[PATCH 1/3] ARM: perf: Check that current->mm is alive before getting user callchain

From: Jean Pihet
Date: Fri Jun 27 2014 - 10:58:28 EST


An event may occur when an mm is already released.

As per commit 20afc60f892d285fde179ead4b24e6a7938c2f1b
'x86, perf: Check that current->mm is alive before getting user callchain'

Signed-off-by: Jean Pihet <jean.pihet@xxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
---
arch/arm/kernel/perf_event.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 4238bcb..6493c4c 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -590,6 +590,10 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
}

perf_callchain_store(entry, regs->ARM_pc);
+
+ if (!current->mm)
+ return;
+
tail = (struct frame_tail __user *)regs->ARM_fp - 1;

while ((entry->nr < PERF_MAX_STACK_DEPTH) &&
--
1.8.1.2

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