gdb/testsuite/gdb.arch/insn-reloc.c

/* This testcase is part of GDB, the GNU debugger.

   Copyright 2015-2020 Free Software Foundation, Inc.

   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 <stddef.h>
#include <stdint.h>

typedef void (*testcase_ftype)(void);

/* Each function checks the correctness of the instruction being
   relocated due to a fast tracepoint.  Call function pass if it is
   correct, otherwise call function fail.  GDB sets a breakpoints on
   pass and fail in order to check the correctness.  */

static void
pass (void)
{
}

static void
fail (void)
{
}

#if (defined __x86_64__ || defined __i386__)

#ifdef SYMBOL_PREFIX
#define SYMBOL(str)     SYMBOL_PREFIX #str
#else
#define SYMBOL(str)     #str
#endif

/* Make sure we can relocate a CALL instruction.  CALL instructions are
   5 bytes long so we can always set a fast tracepoints on them.

     JMP set_point0
   f:
     MOV $1, %[ok]
     JMP end
   set_point0:
     CALL f ; tracepoint here.
   end:

   */

static void
can_relocate_call (void)
{
  int ok = 0;

  asm ("    .global " SYMBOL (set_point0) "\n"
       "  jmp " SYMBOL (set_point0) "\n"
       "0:\n"
       "  mov $1, %[ok]\n"
       "  jmp 1f\n"
       SYMBOL (set_point0) ":\n"
       "  call 0b\n"
       "1:\n"
       : [ok] "=r" (ok));

  if (ok == 1)
    pass ();
  else
    fail ();
}

/* Make sure we can relocate a JMP instruction.  We need the JMP
   instruction to be 5 bytes long in order to set a fast tracepoint on
   it.  To do this, we emit the opcode directly.

     JMP next ; tracepoint here.
   next:
     MOV $1, %[ok]

   */

static void
can_relocate_jump (void)
{
  int ok = 0;

  asm ("    .global " SYMBOL (set_point1) "\n"
       SYMBOL (set_point1) ":\n"
       ".byte 0xe9\n"  /* jmp  */
       ".byte 0x00\n"
       ".byte 0x00\n"
       ".byte 0x00\n"
       ".byte 0x00\n"
       "  mov $1, %[ok]\n"
       : [ok] "=r" (ok));

  if (ok == 1)
    pass ();
  else
    fail ();
}
#elif (defined __aarch64__)

/* Make sure we can relocate a B instruction.

     B set_point0
   set_ok:
     MOV %[ok], #1
     B end
   set_point0:
     B set_ok ; tracepoint here.
     MOV %[ok], #0
   end

   */

static void
can_relocate_b (void)
{
  int ok = 0;

  asm ("  b set_point0\n"
       "0:\n"
       "  mov %[ok], #1\n"
       "  b 1f\n"
       "set_point0:\n"
       "  b 0b\n"
       "  mov %[ok], #0\n"
       "1:\n"
       : [ok] "=r" (ok));

  if (ok == 1)
    pass ();
  else
    fail ();
}

/* Make sure we can relocate a B.cond instruction.

     MOV x0, #8
     TST x0, #8 ; Clear the Z flag.
     B set_point1
   set_ok:
     MOV %[ok], #1
     B end
   set_point1:
     B.NE set_ok ; tracepoint here.
     MOV %[ok], #0
   end

   */

static void
can_relocate_bcond_true (void)
{
  int ok = 0;

  asm ("  mov x0, #8\n"
       "  tst x0, #8\n"
       "  b set_point1\n"
       "0:\n"
       "  mov %[ok], #1\n"
       "  b 1f\n"
       "set_point1:\n"
       "  b.ne 0b\n"
       "  mov %[ok], #0\n"
       "1:\n"
       : [ok] "=r" (ok)
       :
       : "0", "cc");

  if (ok == 1)
    pass ();
  else
    fail ();
}

/* Make sure we can relocate a CBZ instruction.

