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    Subject[PATCH 030/145] ARM: 7765/1: perf: Record the user-mode PC in the call chain.
    Date
    3.8.13.5 -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>
    Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
    ---
    arch/arm/kernel/perf_event.c | 1 +
    1 file changed, 1 insertion(+)

    diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
    index 23fa6a2..5da31bb 100644
    --- a/arch/arm/kernel/perf_event.c
    +++ b/arch/arm/kernel/perf_event.c
    @@ -579,6 +579,7 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
    return;
    }

    + perf_callchain_store(entry, regs->ARM_pc);
    tail = (struct frame_tail __user *)regs->ARM_fp - 1;

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


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