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Message-ID: <20141013073833.GA14790@gmail.com>
Date: Mon, 13 Oct 2014 09:38:33 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL] x86/fpu tree changes for v3.18
Linus,
Please pull the latest x86-fpu-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-fpu-for-linus
# HEAD: 6f46b3aef0031c08a7b439d63013dad2aeb093b2 x86: copy_thread: Don't nullify ->ptrace_bps twice
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.
Thanks,
Ingo
------------------>
Oleg Nesterov (7):
x86, fpu: shift drop_init_fpu() from save_xstate_sig() to handle_signal()
x86, fpu: __restore_xstate_sig()->math_state_restore() needs preempt_disable()
x86, fpu: Change __thread_fpu_begin() to use use_eager_fpu()
x86, fpu: copy_process: Avoid fpu_alloc/copy if !used_math()
x86, fpu: copy_process: Sanitize fpu->last_cpu initialization
x86, fpu: Shift "fpu_counter = 0" from copy_thread() to arch_dup_task_struct()
x86: copy_thread: Don't nullify ->ptrace_bps twice
arch/x86/include/asm/fpu-internal.h | 2 +-
arch/x86/kernel/process.c | 16 +++++++++-------
arch/x86/kernel/process_32.c | 6 +-----
arch/x86/kernel/process_64.c | 3 ---
arch/x86/kernel/signal.c | 5 +++++
arch/x86/kernel/xsave.c | 7 ++++---
6 files changed, 20 insertions(+), 19 deletions(-)
diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h
index 412ececa00b9..e97622f57722 100644
--- a/arch/x86/include/asm/fpu-internal.h
+++ b/arch/x86/include/asm/fpu-internal.h
@@ -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);
}
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index f804dc935d2a..e127ddaa2d5a 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -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;
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 7bc86bbe7485..8f3ebfe710d0 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -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);
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index ca5b02d405c3..3ed4a68d4013 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -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);
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 2851d63c1202..ed37a768d0fc 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -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));
}
diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index 940b142cc11f..4c540c4719d8 100644
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -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 {
--
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