diff options
| author | Christoph Hellwig <hch@lst.de> | 2019-06-04 19:54:12 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2019-06-13 20:57:49 +0200 |
| commit | 8d3289f2fa1e0c7e2f72c7352f1efb75d2ad7c76 (patch) | |
| tree | d785c183839b1f28213f9061a94a4462c9681483 | |
| parent | 71ab8323cc357c68985a2d6fc6cfc22b1dbbc1c3 (diff) | |
x86/fpu: Don't use current->mm to check for a kthread
current->mm can be non-NULL if a kthread calls use_mm(). Check for
PF_KTHREAD instead to decide when to store user mode FP state.
Fixes: 2722146eb784 ("x86/fpu: Remove fpu->initialized")
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Aubrey Li <aubrey.li@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Nicolai Stange <nstange@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190604175411.GA27477@lst.de
| -rw-r--r-- | arch/x86/include/asm/fpu/internal.h | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/fpu/core.c | 2 |
2 files changed, 4 insertions, 4 deletions
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h index 9e27fa05a7ae..4c95c365058a 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -536,7 +536,7 @@ static inline void __fpregs_load_activate(void) struct fpu *fpu = ¤t->thread.fpu; int cpu = smp_processor_id(); - if (WARN_ON_ONCE(current->mm == NULL)) + if (WARN_ON_ONCE(current->flags & PF_KTHREAD)) return; if (!fpregs_state_valid(fpu, cpu)) { @@ -567,11 +567,11 @@ static inline void __fpregs_load_activate(void) * otherwise. * * The FPU context is only stored/restored for a user task and - * ->mm is used to distinguish between kernel and user threads. + * PF_KTHREAD is used to distinguish between kernel and user threads. */ static inline void switch_fpu_prepare(struct fpu *old_fpu, int cpu) { - if (static_cpu_has(X86_FEATURE_FPU) && current->mm) { + if (static_cpu_has(X86_FEATURE_FPU) && !(current->flags & PF_KTHREAD)) { if (!copy_fpregs_to_fpstate(old_fpu)) old_fpu->last_cpu = -1; else diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 466fca686fb9..649fbc3fcf9f 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -102,7 +102,7 @@ static void __kernel_fpu_begin(void) kernel_fpu_disable(); - if (current->mm) { + if (!(current->flags & PF_KTHREAD)) { if (!test_thread_flag(TIF_NEED_FPU_LOAD)) { set_thread_flag(TIF_NEED_FPU_LOAD); /* |