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Linux native: Use TRAP_BRKPT/TRAP_HWBPT

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This patch adjusts the native Linux target backend to tell the core
whether a trap was caused by a breakpoint.

It teaches the target to get that information out of the si_code of
the SIGTRAP siginfo.

Tested on x86-64 Fedora 20, s390 RHEL 7, and PPC64 Fedora 18.  An
earlier version was tested on ARM Fedora 21.

gdb/ChangeLog:
2015-03-04  Pedro Alves  <palves@redhat.com>

	* linux-nat.c (save_sigtrap): Check for breakpoints before
	checking watchpoints.
	(status_callback) [USE_SIGTRAP_SIGINFO]: Don't check whether a
	breakpoint is inserted if relying on SIGTRAP's siginfo.si_code.
	(check_stopped_by_breakpoint) [USE_SIGTRAP_SIGINFO]: Decide whether
	a breakpoint triggered based on the SIGTRAP's siginfo.si_code.
	(linux_nat_stopped_by_sw_breakpoint)
	(linux_nat_supports_stopped_by_sw_breakpoint)
	(linux_nat_stopped_by_hw_breakpoint)
	(linux_nat_supports_stopped_by_hw_breakpoint): New functions.
	(linux_nat_wait_1): Don't re-increment the PC if relying on
	SIGTRAP's siginfo->si_code.
	(linux_nat_add_target): Install new target methods.
	* linux-thread-db.c (check_event): Don't account for breakpoint PC
	offset if the target already adjusted the PC.
	* nat/linux-ptrace.h (USE_SIGTRAP_SIGINFO): New.
	(GDB_ARCH_TRAP_BRKPT): New.
	(TRAP_HWBKPT): Define if not already defined.
This commit is contained in:
Pedro Alves
2015-03-04 20:41:16 +00:00
parent f7e6eed528
commit faf09f0119
4 changed files with 180 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

109
gdb/linux-nat.c
View File

@@ -2399,11 +2399,19 @@ save_sigtrap (struct lwp_info *lp)
gdb_assert (lp->stop_reason == TARGET_STOPPED_BY_NO_REASON);
gdb_assert (lp->status != 0);
if (check_stopped_by_watchpoint (lp))
return;
/* 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. */
@@ -2557,6 +2565,8 @@ status_callback (struct lwp_info *lp, void *data)
paddress (target_gdbarch (), pc));
discard = 1;
}
#if !USE_SIGTRAP_SIGINFO
else if (!breakpoint_inserted_here_p (get_regcache_aspace (regcache), pc))
{
if (debug_linux_nat)
@@ -2567,6 +2577,7 @@ status_callback (struct lwp_info *lp, void *data)
discard = 1;
}
#endif
if (discard)
{
@@ -2669,10 +2680,49 @@ check_stopped_by_breakpoint (struct lwp_info *lp)
struct gdbarch *gdbarch = get_regcache_arch (regcache);
CORE_ADDR pc;
CORE_ADDR sw_bp_pc;
#if USE_SIGTRAP_SIGINFO
siginfo_t siginfo;
#endif
pc = regcache_read_pc (regcache);
sw_bp_pc = pc - target_decr_pc_after_break (gdbarch);
#if USE_SIGTRAP_SIGINFO
if (linux_nat_get_siginfo (lp->ptid, &siginfo))
{
if (siginfo.si_signo == SIGTRAP)
{
if (siginfo.si_code == GDB_ARCH_TRAP_BRKPT)
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"CSBB: Push back software "
"breakpoint for %s\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;
lp->stop_reason = TARGET_STOPPED_BY_SW_BREAKPOINT;
return 1;
}
else if (siginfo.si_code == TRAP_HWBKPT)
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"CSBB: Push back hardware "
"breakpoint/watchpoint for %s\n",
target_pid_to_str (lp->ptid));
lp->stop_pc = pc;
lp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT;
return 1;
}
}
}
#else
if ((!lp->step || lp->stop_pc == sw_bp_pc)
&& software_breakpoint_inserted_here_p (get_regcache_aspace (regcache),
sw_bp_pc))
@@ -2704,10 +2754,53 @@ check_stopped_by_breakpoint (struct lwp_info *lp)
lp->stop_reason = TARGET_STOPPED_BY_HW_BREAKPOINT;
return 1;
}
#endif
return 0;
}
/* Returns true if the LWP had stopped for a software breakpoint. */
static int
linux_nat_stopped_by_sw_breakpoint (struct target_ops *ops)
{
struct lwp_info *lp = find_lwp_pid (inferior_ptid);
gdb_assert (lp != NULL);
return lp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT;
}
/* Implement the supports_stopped_by_sw_breakpoint method. */
static int
linux_nat_supports_stopped_by_sw_breakpoint (struct target_ops *ops)
{
return USE_SIGTRAP_SIGINFO;
}
/* Returns true if the LWP had stopped for a hardware
breakpoint/watchpoint. */
static int
linux_nat_stopped_by_hw_breakpoint (struct target_ops *ops)
{
struct lwp_info *lp = find_lwp_pid (inferior_ptid);
gdb_assert (lp != NULL);
return lp->stop_reason == TARGET_STOPPED_BY_HW_BREAKPOINT;
}
/* Implement the supports_stopped_by_hw_breakpoint method. */
static int
linux_nat_supports_stopped_by_hw_breakpoint (struct target_ops *ops)
{
return USE_SIGTRAP_SIGINFO;
}
/* Select one LWP out of those that have events pending. */
static void
@@ -3360,8 +3453,10 @@ linux_nat_wait_1 (struct target_ops *ops,
gdb_assert (lp != NULL);
/* Now that we've selected our final event LWP, un-adjust its PC if
it was a software breakpoint. */
if (lp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT)
it was a software breakpoint, and we can't reliably support the
"stopped by software breakpoint" stop reason. */
if (lp->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT
&& !USE_SIGTRAP_SIGINFO)
{
struct regcache *regcache = get_thread_regcache (lp->ptid);
struct gdbarch *gdbarch = get_regcache_arch (regcache);
@@ -4651,6 +4746,10 @@ linux_nat_add_target (struct target_ops *t)
t->to_thread_address_space = linux_nat_thread_address_space;
t->to_stopped_by_watchpoint = linux_nat_stopped_by_watchpoint;
t->to_stopped_data_address = linux_nat_stopped_data_address;
t->to_stopped_by_sw_breakpoint = linux_nat_stopped_by_sw_breakpoint;
t->to_supports_stopped_by_sw_breakpoint = linux_nat_supports_stopped_by_sw_breakpoint;
t->to_stopped_by_hw_breakpoint = linux_nat_stopped_by_hw_breakpoint;
t->to_supports_stopped_by_hw_breakpoint = linux_nat_supports_stopped_by_hw_breakpoint;
t->to_can_async_p = linux_nat_can_async_p;
t->to_is_async_p = linux_nat_is_async_p;