From fd3c3ed5d1e3ceb37635cbe6d220ab94aae0781d Mon Sep 17 00:00:00 2001 From: Suresh Siddha Date: Wed, 7 May 2008 12:09:52 -0700 Subject: [PATCH] x86: fix fpu restore from sig return If the task never used fpu, initialize the fpu before restoring the FP state from the signal handler context. This will allocate the fpu state, if the task never needed it before. Reported-and-bisected-by: Eric Sesterhenn Signed-off-by: Suresh Siddha Tested-by: Eric Sesterhenn Cc: Frederik Deweerdt Signed-off-by: Thomas Gleixner --- arch/x86/kernel/i387.c | 12 ++++++++++-- include/asm-x86/i387.h | 10 +++++++++- 2 files changed, 19 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c index db6839b53195..e03cc952f233 100644 --- a/arch/x86/kernel/i387.c +++ b/arch/x86/kernel/i387.c @@ -450,7 +450,6 @@ static inline int restore_i387_fsave(struct _fpstate_ia32 __user *buf) { struct task_struct *tsk = current; - clear_fpu(tsk); return __copy_from_user(&tsk->thread.xstate->fsave, buf, sizeof(struct i387_fsave_struct)); } @@ -461,7 +460,6 @@ static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf) struct user_i387_ia32_struct env; int err; - clear_fpu(tsk); err = __copy_from_user(&tsk->thread.xstate->fxsave, &buf->_fxsr_env[0], sizeof(struct i387_fxsave_struct)); /* mxcsr reserved bits must be masked to zero for security reasons */ @@ -478,6 +476,16 @@ int restore_i387_ia32(struct _fpstate_ia32 __user *buf) int err; if (HAVE_HWFP) { + struct task_struct *tsk = current; + + clear_fpu(tsk); + + if (!used_math()) { + err = init_fpu(tsk); + if (err) + return err; + } + if (cpu_has_fxsr) err = restore_i387_fxsave(buf); else diff --git a/include/asm-x86/i387.h b/include/asm-x86/i387.h index da2adb45f6e3..6b722d315936 100644 --- a/include/asm-x86/i387.h +++ b/include/asm-x86/i387.h @@ -175,7 +175,15 @@ static inline int save_i387(struct _fpstate __user *buf) */ static inline int restore_i387(struct _fpstate __user *buf) { - set_used_math(); + struct task_struct *tsk = current; + int err; + + if (!used_math()) { + err = init_fpu(tsk); + if (err) + return err; + } + if (!(task_thread_info(current)->status & TS_USEDFPU)) { clts(); task_thread_info(current)->status |= TS_USEDFPU; -- 2.20.1