signals: demultiplexing SIGTRAP signal

Currently a SIGTRAP can denote any one of below reasons.
	- Breakpoint hit
	- H/W debug register hit
	- Single step
	- Signal sent through kill() or rasie()

Architectures like powerpc/parisc provides infrastructure to demultiplex
SIGTRAP signal by passing down the information for receiving SIGTRAP through
si_code of siginfot_t structure. Here is an attempt is generalise this
infrastructure by extending it to x86 and x86_64 archs.

Signed-off-by: Srinivasa DS <srinivasa@in.ibm.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: akpm@linux-foundation.org
Cc: paulus@samba.org
Cc: linuxppc-dev@ozlabs.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 8 insertions, 5 deletions

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 9e43a48ad6e0..bf45cdf1aaca 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -1358,7 +1358,8 @@ const struct user_regset_view *task_user_regset_view(struct task_struct *task)
 #endif
 }
 
-void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code)
+void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
+                                         int error_code, int si_code)
 {
         struct siginfo info;
 
@@ -1367,7 +1368,7 @@ void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code)
 
         memset(&info, 0, sizeof(info));
         info.si_signo = SIGTRAP;
-        info.si_code = TRAP_BRKPT;
+        info.si_code = si_code;
 
         /* User-mode ip? */
         info.si_addr = user_mode_vm(regs) ? (void __user *) regs->ip : NULL;
@@ -1454,5 +1455,5 @@ asmregparm void syscall_trace_leave(struct pt_regs *regs)
          */
         if (test_thread_flag(TIF_SINGLESTEP) &&
             tracehook_consider_fatal_signal(current, SIGTRAP, SIG_DFL))
-                send_sigtrap(current, regs, 0);
+                send_sigtrap(current, regs, 0, TRAP_BRKPT);
 }
diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c
index da5a5964fccb..0429c5de5ea9 100644
--- a/arch/x86/kernel/traps_32.c
+++ b/arch/x86/kernel/traps_32.c
@@ -891,6 +891,7 @@ void __kprobes do_debug(struct pt_regs *regs, long error_code)
 {
         struct task_struct *tsk = current;
         unsigned int condition;
+        int si_code;
 
         trace_hardirqs_fixup();
 
@@ -935,8 +936,9 @@ void __kprobes do_debug(struct pt_regs *regs, long error_code)
                         goto clear_TF_reenable;
         }
 
+        si_code = get_si_code((unsigned long)condition);
         /* Ok, finally something we can handle */
-        send_sigtrap(tsk, regs, error_code);
+        send_sigtrap(tsk, regs, error_code, si_code);
 
         /*
          * Disable additional traps. They'll be re-enabled when
diff --git a/arch/x86/kernel/traps_64.c b/arch/x86/kernel/traps_64.c
index 56d6f1147785..011d8e1fac6e 100644
--- a/arch/x86/kernel/traps_64.c
+++ b/arch/x86/kernel/traps_64.c
@@ -941,7 +941,7 @@ asmlinkage void __kprobes do_debug(struct pt_regs *regs,
         tsk->thread.error_code = error_code;
         info.si_signo = SIGTRAP;
         info.si_errno = 0;
-        info.si_code = TRAP_BRKPT;
+        info.si_code = get_si_code(condition);
         info.si_addr = user_mode(regs) ? (void __user *)regs->ip : NULL;
         force_sig_info(SIGTRAP, &info, tsk);