From 67e97fc2ec575adaacca296834f9ea0e1e34b563 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Fri, 3 Apr 2015 12:21:03 +0200 Subject: [PATCH] x86/fpu: Rename init_fpu() to fpu__unlazy_stopped() and add debugging check This function name is a misnomer now that we've split out all the other users from it. Rename it accordingly: it's used to save the FPU state of (ptrace-)stopped child tasks. Add debugging check to double check this intended usage: that this function is only called for non-current, stopped child tasks. Reviewed-by: Borislav Petkov Cc: Andy Lutomirski Cc: Dave Hansen Cc: Fenghua Yu Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar --- arch/x86/kernel/i387.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c index 95079026c386..909d10d2fb70 100644 --- a/arch/x86/kernel/i387.c +++ b/arch/x86/kernel/i387.c @@ -283,27 +283,30 @@ EXPORT_SYMBOL_GPL(fpstate_alloc_init); * value at reset if we support XMM instructions and then * remember the current task has used the FPU. */ -static int init_fpu(struct task_struct *tsk) +static int fpu__unlazy_stopped(struct task_struct *child) { int ret; - if (tsk_used_math(tsk)) { - if (cpu_has_fpu && tsk == current) - fpu__save(tsk); - task_disable_lazy_fpu_restore(tsk); + if (WARN_ON_ONCE(child == current)) + return -EINVAL; + + if (tsk_used_math(child)) { + if (cpu_has_fpu && child == current) + fpu__save(child); + task_disable_lazy_fpu_restore(child); return 0; } /* * Memory allocation at the first usage of the FPU and other state. */ - ret = fpu_alloc(&tsk->thread.fpu); + ret = fpu_alloc(&child->thread.fpu); if (ret) return ret; - fpu_finit(&tsk->thread.fpu); + fpu_finit(&child->thread.fpu); - set_stopped_child_used_math(tsk); + set_stopped_child_used_math(child); return 0; } @@ -331,7 +334,7 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset, if (!cpu_has_fxsr) return -ENODEV; - ret = init_fpu(target); + ret = fpu__unlazy_stopped(target); if (ret) return ret; @@ -350,7 +353,7 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset, if (!cpu_has_fxsr) return -ENODEV; - ret = init_fpu(target); + ret = fpu__unlazy_stopped(target); if (ret) return ret; @@ -384,7 +387,7 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset, if (!cpu_has_xsave) return -ENODEV; - ret = init_fpu(target); + ret = fpu__unlazy_stopped(target); if (ret) return ret; @@ -414,7 +417,7 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset, if (!cpu_has_xsave) return -ENODEV; - ret = init_fpu(target); + ret = fpu__unlazy_stopped(target); if (ret) return ret; @@ -577,7 +580,7 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset, struct user_i387_ia32_struct env; int ret; - ret = init_fpu(target); + ret = fpu__unlazy_stopped(target); if (ret) return ret; @@ -608,7 +611,7 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset, struct user_i387_ia32_struct env; int ret; - ret = init_fpu(target); + ret = fpu__unlazy_stopped(target); if (ret) return ret; -- 2.30.2