diff options
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/process_64.c | 5 | ||||
| -rw-r--r-- | arch/x86/kernel/traps.c | 14 |
2 files changed, 16 insertions, 3 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 992b4e5..753e803 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -387,6 +387,8 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) struct tss_struct *tss = &per_cpu(init_tss, cpu); unsigned fsindex, gsindex; + __unlazy_fpu(prev_p); + /* * Reload esp0, LDT and the page table pointer: */ @@ -415,9 +417,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) load_TLS(next, cpu); - /* Must be after DS reload */ - __unlazy_fpu(prev_p); - /* * Leave lazy mode, flushing any hypercalls made here. * This must be done before restoring TLS segments so diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 5afe824..4d42300 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -585,6 +585,10 @@ void math_state_restore(void) struct thread_info *thread = current_thread_info(); struct task_struct *tsk = thread->task; + /* We need a safe address that is cheap to find and that is already + in L1. We just brought in "thread->task", so use that */ +#define safe_address (thread->task) + if (!tsk_used_math(tsk)) { local_irq_enable(); /* @@ -602,6 +606,16 @@ void math_state_restore(void) __thread_fpu_begin(thread); + /* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception + is pending. Clear the x87 state here by setting it to fixed + values. safe_address is a random variable that should be in L1 */ + alternative_input( + ASM_NOP8 ASM_NOP2, + "emms\n\t" /* clear stack tags */ + "fildl %P[addr]", /* set F?P to defined value */ + X86_FEATURE_FXSAVE_LEAK, + [addr] "m" (safe_address)); + /* * Paranoid restore. send a SIGSEGV if we fail to restore the state. */ |
