ARM: 7765/1: perf: Record the user-mode PC in the call chain.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 85d6332..a99ed7a 100644 (file)
--- 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) &&