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x86/xsaves: Enable xsaves/xrstors

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If xsaves/xrstors is enabled, compacted format of xsave area will be used
and less memory may be used for context per process. And modified
optimization implemented in xsaves/xrstors improves performance of saving
xstate.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1401387164-43416-16-git-send-email-fenghua.yu@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Fenghua Yu 2014-05-29 11:12:43 -07:00 committed by H. Peter Anvin
parent 47c2f292cc
commit 7e7ce87f6a
1 changed files with 33 additions and 6 deletions
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39
arch/x86/kernel/xsave.c
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@ -8,6 +8,7 @@
#include <linux/bootmem.h>
#include <linux/compat.h>
#include <linux/cpu.h>
#include <asm/i387.h>
#include <asm/fpu-internal.h>
#include <asm/sigframe.h>
@ -24,7 +25,9 @@ u64 pcntxt_mask;
struct xsave_struct *init_xstate_buf;
static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;
static unsigned int *xstate_offsets, *xstate_sizes, xstate_features;
static unsigned int *xstate_offsets, *xstate_sizes;
static unsigned int *xstate_comp_offsets, *xstate_comp_sizes;
static unsigned int xstate_features;
/*
* If a processor implementation discern that a processor state component is
@ -283,7 +286,7 @@ sanitize_restored_xstate(struct task_struct *tsk,
if (use_xsave()) {
/* These bits must be zero. */
xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0;
memset(xsave_hdr->reserved, 0, 48);
/*
* Init the state that is not present in the memory
@ -526,6 +529,30 @@ static int __init eager_fpu_setup(char *s)
}
__setup("eagerfpu=", eager_fpu_setup);
/*
* Calculate total size of enabled xstates in XCR0/pcntxt_mask.
*/
static void __init init_xstate_size(void)
{
unsigned int eax, ebx, ecx, edx;
int i;
if (!cpu_has_xsaves) {
cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
xstate_size = ebx;
return;
}
xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
for (i = 2; i < 64; i++) {
if (test_bit(i, (unsigned long *)&pcntxt_mask)) {
cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
xstate_size += eax;
}
}
}
/*
* Enable and initialize the xsave feature.
*/
@ -557,8 +584,7 @@ static void __init xstate_enable_boot_cpu(void)
/*
* Recompute the context size for enabled features
*/
cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
xstate_size = ebx;
init_xstate_size();
update_regset_xstate_info(xstate_size, pcntxt_mask);
prepare_fx_sw_frame();
@ -578,8 +604,9 @@ static void __init xstate_enable_boot_cpu(void)
}
}
pr_info("enabled xstate_bv 0x%llx, cntxt size 0x%x\n",
pcntxt_mask, xstate_size);
pr_info("enabled xstate_bv 0x%llx, cntxt size 0x%x using %s\n",
pcntxt_mask, xstate_size,
cpu_has_xsaves ? "compacted form" : "standard form");
}
/*