lkml.org 
[lkml]   [2017]   [Sep]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] powerpc/sysrq: Fix oops whem ppmu is not registered
Date
Kernel crashes if power pmu is not registered and user tries to dump
regs with 'echo p > /proc/sysrq-trigger'. Sample log:

Unable to handle kernel paging request for data at address 0x00000008
Faulting instruction address: 0xc0000000000d52f0

NIP [c0000000000d52f0] perf_event_print_debug+0x10/0x230
LR [c00000000058a938] sysrq_handle_showregs+0x38/0x50
Call Trace:
printk+0x38/0x4c (unreliable)
__handle_sysrq+0xe4/0x270
write_sysrq_trigger+0x64/0x80
proc_reg_write+0x80/0xd0
__vfs_write+0x40/0x200
vfs_write+0xc8/0x240
SyS_write+0x60/0x110
system_call+0x58/0x6c

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
---
arch/powerpc/perf/core-book3s.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 2e3eb74..9e3da16 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -793,6 +793,11 @@ void perf_event_print_debug(void)
u32 pmcs[MAX_HWEVENTS];
int i;

+ if (!ppmu) {
+ pr_info("Performance monitor hardware not registered.\n");
+ return;
+ }
+
if (!ppmu->n_counter)
return;

--
1.8.3.1
\
 
 \ /
  Last update: 2017-09-19 08:18    [W:0.060 / U:0.688 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site