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df24fb859a
Add preempt_disable() + preempt_enable() around math_state_restore() in __restore_xstate_sig(). Otherwise __switch_to() after __thread_fpu_begin() can overwrite fpu->state we are going to restore. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Link: http://lkml.kernel.org/r/20140902175717.GA21649@redhat.com Cc: <stable@vger.kernel.org> # v3.7+ Reviewed-by: Suresh Siddha <sbsiddha@gmail.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
740 lines
19 KiB
C
740 lines
19 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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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/bootmem.h>
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#include <linux/compat.h>
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#include <linux/cpu.h>
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#include <asm/i387.h>
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#include <asm/fpu-internal.h>
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#include <asm/sigframe.h>
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#include <asm/xcr.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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u64 pcntxt_mask;
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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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static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;
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static unsigned int *xstate_offsets, *xstate_sizes;
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static unsigned int xstate_comp_offsets[sizeof(pcntxt_mask)*8];
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static unsigned int xstate_features;
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/*
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* If a processor implementation discern that a processor state component is
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* in its initialized state it may modify the corresponding bit in the
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* xsave_hdr.xstate_bv as '0', with out modifying the corresponding memory
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* layout in the case of xsaveopt. While presenting the xstate information to
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* the user, we always ensure that the memory layout of a feature will be in
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* the init state if the corresponding header bit is zero. This is to ensure
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* that the user doesn't see some stale state in the memory layout during
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* signal handling, debugging etc.
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*/
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void __sanitize_i387_state(struct task_struct *tsk)
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{
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struct i387_fxsave_struct *fx = &tsk->thread.fpu.state->fxsave;
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int feature_bit = 0x2;
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u64 xstate_bv;
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if (!fx)
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return;
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xstate_bv = tsk->thread.fpu.state->xsave.xsave_hdr.xstate_bv;
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/*
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* None of the feature bits are in init state. So nothing else
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* to do for us, as the memory layout is up to date.
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*/
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if ((xstate_bv & pcntxt_mask) == pcntxt_mask)
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return;
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/*
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* FP is in init state
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*/
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if (!(xstate_bv & XSTATE_FP)) {
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fx->cwd = 0x37f;
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fx->swd = 0;
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fx->twd = 0;
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fx->fop = 0;
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fx->rip = 0;
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fx->rdp = 0;
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memset(&fx->st_space[0], 0, 128);
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}
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/*
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* SSE is in init state
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*/
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if (!(xstate_bv & XSTATE_SSE))
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memset(&fx->xmm_space[0], 0, 256);
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xstate_bv = (pcntxt_mask & ~xstate_bv) >> 2;
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/*
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* Update all the other memory layouts for which the corresponding
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* header bit is in the init state.
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*/
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while (xstate_bv) {
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if (xstate_bv & 0x1) {
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int offset = xstate_offsets[feature_bit];
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int size = xstate_sizes[feature_bit];
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memcpy(((void *) fx) + offset,
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((void *) init_xstate_buf) + offset,
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size);
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}
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xstate_bv >>= 1;
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feature_bit++;
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}
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}
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/*
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* Check for the presence of extended state information in the
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* user fpstate pointer in the sigcontext.
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*/
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static inline 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 *fx_sw)
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{
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int min_xstate_size = sizeof(struct i387_fxsave_struct) +
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sizeof(struct xsave_hdr_struct);
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unsigned int magic2;
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if (__copy_from_user(fx_sw, &buf->sw_reserved[0], sizeof(*fx_sw)))
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return -1;
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/* Check for the first magic field and other error scenarios. */
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if (fx_sw->magic1 != FP_XSTATE_MAGIC1 ||
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fx_sw->xstate_size < min_xstate_size ||
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fx_sw->xstate_size > xstate_size ||
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fx_sw->xstate_size > fx_sw->extended_size)
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return -1;
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/*
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* Check for the presence of second magic word at the end of memory
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* layout. This detects the case where the user just copied the legacy
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* fpstate layout with out copying the extended state information
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* in the memory layout.
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*/
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if (__get_user(magic2, (__u32 __user *)(fpstate + fx_sw->xstate_size))
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|| magic2 != FP_XSTATE_MAGIC2)
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return -1;
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return 0;
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}
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/*
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* Signal frame handlers.
