8e221b6db4
fxsave/xsave doesn't touch all the bytes in the memory layout used by these instructions. Specifically SW reserved (bytes 464..511) fields in the fxsave frame and the reserved fields in the xsave header. To present a clean context for the signal handling, just clear these fields instead of clearing the complete fxsave/xsave memory layout, when we dump these registers directly to the user signal frame. Also avoid the call to second xrstor (which inits the state not passed in the signal frame) in restore_user_xstate() if all the state has already been restored by the first xrstor. These changes improve the performance of signal handling(by ~3-5% as measured by the lat_sig). Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> LKML-Reference: <1277249017.2847.85.camel@sbs-t61.sc.intel.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
132 lines
3.4 KiB
C
132 lines
3.4 KiB
C
#ifndef __ASM_X86_XSAVE_H
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#define __ASM_X86_XSAVE_H
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#include <linux/types.h>
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#include <asm/processor.h>
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#include <asm/i387.h>
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#define XSTATE_FP 0x1
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#define XSTATE_SSE 0x2
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#define XSTATE_YMM 0x4
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#define XSTATE_FPSSE (XSTATE_FP | XSTATE_SSE)
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#define FXSAVE_SIZE 512
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/*
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* These are the features that the OS can handle currently.
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*/
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#define XCNTXT_MASK (XSTATE_FP | XSTATE_SSE | XSTATE_YMM)
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#ifdef CONFIG_X86_64
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#define REX_PREFIX "0x48, "
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#else
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#define REX_PREFIX
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#endif
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extern unsigned int xstate_size;
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extern u64 pcntxt_mask;
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extern struct xsave_struct *init_xstate_buf;
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extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];
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extern void xsave_cntxt_init(void);
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extern void xsave_init(void);
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extern void update_regset_xstate_info(unsigned int size, u64 xstate_mask);
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extern int init_fpu(struct task_struct *child);
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extern int check_for_xstate(struct i387_fxsave_struct __user *buf,
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void __user *fpstate,
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struct _fpx_sw_bytes *sw);
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static inline int fpu_xrstor_checking(struct fpu *fpu)
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{
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struct xsave_struct *fx = &fpu->state->xsave;
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int err;
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asm volatile("1: .byte " REX_PREFIX "0x0f,0xae,0x2f\n\t"
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"2:\n"
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".section .fixup,\"ax\"\n"
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"3: movl $-1,%[err]\n"
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" jmp 2b\n"
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".previous\n"
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_ASM_EXTABLE(1b, 3b)
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: [err] "=r" (err)
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: "D" (fx), "m" (*fx), "a" (-1), "d" (-1), "0" (0)
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: "memory");
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return err;
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}
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static inline int xsave_user(struct xsave_struct __user *buf)
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{
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int err;
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/*
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* Clear the xsave header first, so that reserved fields are
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* initialized to zero.
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*/
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err = __clear_user(&buf->xsave_hdr,
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sizeof(struct xsave_hdr_struct));
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if (unlikely(err))
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return -EFAULT;
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__asm__ __volatile__("1: .byte " REX_PREFIX "0x0f,0xae,0x27\n"
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"2:\n"
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".section .fixup,\"ax\"\n"
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"3: movl $-1,%[err]\n"
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" jmp 2b\n"
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".previous\n"
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".section __ex_table,\"a\"\n"
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_ASM_ALIGN "\n"
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_ASM_PTR "1b,3b\n"
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".previous"
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: [err] "=r" (err)
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: "D" (buf), "a" (-1), "d" (-1), "0" (0)
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: "memory");
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if (unlikely(err) && __clear_user(buf, xstate_size))
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err = -EFAULT;
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/* No need to clear here because the caller clears USED_MATH */
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return err;
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}
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static inline int xrestore_user(struct xsave_struct __user *buf, u64 mask)
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{
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int err;
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struct xsave_struct *xstate = ((__force struct xsave_struct *)buf);
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u32 lmask = mask;
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u32 hmask = mask >> 32;
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__asm__ __volatile__("1: .byte " REX_PREFIX "0x0f,0xae,0x2f\n"
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"2:\n"
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".section .fixup,\"ax\"\n"
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"3: movl $-1,%[err]\n"
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" jmp 2b\n"
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".previous\n"
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".section __ex_table,\"a\"\n"
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_ASM_ALIGN "\n"
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_ASM_PTR "1b,3b\n"
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".previous"
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: [err] "=r" (err)
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: "D" (xstate), "a" (lmask), "d" (hmask), "0" (0)
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: "memory"); /* memory required? */
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return err;
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}
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static inline void xrstor_state(struct xsave_struct *fx, u64 mask)
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{
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u32 lmask = mask;
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u32 hmask = mask >> 32;
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asm volatile(".byte " REX_PREFIX "0x0f,0xae,0x2f\n\t"
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: : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
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: "memory");
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}
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static inline void fpu_xsave(struct fpu *fpu)
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{
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/* This, however, we can work around by forcing the compiler to select
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an addressing mode that doesn't require extended registers. */
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__asm__ __volatile__(".byte " REX_PREFIX "0x0f,0xae,0x27"
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: : "D" (&(fpu->state->xsave)),
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"a" (-1), "d"(-1) : "memory");
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}
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#endif
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