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authorSuresh Siddha <suresh.b.siddha@intel.com>2008-05-07 12:09:52 -0700
committerThomas Gleixner <tglx@linutronix.de>2008-05-10 19:31:45 +0200
commitfd3c3ed5d1e3ceb37635cbe6d220ab94aae0781d (patch)
tree67cc2a950e670e5362173efd88ea6ded708b7e6c
parent0646153921892cc7a81320a6920beaca06b3e9f0 (diff)
downloadlinux-fd3c3ed5d1e3ceb37635cbe6d220ab94aae0781d.tar.bz2
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 <snakebyte@gmx.de> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Tested-by: Eric Sesterhenn <snakebyte@gmx.de> Cc: Frederik Deweerdt <deweerdt@free.fr> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--arch/x86/kernel/i387.c12
-rw-r--r--include/asm-x86/i387.h10
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;