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http://sourceware.org/ml/gdb-patches/2015-02/msg00731.html
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Subject: [PATCH 5/8] Linux native: Use TRAP_BRKPT/TRAP_HWBPT
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This patch adjusts the native Linux target backend to tell the core
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whether a trap was caused by a breakpoint.
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It teaches the target to get that information out of the si_code of
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the SIGTRAP siginfo.
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Tested on x86-64 Fedora 20, s390 RHEL 7, and PPC64 Fedora 18. An
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earlier version was tested on ARM Fedora 21.
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gdb/ChangeLog:
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2015-02-25 Pedro Alves <palves@redhat.com>
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* linux-nat.c (save_sigtrap): Check for breakpoints before
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checking watchpoints.
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(status_callback) [USE_SIGTRAP_SIGINFO]: Don't check whether a
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breakpoint is inserted if relying on SIGTRAP's siginfo.si_code.
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(check_stopped_by_breakpoint) [USE_SIGTRAP_SIGINFO]: Decide whether
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a breakpoint triggered based on the SIGTRAP's siginfo.si_code.
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(linux_nat_stopped_by_sw_breakpoint)
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(linux_nat_supports_stopped_by_sw_breakpoint)
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(linux_nat_stopped_by_hw_breakpoint)
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(linux_nat_supports_stopped_by_hw_breakpoint): New functions.
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(linux_nat_wait_1): Don't re-increment the PC if relying on
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SIGTRAP's siginfo->si_code.
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(linux_nat_add_target): Install new target methods.
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* linux-thread-db.c (check_event): Don't account for breakpoint PC
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offset if the target already adjusted the PC.
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* nat/linux-ptrace.h (USE_SIGTRAP_SIGINFO): New.
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(GDB_ARCH_TRAP_BRKPT): New.
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(TRAP_HWBKPT): Define if not already defined.
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---
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gdb/linux-nat.c | 109 ++++++++++++++++++++++++++++++++++++++++++++++---
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gdb/linux-thread-db.c | 6 ++-
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gdb/nat/linux-ptrace.h | 51 +++++++++++++++++++++++
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3 files changed, 159 insertions(+), 7 deletions(-)
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Index: gdb-7.6.1/gdb/linux-nat.c
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===================================================================
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--- gdb-7.6.1.orig/gdb/linux-nat.c 2016-03-13 19:26:22.736952457 +0100
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+++ gdb-7.6.1/gdb/linux-nat.c 2016-03-13 19:45:29.343367943 +0100
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@@ -1953,6 +1953,7 @@
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otherwise handle_zombie_lwp_error would get confused. */
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lp->stopped = 0;
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lp->stopped_by_watchpoint = 0;
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+ lp->stopped_by_hw_breakpoint = 0;
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registers_changed_ptid (lp->ptid);
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}
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@@ -2874,6 +2875,15 @@
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}
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do_cleanups (old_chain);
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+
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+ {
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+#define __SI_FAULT 0
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+#define TRAP_HWBKPT (__SI_FAULT|4) /* hardware breakpoint/watchpoint */
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+ siginfo_t siginfo;
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+ if (linux_nat_get_siginfo (lp->ptid, &siginfo)
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+ && siginfo.si_signo == SIGTRAP && siginfo.si_code == TRAP_HWBKPT)
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+ lp->stopped_by_hw_breakpoint = 1;
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+ }
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}
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/* See save_sigtrap. */
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@@ -3162,6 +3172,17 @@
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return 0;
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}
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+static int
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+linux_nat_stopped_by_hw_breakpoint (struct target_ops *ops)
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+{
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+ struct lwp_info *lp = find_lwp_pid (inferior_ptid);
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+
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+ if (lp == NULL)
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+ return 0;
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+
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+ return lp->stopped_by_hw_breakpoint;
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+}
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+
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/* Select one LWP out of those that have events pending. */
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static void
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@@ -5233,6 +5254,7 @@
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t->to_thread_address_space = linux_nat_thread_address_space;
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t->to_stopped_by_watchpoint = linux_nat_stopped_by_watchpoint;
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t->to_stopped_data_address = linux_nat_stopped_data_address;
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+ t->to_stopped_by_hw_breakpoint = linux_nat_stopped_by_hw_breakpoint;
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t->to_can_async_p = linux_nat_can_async_p;
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t->to_is_async_p = linux_nat_is_async_p;
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Index: gdb-7.6.1/gdb/linux-nat.h
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===================================================================
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--- gdb-7.6.1.orig/gdb/linux-nat.h 2016-03-13 19:26:19.411928036 +0100
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+++ gdb-7.6.1/gdb/linux-nat.h 2016-03-13 19:44:29.437928457 +0100
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@@ -80,6 +80,9 @@
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watchpoint trap. */
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int stopped_by_watchpoint;
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+ /* RHEL: TARGET_STOPPED_BY_HW_BREAKPOINT */
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+ int stopped_by_hw_breakpoint;
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+
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/* On architectures where it is possible to know the data address of
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a triggered watchpoint, STOPPED_DATA_ADDRESS_P is non-zero, and
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STOPPED_DATA_ADDRESS contains such data address. Otherwise,
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