[tip:x86/xsave] x86, xsave: Use xsaveopt in context-switch path when supported
in [Kernel]
|
Prev: [tip:x86/xsave] x86, xsave: Track the offset, size of state in the xsave layout
Next: [tip:x86/xsave] x86, xsave: Sync xsave memory layout with its header for user handling
From: tip-bot for Suresh Siddha on 19 Jul 2010 22:00 Commit-ID: 6bad06b768920e278c7cedfdda56a0b4c6a35ee9 Gitweb: http://git.kernel.org/tip/6bad06b768920e278c7cedfdda56a0b4c6a35ee9 Author: Suresh Siddha <suresh.b.siddha(a)intel.com> AuthorDate: Mon, 19 Jul 2010 16:05:52 -0700 Committer: H. Peter Anvin <hpa(a)linux.intel.com> CommitDate: Mon, 19 Jul 2010 17:52:24 -0700 x86, xsave: Use xsaveopt in context-switch path when supported xsaveopt is a more optimized form of xsave specifically designed for the context switch usage. xsaveopt doesn't save the state that's not modified from the prior xrstor. And if a specific feature state gets modified to the init state, then xsaveopt just updates the header bit in the xsave memory layout without updating the corresponding memory layout. Signed-off-by: Suresh Siddha <suresh.b.siddha(a)intel.com> LKML-Reference: <20100719230205.604014179(a)sbs-t61.sc.intel.com> Signed-off-by: H. Peter Anvin <hpa(a)linux.intel.com> --- arch/x86/include/asm/i387.h | 2 +- arch/x86/include/asm/xsave.h | 9 ++++++--- arch/x86/kernel/cpu/common.c | 8 ++++++++ 3 files changed, 15 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h index bb370fd..59bd93a 100644 --- a/arch/x86/include/asm/i387.h +++ b/arch/x86/include/asm/i387.h @@ -60,7 +60,7 @@ extern int restore_i387_xstate_ia32(void __user *buf); static __always_inline __pure bool use_xsaveopt(void) { - return 0; + return static_cpu_has(X86_FEATURE_XSAVEOPT); } static __always_inline __pure bool use_xsave(void) diff --git a/arch/x86/include/asm/xsave.h b/arch/x86/include/asm/xsave.h index 0c72adc..ec86c5f 100644 --- a/arch/x86/include/asm/xsave.h +++ b/arch/x86/include/asm/xsave.h @@ -125,8 +125,11 @@ static inline void fpu_xsave(struct fpu *fpu) { /* This, however, we can work around by forcing the compiler to select an addressing mode that doesn't require extended registers. */ - __asm__ __volatile__(".byte " REX_PREFIX "0x0f,0xae,0x27" - : : "D" (&(fpu->state->xsave)), - "a" (-1), "d"(-1) : "memory"); + alternative_input( + ".byte " REX_PREFIX "0x0f,0xae,0x27", + ".byte " REX_PREFIX "0x0f,0xae,0x37", + X86_FEATURE_XSAVEOPT, + [fx] "D" (&fpu->state->xsave), "a" (-1), "d" (-1) : + "memory"); } #endif diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index c735830..3f715ef 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -140,10 +140,18 @@ EXPORT_PER_CPU_SYMBOL_GPL(gdt_page); static int __init x86_xsave_setup(char *s) { setup_clear_cpu_cap(X86_FEATURE_XSAVE); + setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT); return 1; } __setup("noxsave", x86_xsave_setup); +static int __init x86_xsaveopt_setup(char *s) +{ + setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT); + return 1; +} +__setup("noxsaveopt", x86_xsaveopt_setup); + #ifdef CONFIG_X86_32 static int cachesize_override __cpuinitdata = -1; static int disable_x86_serial_nr __cpuinitdata = 1; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |