+2016-02-24 Pedro Alves <palves@redhat.com>
+
+ * linux-nat.c (save_sigtrap) Delete.
+ (stop_wait_callback): Call save_stop_reason instead of
+ save_sigtrap.
+ (check_stopped_by_breakpoint): Rename to ...
+ (save_stop_reason): ... this. Bits of save_sigtrap folded here.
+ Use GDB_ARCH_IS_TRAP_HWBKPT and handle ambiguous
+ GDB_ARCH_IS_TRAP_BRKPT / GDB_ARCH_IS_TRAP_HWBKPT. Factor out
+ common code between the USE_SIGTRAP_SIGINFO and
+ !USE_SIGTRAP_SIGINFO blocks.
+ (linux_nat_filter_event): Call save_stop_reason instead of
+ save_sigtrap.
+ * nat/linux-ptrace.h: Check for both SI_KERNEL and TRAP_BRKPT
+ si_code for MIPS.
+ * nat/linux-ptrace.h: Fix "TRAP_HWBPT" typo in x86 table. Add
+ comments on MIPS behavior.
+ (GDB_ARCH_IS_TRAP_HWBKPT): Define for all archs.
+
2016-02-24 Marcin KoĆcielnicki <koriakin@0x04.net>
* rs6000-tdep.c (rs6000_frame_cache): Initialize frame and pc to 0
+2016-02-24 Pedro Alves <palves@redhat.com>
+
+ * linux-low.c (check_stopped_by_breakpoint): Rename to ...
+ (save_stop_reason): ... this. Use GDB_ARCH_IS_TRAP_HWBKPT and
+ handle ambiguous GDB_ARCH_IS_TRAP_BRKPT / GDB_ARCH_IS_TRAP_HWBKPT.
+ Factor out common code between the USE_SIGTRAP_SIGINFO and
+ !USE_SIGTRAP_SIGINFO blocks.
+ (linux_low_filter_event): Call save_stop_reason instead of
+ check_stopped_by_breakpoint and check_stopped_by_watchpoint.
+ Update comments.
+ (linux_wait_1): Update comments.
+
2016-02-24 Wei-cheng Wang <cole945@gmail.com>
* linux-ppc-low.c (ppc_supports_z_point_type): New function:
current_thread = saved_thread;
}
-/* This function should only be called if LWP got a SIGTRAP.
- The SIGTRAP could mean several things.
+static int check_stopped_by_watchpoint (struct lwp_info *child);
- On i386, where decr_pc_after_break is non-zero:
-
- If we were single-stepping this process using PTRACE_SINGLESTEP, we
- will get only the one SIGTRAP. The value of $eip will be the next
- instruction. If the instruction we stepped over was a breakpoint,
- we need to decrement the PC.
-
- If we continue the process using PTRACE_CONT, we will get a
- SIGTRAP when we hit a breakpoint. The value of $eip will be
- the instruction after the breakpoint (i.e. needs to be
- decremented). If we report the SIGTRAP to GDB, we must also
- report the undecremented PC. If the breakpoint is removed, we
- must resume at the decremented PC.
