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| author | Yao Qi <yao.qi@linaro.org> | 2016-04-25 09:16:21 +0100 |
|---|---|---|
| committer | Yao Qi <yao.qi@linaro.org> | 2016-04-25 09:16:21 +0100 |
| commit | 21edc42f4e1ec6fe8cfce171232bab27ad4af372 (patch) | |
| tree | e78cffc7c9c92a0492e51e2d0b9b989518ed4e39 /gdb/breakpoint.c | |
| parent | 101ae4cd3167bcb6fa1becee4f0c3ad1ffc41f15 (diff) | |
| download | gdb-21edc42f4e1ec6fe8cfce171232bab27ad4af372.zip gdb-21edc42f4e1ec6fe8cfce171232bab27ad4af372.tar.gz gdb-21edc42f4e1ec6fe8cfce171232bab27ad4af372.tar.bz2 | |
Force to insert software single step breakpoint
GDB doesn't insert software single step breakpoint if the instruction
branches to itself, so that the program can't stop after command "si".
(gdb) b 32
Breakpoint 2 at 0x8680: file git/gdb/testsuite/gdb.base/branch-to-self.c, line 32.
(gdb) c
Continuing.
Breakpoint 2, main () at gdb/git/gdb/testsuite/gdb.base/branch-to-self.c:32
32 asm (".Lhere: " BRANCH_INSN " .Lhere"); /* loop-line */
(gdb) si
infrun: clear_proceed_status_thread (Thread 3991.3991)
infrun: proceed (addr=0xffffffff, signal=GDB_SIGNAL_DEFAULT)
infrun: step-over queue now empty
infrun: resuming [Thread 3991.3991] for step-over
infrun: skipping breakpoint: stepping past insn at: 0x8680
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Sending packet: $Z0,8678,4#f3...Packet received: OK
infrun: skipping breakpoint: stepping past insn at: 0x8680
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Sending packet: $Z0,b6fe86c8,4#82...Packet received: OK
infrun: resume (step=1, signal=GDB_SIGNAL_0), trap_expected=1, current thread [Thread 3991.3991] at 0x868
breakpoint.c:should_be_inserted thinks the breakpoint shouldn't be
inserted, which is wrong. This patch restrict the condition that
only skip the non-single-step breakpoints if they are inserted at
the place we are stepping over, however we don't want to skip
single-step breakpoint if its thread is the thread we are stepping
over, so in this patch, I add a thread num in 'struct step_over_info'
to record the thread we're stepping over.
gdb:
2016-04-25 Yao Qi <yao.qi@linaro.org>
* breakpoint.c (should_be_inserted): Return 0 if the location's
owner is not single step breakpoint or single step breakpoint's
thread isn't the thread which is stepping past a breakpoint.
* gdbarch.sh (software_single_step): Update comments.
* gdbarch.h: Regenerated.
* infrun.c (struct step_over_info) <thread>: New field.
(set_step_over_info): New argument 'thread'. Callers updated.
(clear_step_over_info): Set field thread to -1.
(thread_is_stepping_over_breakpoint): New function.
* infrun.h (thread_is_stepping_over_breakpoint): Declaration.
Diffstat (limited to 'gdb/breakpoint.c')
| -rw-r--r-- | gdb/breakpoint.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c index f99a7ab..a39a15c 100644 --- a/gdb/breakpoint.c +++ b/gdb/breakpoint.c @@ -2219,11 +2219,22 @@ should_be_inserted (struct bp_location *bl) return 0; /* Don't insert a breakpoint if we're trying to step past its - location. */ + location, except if the breakpoint is a single-step breakpoint, + and the breakpoint's thread is the thread which is stepping past + a breakpoint. */ if ((bl->loc_type == bp_loc_software_breakpoint || bl->loc_type == bp_loc_hardware_breakpoint) && stepping_past_instruction_at (bl->pspace->aspace, - bl->address)) + bl->address) + /* The single-step breakpoint may be inserted at the location + we're trying to step if the instruction branches to itself. + However, the instruction won't be executed at all and it may + break the semantics of the instruction, for example, the + instruction is a conditional branch or updates some flags. + We can't fix it unless GDB is able to emulate the instruction + or switch to displaced stepping. */ + && !(bl->owner->type == bp_single_step + && thread_is_stepping_over_breakpoint (bl->owner->thread))) { if (debug_infrun) { |