Re: [PATCH 1/2,v3] [AArch64] Recognize more program breakpoint patterns

[Luis Machado <luis.machado@linaro.org>]

Thanks Alan.

Any other feedback?

On 1/21/20 8:32 AM, Alan Hayward wrote:
> I’m happy with this from AArch64 side.
> 
> Alan.
> 
>> On 15 Jan 2020, at 11:51, Luis Machado <luis.machado@linaro.org> wrote:
>>
>> New in v3:
>>
>> - Code cleanups based on reviews.
>>
>> New in v2:
>>
>> - Fixed misc problems based on reviews.
>> - Switched to using gdbarch_program_breakpoint_here_p as opposed to
>> gdbarch_insn_is_breakpoint.
>> - Fixed matching of brk instructions. Previously the mask was incorrect, which
>> was showing up as a few failures in the testsuite. Now it is clean.
>> - New testcase (separate patch).
>> - Moved program_breakpoint_here () to arch-utils.c and made it the default
>> implementation of gdbarch_program_breakpoint_here_p.
>>
>> --
>>
>> It was reported to me that program breakpoints (permanent ones inserted into
>> the code itself) other than the one GDB uses for AArch64 (0xd4200000) do not
>> generate visible stops when continuing, and GDB will continue spinning
>> infinitely.
>>
>> This happens because GDB, upon hitting one of those program breakpoints, thinks
>> the SIGTRAP came from a delayed breakpoint hit...
>>
>> (gdb) x/i $pc
>> => 0x4005c0 <problem_function>: brk     #0x90f
>> (gdb) c
>> Continuing.
>> infrun: clear_proceed_status_thread (process 14198)
>> infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT)
>> infrun: proceed: resuming process 14198
>> infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0
>> infrun: infrun_async(1)
>> infrun: prepare_to_wait
>> infrun: target_wait (-1.0.0, status) =
>> infrun:   14198.14198.0 [process 14198],
>> infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
>> infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP
>> infrun: stop_pc = 0x4005c0
>> infrun: delayed software breakpoint trap, ignoring
>> infrun: no stepping, continue
>> infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0
>> infrun: prepare_to_wait
>> infrun: target_wait (-1.0.0, status) =
>> infrun:   14198.14198.0 [process 14198],
>> infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
>> infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP
>> infrun: stop_pc = 0x4005c0
>> infrun: delayed software breakpoint trap, ignoring
>> infrun: no stepping, continue
>> infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0
>> infrun: prepare_to_wait
>> infrun: target_wait (-1.0.0, status) =
>> infrun:   14198.14198.0 [process 14198],
>> infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
>> infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP
>> infrun: stop_pc = 0x4005c0
>> infrun: delayed software breakpoint trap, ignoring
>> infrun: no stepping, continue
>> infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0
>> infrun: prepare_to_wait
>> infrun: target_wait (-1.0.0, status) =
>> infrun:   14198.14198.0 [process 14198],
>> infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
>> infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP
>> infrun: stop_pc = 0x4005c0
>> infrun: delayed software breakpoint trap, ignoring
>> infrun: no stepping, continue
>> infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14198] at 0x4005c0
>> infrun: prepare_to_wait
>> infrun: target_wait (-1.0.0, status) =
>> infrun:   14198.14198.0 [process 14198],
>> infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
>> ...
>>
>> ... which is not the case.
>>
>> If the program breakpoint is one GDB recognizes, then it will stop when it
>> hits it.
>>
>> (gdb) x/i $pc
>> => 0x4005c0 <problem_function>: brk     #0x0
>> (gdb) c
>> Continuing.
>> infrun: clear_proceed_status_thread (process 14193)
>> infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT)
>> infrun: proceed: resuming process 14193
>> infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 14193] at 0x4005c0
>> infrun: infrun_async(1)
>> infrun: prepare_to_wait
>> infrun: target_wait (-1.0.0, status) =
>> infrun:   14193.14193.0 [process 14193],
>> infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
>> infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP
>> infrun: stop_pc = 0x4005c0
>> infrun: random signal (GDB_SIGNAL_TRAP)
>> infrun: stop_waiting
>> infrun: stop_all_threads
>> infrun: stop_all_threads, pass=0, iterations=0
>> infrun:   process 14193 not executing
>> infrun: stop_all_threads, pass=1, iterations=1
>> infrun:   process 14193 not executing
>> infrun: stop_all_threads done
>>
>> Program received signal SIGTRAP, Trace/breakpoint trap.