     MOV x0, #0
     B set_point2
   set_ok:
     MOV %[ok], #1
     B end
   set_point2:
     CBZ x0, set_ok ; tracepoint here.
     MOV %[ok], #0
   end

   */

static void
can_relocate_cbz (void)
{
  int ok = 0;

  asm ("  mov x0, #0\n"
       "  b set_point2\n"
       "0:\n"
       "  mov %[ok], #1\n"
       "  b 1f\n"
       "set_point2:\n"
       "  cbz x0, 0b\n"
       "  mov %[ok], #0\n"
       "1:\n"
       : [ok] "=r" (ok)
       :
       : "0");

  if (ok == 1)
    pass ();
  else
    fail ();
}

/* Make sure we can relocate a CBNZ instruction.

     MOV x0, #8
     B set_point3
   set_ok:
     MOV %[ok], #1
     B end
   set_point3:
     CBNZ x0, set_ok ; tracepoint here.
     MOV %[ok], #0
   end

   */

static void
can_relocate_cbnz (void)
{
  int ok = 0;

  asm ("  mov x0, #8\n"
       "  b set_point3\n"
       "0:\n"
       "  mov %[ok], #1\n"
       "  b 1f\n"
       "set_point3:\n"
       "  cbnz x0, 0b\n"
       "  mov %[ok], #0\n"
       "1:\n"
       : [ok] "=r" (ok)
       :
       : "0");

  if (ok == 1)
    pass ();
  else
    fail ();
}

/* Make sure we can relocate a TBZ instruction.

     MOV x0, #8
     MVN x0, x0 ; Clear bit 3.
     B set_point4
   set_ok:
     MOV %[ok], #1
     B end
   set_point4:
     TBZ x0, #3, set_ok ; tracepoint here.
     MOV %[ok], #0
   end

   */

static void
can_relocate_tbz (void)
{
  int ok = 0;

  asm ("  mov x0, #8\n"
       "  mvn x0, x0\n"
       "  b set_point4\n"
       "0:\n"
       "  mov %[ok], #1\n"
       "  b 1f\n"
       "set_point4:\n"
       "  tbz x0, #3, 0b\n"
       "  mov %[ok], #0\n"
       "1:\n"
       : [ok] "=r" (ok)
       :
       : "0");

  if (ok == 1)
    pass ();
  else
    fail ();
}

/* Make sure we can relocate a TBNZ instruction.

     MOV x0, #8 ; Set bit 3.
     B set_point5
   set_ok:
     MOV %[ok], #1
     B end
   set_point5:
     TBNZ x0, #3, set_ok ; tracepoint here.
     MOV %[ok], #0
   end

   */

static void
can_relocate_tbnz (void)
{
  int ok = 0;

  asm ("  mov x0, #8\n"
       "  b set_point5\n"
       "0:\n"
       "  mov %[ok], #1\n"
       "  b 1f\n"
       "set_point5:\n"
       "  tbnz x0, #3, 0b\n"
       "  mov %[ok], #0\n"
       "1:\n"
       : [ok] "=r" (ok)
       :
       : "0");

  if (ok == 1)
    pass ();
  else
    fail ();
}

/* Make sure we can relocate an ADR instruction with a positive offset.

   set_point6:
     ADR x0, target ; tracepoint here.
     BR x0 ; jump to target
     MOV %[ok], #0
     B end
   target:
     MOV %[ok], #1
   end

   */

static void
can_relocate_adr_forward (void)
{
  int ok = 0;

  asm ("set_point6:\n"
       "  adr x0, 0f\n"
       "  br x0\n"
       "  mov %[ok], #0\n"
       "  b 1f\n"
       "0:\n"
       "  mov %[ok], #1\n"
       "1:\n"
       : [ok] "=r" (ok)
       :
       : "0");

  if (ok == 1)
    pass ();
  else
    fail ();
}

/* Make sure we can relocate an ADR instruction with a negative offset.

