                        /* %rip */
  186.   17 * 8,                        /* %eflags */
  187.   18 * 8,                        /* %cs */
  188.   19 * 8,                        /* %ss */
  189.   20 * 8,                        /* %ds */
  190.   21 * 8,                        /* %es */
  191.   22 * 8,                        /* %fs */
  192.   23 * 8                        /* %gs */
  193. };

  195. /* From <machine/signal.h>.  */
  196. ‌static int amd64obsd_sc_reg_offset[] =
  197. {
  198.   14 * 8,                        /* %rax */
  199.   13 * 8,                        /* %rbx */
  200.   3 * 8,                        /* %rcx */
  201.   2 * 8,                        /* %rdx */
  202.   1 * 8,                        /* %rsi */
  203.   0 * 8,                        /* %rdi */
  204.   12 * 8,                        /* %rbp */
  205.   24 * 8,                        /* %rsp */
  206.   4 * 8,                        /* %r8 ...  */
  207.   5 * 8,
  208.   6 * 8,
  209.   7 * 8,
  210.   8 * 8,
  211.   9 * 8,
  212.   10 * 8,
  213.   11 * 8,                        /* ... %r15 */
  214.   21 * 8,                        /* %rip */
  215.   23 * 8,                        /* %eflags */
  216.   22 * 8,                        /* %cs */
  217.   25 * 8,                        /* %ss */
  218.   18 * 8,                        /* %ds */
  219.   17 * 8,                        /* %es */
  220.   16 * 8,                        /* %fs */
  221.   15 * 8                        /* %gs */
  222. };

  224. /* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c.  */
  225. ‌static int amd64obsd_uthread_reg_offset[] =
  226. {
  227.   19 * 8,                        /* %rax */
  228.   16 * 8,                        /* %rbx */
  229.   18 * 8,                        /* %rcx */
  230.   17 * 8,                        /* %rdx */
  231.   14 * 8,                        /* %rsi */
  232.   13 * 8,                        /* %rdi */
  233.   15 * 8,                        /* %rbp */
  234.   -1,                                /* %rsp */
  235.   12 * 8,                        /* %r8 ...  */
  236.   11 * 8,
  237.   10 * 8,
  238.   9 * 8,
  239.   8 * 8,
  240.   7 * 8,
  241.   6 * 8,
  242.   5 * 8,                        /* ... %r15 */
  243.   20 * 8,                        /* %rip */
  244.   4 * 8,                        /* %eflags */
  245.   21 * 8,                        /* %cs */
  246.   -1,                                /* %ss */
  247.   3 * 8,                        /* %ds */
  248.   2 * 8,                        /* %es */
  249.   1 * 8,                        /* %fs */
  250.   0 * 8                                /* %gs */
  251. };

  253. /* Offset within the thread structure where we can find the saved
  254.    stack pointer (%esp).  */
  255. ‌#define AMD64OBSD_UTHREAD_RSP_OFFSET        400

  257. static void
  258. ‌amd64obsd_supply_uthread (struct regcache *regcache,
  259.                           int regnum, CORE_ADDR addr)
  260. {
  261.   struct gdbarch *gdbarch = get_regcache_arch (regcache);
  262.   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  263.   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
  264.   CORE_ADDR sp = 0;
  265.   gdb_byte buf[8];
  266.   int i;

  268.   gdb_assert (regnum >= -1);

  270.   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
  271.     {
  272.       int offset;

  274.       /* Fetch stack pointer from thread structure.  */
  275.       sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);

  277.       /* Adjust the stack pointer such that it looks as if we just
  278.          returned from _thread_machdep_switch.  */
  279.       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
  280.       store_unsigned_integer (buf, 8, byte_order, sp + offset);
  281.       regcache_raw_supply (regcache, AMD64_RSP_REGNUM, buf);
  282.     }

  284.   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
  285.     {
  286.       if (amd64obsd_uthread_reg_offset[i] != -1
  287.           && (regnum == -1 || regnum == i))
  288.         {
  289.           /* Fetch stack pointer from thread structure (if we didn't
  290.              do so already).  */
  291.           if (sp == 0)
  292.             sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);