>> problem_function () at brk_0.c:7
>> 7        asm("brk %0\n\t" ::"n"(0x0));
>> infrun: infrun_async(0)
>>
>> Otherwise GDB will keep trying to resume the inferior and will keep
>> seeing the SIGTRAP's, without stopping.
>>
>> To the user it appears GDB has gone into an infinite loop, interruptible only
>> by Ctrl-C.
>>
>> Also, windbg seems to use a different variation of AArch64 breakpoint compared
>> to GDB. This causes problems when debugging Windows on ARM binaries, when
>> program breakpoints are being used.
>>
>> The proposed patch creates a new gdbarch method (gdbarch_program_breakpoint_here_p)
>> that tells GDB whether the underlying instruction is a breakpoint instruction
>> or not.
>>
>> This is more general than only checking for the instruction GDB uses as
>> breakpoint.
>>
>> The existing logic is still preserved for targets that do not implement this
>> new gdbarch method.
>>
>> The end result is like so:
>>
>> (gdb) x/i $pc
>> => 0x4005c0 <problem_function>: brk     #0x90f
>> (gdb) c
>> Continuing.
>> infrun: clear_proceed_status_thread (process 16417)
>> infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT)
>> infrun: proceed: resuming process 16417
>> infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 16417] at 0x4005c0
>> infrun: infrun_async(1)
>> infrun: prepare_to_wait
>> infrun: target_wait (-1.0.0, status) =
>> infrun:   16417.16417.0 [process 16417],
>> infrun:   status->kind = stopped, signal = GDB_SIGNAL_TRAP
>> infrun: handle_inferior_event status->kind = stopped, signal = GDB_SIGNAL_TRAP
>> infrun: stop_pc = 0x4005c0
>> infrun: random signal (GDB_SIGNAL_TRAP)
>> infrun: stop_waiting
>> infrun: stop_all_threads
>> infrun: stop_all_threads, pass=0, iterations=0
>> infrun:   process 16417 not executing
>> infrun: stop_all_threads, pass=1, iterations=1
>> infrun:   process 16417 not executing
>> infrun: stop_all_threads done
>>
>> Program received signal SIGTRAP, Trace/breakpoint trap.
>> problem_function () at brk.c:7
>> 7        asm("brk %0\n\t" ::"n"(0x900 + 0xf));
>> infrun: infrun_async(0)
>>
>> gdb/ChangeLog:
>>
>> 2020-01-15  Luis Machado  <luis.machado@linaro.org>
>>
>> 	* aarch64-tdep.c (BRK_INSN_MASK): Define to 0xffe0001f.
>> 	(BRK_INSN_MASK): Define to 0xd4200000.
>> 	(aarch64_program_breakpoint_here_p): New function.
>> 	(aarch64_gdbarch_init): Set gdbarch_program_breakpoint_here_p hook.
>> 	* arch-utils.c (default_program_breakpoint_here_p): Moved from
>> 	breakpoint.c.
>> 	* arch-utils.h (default_program_breakpoint_here_p): Moved from
>> 	breakpoint.h
>> 	* breakpoint.c (bp_loc_is_permanent): Changed return type to bool and
>> 	call gdbarch_program_breakpoint_here_p.
>> 	(program_breakpoint_here): Moved to arch-utils.c, renamed to
>> 	default_program_breakpoint_here_p, changed return type to bool and
>> 	simplified.
>> 	* breakpoint.h (program_breakpoint_here): Moved prototype to
>> 	arch-utils.h, renamed to default_program_breakpoint_here_p and changed
>> 	return type to bool.
>> 	* gdbarch.c: Regenerate.
>> 	* gdbarch.h: Regenerate.
>> 	* gdbarch.sh (program_breakpoint_here_p): New method.
>> 	* infrun.c (handle_signal_stop): Call
>> 	gdbarch_program_breakpoint_here_p.