-
- On a non-decr_pc_after_break machine with hardware or kernel
- single-step:
-
- If we either single-step a breakpoint instruction, or continue and
- hit a breakpoint instruction, our PC will point at the breakpoint
- instruction. */
+/* Called when the LWP stopped for a signal/trap. If it stopped for a
+ trap check what caused it (breakpoint, watchpoint, trace, etc.),
+ and save the result in the LWP's stop_reason field. If it stopped
+ for a breakpoint, decrement the PC if necessary on the lwp's
+ architecture. Returns true if we now have the LWP's stop PC. */
static int
-check_stopped_by_breakpoint (struct lwp_info *lwp)
+save_stop_reason (struct lwp_info *lwp)
{
CORE_ADDR pc;
CORE_ADDR sw_breakpoint_pc;
{
if (siginfo.si_signo == SIGTRAP)
{
- if (GDB_ARCH_IS_TRAP_BRKPT (siginfo.si_code))
+ if (GDB_ARCH_IS_TRAP_BRKPT (siginfo.si_code)
+ && GDB_ARCH_IS_TRAP_HWBKPT (siginfo.si_code))
{
- if (debug_threads)
- {
- struct thread_info *thr = get_lwp_thread (lwp);
-
- debug_printf ("CSBB: %s stopped by software breakpoint\n",
- target_pid_to_str (ptid_of (thr)));
- }
-
- /* Back up the PC if necessary. */
- if (pc != sw_breakpoint_pc)
- {
- struct regcache *regcache
- = get_thread_regcache (current_thread, 1);
- (*the_low_target.set_pc) (regcache, sw_breakpoint_pc);
- }
-
- lwp->stop_pc = sw_breakpoint_pc;
+ /* The si_code is ambiguous on this arch -- check debug
+ registers. */
+ if (!check_stopped_by_watchpoint (lwp))
+ lwp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT;
+ }
+ else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo.si_code))
+ {
+ /* If we determine the LWP stopped for a SW breakpoint,
+ trust it. Particularly don't check watchpoint
+ registers, because at least on s390, we'd find
+ stopped-by-watchpoint as long as there's a watchpoint
+ set. */
lwp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT;
- current_thread = saved_thread;
- return 1;
}
- else if (siginfo.si_code == TRAP_HWBKPT)
+ else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo.si_code))
{
- if (debug_threads)
- {
- struct thread_info *thr = get_lwp_thread (lwp);
-
- debug_printf ("CSBB: %s stopped by hardware "
- "breakpoint/watchpoint\n",
- target_pid_to_str (ptid_of (thr)));
- }
-
- lwp->stop_pc = pc;
- lwp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT;
- current_thread = saved_thread;
- return 1;
+ /* This can indicate either a hardware breakpoint or
+ hardware watchpoint. Check debug registers. */
+ if (!check_stopped_by_watchpoint (lwp))
+ lwp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT;
}
else if (siginfo.si_code == TRAP_TRACE)
{
- if (debug_threads)
- {
- struct thread_info *thr = get_lwp_thread (lwp);
-
- debug_printf ("CSBB: %s stopped by trace\n",
- target_pid_to_str (ptid_of (thr)));
- }
-
- lwp->stop_reason = TARGET_STOPPED_BY_SINGLE_STEP;
+ /* We may have single stepped an instruction that
+ triggered a watchpoint. In that case, on some
+ architectures (such as x86), instead of TRAP_HWBKPT,
+ si_code indicates TRAP_TRACE, and we need to check
+ the debug registers separately. */
+ if (!check_stopped_by_watchpoint (lwp))
+ lwp->stop_reason = TARGET_STOPPED_BY_SINGLE_STEP;
}
}
}
case we need to report the breakpoint PC. */
if ((!lwp->stepping || lwp->stop_pc == sw_breakpoint_pc)
&& (*the_low_target.breakpoint_at) (sw_breakpoint_pc))
+ lwp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT;
+
+ if (hardware_breakpoint_inserted_here (pc))
+ lwp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT;
+
+ if (lwp->stop_reason == TARGET_STOPPED_BY_NO_REASON)
+ check_stopped_by_watchpoint (lwp);
+#endif
+
+ if (lwp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT)
{
if (debug_threads)
{
/* Back up the PC if necessary. */
if (pc != sw_breakpoint_pc)
- {
+ {
struct regcache *regcache
= get_thread_regcache (current_thread, 1);
(*the_low_target.set_pc) (regcache, sw_breakpoint_pc);
}
- lwp->stop_pc = sw_breakpoint_pc;
- lwp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT;
- current_thread = saved_thread;
- return 1;
+ /* Update this so we record the correct stop PC below. */
+ pc = sw_breakpoint_pc;
}
-
- if (hardware_breakpoint_inserted_here (pc))
+ else if (lwp->stop_reason == TARGET_STOPPED_BY_HW_BREAKPOINT)
{
if (debug_threads)
{
debug_printf ("CSBB: %s stopped by hardware breakpoint\n",
target_pid_to_str (ptid_of (thr)));
}
+ }
+ else if (lwp->stop_reason == TARGET_STOPPED_BY_WATCHPOINT)
+ {
+ if (debug_threads)
+ {
+ struct thread_info *thr = get_lwp_thread (lwp);
- lwp->stop_pc = pc;
- lwp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT;