  294.           /* Read the saved register from the stack frame.  */
  295.           read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
  296.           regcache_raw_supply (regcache, i, buf);
  297.         }
  298.     }
  299. }

  301. static void
  302. ‌amd64obsd_collect_uthread (const struct regcache *regcache,
  303.                            int regnum, CORE_ADDR addr)
  304. {
  305.   struct gdbarch *gdbarch = get_regcache_arch (regcache);
  306.   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  307.   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
  308.   CORE_ADDR sp = 0;
  309.   gdb_byte buf[8];
  310.   int i;

  312.   gdb_assert (regnum >= -1);

  314.   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
  315.     {
  316.       int offset;

  318.       /* Calculate the stack pointer (frame pointer) that will be
  319.          stored into the thread structure.  */
  320.       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
  321.       regcache_raw_collect (regcache, AMD64_RSP_REGNUM, buf);
  322.       sp = extract_unsigned_integer (buf, 8, byte_order) - offset;

  324.       /* Store the stack pointer.  */
  325.       write_memory_unsigned_integer (sp_addr, 8, byte_order, sp);

  327.       /* The stack pointer was (potentially) modified.  Make sure we
  328.          build a proper stack frame.  */
  329.       regnum = -1;
  330.     }

  332.   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
  333.     {
  334.       if (amd64obsd_uthread_reg_offset[i] != -1
  335.           && (regnum == -1 || regnum == i))
  336.         {
  337.           /* Fetch stack pointer from thread structure (if we didn't
  338.              calculate it already).  */
  339.           if (sp == 0)
  340.             sp = read_memory_unsigned_integer (sp_addr, 8, byte_order);

  342.           /* Write the register into the stack frame.  */
  343.           regcache_raw_collect (regcache, i, buf);
  344.           write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
  345.         }
  346.     }
  347. }
  348. /* Kernel debugging support.  */

  350. /* From <machine/frame.h>.  Easy since `struct trapframe' matches
  351.    `struct sigcontext'.  */
  352. ‌#define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset

  354. static struct trad_frame_cache *
  355. ‌amd64obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache)
  356. {
  357.   struct gdbarch *gdbarch = get_frame_arch (this_frame);
  358.   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
  359.   struct trad_frame_cache *cache;
  360.   CORE_ADDR func, sp, addr;
  361.   ULONGEST cs;
  362.   const char *name;
  363.   int i;

  365.   if (*this_cache)
  366.     return *this_cache;

  368.   cache = trad_frame_cache_zalloc (this_frame);
  369.   *this_cache = cache;

  371.   func = get_frame_func (this_frame);
  372.   sp = get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);

  374.   find_pc_partial_function (func, &name, NULL, NULL);
  375.   if (name && strncmp (name, "Xintr", 5) == 0)
  376.     addr = sp + 8;                /* It's an interrupt frame.  */
  377.   else
  378.     addr = sp;

  380.   for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++)
  381.     if (amd64obsd_tf_reg_offset[i] != -1)
  382.       trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]);

  384.   /* Read %cs from trap frame.  */
  385.   addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM];
  386.   cs = read_memory_unsigned_integer (addr, 8, byte_order);
  387.   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
  388.     {
  389.       /* Trap from user space; terminate backtrace.  */
  390.       trad_frame_set_id (cache, outer_frame_id);
  391.     }
  392.   else
  393.     {
  394.       /* Construct the frame ID using the function start.  */
  395.       trad_frame_set_id (cache, frame_id_build (sp + 16, func));
  396.     }

  398.   return cache;
  399. }

  401. static void
  402. ‌amd64obsd_trapframe_this_id (struct frame_info *this_frame,
  403.                              void **this_cache, struct frame_id *this_id)
  404. {
  405.   struct trad_frame_cache *cache =
  406.     amd64obsd_trapframe_cache (this_frame, this_cache);

