171 lines
3.4 KiB
C
171 lines
3.4 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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#ifdef CONFIG_X86_64
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/*
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* Signal frame handlers.
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*/
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int save_i387_xstate(void __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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if (!access_ok(VERIFY_WRITE, buf, sig_xstate_size))
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return -EACCES;
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BUILD_BUG_ON(sizeof(struct user_i387_struct) !=
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sizeof(tsk->thread.xstate->fxsave));
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if ((unsigned long)buf % 16)
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printk("save_i387_xstate: 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 *)
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buf);
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if (err)
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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.xstate->fxsave,
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xstate_size))
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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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* This restores directly out of user space. Exceptions are handled.
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*/
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int restore_i387_xstate(void __user *buf)
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{
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struct task_struct *tsk = current;
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int err;
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if (!buf) {
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if (used_math()) {
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clear_fpu(tsk);
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clear_used_math();
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}
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return 0;
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} else
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if (!access_ok(VERIFY_READ, buf, sig_xstate_size))
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return -EACCES;
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if (!used_math()) {
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err = init_fpu(tsk);
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if (err)
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return err;
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}
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if (!(task_thread_info(current)->status & TS_USEDFPU)) {
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clts();
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task_thread_info(current)->status |= TS_USEDFPU;
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}
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err = fxrstor_checking((__force struct i387_fxsave_struct *)buf);
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if (unlikely(err)) {
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/*
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* Encountered an error while doing the restore from the
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* user buffer, clear the fpu state.
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*/
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clear_fpu(tsk);
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clear_used_math();
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}
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return err;
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}
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#endif
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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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