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Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull x86 FPU updates from Ingo Molnar:
 "x86 FPU handling fixes, cleanups and enhancements from Oleg.

  The signal handling race fix and the __restore_xstate_sig() preemption
  fix for eager-mode is marked for -stable as well"

* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86: copy_thread: Don't nullify ->ptrace_bps twice
  x86, fpu: Shift "fpu_counter = 0" from copy_thread() to arch_dup_task_struct()
  x86, fpu: copy_process: Sanitize fpu->last_cpu initialization
  x86, fpu: copy_process: Avoid fpu_alloc/copy if !used_math()
  x86, fpu: Change __thread_fpu_begin() to use use_eager_fpu()
  x86, fpu: __restore_xstate_sig()->math_state_restore() needs preempt_disable()
  x86, fpu: shift drop_init_fpu() from save_xstate_sig() to handle_signal()
This commit is contained in:
Linus Torvalds 2014-10-14 02:20:50 +02:00
commit c7b228adca
6 changed files with 20 additions and 19 deletions
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2
arch/x86/include/asm/fpu-internal.h
View File

@ -344,7 +344,7 @@ static inline void __thread_fpu_end(struct task_struct *tsk)
static inline void __thread_fpu_begin(struct task_struct *tsk)
{
if (!static_cpu_has_safe(X86_FEATURE_EAGER_FPU))
if (!use_eager_fpu())
clts();
__thread_set_has_fpu(tsk);
}

16
arch/x86/kernel/process.c
View File

@ -64,14 +64,16 @@ EXPORT_SYMBOL_GPL(task_xstate_cachep);
*/
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
int ret;
*dst = *src;
if (fpu_allocated(&src->thread.fpu)) {
memset(&dst->thread.fpu, 0, sizeof(dst->thread.fpu));
ret = fpu_alloc(&dst->thread.fpu);
if (ret)
return ret;
dst->thread.fpu_counter = 0;
dst->thread.fpu.has_fpu = 0;
dst->thread.fpu.last_cpu = ~0;
dst->thread.fpu.state = NULL;
if (tsk_used_math(src)) {
int err = fpu_alloc(&dst->thread.fpu);
if (err)
return err;
fpu_copy(dst, src);
}
return 0;

6
arch/x86/kernel/process_32.c
View File

@ -138,6 +138,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
p->thread.sp = (unsigned long) childregs;
p->thread.sp0 = (unsigned long) (childregs+1);
memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
if (unlikely(p->flags & PF_KTHREAD)) {
/* kernel thread */
@ -152,9 +153,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
childregs->orig_ax = -1;
childregs->cs = __KERNEL_CS | get_kernel_rpl();
childregs->flags = X86_EFLAGS_IF | X86_EFLAGS_FIXED;
p->thread.fpu_counter = 0;
p->thread.io_bitmap_ptr = NULL;
memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
return 0;
}
*childregs = *current_pt_regs();
@ -165,13 +164,10 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
p->thread.ip = (unsigned long) ret_from_fork;
task_user_gs(p) = get_user_gs(current_pt_regs());
p->thread.fpu_counter = 0;
p->thread.io_bitmap_ptr = NULL;
tsk = current;
err = -ENOMEM;
memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr,
IO_BITMAP_BYTES, GFP_KERNEL);

3
arch/x86/kernel/process_64.c
View File

@ -163,7 +163,6 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
p->thread.sp = (unsigned long) childregs;
p->thread.usersp = me->thread.usersp;
set_tsk_thread_flag(p, TIF_FORK);
p->thread.fpu_counter = 0;
p->thread.io_bitmap_ptr = NULL;
savesegment(gs, p->thread.gsindex);
@ -193,8 +192,6 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
childregs->sp = sp;
err = -ENOMEM;
memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
p->thread.io_bitmap_ptr = kmemdup(me->thread.io_bitmap_ptr,
IO_BITMAP_BYTES, GFP_KERNEL);

5
arch/x86/kernel/signal.c
View File

@ -675,6 +675,11 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs)
* handler too.
*/
regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
/*
* Ensure the signal handler starts with the new fpu state.
*/
if (used_math())
drop_init_fpu(current);
}
signal_setup_done(failed, ksig, test_thread_flag(TIF_SINGLESTEP));
}

7
arch/x86/kernel/xsave.c
View File

@ -271,8 +271,6 @@ int save_xstate_sig(void __user *buf, void __user *buf_fx, int size)
if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
return -1;
drop_init_fpu(tsk); /* trigger finit */
return 0;
}
@ -402,8 +400,11 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
set_used_math();
}
if (use_eager_fpu())
if (use_eager_fpu()) {
preempt_disable();
math_state_restore();
preempt_enable();
}
return err;
} else {