Patchwork [30/98] ARM: 7765/1: perf: Record the user-mode PC in the call chain.

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Submitter Luis Henriques
Date July 11, 2013, 2:24 p.m.
Message ID <1373552708-15235-31-git-send-email-luis.henriques@canonical.com>
Download mbox | patch
Permalink /patch/258505/
State New
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Luis Henriques - July 11, 2013, 2:24 p.m.
3.5.7.17 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jed Davis <jld@mozilla.com>

commit c5f927a6f62196226915f12194c9d0df4e2210d7 upstream.

With this change, we no longer lose the innermost entry in the user-mode
part of the call chain.  See also the x86 port, which includes the ip.

It's possible to partially work around this problem by post-processing
the data to use the PERF_SAMPLE_IP value, but this works only if the CPU
wasn't in the kernel when the sample was taken.

Signed-off-by: Jed Davis <jld@mozilla.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
[ luis: backported to 3.5: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 arch/arm/kernel/perf_event.c | 1 +
 1 file changed, 1 insertion(+)

Patch

diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 952a5a7..55790a5 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -824,6 +824,7 @@  perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
 	struct frame_tail __user *tail;
 
 
+	perf_callchain_store(entry, regs->ARM_pc);
 	tail = (struct frame_tail __user *)regs->ARM_fp - 1;
 
 	while ((entry->nr < PERF_MAX_STACK_DEPTH) &&