3c1c7f1014
dynamically allocate fpstate on the stack, instead of static allocation in the current sigframe layout on the user stack. This will allow the fpstate structure to grow in the future, which includes extended state information supporting xsave/xrstor. signal handlers will be able to access the fpstate pointer from the sigcontext structure asusual, with no change. For the non RT sigframe's (which are supported only for 32bit apps), current static fpstate layout in the sigframe will be unused(so that we don't change the extramask[] offset in the sigframe and thus prevent breaking app's which modify extramask[]). Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
91 lines
1.8 KiB
C
91 lines
1.8 KiB
C
/*
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* xsave/xrstor support.
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*
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* Author: Suresh Siddha <suresh.b.siddha@intel.com>
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*/
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#include <linux/bootmem.h>
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#include <linux/compat.h>
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#include <asm/i387.h>
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/*
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* Supported feature mask by the CPU and the kernel.
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*/
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unsigned int pcntxt_hmask, pcntxt_lmask;
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/*
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* Represents init state for the supported extended state.
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*/
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struct xsave_struct *init_xstate_buf;
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#ifdef CONFIG_X86_64
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unsigned int sig_xstate_size = sizeof(struct _fpstate);
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#endif
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/*
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* Enable the extended processor state save/restore feature
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*/
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void __cpuinit xsave_init(void)
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{
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if (!cpu_has_xsave)
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return;
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set_in_cr4(X86_CR4_OSXSAVE);
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/*
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* Enable all the features that the HW is capable of
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* and the Linux kernel is aware of.
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*
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* xsetbv();
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*/
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asm volatile(".byte 0x0f,0x01,0xd1" : : "c" (0),
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"a" (pcntxt_lmask), "d" (pcntxt_hmask));
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}
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/*
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* setup the xstate image representing the init state
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*/
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void setup_xstate_init(void)
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{
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init_xstate_buf = alloc_bootmem(xstate_size);
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init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT;
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}
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/*
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* Enable and initialize the xsave feature.
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*/
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void __init xsave_cntxt_init(void)
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{
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unsigned int eax, ebx, ecx, edx;
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cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx);
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pcntxt_lmask = eax;
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pcntxt_hmask = edx;
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if ((pcntxt_lmask & XSTATE_FPSSE) != XSTATE_FPSSE) {
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printk(KERN_ERR "FP/SSE not shown under xsave features %x\n",
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pcntxt_lmask);
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BUG();
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}
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/*
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* for now OS knows only about FP/SSE
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*/
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pcntxt_lmask = pcntxt_lmask & XCNTXT_LMASK;
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pcntxt_hmask = pcntxt_hmask & XCNTXT_HMASK;
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xsave_init();
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/*
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* Recompute the context size for enabled features
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*/
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cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx);
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xstate_size = ebx;
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setup_xstate_init();
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printk(KERN_INFO "xsave/xrstor: enabled xstate_bv 0x%Lx, "
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"cntxt size 0x%x\n",
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(pcntxt_lmask | ((u64) pcntxt_hmask << 32)), xstate_size);
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}
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