     B set_point7
   target:
     MOV %[ok], #1
     B end
   set_point7:
     ADR x0, target ; tracepoint here.
     BR x0 ; jump to target
     MOV %[ok], #0
   end

   */

static void
can_relocate_adr_backward (void)
{
  int ok = 0;

  asm ("b set_point7\n"
       "0:\n"
       "  mov %[ok], #1\n"
       "  b 1f\n"
       "set_point7:\n"
       "  adr x0, 0b\n"
       "  br x0\n"
       "  mov %[ok], #0\n"
       "1:\n"
       : [ok] "=r" (ok)
       :
       : "0");

  if (ok == 1)
    pass ();
  else
    fail ();
}

/* Make sure we can relocate an ADRP instruction.

   set_point8:
     ADRP %[addr], set_point8 ; tracepoint here.
     ADR %[pc], set_point8

   ADR computes the address of the given label.  While ADRP gives us its
   page, on a 4K boundary.  We can check ADRP executed normally by
   making sure the result of ADR and ADRP are equivalent, except for the
   12 lowest bits which should be cleared.

   */

static void
can_relocate_adrp (void)
{
  uintptr_t page;
  uintptr_t pc;

  asm ("set_point8:\n"
       "  adrp %[page], set_point8\n"
       "  adr %[pc], set_point8\n"
       : [page] "=r" (page), [pc] "=r" (pc));

  if (page == (pc & ~0xfff))
    pass ();
  else
    fail ();
}

/* Make sure we can relocate an LDR instruction, where the memory to
   read is an offset from the current PC.

     B set_point9
   data:
     .word 0x0cabba9e
   set_point9:
     LDR %[result], data ; tracepoint here.

   */

static void
can_relocate_ldr (void)
{
  uint32_t result = 0;

  asm ("b set_point9\n"
       "0:\n"
       "  .word 0x0cabba9e\n"
       "set_point9:\n"
       "  ldr %w[result], 0b\n"
       : [result] "=r" (result));

  if (result == 0x0cabba9e)
    pass ();
  else
    fail ();
}

/* Make sure we can relocate a B.cond instruction and condition is false.  */

static void
can_relocate_bcond_false (void)
{
  int ok = 0;

  asm ("  mov x0, #8\n"
       "  tst x0, #8\n" /* Clear the Z flag.  */
       "set_point10:\n" /* Set tracepoint here.  */
       "  b.eq 0b\n"    /* Condition is false.  */
       "  mov %[ok], #1\n"
       "  b 1f\n"
       "0:\n"
       "  mov %[ok], #0\n"
       "1:\n"
       : [ok] "=r" (ok)
       :
       : "0", "cc");

  if (ok == 1)
    pass ();
  else
    fail ();
}

static void
foo (void)
{
}

/* Make sure we can relocate a BL instruction.  */

static void
can_relocate_bl (void)
{
  asm ("set_point11:\n"
       "  bl foo\n"
       "  bl pass\n"
       : : : "x30"); /* Test that LR is updated correctly.  */
}

#endif

/* Functions testing relocations need to be placed here.  GDB will read
   n_testcases to know how many fast tracepoints to place.  It will look
   for symbols in the form of 'set_point\[0-9\]+' so each functions
   needs one, starting at 0.  */

static testcase_ftype testcases[] = {
#if (defined __x86_64__ || defined __i386__)
  can_relocate_call,
  can_relocate_jump
#elif (defined __aarch64__)
  can_relocate_b,
  can_relocate_bcond_true,
  can_relocate_cbz,
  can_relocate_cbnz,
  can_relocate_tbz,
  can_relocate_tbnz,
  can_relocate_adr_forward,
  can_relocate_adr_backward,
  can_relocate_adrp,
  can_relocate_ldr,
  can_relocate_bcond_false,
  can_relocate_bl,
#endif
};

static size_t n_testcases = (sizeof (testcases) / sizeof (testcase_ftype));

int
main ()
{
  int i = 0;

  for (i = 0; i < n_testcases; i++)
    testcases[i] ();

  return 0;
}