>> ---
>> gdb/aarch64-tdep.c | 37 +++++++++++++++++++++++++++++++++++++
>> gdb/arch-utils.c   | 32 ++++++++++++++++++++++++++++++++
>> gdb/arch-utils.h   |  4 ++++
>> gdb/breakpoint.c   | 46 +++++++---------------------------------------
>> gdb/breakpoint.h   |  5 -----
>> gdb/gdbarch.c      | 23 +++++++++++++++++++++++
>> gdb/gdbarch.h      |  7 +++++++
>> gdb/gdbarch.sh     |  4 ++++
>> gdb/infrun.c       |  4 ++--
>> 9 files changed, 116 insertions(+), 46 deletions(-)
>>
>> diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c
>> index 8451a916dc..7f32df3ec0 100644
>> --- a/gdb/aarch64-tdep.c
>> +++ b/gdb/aarch64-tdep.c
>> @@ -1201,6 +1201,39 @@ aarch64_execute_dwarf_cfa_vendor_op (struct gdbarch *gdbarch, gdb_byte op,
>>    return false;
>> }
>>
>> +/* Used for matching BRK instructions for AArch64.  */
>> +static constexpr uint32_t BRK_INSN_MASK = 0xffe0001f;
>> +static constexpr uint32_t BRK_INSN_BASE = 0xd4200000;
>> +
>> +/* Implementation of gdbarch_program_breakpoint_here_p for aarch64.  */
>> +
>> +static bool
>> +aarch64_program_breakpoint_here_p (gdbarch *gdbarch, CORE_ADDR address)
>> +{
>> +  const uint32_t insn_len = 4;
>> +  gdb_byte target_mem[4];
>> +
>> +  /* Enable the automatic memory restoration from breakpoints while
>> +     we read the memory.  Otherwise we may find temporary breakpoints, ones
>> +     inserted by GDB, and flag them as permanent breakpoints.  */
>> +  scoped_restore restore_memory
>> +    = make_scoped_restore_show_memory_breakpoints (0);
>> +
>> +  if (target_read_memory (address, target_mem, insn_len) == 0)
>> +    {
>> +      uint32_t insn =
>> +	(uint32_t) extract_unsigned_integer (target_mem, insn_len,
>> +					     gdbarch_byte_order_for_code (gdbarch));
>> +
>> +      /* Check if INSN is a BRK instruction pattern.  There are multiple choices
>> +	 of such instructions with different immediate values.  Different OS'
>> +	 may use a different variation, but they have the same outcome.  */
>> +	return ((insn & BRK_INSN_MASK) == BRK_INSN_BASE);
>> +    }
>> +
>> +  return false;
>> +}
>> +
>> /* When arguments must be pushed onto the stack, they go on in reverse
>>     order.  The code below implements a FILO (stack) to do this.  */
>>
>> @@ -3357,6 +3390,10 @@ aarch64_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
>>    set_gdbarch_execute_dwarf_cfa_vendor_op (gdbarch,
>> 					   aarch64_execute_dwarf_cfa_vendor_op);
>>
>> +  /* Permanent/Program breakpoint handling.  */
>> +  set_gdbarch_program_breakpoint_here_p (gdbarch,
>> +					 aarch64_program_breakpoint_here_p);
>> +
>>    /* Add some default predicates.  */
>>    frame_unwind_append_unwinder (gdbarch, &aarch64_stub_unwind);
>>    dwarf2_append_unwinders (gdbarch);
>> diff --git a/gdb/arch-utils.c b/gdb/arch-utils.c
>> index 92d7153ccb..04955ea847 100644
>> --- a/gdb/arch-utils.c
>> +++ b/gdb/arch-utils.c
>> @@ -876,6 +876,38 @@ int default_insn_is_jump (struct gdbarch *gdbarch, CORE_ADDR addr)
>>    return 0;
>> }
>>
>> +/*  See arch-utils.h.  */
>> +
>> +bool
>> +default_program_breakpoint_here_p (struct gdbarch *gdbarch,
>> +				   CORE_ADDR address)
>> +{
>> +  int len;
>> +  const gdb_byte *bpoint = gdbarch_breakpoint_from_pc (gdbarch, &address, &len);
>> +
>> +  /* Software breakpoints unsupported?  */
>> +  if (bpoint == nullptr)
>> +    return false;
>> +
>> +  gdb_byte *target_mem = (gdb_byte *) alloca (len);
>> +