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*/
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static inline int save_fsave_header(struct task_struct *tsk, void __user *buf)
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{
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if (use_fxsr()) {
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struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;
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struct user_i387_ia32_struct env;
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struct _fpstate_ia32 __user *fp = buf;
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convert_from_fxsr(&env, tsk);
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if (__copy_to_user(buf, &env, sizeof(env)) ||
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__put_user(xsave->i387.swd, &fp->status) ||
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__put_user(X86_FXSR_MAGIC, &fp->magic))
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return -1;
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} else {
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struct i387_fsave_struct __user *fp = buf;
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u32 swd;
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if (__get_user(swd, &fp->swd) || __put_user(swd, &fp->status))
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return -1;
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}
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return 0;
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}
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static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
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{
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struct xsave_struct __user *x = buf;
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struct _fpx_sw_bytes *sw_bytes;
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u32 xstate_bv;
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int err;
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/* Setup the bytes not touched by the [f]xsave and reserved for SW. */
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sw_bytes = ia32_frame ? &fx_sw_reserved_ia32 : &fx_sw_reserved;
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err = __copy_to_user(&x->i387.sw_reserved, sw_bytes, sizeof(*sw_bytes));
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if (!use_xsave())
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return err;
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err |= __put_user(FP_XSTATE_MAGIC2, (__u32 *)(buf + xstate_size));
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/*
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* Read the xstate_bv which we copied (directly from the cpu or
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* from the state in task struct) to the user buffers.
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*/
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err |= __get_user(xstate_bv, (__u32 *)&x->xsave_hdr.xstate_bv);
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/*
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* For legacy compatible, we always set FP/SSE bits in the bit
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* vector while saving the state to the user context. This will
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* enable us capturing any changes(during sigreturn) to
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* the FP/SSE bits by the legacy applications which don't touch
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* xstate_bv in the xsave header.
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*
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* xsave aware apps can change the xstate_bv in the xsave
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* header as well as change any contents in the memory layout.
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* xrestore as part of sigreturn will capture all the changes.
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*/
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xstate_bv |= XSTATE_FPSSE;
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err |= __put_user(xstate_bv, (__u32 *)&x->xsave_hdr.xstate_bv);
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return err;
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}
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static inline int save_user_xstate(struct xsave_struct __user *buf)
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{
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int err;
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if (use_xsave())
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err = xsave_user(buf);
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else if (use_fxsr())
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err = fxsave_user((struct i387_fxsave_struct __user *) buf);
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else
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err = fsave_user((struct i387_fsave_struct __user *) buf);
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if (unlikely(err) && __clear_user(buf, xstate_size))
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err = -EFAULT;
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return err;
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}
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/*
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* Save the fpu, extended register state to the user signal frame.
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*
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* 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
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* state is copied.
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* 'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
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*
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* buf == buf_fx for 64-bit frames and 32-bit fsave frame.
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* buf != buf_fx for 32-bit frames with fxstate.
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*
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* If the fpu, extended register state is live, save the state directly
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* to the user frame pointed by the aligned pointer 'buf_fx'. Otherwise,
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* copy the thread's fpu state to the user frame starting at 'buf_fx'.
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*
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* If this is a 32-bit frame with fxstate, put a fsave header before
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* the aligned state at 'buf_fx'.
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*
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* For [f]xsave state, update the SW reserved fields in the [f]xsave frame
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* indicating the absence/presence of the extended state to the user.
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*/
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int save_xstate_sig(void __user *buf, void __user *buf_fx, int size)
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{
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struct xsave_struct *xsave = ¤t->thread.fpu.state->xsave;
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struct task_struct *tsk = current;
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int ia32_fxstate = (buf != buf_fx);
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ia32_fxstate &= (config_enabled(CONFIG_X86_32) ||
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config_enabled(CONFIG_IA32_EMULATION));
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if (!access_ok(VERIFY_WRITE, buf, size))
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return -EACCES;
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if (!static_cpu_has(X86_FEATURE_FPU))
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return fpregs_soft_get(current, NULL, 0,
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sizeof(struct user_i387_ia32_struct), NULL,
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(struct _fpstate_ia32 __user *) buf) ? -1 : 1;
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if (user_has_fpu()) {
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/* Save the live register state to the user directly. */
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if (save_user_xstate(buf_fx))
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return -1;
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/* Update the thread's fxstate to save the fsave header. */
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if (ia32_fxstate)
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fpu_fxsave(&tsk->thread.fpu);
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} else {
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sanitize_i387_state(tsk);
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if (__copy_to_user(buf_fx, xsave, xstate_size))
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return -1;
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}
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/* Save the fsave header for the 32-bit frames. */
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if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
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return -1;
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if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
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return -1;
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return 0;
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}
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static inline void
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sanitize_restored_xstate(struct task_struct *tsk,
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struct user_i387_ia32_struct *ia32_env,
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u64 xstate_bv, int fx_only)
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{
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struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;
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struct xsave_hdr_struct *xsave_hdr = &xsave->xsave_hdr;
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if (use_xsave()) {
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/* These bits must be zero. */
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memset(xsave_hdr->reserved, 0, 48);
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/*
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* Init the state that is not present in the memory
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* layout and not enabled by the OS.
