From 32365e64a20edcc783137ad17fdd951ab814a2fe Mon Sep 17 00:00:00 2001 From: Janet Liu Date: Thu, 11 Jun 2015 12:02:45 +0800 Subject: [PATCH] arm64: fix bug for reloading FPSIMD state after CPU hotplug. Now FPSIMD don't handle HOTPLUG_CPU. This introduces bug after cpu down/up process. After cpu down/up process, the FPSMID hardware register is default value, not any process's fpsimd context. when CPU_DEAD set cpu's fpsimd_state to NULL, it will force to load the fpsimd context for the thread, to avoid the chance to skip to load the context. If process A is the last user process on CPU N before cpu down, and the first user process on the same CPU N after cpu up, A's fpsimd_state.cpu is the current cpu id, and per_cpu(fpsimd_last_state) points A's fpsimd_state, so kernel will not reload the context during it return to user space. Signed-off-by: Janet Liu Signed-off-by: Xiongshan An Signed-off-by: Chunyan Zhang [catalin.marinas@arm.com: some mostly cosmetic clean-ups] Signed-off-by: Catalin Marinas --- arch/arm64/kernel/fpsimd.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 3dca15634e69..44d6f7545505 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -17,6 +17,7 @@ * along with this program. If not, see . */ +#include #include #include #include @@ -296,6 +297,35 @@ static void fpsimd_pm_init(void) static inline void fpsimd_pm_init(void) { } #endif /* CONFIG_CPU_PM */ +#ifdef CONFIG_HOTPLUG_CPU +static int fpsimd_cpu_hotplug_notifier(struct notifier_block *nfb, + unsigned long action, + void *hcpu) +{ + unsigned int cpu = (long)hcpu; + + switch (action) { + case CPU_DEAD: + case CPU_DEAD_FROZEN: + per_cpu(fpsimd_last_state, cpu) = NULL; + break; + } + return NOTIFY_OK; +} + +static struct notifier_block fpsimd_cpu_hotplug_notifier_block = { + .notifier_call = fpsimd_cpu_hotplug_notifier, +}; + +static inline void fpsimd_hotplug_init(void) +{ + register_cpu_notifier(&fpsimd_cpu_hotplug_notifier_block); +} + +#else +static inline void fpsimd_hotplug_init(void) { } +#endif + /* * FP/SIMD support code initialisation. */ @@ -315,6 +345,7 @@ static int __init fpsimd_init(void) elf_hwcap |= HWCAP_ASIMD; fpsimd_pm_init(); + fpsimd_hotplug_init(); return 0; } -- 2.20.1