92d140e21f
restore sigcontext is taking a DNA exception while restoring FP context from the user stack, during the sigreturn. Appended patch fixes it by doing clts() if the app doesn't touch FP during the signal handler execution. This will stop generating a DNA, during the fxrstor in the sigreturn. This improves 64-bit lat_sig numbers by ~30% on my core2 platform. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
151 lines
3.6 KiB
C
151 lines
3.6 KiB
C
/*
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* Copyright (C) 1994 Linus Torvalds
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* Copyright (C) 2002 Andi Kleen, SuSE Labs
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*
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* Pentium III FXSR, SSE support
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* General FPU state handling cleanups
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* Gareth Hughes <gareth@valinux.com>, May 2000
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*
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* x86-64 rework 2002 Andi Kleen.
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* Does direct fxsave in and out of user space now for signal handlers.
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* All the FSAVE<->FXSAVE conversion code has been moved to the 32bit emulation,
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* the 64bit user space sees a FXSAVE frame directly.
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*/
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#include <linux/sched.h>
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#include <linux/init.h>
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#include <asm/processor.h>
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#include <asm/i387.h>
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#include <asm/sigcontext.h>
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#include <asm/user.h>
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#include <asm/ptrace.h>
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#include <asm/uaccess.h>
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unsigned int mxcsr_feature_mask __read_mostly = 0xffffffff;
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void mxcsr_feature_mask_init(void)
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{
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unsigned int mask;
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clts();
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memset(¤t->thread.i387.fxsave, 0, sizeof(struct i387_fxsave_struct));
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asm volatile("fxsave %0" : : "m" (current->thread.i387.fxsave));
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mask = current->thread.i387.fxsave.mxcsr_mask;
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if (mask == 0) mask = 0x0000ffbf;
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mxcsr_feature_mask &= mask;
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stts();
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}
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/*
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* Called at bootup to set up the initial FPU state that is later cloned
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* into all processes.
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*/
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void __cpuinit fpu_init(void)
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{
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unsigned long oldcr0 = read_cr0();
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extern void __bad_fxsave_alignment(void);
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if (offsetof(struct task_struct, thread.i387.fxsave) & 15)
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__bad_fxsave_alignment();
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set_in_cr4(X86_CR4_OSFXSR);
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set_in_cr4(X86_CR4_OSXMMEXCPT);
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write_cr0(oldcr0 & ~((1UL<<3)|(1UL<<2))); /* clear TS and EM */
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mxcsr_feature_mask_init();
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/* clean state in init */
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current_thread_info()->status = 0;
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clear_used_math();
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}
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void init_fpu(struct task_struct *child)
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{
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if (tsk_used_math(child)) {
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if (child == current)
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unlazy_fpu(child);
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return;
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}
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memset(&child->thread.i387.fxsave, 0, sizeof(struct i387_fxsave_struct));
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child->thread.i387.fxsave.cwd = 0x37f;
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child->thread.i387.fxsave.mxcsr = 0x1f80;
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/* only the device not available exception or ptrace can call init_fpu */
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set_stopped_child_used_math(child);
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}
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/*
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* Signal frame handlers.
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*/
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int save_i387(struct _fpstate __user *buf)
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{
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struct task_struct *tsk = current;
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int err = 0;
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BUILD_BUG_ON(sizeof(struct user_i387_struct) !=
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sizeof(tsk->thread.i387.fxsave));
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if ((unsigned long)buf % 16)
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printk("save_i387: bad fpstate %p\n",buf);
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if (!used_math())
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return 0;
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clear_used_math(); /* trigger finit */
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if (task_thread_info(tsk)->status & TS_USEDFPU) {
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err = save_i387_checking((struct i387_fxsave_struct __user *)buf);
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if (err) return err;
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task_thread_info(tsk)->status &= ~TS_USEDFPU;
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stts();
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} else {
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if (__copy_to_user(buf, &tsk->thread.i387.fxsave,
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sizeof(struct i387_fxsave_struct)))
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return -1;
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}
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return 1;
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}
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/*
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* ptrace request handlers.
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*/
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int get_fpregs(struct user_i387_struct __user *buf, struct task_struct *tsk)
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{
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init_fpu(tsk);
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return __copy_to_user(buf, &tsk->thread.i387.fxsave,
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sizeof(struct user_i387_struct)) ? -EFAULT : 0;
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}
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int set_fpregs(struct task_struct *tsk, struct user_i387_struct __user *buf)
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{
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if (__copy_from_user(&tsk->thread.i387.fxsave, buf,
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sizeof(struct user_i387_struct)))
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return -EFAULT;
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return 0;
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}
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/*
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* FPU state for core dumps.
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*/
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int dump_fpu( struct pt_regs *regs, struct user_i387_struct *fpu )
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{
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struct task_struct *tsk = current;
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if (!used_math())
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return 0;
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unlazy_fpu(tsk);
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memcpy(fpu, &tsk->thread.i387.fxsave, sizeof(struct user_i387_struct));
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return 1;
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}
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int dump_task_fpu(struct task_struct *tsk, struct user_i387_struct *fpu)
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{
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int fpvalid = !!tsk_used_math(tsk);
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if (fpvalid) {
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if (tsk == current)
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unlazy_fpu(tsk);
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memcpy(fpu, &tsk->thread.i387.fxsave, sizeof(struct user_i387_struct));
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}
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return fpvalid;
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}
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