From a88ce63b642cf8cd82cbc278429ccd9de4455a07 Mon Sep 17 00:00:00 2001 From: Hoeun Ryu Date: Thu, 17 Aug 2017 11:24:27 +0900 Subject: arm64: kexec: have own crash_smp_send_stop() for crash dump for nonpanic cores Commit 0ee5941 : (x86/panic: replace smp_send_stop() with kdump friendly version in panic path) introduced crash_smp_send_stop() which is a weak function and can be overridden by architecture codes to fix the side effect caused by commit f06e515 : (kernel/panic.c: add "crash_kexec_post_ notifiers" option). ARM64 architecture uses the weak version function and the problem is that the weak function simply calls smp_send_stop() which makes other CPUs offline and takes away the chance to save crash information for nonpanic CPUs in machine_crash_shutdown() when crash_kexec_post_notifiers kernel option is enabled. Calling smp_send_crash_stop() in machine_crash_shutdown() is useless because all nonpanic CPUs are already offline by smp_send_stop() in this case and smp_send_crash_stop() only works against online CPUs. The result is that secondary CPUs registers are not saved by crash_save_cpu() and the vmcore file misreports these CPUs as being offline. crash_smp_send_stop() is implemented to fix this problem by replacing the existing smp_send_crash_stop() and adding a check for multiple calling to the function. The function (strong symbol version) saves crash information for nonpanic CPUs and machine_crash_shutdown() tries to save crash information for nonpanic CPUs only when crash_kexec_post_notifiers kernel option is disabled. * crash_kexec_post_notifiers : false panic() __crash_kexec() machine_crash_shutdown() crash_smp_send_stop() <= save crash dump for nonpanic cores * crash_kexec_post_notifiers : true panic() crash_smp_send_stop() <= save crash dump for nonpanic cores __crash_kexec() machine_crash_shutdown() crash_smp_send_stop() <= just return. Signed-off-by: Hoeun Ryu Reviewed-by: James Morse Tested-by: James Morse Signed-off-by: Catalin Marinas --- arch/arm64/kernel/machine_kexec.c | 2 +- arch/arm64/kernel/smp.c | 12 +++++++++++- 2 files changed, 12 insertions(+), 2 deletions(-) (limited to 'arch/arm64/kernel') diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c index 481f54a866c5..11121f608eb5 100644 --- a/arch/arm64/kernel/machine_kexec.c +++ b/arch/arm64/kernel/machine_kexec.c @@ -252,7 +252,7 @@ void machine_crash_shutdown(struct pt_regs *regs) local_irq_disable(); /* shutdown non-crashing cpus */ - smp_send_crash_stop(); + crash_smp_send_stop(); /* for crashing cpu */ crash_save_cpu(regs, smp_processor_id()); diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index f13ddb2404f9..ffe089942ac4 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -977,11 +977,21 @@ void smp_send_stop(void) } #ifdef CONFIG_KEXEC_CORE -void smp_send_crash_stop(void) +void crash_smp_send_stop(void) { + static int cpus_stopped; cpumask_t mask; unsigned long timeout; + /* + * This function can be called twice in panic path, but obviously + * we execute this only once. + */ + if (cpus_stopped) + return; + + cpus_stopped = 1; + if (num_online_cpus() == 1) return; -- cgit v1.2.3-59-g8ed1b