>> +  /* Enable the automatic memory restoration from breakpoints while
>> +     we read the memory.  Otherwise we may find temporary breakpoints, ones
>> +     inserted by GDB, and flag them as permanent breakpoints.  */
>> +  scoped_restore restore_memory
>> +    = make_scoped_restore_show_memory_breakpoints (0);
>> +
>> +  if (target_read_memory (address, target_mem, len) == 0)
>> +    {
>> +      /* Check if this is a breakpoint instruction for this architecture,
>> +	 including ones used by GDB.  */
>> +      if (memcmp (target_mem, bpoint, len) == 0)
>> +	return true;
>> +    }
>> +
>> +  return false;
>> +}
>> +
>> void
>> default_skip_permanent_breakpoint (struct regcache *regcache)
>> {
>> diff --git a/gdb/arch-utils.h b/gdb/arch-utils.h
>> index 3fb9ad317a..43d64b1f4f 100644
>> --- a/gdb/arch-utils.h
>> +++ b/gdb/arch-utils.h
>> @@ -228,6 +228,10 @@ extern int default_insn_is_call (struct gdbarch *, CORE_ADDR);
>> extern int default_insn_is_ret (struct gdbarch *, CORE_ADDR);
>> extern int default_insn_is_jump (struct gdbarch *, CORE_ADDR);
>>
>> +/* Default implementation of gdbarch_program_breakpoint_here_p.  */
>> +extern bool default_program_breakpoint_here_p (struct gdbarch *gdbarch,
>> +					       CORE_ADDR addr);
>> +
>> /* Do-nothing version of vsyscall_range.  Returns false.  */
>>
>> extern int default_vsyscall_range (struct gdbarch *gdbarch, struct mem_range *range);
>> diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
>> index a7a378131a..5a9352c26f 100644
>> --- a/gdb/breakpoint.c
>> +++ b/gdb/breakpoint.c
>> @@ -8515,7 +8515,7 @@ mention (struct breakpoint *b)
>> }
>>
>>
>> -static int bp_loc_is_permanent (struct bp_location *loc);
>> +static bool bp_loc_is_permanent (struct bp_location *loc);
>>
>> static struct bp_location *
>> add_location_to_breakpoint (struct breakpoint *b,
>> @@ -8581,42 +8581,10 @@ add_location_to_breakpoint (struct breakpoint *b,
>> }
>>
>>
>> -/* See breakpoint.h.  */
>> -
>> -int
>> -program_breakpoint_here_p (struct gdbarch *gdbarch, CORE_ADDR address)
>> -{
>> -  int len;
>> -  CORE_ADDR addr;
>> -  const gdb_byte *bpoint;
>> -  gdb_byte *target_mem;
>> -
>> -  addr = address;
>> -  bpoint = gdbarch_breakpoint_from_pc (gdbarch, &addr, &len);
>> -
>> -  /* Software breakpoints unsupported?  */
>> -  if (bpoint == NULL)
>> -    return 0;
>> -
>> -  target_mem = (gdb_byte *) alloca (len);
>> -
>> -  /* Enable the automatic memory restoration from breakpoints while
>> -     we read the memory.  Otherwise we could say about our temporary
>> -     breakpoints they are permanent.  */
>> -  scoped_restore restore_memory
>> -    = make_scoped_restore_show_memory_breakpoints (0);
>> +/* Return true if LOC is pointing to a permanent breakpoint,
>> +   return false otherwise.  */
>>
>> -  if (target_read_memory (address, target_mem, len) == 0
>> -      && memcmp (target_mem, bpoint, len) == 0)
>> -    return 1;
>> -
>> -  return 0;
>> -}
>> -
>> -/* Return 1 if LOC is pointing to a permanent breakpoint,
>> -   return 0 otherwise.  */
>> -
>> -static int
>> +static bool
>> bp_loc_is_permanent (struct bp_location *loc)
>> {
>>    gdb_assert (loc != NULL);
>> @@ -8624,14 +8592,14 @@ bp_loc_is_permanent (struct bp_location *loc)
>>    /* If we have a non-breakpoint-backed catchpoint or a software
>>       watchpoint, just return 0.  We should not attempt to read from
>>       the addresses the locations of these breakpoint types point to.