- current_thread = saved_thread;
- return 1;
+ debug_printf ("CSBB: %s stopped by hardware watchpoint\n",
+ target_pid_to_str (ptid_of (thr)));
+ }
}
-#endif
+ else if (lwp->stop_reason == TARGET_STOPPED_BY_SINGLE_STEP)
+ {
+ if (debug_threads)
+ {
+ struct thread_info *thr = get_lwp_thread (lwp);
+ debug_printf ("CSBB: %s stopped by trace\n",
+ target_pid_to_str (ptid_of (thr)));
+ }
+ }
+
+ lwp->stop_pc = pc;
current_thread = saved_thread;
- return 0;
+ return 1;
}
static struct lwp_info *
child->syscall_state = TARGET_WAITKIND_IGNORE;
}
- /* Be careful to not overwrite stop_pc until
- check_stopped_by_breakpoint is called. */
+ /* Be careful to not overwrite stop_pc until save_stop_reason is
+ called. */
if (WIFSTOPPED (wstat) && WSTOPSIG (wstat) == SIGTRAP
&& linux_is_extended_waitstatus (wstat))
{
}
}
- /* Check first whether this was a SW/HW breakpoint before checking
- watchpoints, because at least s390 can't tell the data address of
- hardware watchpoint hits, and returns stopped-by-watchpoint as
- long as there's a watchpoint set. */
if (WIFSTOPPED (wstat) && linux_wstatus_maybe_breakpoint (wstat))
{
- if (check_stopped_by_breakpoint (child))
+ if (save_stop_reason (child))
have_stop_pc = 1;
}
- /* Note that TRAP_HWBKPT can indicate either a hardware breakpoint
- or hardware watchpoint. Check which is which if we got
- TARGET_STOPPED_BY_HW_BREAKPOINT. Likewise, we may have single
- stepped an instruction that triggered a watchpoint. In that
- case, on some architectures (such as x86), instead of
- TRAP_HWBKPT, si_code indicates TRAP_TRACE, and we need to check
- the debug registers separately. */
- if (WIFSTOPPED (wstat) && WSTOPSIG (wstat) == SIGTRAP
- && child->stop_reason != TARGET_STOPPED_BY_SW_BREAKPOINT)
- check_stopped_by_watchpoint (child);
-
if (!have_stop_pc)
child->stop_pc = get_pc (child);
hardware single step it means a gdb/gdbserver breakpoint had been
planted on top of a permanent breakpoint, in the case of a software
single step it may just mean that gdbserver hit the reinsert breakpoint.
- The PC has been adjusted by check_stopped_by_breakpoint to point at
+ The PC has been adjusted by save_stop_reason to point at
the breakpoint address.
So in the case of the hardware single step advance the PC manually
past the breakpoint and in the case of software single step advance only
static int lwp_status_pending_p (struct lwp_info *lp);
-static int check_stopped_by_breakpoint (struct lwp_info *lp);
static int sigtrap_is_event (int status);
static int (*linux_nat_status_is_event) (int status) = sigtrap_is_event;
+static void save_stop_reason (struct lwp_info *lp);
+
\f
/* LWP accessors. */
return lp->stop_reason == TARGET_STOPPED_BY_WATCHPOINT;
}
-/* Called when the LWP stopped for a trap that could be explained by a
- watchpoint or a breakpoint. */
-
-static void
-save_sigtrap (struct lwp_info *lp)
-{
- gdb_assert (lp->stop_reason == TARGET_STOPPED_BY_NO_REASON);
- gdb_assert (lp->status != 0);
-
- /* Check first if this was a SW/HW breakpoint before checking
- watchpoints, because at least s390 can't tell the data address of
- hardware watchpoint hits, and the kernel returns
- stopped-by-watchpoint as long as there's a watchpoint set. */
- if (linux_nat_status_is_event (lp->status))
- check_stopped_by_breakpoint (lp);
-
- /* Note that TRAP_HWBKPT can indicate either a hardware breakpoint
- or hardware watchpoint. Check which is which if we got
- TARGET_STOPPED_BY_HW_BREAKPOINT. */
- if (lp->stop_reason == TARGET_STOPPED_BY_NO_REASON
- || lp->stop_reason == TARGET_STOPPED_BY_HW_BREAKPOINT)
- check_stopped_by_watchpoint (lp);
-}
-
/* Returns true if the LWP had stopped for a watchpoint. */
static int
/* Save the sigtrap event. */
lp->status = status;
gdb_assert (lp->signalled);
- save_sigtrap (lp);
+ save_stop_reason (lp);
}
else
{
return 0;
}
-/* Called when the LWP got a signal/trap that could be explained by a
- software or hardware breakpoint. */
+/* Called when the LWP stopped for a signal/trap. If it stopped for a
+ trap check what caused it (breakpoint, watchpoint, trace, etc.),
+ and save the result in the LWP's stop_reason field. If it stopped
+ for a breakpoint, decrement the PC if necessary on the lwp's
+ architecture. */
-static int
-check_stopped_by_breakpoint (struct lwp_info *lp)
+static void
+save_stop_reason (struct lwp_info *lp)
{
- /* Arrange for a breakpoint to be hit again later. We don't keep
- the SIGTRAP status and don't forward the SIGTRAP signal to the
- LWP. We will handle the current event, eventually we will resume
- this LWP, and this breakpoint will trap again.
