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authorJanet Liu <janet.liu@spreadtrum.com>2015-06-11 04:02:45 (GMT)
committerCatalin Marinas <catalin.marinas@arm.com>2015-06-11 16:08:11 (GMT)
commit32365e64a20edcc783137ad17fdd951ab814a2fe (patch)
tree68245a2a02b0c86ee09bd6640032018f87d2b6aa /arch/arm64
parent6eb6c80187c55b7f95683bc6502dccac54b95b92 (diff)
downloadlinux-32365e64a20edcc783137ad17fdd951ab814a2fe.tar.xz
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 <janet.liu@spreadtrum.com> Signed-off-by: Xiongshan An <xiongshan.an@spreadtrum.com> Signed-off-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com> [catalin.marinas@arm.com: some mostly cosmetic clean-ups] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64')
-rw-r--r--arch/arm64/kernel/fpsimd.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 3dca156..44d6f75 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -17,6 +17,7 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <linux/cpu.h>
#include <linux/cpu_pm.h>
#include <linux/kernel.h>
#include <linux/init.h>
@@ -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;
}