linux-kernel - [PATCH 4.4 13/79] arm64: make secondary_start

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Message-Id: <20180823074919.560145811@linuxfoundation.org>
Date:   Thu, 23 Aug 2018 09:52:49 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Mark Rutland <mark.rutland@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Zhizhou Zhang <zhizhouzhang@...micro.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.4 13/79] arm64: make secondary_start_kernel() notrace

4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Zhizhou Zhang <zhizhouzhang@...micro.com>

[ Upstream commit b154886f7892499d0d3054026e19dfb9a731df61 ]

We can't call function trace hook before setup percpu offset.
When entering secondary_start_kernel(), percpu offset has not
been initialized.  So this lead hotplug malfunction.
Here is the flow to reproduce this bug:

echo 0 > /sys/devices/system/cpu/cpu1/online
echo function > /sys/kernel/debug/tracing/current_tracer
echo 1 > /sys/kernel/debug/tracing/tracing_on
echo 1 > /sys/devices/system/cpu/cpu1/online

Acked-by: Mark Rutland <mark.rutland@....com>
Tested-by: Suzuki K Poulose <suzuki.poulose@....com>
Signed-off-by: Zhizhou Zhang <zhizhouzhang@...micro.com>
Signed-off-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/arm64/kernel/smp.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -131,7 +131,7 @@ static void smp_store_cpu_info(unsigned
  * This is the secondary CPU boot entry.  We're using this CPUs
  * idle thread stack, but a set of temporary page tables.
  */
-asmlinkage void secondary_start_kernel(void)
+asmlinkage notrace void secondary_start_kernel(void)
 {
 	struct mm_struct *mm = &init_mm;
 	unsigned int cpu = smp_processor_id();