  408.   trad_frame_get_id (cache, this_id);
  409. }

  411. static struct value *
  412. ‌amd64obsd_trapframe_prev_register (struct frame_info *this_frame,
  413.                                    void **this_cache, int regnum)
  414. {
  415.   struct trad_frame_cache *cache =
  416.     amd64obsd_trapframe_cache (this_frame, this_cache);

  418.   return trad_frame_get_register (cache, this_frame, regnum);
  419. }

  421. static int
  422. ‌amd64obsd_trapframe_sniffer (const struct frame_unwind *self,
  423.                              struct frame_info *this_frame,
  424.                              void **this_prologue_cache)
  425. {
  426.   ULONGEST cs;
  427.   const char *name;

  429.   /* Check Current Privilege Level and bail out if we're not executing
  430.      in kernel space.  */
  431.   cs = get_frame_register_unsigned (this_frame, AMD64_CS_REGNUM);
  432.   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
  433.     return 0;

  435.   find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL);
  436.   return (name && ((strcmp (name, "calltrap") == 0)
  437.                    || (strcmp (name, "osyscall1") == 0)
  438.                    || (strcmp (name, "Xsyscall") == 0)
  439.                    || (strncmp (name, "Xintr", 5) == 0)));
  440. }

  442. ‌static const struct frame_unwind amd64obsd_trapframe_unwind = {
  443.   /* FIXME: kettenis/20051219: This really is more like an interrupt
  444.      frame, but SIGTRAMP_FRAME would print <signal handler called>,
  445.      which really is not what we want here.  */
  446.   NORMAL_FRAME,
  447.   default_frame_unwind_stop_reason,
  448.   amd64obsd_trapframe_this_id,
  449.   amd64obsd_trapframe_prev_register,
  450.   NULL,
  451.   amd64obsd_trapframe_sniffer
  452. };


  455. static void
  456. ‌amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
  457. {
  458.   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  460.   amd64_init_abi (info, gdbarch);
  461.   obsd_init_abi (info, gdbarch);

  463.   /* Initialize general-purpose register set details.  */
  464.   tdep->gregset_reg_offset = amd64obsd_r_reg_offset;
  465.   tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
  466.   tdep->sizeof_gregset = 24 * 8;

  468.   tdep->jb_pc_offset = 7 * 8;

  470.   tdep->sigtramp_p = amd64obsd_sigtramp_p;
  471.   tdep->sigcontext_addr = amd64obsd_sigcontext_addr;
  472.   tdep->sc_reg_offset = amd64obsd_sc_reg_offset;
  473.   tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);

  475.   /* OpenBSD provides a user-level threads implementation.  */
  476.   bsd_uthread_set_supply_uthread (gdbarch, amd64obsd_supply_uthread);
  477.   bsd_uthread_set_collect_uthread (gdbarch, amd64obsd_collect_uthread);

  479.   /* OpenBSD uses SVR4-style shared libraries.  */
  480.   set_solib_svr4_fetch_link_map_offsets
  481.     (gdbarch, svr4_lp64_fetch_link_map_offsets);

  483.   /* Unwind kernel trap frames correctly.  */
  484.   frame_unwind_prepend_unwinder (gdbarch, &amd64obsd_trapframe_unwind);
  485. }

  487. /* Traditional (a.out) NetBSD-style core dumps.  */

  489. static void
  490. ‌amd64obsd_core_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
  491. {
  492.   amd64obsd_init_abi (info, gdbarch);

  494.   set_gdbarch_iterate_over_regset_sections
  495.     (gdbarch, amd64obsd_iterate_over_regset_sections);
  496. }


  499. /* Provide a prototype to silence -Wmissing-prototypes.  */
  500. void _initialize_amd64obsd_tdep (void);

  502. void
  503. ‌_initialize_amd64obsd_tdep (void)
  504. {
  505.   /* The OpenBSD/amd64 native dependent code makes this assumption.  */
  506.   gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);

  508.   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
  509.                           GDB_OSABI_OPENBSD_ELF, amd64obsd_init_abi);

  511.   /* OpenBSD uses traditional (a.out) NetBSD-style core dumps.  */
  512.   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
  513.                           GDB_OSABI_NETBSD_AOUT, amd64obsd_core_init_abi);
  514. }