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x86-64: Clean up 'save/restore_i387()' usage 

Suresh Siddha wants to fix a possible FPU leakage in error conditions,
but the fact that save/restore_i387() are inlines in a header file makes
that harder to do than necessary.  So start off with an obvious cleanup.

This just moves the x86-64 version of save/restore_i387() out of the
header file, and moves it to the only file that it is actually used in:
arch/x86/kernel/signal_64.c.  So exposing it in a header file was wrong
to begin with.

[ Side note: I'd like to fix up some of the games we play with the
  32-bit version of these functions too, but that's a separate
  matter.  The 32-bit versions are shared - under different names
  at that! - by both the native x86-32 code and the x86-64 32-bit
  compatibility code ]

Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2008-07-24 15:43:44 -07:00
parent b5684b83b1
commit b30f3ae50c
2 changed files with 53 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
arch/x86/kernel/signal_64.c
View File

@ -53,6 +53,59 @@ sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
return do_sigaltstack(uss, uoss, regs->sp);
}
/*
* Signal frame handlers.
*/
static inline int save_i387(struct _fpstate __user *buf)
{
struct task_struct *tsk = current;
int err = 0;
BUILD_BUG_ON(sizeof(struct user_i387_struct) !=
sizeof(tsk->thread.xstate->fxsave));
if ((unsigned long)buf % 16)
printk("save_i387: bad fpstate %p\n", buf);
if (!used_math())
return 0;
clear_used_math(); /* trigger finit */
if (task_thread_info(tsk)->status & TS_USEDFPU) {
err = save_i387_checking((struct i387_fxsave_struct __user *)
buf);
if (err)
return err;
task_thread_info(tsk)->status &= ~TS_USEDFPU;
stts();
} else {
if (__copy_to_user(buf, &tsk->thread.xstate->fxsave,
sizeof(struct i387_fxsave_struct)))
return -1;
}
return 1;
}
/*
* This restores directly out of user space. Exceptions are handled.
*/
static inline int restore_i387(struct _fpstate __user *buf)
{
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;
}
return restore_fpu_checking((__force struct i387_fxsave_struct *)buf);
}
/*
* Do a signal return; undo the signal stack.

54
include/asm-x86/i387.h
View File

@ -137,60 +137,6 @@ static inline void __save_init_fpu(struct task_struct *tsk)
task_thread_info(tsk)->status &= ~TS_USEDFPU;
}
/*
* Signal frame handlers.
*/
static inline int save_i387(struct _fpstate __user *buf)
{
struct task_struct *tsk = current;
int err = 0;
BUILD_BUG_ON(sizeof(struct user_i387_struct) !=
sizeof(tsk->thread.xstate->fxsave));
if ((unsigned long)buf % 16)
printk("save_i387: bad fpstate %p\n", buf);
if (!used_math())
return 0;
clear_used_math(); /* trigger finit */
if (task_thread_info(tsk)->status & TS_USEDFPU) {
err = save_i387_checking((struct i387_fxsave_struct __user *)
buf);
if (err)
return err;
task_thread_info(tsk)->status &= ~TS_USEDFPU;
stts();
} else {
if (__copy_to_user(buf, &tsk->thread.xstate->fxsave,
sizeof(struct i387_fxsave_struct)))
return -1;
}
return 1;
}
/*
* This restores directly out of user space. Exceptions are handled.
*/
static inline int restore_i387(struct _fpstate __user *buf)
{
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;
}
return restore_fpu_checking((__force struct i387_fxsave_struct *)buf);
}
#else /* CONFIG_X86_32 */
extern void finit(void);