diff options
Diffstat (limited to 'arch/sh/kernel/process_64.c')
| -rw-r--r-- | arch/sh/kernel/process_64.c | 29 |
1 files changed, 16 insertions, 13 deletions
diff --git a/arch/sh/kernel/process_64.c b/arch/sh/kernel/process_64.c index 973dd1a3d292..cff3b7dc9c56 100644 --- a/arch/sh/kernel/process_64.c +++ b/arch/sh/kernel/process_64.c @@ -421,19 +421,22 @@ int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) */ void exit_thread(void) { - /* See arch/sparc/kernel/process.c for the precedent for doing this -- RPC. - - The SH-5 FPU save/restore approach relies on last_task_used_math - pointing to a live task_struct. When another task tries to use the - FPU for the 1st time, the FPUDIS trap handling (see - arch/sh64/kernel/fpu.c) will save the existing FPU state to the - FP regs field within last_task_used_math before re-loading the new - task's FPU state (or initialising it if the FPU has been used - before). So if last_task_used_math is stale, and its page has already been - re-allocated for another use, the consequences are rather grim. Unless we - null it here, there is no other path through which it would get safely - nulled. */ - + /* + * See arch/sparc/kernel/process.c for the precedent for doing + * this -- RPC. + * + * The SH-5 FPU save/restore approach relies on + * last_task_used_math pointing to a live task_struct. When + * another task tries to use the FPU for the 1st time, the FPUDIS + * trap handling (see arch/sh/kernel/cpu/sh5/fpu.c) will save the + * existing FPU state to the FP regs field within + * last_task_used_math before re-loading the new task's FPU state + * (or initialising it if the FPU has been used before). So if + * last_task_used_math is stale, and its page has already been + * re-allocated for another use, the consequences are rather + * grim. Unless we null it here, there is no other path through + * which it would get safely nulled. + */ #ifdef CONFIG_SH_FPU if (last_task_used_math == current) { last_task_used_math = NULL; |