From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suzuki.Poulose@arm.com (Suzuki K Poulose) Date: Tue, 12 Jun 2018 10:27:03 +0100 Subject: [PATCH] arm64: make secondary_start_kernel() notrace In-Reply-To: <1528794457-14129-1-git-send-email-zhizhouzhang@asrmicro.com> References: <1528794457-14129-1-git-send-email-zhizhouzhang@asrmicro.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 12/06/18 10:07, Zhizhou Zhang wrote: > 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 > > Signed-off-by: Zhizhou Zhang > --- > arch/arm64/kernel/smp.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index f3e2e3ae..11b0f30 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -179,7 +179,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle) > * 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) > +notrace asmlinkage void secondary_start_kernel(void) > { > u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK; > struct mm_struct *mm = &init_mm; > Tested-by: Suzuki K Poulose I think this should go to stable releases as well. Suzuki