From 41ab5266c3622354353433618edb92ab278025fa Mon Sep 17 00:00:00 2001
From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Date: Thu, 23 Aug 2012 21:27:09 +0000
Subject: 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>

diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 53b6dfa..e0f6710 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -219,6 +219,7 @@ struct thread_struct {
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 #endif
 	unsigned long	dabr;		/* Data address breakpoint register */
+	unsigned long	trap_nr;	/* last trap # on this thread */
 #ifdef CONFIG_ALTIVEC
 	/* Complete AltiVec register set */
 	vector128	vr[32] __attribute__((aligned(16)));
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 710f400..8e701a4 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 1589723..8831322 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;
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 08ffcf5..995f924 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -133,6 +133,7 @@ static int do_sigbus(struct pt_regs *regs, unsigned long address)
 	up_read(&current->mm->mmap_sem);
 
 	if (user_mode(regs)) {
+		current->thread.trap_nr = BUS_ADRERR;
 		info.si_signo = SIGBUS;
 		info.si_errno = 0;
 		info.si_code = BUS_ADRERR;
-- 
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