powerpc: Add trap_nr to thread_struct

Add thread_struct.trap_nr and use it to store the last exception
the thread experienced. In this patch, we populate the field at
various places where we force_sig_info() to the process.

This is also used in uprobes to determine if the probed instruction
caused an exception.

Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

2 files changed, 3 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 710f400476de..8e701a4ed36b 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -258,6 +258,7 @@ void do_send_trap(struct pt_regs *regs, unsigned long address,
 {
         siginfo_t info;
 
+        current->thread.trap_nr = signal_code;
         if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
                         11, SIGSEGV) == NOTIFY_STOP)
                 return;
@@ -275,6 +276,7 @@ void do_dabr(struct pt_regs *regs, unsigned long address,
 {
         siginfo_t info;
 
+        current->thread.trap_nr = TRAP_HWBKPT;
         if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
                         11, SIGSEGV) == NOTIFY_STOP)
                 return;
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 158972341a2d..8831322962d3 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -251,6 +251,7 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
         if (arch_irqs_disabled() && !arch_irq_disabled_regs(regs))
                 local_irq_enable();
 
+        current->thread.trap_nr = code;
         memset(&info, 0, sizeof(info));
         info.si_signo = signr;
         info.si_code = code;