generic bug: use show_regs() instead of dump_stack()

The current generic bug implementation has a call to dump_stack() in case a
WARN_ON(whatever) gets hit.  Since report_bug(), which calls dump_stack(),
gets called from an exception handler we can do better: just pass the
pt_regs structure to report_bug() and pass it to show_regs() in case of a
warning.  This will give more debug informations like register contents,
etc...  In addition this avoids some pointless lines that dump_stack()
emits, since it includes a stack backtrace of the exception handler which
is of no interest in case of a warning.  E.g.  on s390 the following lines
are currently always present in a stack backtrace if dump_stack() gets
called from report_bug():

 [<000000000001517a>] show_trace+0x92/0xe8)
 [<0000000000015270>] show_stack+0xa0/0xd0
 [<00000000000152ce>] dump_stack+0x2e/0x3c
 [<0000000000195450>] report_bug+0x98/0xf8
 [<0000000000016cc8>] illegal_op+0x1fc/0x21c
 [<00000000000227d6>] sysc_return+0x0/0x10

Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Kyle McMartin <kyle@parisc-linux.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

8 files changed, 8 insertions, 8 deletions

diff --git a/arch/avr32/kernel/traps.c b/arch/avr32/kernel/traps.c
index 86d107511dd..aaa792815cd 100644
--- a/arch/avr32/kernel/traps.c
+++ b/arch/avr32/kernel/traps.c
@@ -184,7 +184,7 @@ asmlinkage void do_illegal_opcode(unsigned long ecr, struct pt_regs *regs)
 	if (!user_mode(regs) && (ecr == ECR_ILLEGAL_OPCODE)) {
 		enum bug_trap_type type;
 
-		type = report_bug(regs->pc);
+		type = report_bug(regs->pc, regs);
 		switch (type) {
 		case BUG_TRAP_TYPE_NONE:
 			break;
diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index 90da0575fcf..28bd1c5163e 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -390,7 +390,7 @@ void die(const char * str, struct pt_regs * regs, long err)
 		unsigned long esp;
 		unsigned short ss;
 
-		report_bug(regs->eip);
+		report_bug(regs->eip, regs);
 
 		printk(KERN_EMERG "%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
 #ifdef CONFIG_PREEMPT
diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c
index c3ec9f1ec0f..f9bca2d74b3 100644
--- a/arch/parisc/kernel/traps.c
+++ b/arch/parisc/kernel/traps.c
@@ -302,7 +302,7 @@ static void handle_break(struct pt_regs *regs)
 	if (unlikely(iir == PARISC_BUG_BREAK_INSN && !user_mode(regs))) {
 		/* check if a BUG() or WARN() trapped here.  */
 		enum bug_trap_type tt;
-		tt = report_bug(regs->iaoq[0] & ~3);
+		tt = report_bug(regs->iaoq[0] & ~3, regs);
 		if (tt == BUG_TRAP_TYPE_WARN) {
 			regs->iaoq[0] += 4;
 			regs->iaoq[1] += 4;
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index bf6445ac9f1..3b8427e6283 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -777,7 +777,7 @@ void __kprobes program_check_exception(struct pt_regs *regs)
 			return;
 
 		if (!(regs->msr & MSR_PR) &&  /* not user-mode */
-		    report_bug(regs->nip) == BUG_TRAP_TYPE_WARN) {
+		    report_bug(regs->nip, regs) == BUG_TRAP_TYPE_WARN) {
 			regs->nip += 4;
 			return;
 		}
diff --git a/arch/ppc/kernel/traps.c b/arch/ppc/kernel/traps.c
index aea100be52c..0eaef7c8378 100644
--- a/arch/ppc/kernel/traps.c
+++ b/arch/ppc/kernel/traps.c
@@ -619,7 +619,7 @@ void program_check_exception(struct pt_regs *regs)
 			return;
 
 		if (!(regs->msr & MSR_PR) &&  /* not user-mode */
-		    report_bug(regs->nip) == BUG_TRAP_TYPE_WARN) {
+		    report_bug(regs->nip, regs) == BUG_TRAP_TYPE_WARN) {
 			regs->nip += 4;
 			return;
 		}
diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
index ee9186f8fb0..81e03b9c384 100644
--- a/arch/s390/kernel/traps.c
+++ b/arch/s390/kernel/traps.c
@@ -319,7 +319,7 @@ static void __kprobes inline do_trap(long interruption_code, int signr,
 		else {
 			enum bug_trap_type btt;
 
-			btt = report_bug(regs->psw.addr & PSW_ADDR_INSN);
+			btt = report_bug(regs->psw.addr & PSW_ADDR_INSN, regs);
 			if (btt == BUG_TRAP_TYPE_WARN)
 				return;
 			die(str, regs, interruption_code);
diff --git a/arch/sh/kernel/traps.c b/arch/sh/kernel/traps.c
index 8f18930d5bf..09480887076 100644
--- a/arch/sh/kernel/traps.c
+++ b/arch/sh/kernel/traps.c
@@ -874,7 +874,7 @@ void __init trap_init(void)
 void handle_BUG(struct pt_regs *regs)
 {
 	enum bug_trap_type tt;
-	tt = report_bug(regs->pc);
+	tt = report_bug(regs->pc, regs);
 	if (tt == BUG_TRAP_TYPE_WARN) {
 		regs->pc += 2;
 		return;
diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index aac1c0be54c..7fa155c394d 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -531,7 +531,7 @@ void die(const char * str, struct pt_regs * regs, long err)
 	unsigned long flags = oops_begin();
 
 	if (!user_mode(regs))
-		report_bug(regs->rip);
+		report_bug(regs->rip, regs);
 
 	__die(str, regs, err);
 	oops_end(flags);