[AArch64] Only check breakpoint alignment on inserting
Commit Message
This patch fixes the GDB internal error on AArch64 when running
watchpoint-fork.exp
top?bt 15
at ../../binutils-gdb/gdb/common/errors.c:51
...
...
at ../../binutils-gdb/gdb/nat/aarch64-linux-hw-point.c:465
at ../../binutils-gdb/gdb/aarch64-linux-nat.c:657
at ../../binutils-gdb/gdb/target-delegates.c:492
After the fork, GDB will physically remove the breakpoints from the child
process (in frame #14), but at that time, GDB doesn't create an inferior
yet for child, but inferior_ptid is set to child's ptid (in frame #13).
In aarch64_point_is_aligned, we'll get the regcache of current_lwp_ptid
to determine if the current process is 32-bit or 64-bit, so the inferior
can't be found, and the internal error is caused.
I don't find a better fix other than not checking alignment on removing
breakpoint.
gdb:
2015-11-23 Yao Qi <yao.qi@linaro.org>
* nat/aarch64-linux-hw-point.c (aarch64_dr_state_remove_one_point):
Don't assert on alignment.
(aarch64_handle_breakpoint): Only check alignment when IS_INSERT
is true.
---
gdb/nat/aarch64-linux-hw-point.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
Comments
Yao Qi <qiyaoltc@gmail.com> writes:
> top?bt 15
> at ../../binutils-gdb/gdb/common/errors.c:51
> ...
> ...
> at ../../binutils-gdb/gdb/nat/aarch64-linux-hw-point.c:465
> at ../../binutils-gdb/gdb/aarch64-linux-nat.c:657
> at ../../binutils-gdb/gdb/target-delegates.c:492
Oops, stack frames prefixed by "#" are eaten by git, post the stack
frames again here,
top?bt 15
internal_error (file=file@entry=0x79d558 "../../binutils-gdb/gdb/linux-nat.c", line=line@entry=4866, fmt=0x793b20 "%s: Assertion `%s' failed.")
at ../../binutils-gdb/gdb/common/errors.c:51
#1 0x0000000000495bc4 in linux_nat_thread_address_space (t=<optimized out>, ptid=<error reading variable: Cannot access memory at address 0x1302>)
at ../../binutils-gdb/gdb/linux-nat.c:4866
#2 0x00000000005db2c8 in delegate_thread_address_space (self=<optimized out>, arg1=<error reading variable: Cannot access memory at address 0x1302>)
at ../../binutils-gdb/gdb/target-delegates.c:2447
#3 0x00000000005e8c7c in target_thread_address_space (ptid=<error reading variable: Cannot access memory at address 0x1302>)
at ../../binutils-gdb/gdb/target.c:2727
#4 0x000000000054eef8 in get_thread_arch_regcache (ptid=..., gdbarch=0xad51e0) at ../../binutils-gdb/gdb/regcache.c:529
#5 0x000000000054efcc in get_thread_regcache (ptid=...) at ../../binutils-gdb/gdb/regcache.c:546
#6 0x000000000054f120 in get_thread_regcache_for_ptid (ptid=...) at ../../binutils-gdb/gdb/regcache.c:560
#7 0x00000000004a2278 in aarch64_point_is_aligned (is_watchpoint=0, addr=34168, len=2) at ../../binutils-gdb/gdb/nat/aarch64-linux-hw-point.c:122
#8 0x00000000004a2e68 in aarch64_handle_breakpoint (type=hw_execute, addr=34168, len=2, is_insert=0, state=0xae8880)
at ../../binutils-gdb/gdb/nat/aarch64-linux-hw-point.c:465
#9 0x000000000048edf0 in aarch64_linux_remove_hw_breakpoint (self=<optimized out>, gdbarch=<optimized out>, bp_tgt=<optimized out>)
at ../../binutils-gdb/gdb/aarch64-linux-nat.c:657
#10 0x00000000005da8dc in delegate_remove_hw_breakpoint (self=<optimized out>, arg1=<optimized out>, arg2=<optimized out>)
at ../../binutils-gdb/gdb/target-delegates.c:492
#11 0x0000000000536a24 in bkpt_remove_location (bl=<optimized out>) at ../../binutils-gdb/gdb/breakpoint.c:13065
#12 0x000000000053351c in remove_breakpoint_1 (bl=0xb3fe70, is=is@entry=mark_inserted) at ../../binutils-gdb/gdb/breakpoint.c:4026
#13 0x000000000053ccc0 in detach_breakpoints (ptid=...) at ../../binutils-gdb/gdb/breakpoint.c:3930
#14 0x00000000005a3ac0 in handle_inferior_event_1 (ecs=0x7ffffff048) at ../../binutils-gdb/gdb/infrun.c:5042
Yao Qi <qiyaoltc@gmail.com> writes:
> gdb:
>
> 2015-11-23 Yao Qi <yao.qi@linaro.org>
>
> * nat/aarch64-linux-hw-point.c (aarch64_dr_state_remove_one_point):
> Don't assert on alignment.
> (aarch64_handle_breakpoint): Only check alignment when IS_INSERT
> is true.
Patch is pushed in.
@@ -411,7 +411,6 @@ aarch64_dr_state_remove_one_point (struct aarch64_debug_reg_state *state,
/* Set up state pointers. */
is_watchpoint = (type != hw_execute);
- gdb_assert (aarch64_point_is_aligned (is_watchpoint, addr, len));
if (is_watchpoint)
{
num_regs = aarch64_num_wp_regs;
@@ -460,13 +459,21 @@ aarch64_handle_breakpoint (enum target_hw_bp_type type, CORE_ADDR addr,
int len, int is_insert,
struct aarch64_debug_reg_state *state)
{
- /* The hardware breakpoint on AArch64 should always be 4-byte
- aligned, but on AArch32, it can be 2-byte aligned. */
- if (!aarch64_point_is_aligned (0 /* is_watchpoint */ , addr, len))
- return -1;
-
if (is_insert)
- return aarch64_dr_state_insert_one_point (state, type, addr, len);
+ {
+ /* The hardware breakpoint on AArch64 should always be 4-byte
+ aligned, but on AArch32, it can be 2-byte aligned. Note that
+ we only check the alignment on inserting breakpoint because
+ aarch64_point_is_aligned needs the inferior_ptid inferior's
+ regcache to decide whether the inferior is 32-bit or 64-bit.
+ However when GDB follows the parent process and detach breakpoints
+ from child process, inferior_ptid is the child ptid, but the
+ child inferior doesn't exist in GDB's view yet. */
+ if (!aarch64_point_is_aligned (0 /* is_watchpoint */ , addr, len))
+ return -1;
+
+ return aarch64_dr_state_insert_one_point (state, type, addr, len);
+ }
else
return aarch64_dr_state_remove_one_point (state, type, addr, len);
}