>> -     program_breakpoint_here_p, below, will attempt to read
>> +     gdbarch_program_breakpoint_here_p, below, will attempt to read
>>       memory.  */
>>    if (!bl_address_is_meaningful (loc))
>> -    return 0;
>> +    return false;
>>
>>    scoped_restore_current_pspace_and_thread restore_pspace_thread;
>>    switch_to_program_space_and_thread (loc->pspace);
>> -  return program_breakpoint_here_p (loc->gdbarch, loc->address);
>> +  return gdbarch_program_breakpoint_here_p (loc->gdbarch, loc->address);
>> }
>>
>> /* Build a command list for the dprintf corresponding to the current
>> diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h
>> index 13d8102c17..347aeb75f3 100644
>> --- a/gdb/breakpoint.h
>> +++ b/gdb/breakpoint.h
>> @@ -1194,11 +1194,6 @@ enum breakpoint_here
>>
>> /* Prototypes for breakpoint-related functions.  */
>>
>> -/* Return 1 if there's a program/permanent breakpoint planted in
>> -   memory at ADDRESS, return 0 otherwise.  */
>> -
>> -extern int program_breakpoint_here_p (struct gdbarch *gdbarch, CORE_ADDR address);
>> -
>> extern enum breakpoint_here breakpoint_here_p (const address_space *,
>> 					       CORE_ADDR);
>>
>> diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
>> index cc8569f5c9..d763fc85e6 100644
>> --- a/gdb/gdbarch.c
>> +++ b/gdb/gdbarch.c
>> @@ -345,6 +345,7 @@ struct gdbarch
>>    gdbarch_insn_is_call_ftype *insn_is_call;
>>    gdbarch_insn_is_ret_ftype *insn_is_ret;
>>    gdbarch_insn_is_jump_ftype *insn_is_jump;
>> +  gdbarch_program_breakpoint_here_p_ftype *program_breakpoint_here_p;
>>    gdbarch_auxv_parse_ftype *auxv_parse;
>>    gdbarch_print_auxv_entry_ftype *print_auxv_entry;
>>    gdbarch_vsyscall_range_ftype *vsyscall_range;
>> @@ -464,6 +465,7 @@ gdbarch_alloc (const struct gdbarch_info *info,
>>    gdbarch->insn_is_call = default_insn_is_call;
>>    gdbarch->insn_is_ret = default_insn_is_ret;
>>    gdbarch->insn_is_jump = default_insn_is_jump;
>> +  gdbarch->program_breakpoint_here_p = default_program_breakpoint_here_p;
>>    gdbarch->print_auxv_entry = default_print_auxv_entry;
>>    gdbarch->vsyscall_range = default_vsyscall_range;
>>    gdbarch->infcall_mmap = default_infcall_mmap;
>> @@ -708,6 +710,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
>>    /* Skip verify of insn_is_call, invalid_p == 0 */
>>    /* Skip verify of insn_is_ret, invalid_p == 0 */
>>    /* Skip verify of insn_is_jump, invalid_p == 0 */
>> +  /* Skip verify of program_breakpoint_here_p, invalid_p == 0 */
>>    /* Skip verify of auxv_parse, has predicate.  */
>>    /* Skip verify of print_auxv_entry, invalid_p == 0 */
>>    /* Skip verify of vsyscall_range, invalid_p == 0 */
>> @@ -1248,6 +1251,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
>>    fprintf_unfiltered (file,
>>                        "gdbarch_dump: process_record_signal = <%s>\n",
>>                        host_address_to_string (gdbarch->process_record_signal));
>> +  fprintf_unfiltered (file,
>> +                      "gdbarch_dump: program_breakpoint_here_p = <%s>\n",
>> +                      host_address_to_string (gdbarch->program_breakpoint_here_p));
>>    fprintf_unfiltered (file,
>>                        "gdbarch_dump: ps_regnum = %s\n",
>>                        plongest (gdbarch->ps_regnum));
>> @@ -4928,6 +4934,23 @@ set_gdbarch_insn_is_jump (struct gdbarch *gdbarch,