-
- If we do not do this, then we run the risk that the user will
- delete or disable the breakpoint, but the LWP will have already
- tripped on it. */
-
- struct regcache *regcache = get_thread_regcache (lp->ptid);
- struct gdbarch *gdbarch = get_regcache_arch (regcache);
+ struct regcache *regcache;
+ struct gdbarch *gdbarch;
CORE_ADDR pc;
CORE_ADDR sw_bp_pc;
#if USE_SIGTRAP_SIGINFO
siginfo_t siginfo;
#endif
+ gdb_assert (lp->stop_reason == TARGET_STOPPED_BY_NO_REASON);
+ gdb_assert (lp->status != 0);
+
+ if (!linux_nat_status_is_event (lp->status))
+ return;
+
+ regcache = get_thread_regcache (lp->ptid);
+ gdbarch = get_regcache_arch (regcache);
+
pc = regcache_read_pc (regcache);
sw_bp_pc = pc - gdbarch_decr_pc_after_break (gdbarch);
{
if (siginfo.si_signo == SIGTRAP)
{
- if (GDB_ARCH_IS_TRAP_BRKPT (siginfo.si_code))
+ if (GDB_ARCH_IS_TRAP_BRKPT (siginfo.si_code)
+ && GDB_ARCH_IS_TRAP_HWBKPT (siginfo.si_code))
{
- if (debug_linux_nat)
- fprintf_unfiltered (gdb_stdlog,
- "CSBB: %s stopped by software "
- "breakpoint\n",
- target_pid_to_str (lp->ptid));
-
- /* Back up the PC if necessary. */
- if (pc != sw_bp_pc)
- regcache_write_pc (regcache, sw_bp_pc);
-
- lp->stop_pc = sw_bp_pc;
+ /* The si_code is ambiguous on this arch -- check debug
+ registers. */
+ if (!check_stopped_by_watchpoint (lp))
+ lp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT;
+ }
+ else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo.si_code))
+ {
+ /* If we determine the LWP stopped for a SW breakpoint,
+ trust it. Particularly don't check watchpoint
+ registers, because at least on s390, we'd find
+ stopped-by-watchpoint as long as there's a watchpoint
+ set. */
lp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT;
- return 1;
}
- else if (siginfo.si_code == TRAP_HWBKPT)
+ else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo.si_code))
{
- if (debug_linux_nat)
- fprintf_unfiltered (gdb_stdlog,
- "CSBB: %s stopped by hardware "
- "breakpoint/watchpoint\n",
- target_pid_to_str (lp->ptid));
-
- lp->stop_pc = pc;
- lp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT;
- return 1;
+ /* This can indicate either a hardware breakpoint or
+ hardware watchpoint. Check debug registers. */
+ if (!check_stopped_by_watchpoint (lp))
+ lp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT;
}
else if (siginfo.si_code == TRAP_TRACE)
{
fprintf_unfiltered (gdb_stdlog,
"CSBB: %s stopped by trace\n",
target_pid_to_str (lp->ptid));
+
+ /* We may have single stepped an instruction that
+ triggered a watchpoint. In that case, on some
+ architectures (such as x86), instead of TRAP_HWBKPT,
+ si_code indicates TRAP_TRACE, and we need to check
+ the debug registers separately. */
+ check_stopped_by_watchpoint (lp);
}
}
}
{
/* The LWP was either continued, or stepped a software
breakpoint instruction. */
+ lp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT;
+ }
+
+ if (hardware_breakpoint_inserted_here_p (get_regcache_aspace (regcache), pc))
+ lp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT;
+
+ if (lp->stop_reason == TARGET_STOPPED_BY_NO_REASON)
+ check_stopped_by_watchpoint (lp);
+#endif
+
+ if (lp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT)
+ {
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"CSBB: %s stopped by software breakpoint\n",
if (pc != sw_bp_pc)
regcache_write_pc (regcache, sw_bp_pc);
