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Message-ID: <1293169566.22802.420.camel@gandalf.stny.rr.com>
Date: Fri, 24 Dec 2010 00:46:06 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Joerg Sommer <joerg@...a.gnuu.de>,
linuxppc-dev <linuxppc-dev@...abs.org>
Subject: [PATCH][GIT PULL] powerpc64/tracing: Add frame buffer to calls of
trace_hardirqs_on/off
Ben,
Joerg reported a crash with the irqsoff tracer with PPC32.
Unfortunately, I don't have a ppc32 that I can work with (my kids took
it from me). I posted a test patch on the BZ that was opened for it:
https://bugzilla.kernel.org/show_bug.cgi?id=16573
Anyway, I was also able to reproduce the crash on PPC64. This patch
handles that case.
The following patch is in:
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
branch: ppc/ftrace
Steven Rostedt (1):
powerpc64/tracing: Add frame buffer to calls of trace_hardirqs_on/off
----
arch/powerpc/include/asm/irqflags.h | 40 ++++++++++++++++++++++++++--------
1 files changed, 30 insertions(+), 10 deletions(-)
---------------------------
commit 5025019505da6731f8be13940bb978617599c935
Author: Steven Rostedt <srostedt@...hat.com>
Date: Thu Dec 23 21:07:39 2010 -0800
powerpc64/tracing: Add frame buffer to calls of trace_hardirqs_on/off
When an interrupt occurs in userspace, we can call trace_hardirqs_on/off()
With one level stack. But if we have irqsoff tracing enabled,
it checks both CALLER_ADDR0 and CALLER_ADDR1. The second call
goes two stack frames up. If this is from user space, then there may
not exist a second stack.
Add a second stack when calling trace_hardirqs_on/off() otherwise
the following oops might occur:
Oops: Kernel access of bad area, sig: 11 [#1]
PREEMPT SMP NR_CPUS=2 PA Semi PWRficient
last sysfs file: /sys/block/sda/size
Modules linked in: ohci_hcd ehci_hcd usbcore
NIP: c0000000000e1c00 LR: c0000000000034d4 CTR: 000000011012c440
REGS: c00000003e2f3af0 TRAP: 0300 Not tainted (2.6.37-rc6+)
MSR: 9000000000001032 <ME,IR,DR> CR: 48044444 XER: 20000000
DAR: 00000001ffb9db50, DSISR: 0000000040000000
TASK = c00000003e1a00a0[2088] 'emacs' THREAD: c00000003e2f0000 CPU: 1
GPR00: 0000000000000001 c00000003e2f3d70 c00000000084e0d0 c0000000008816e8
GPR04: 000000001034c678 000000001032e8f9 0000000010336540 0000000040020000
GPR08: 0000000040020000 00000001ffb9db40 c00000003e2f3e30 0000000060000000
GPR12: 100000000000f032 c00000000fff0280 000000001032e8c9 0000000000000008
GPR16: 00000000105be9c0 00000000105be950 00000000105be9b0 00000000105be950
GPR20: 00000000ffb9dc50 00000000ffb9dbf0 00000000102f0000 00000000102f0000
GPR24: 00000000102e0000 00000000102f0000 0000000010336540 c0000000009ded38
GPR28: 00000000102e0000 c0000000000034d4 c0000000007ccb10 c00000003e2f3d70
NIP [c0000000000e1c00] .trace_hardirqs_off+0xb0/0x1d0
LR [c0000000000034d4] decrementer_common+0xd4/0x100
Call Trace:
[c00000003e2f3d70] [c00000003e2f3e30] 0xc00000003e2f3e30 (unreliable)
[c00000003e2f3e30] [c0000000000034d4] decrementer_common+0xd4/0x100
Instruction dump:
81690000 7f8b0000 419e0018 f84a0028 60000000 60000000 60000000 e95f0000
80030000 e92a0000 eb6301f8 2f800000 <eb890010> 41fe00dc a06d000a eb1e8050
---[ end trace 4ec7fd2be9240928 ]---
Reported-by: Joerg Sommer <joerg@...a.gnuu.de>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
diff --git a/arch/powerpc/include/asm/irqflags.h b/arch/powerpc/include/asm/irqflags.h
index b85d8dd..b0b06d8 100644
--- a/arch/powerpc/include/asm/irqflags.h
+++ b/arch/powerpc/include/asm/irqflags.h
@@ -12,24 +12,44 @@
#else
#ifdef CONFIG_TRACE_IRQFLAGS
+#ifdef CONFIG_IRQSOFF_TRACER
+/*
+ * Since the ftrace irqsoff latency trace checks CALLER_ADDR1,
+ * which is the stack frame here, we need to force a stack frame
+ * in case we came from user space.
+ */
+#define TRACE_WITH_FRAME_BUFFER(func) \
+ mflr r0; \
+ stdu r1, -32(r1); \
+ std r0, 16(r1); \
+ stdu r1, -32(r1); \
+ bl func; \
+ ld r1, 0(r1); \
+ ld r1, 0(r1);
+#else
+#define TRACE_WITH_FRAME_BUFFER(func) \
+ bl func;
+#endif
+
/*
* Most of the CPU's IRQ-state tracing is done from assembly code; we
* have to call a C function so call a wrapper that saves all the
* C-clobbered registers.
*/
-#define TRACE_ENABLE_INTS bl .trace_hardirqs_on
-#define TRACE_DISABLE_INTS bl .trace_hardirqs_off
-#define TRACE_AND_RESTORE_IRQ_PARTIAL(en,skip) \
- cmpdi en,0; \
- bne 95f; \
- stb en,PACASOFTIRQEN(r13); \
- bl .trace_hardirqs_off; \
- b skip; \
-95: bl .trace_hardirqs_on; \
+#define TRACE_ENABLE_INTS TRACE_WITH_FRAME_BUFFER(.trace_hardirqs_on)
+#define TRACE_DISABLE_INTS TRACE_WITH_FRAME_BUFFER(.trace_hardirqs_off)
+
+#define TRACE_AND_RESTORE_IRQ_PARTIAL(en,skip) \
+ cmpdi en,0; \
+ bne 95f; \
+ stb en,PACASOFTIRQEN(r13); \
+ TRACE_WITH_FRAME_BUFFER(.trace_hardirqs_off) \
+ b skip; \
+95: TRACE_WITH_FRAME_BUFFER(.trace_hardirqs_on) \
li en,1;
#define TRACE_AND_RESTORE_IRQ(en) \
TRACE_AND_RESTORE_IRQ_PARTIAL(en,96f); \
- stb en,PACASOFTIRQEN(r13); \
+ stb en,PACASOFTIRQEN(r13); \
96:
#else
#define TRACE_ENABLE_INTS
--
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