>>    gdbarch->insn_is_jump = insn_is_jump;
>> }
>>
>> +bool
>> +gdbarch_program_breakpoint_here_p (struct gdbarch *gdbarch, CORE_ADDR address)
>> +{
>> +  gdb_assert (gdbarch != NULL);
>> +  gdb_assert (gdbarch->program_breakpoint_here_p != NULL);
>> +  if (gdbarch_debug >= 2)
>> +    fprintf_unfiltered (gdb_stdlog, "gdbarch_program_breakpoint_here_p called\n");
>> +  return gdbarch->program_breakpoint_here_p (gdbarch, address);
>> +}
>> +
>> +void
>> +set_gdbarch_program_breakpoint_here_p (struct gdbarch *gdbarch,
>> +                                       gdbarch_program_breakpoint_here_p_ftype program_breakpoint_here_p)
>> +{
>> +  gdbarch->program_breakpoint_here_p = program_breakpoint_here_p;
>> +}
>> +
>> int
>> gdbarch_auxv_parse_p (struct gdbarch *gdbarch)
>> {
>> diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h
>> index 9f32ac23ab..800a4e8b16 100644
>> --- a/gdb/gdbarch.h
>> +++ b/gdb/gdbarch.h
>> @@ -1545,6 +1545,13 @@ typedef int (gdbarch_insn_is_jump_ftype) (struct gdbarch *gdbarch, CORE_ADDR add
>> extern int gdbarch_insn_is_jump (struct gdbarch *gdbarch, CORE_ADDR addr);
>> extern void set_gdbarch_insn_is_jump (struct gdbarch *gdbarch, gdbarch_insn_is_jump_ftype *insn_is_jump);
>>
>> +/* Return true if there's a program/permanent breakpoint planted in
>> +   memory at ADDRESS, return false otherwise. */
>> +
>> +typedef bool (gdbarch_program_breakpoint_here_p_ftype) (struct gdbarch *gdbarch, CORE_ADDR address);
>> +extern bool gdbarch_program_breakpoint_here_p (struct gdbarch *gdbarch, CORE_ADDR address);
>> +extern void set_gdbarch_program_breakpoint_here_p (struct gdbarch *gdbarch, gdbarch_program_breakpoint_here_p_ftype *program_breakpoint_here_p);
>> +
>> /* Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
>>     Return 0 if *READPTR is already at the end of the buffer.
>>     Return -1 if there is insufficient buffer for a whole entry.
>> diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh
>> index 0be3e88bb2..66b54dd700 100755
>> --- a/gdb/gdbarch.sh
>> +++ b/gdb/gdbarch.sh
>> @@ -1152,6 +1152,10 @@ m;int;insn_is_ret;CORE_ADDR addr;addr;;default_insn_is_ret;;0
>> # Return non-zero if the instruction at ADDR is a jump; zero otherwise.
>> m;int;insn_is_jump;CORE_ADDR addr;addr;;default_insn_is_jump;;0
>>
>> +# Return true if there's a program/permanent breakpoint planted in
>> +# memory at ADDRESS, return false otherwise.
>> +m;bool;program_breakpoint_here_p;CORE_ADDR address;address;;default_program_breakpoint_here_p;;0
>> +
>> # Read one auxv entry from *READPTR, not reading locations >= ENDPTR.
>> # Return 0 if *READPTR is already at the end of the buffer.
>> # Return -1 if there is insufficient buffer for a whole entry.
>> diff --git a/gdb/infrun.c b/gdb/infrun.c
>> index a8636284f1..494324d72b 100644
>> --- a/gdb/infrun.c
>> +++ b/gdb/infrun.c
>> @@ -6157,8 +6157,8 @@ handle_signal_stop (struct execution_control_state *ecs)
>>       been removed.  */
>>    if (random_signal && target_stopped_by_sw_breakpoint ())
>>      {
>> -      if (program_breakpoint_here_p (gdbarch,
>> -				     ecs->event_thread->suspend.stop_pc))
>> +      if (gdbarch_program_breakpoint_here_p (gdbarch,
>> +					     ecs->event_thread->suspend.stop_pc))
>> 	{
>> 	  struct regcache *regcache;
>> 	  int decr_pc;
>> -- 
>> 2.17.1
>>
>