- lp->stop_pc = sw_bp_pc;
- lp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT;
- return 1;
+ /* Update this so we record the correct stop PC below. */
+ pc = sw_bp_pc;
}
-
- if (hardware_breakpoint_inserted_here_p (get_regcache_aspace (regcache), pc))
+ else if (lp->stop_reason == TARGET_STOPPED_BY_HW_BREAKPOINT)
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
- "CSBB: stopped by hardware breakpoint %s\n",
+ "CSBB: %s stopped by hardware breakpoint\n",
+ target_pid_to_str (lp->ptid));
+ }
+ else if (lp->stop_reason == TARGET_STOPPED_BY_WATCHPOINT)
+ {
+ if (debug_linux_nat)
+ fprintf_unfiltered (gdb_stdlog,
+ "CSBB: %s stopped by hardware watchpoint\n",
target_pid_to_str (lp->ptid));
-
- lp->stop_pc = pc;
- lp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT;
- return 1;
}
-#endif
- return 0;
+ lp->stop_pc = pc;
}
/* An interesting event. */
gdb_assert (lp);
lp->status = status;
- save_sigtrap (lp);
+ save_stop_reason (lp);
return lp;
}
/* The x86 kernel gets some of the si_code values backwards, like
this:
- | what | si_code |
- |------------------------------------------+------------|
- | software breakpoints (int3) | SI_KERNEL |
- | single-steps | TRAP_TRACE |
- | single-stepping a syscall | TRAP_BRKPT |
- | user sent SIGTRAP | 0 |
- | exec SIGTRAP (when no PTRACE_EVENT_EXEC) | 0 |
- | hardware breakpoints/watchpoints | TRAP_HWBPT |
+ | what | si_code |
+ |------------------------------------------+-------------|
+ | software breakpoints (int3) | SI_KERNEL |
+ | single-steps | TRAP_TRACE |
+ | single-stepping a syscall | TRAP_BRKPT |
+ | user sent SIGTRAP | 0 |
+ | exec SIGTRAP (when no PTRACE_EVENT_EXEC) | 0 |
+ | hardware breakpoints/watchpoints | TRAP_HWBKPT |
That is, it reports SI_KERNEL for software breakpoints (and only
for those), and TRAP_BRKPT for single-stepping a syscall... If the
in SPU code on a Cell/B.E. However, SI_KERNEL is never seen
on a SIGTRAP for any other reason.
- The generic Linux target code should use GDB_ARCH_IS_TRAP_BRKPT
- instead of TRAP_BRKPT to abstract out these peculiarities. */
+ The MIPS kernel uses SI_KERNEL for all kernel generated traps.
+ Since:
+
+ - MIPS doesn't do hardware single-step.
+ - We don't need to care about exec SIGTRAPs --- we assume
+ PTRACE_EVENT_EXEC is available.
+ - The MIPS kernel doesn't support hardware breakpoints.
+
+ on MIPS, all we need to care about is distinguishing between
+ software breakpoints and hardware watchpoints, which can be done by
+ peeking the debug registers.
+
+ The generic Linux target code should use GDB_ARCH_IS_TRAP_* instead
+ of TRAP_* to abstract out these peculiarities. */
#if defined __i386__ || defined __x86_64__
# define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL)
+# define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == TRAP_HWBKPT)
#elif defined __powerpc__
# define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL || (X) == TRAP_BRKPT)
+# define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == TRAP_HWBKPT)
+#elif defined __mips__
+# define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == SI_KERNEL)
+# define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == SI_KERNEL)
#else
# define GDB_ARCH_IS_TRAP_BRKPT(X) ((X) == TRAP_BRKPT)
+# define GDB_ARCH_IS_TRAP_HWBKPT(X) ((X) == TRAP_HWBKPT)
#endif
#ifndef TRAP_HWBKPT