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*/
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if (fx_only)
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xsave_hdr->xstate_bv = XSTATE_FPSSE;
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else
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xsave_hdr->xstate_bv &= (pcntxt_mask & xstate_bv);
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}
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if (use_fxsr()) {
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/*
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* mscsr reserved bits must be masked to zero for security
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* reasons.
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*/
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xsave->i387.mxcsr &= mxcsr_feature_mask;
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convert_to_fxsr(tsk, ia32_env);
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}
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}
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/*
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* Restore the extended state if present. Otherwise, restore the FP/SSE state.
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*/
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static inline int restore_user_xstate(void __user *buf, u64 xbv, int fx_only)
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{
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if (use_xsave()) {
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if ((unsigned long)buf % 64 || fx_only) {
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u64 init_bv = pcntxt_mask & ~XSTATE_FPSSE;
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xrstor_state(init_xstate_buf, init_bv);
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return fxrstor_user(buf);
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} else {
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u64 init_bv = pcntxt_mask & ~xbv;
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if (unlikely(init_bv))
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xrstor_state(init_xstate_buf, init_bv);
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return xrestore_user(buf, xbv);
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}
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} else if (use_fxsr()) {
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return fxrstor_user(buf);
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} else
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return frstor_user(buf);
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}
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int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
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{
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int ia32_fxstate = (buf != buf_fx);
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struct task_struct *tsk = current;
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int state_size = xstate_size;
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u64 xstate_bv = 0;
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int fx_only = 0;
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ia32_fxstate &= (config_enabled(CONFIG_X86_32) ||
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config_enabled(CONFIG_IA32_EMULATION));
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if (!buf) {
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drop_init_fpu(tsk);
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return 0;
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}
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if (!access_ok(VERIFY_READ, buf, size))
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return -EACCES;
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if (!used_math() && init_fpu(tsk))
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return -1;
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if (!static_cpu_has(X86_FEATURE_FPU))
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return fpregs_soft_set(current, NULL,
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0, sizeof(struct user_i387_ia32_struct),
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NULL, buf) != 0;
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if (use_xsave()) {
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struct _fpx_sw_bytes fx_sw_user;
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if (unlikely(check_for_xstate(buf_fx, buf_fx, &fx_sw_user))) {
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/*
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* Couldn't find the extended state information in the
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* memory layout. Restore just the FP/SSE and init all
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* the other extended state.
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*/
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state_size = sizeof(struct i387_fxsave_struct);
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fx_only = 1;
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} else {
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state_size = fx_sw_user.xstate_size;
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xstate_bv = fx_sw_user.xstate_bv;
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}
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}
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if (ia32_fxstate) {
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/*
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* For 32-bit frames with fxstate, copy the user state to the
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* thread's fpu state, reconstruct fxstate from the fsave
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* header. Sanitize the copied state etc.
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*/
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struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;
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struct user_i387_ia32_struct env;
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int err = 0;
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/*
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* Drop the current fpu which clears used_math(). This ensures
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* that any context-switch during the copy of the new state,
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* avoids the intermediate state from getting restored/saved.
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* Thus avoiding the new restored state from getting corrupted.
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* We will be ready to restore/save the state only after
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* set_used_math() is again set.
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*/
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drop_fpu(tsk);
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if (__copy_from_user(xsave, buf_fx, state_size) ||
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__copy_from_user(&env, buf, sizeof(env))) {
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err = -1;
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} else {
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sanitize_restored_xstate(tsk, &env, xstate_bv, fx_only);
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set_used_math();
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}
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if (use_eager_fpu()) {
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preempt_disable();
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math_state_restore();
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preempt_enable();
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}
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return err;
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} else {
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/*
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* For 64-bit frames and 32-bit fsave frames, restore the user
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* state to the registers directly (with exceptions handled).
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*/
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user_fpu_begin();
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if (restore_user_xstate(buf_fx, xstate_bv, fx_only)) {
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drop_init_fpu(tsk);
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return -1;
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}
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}
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return 0;
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}
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/*
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* Prepare the SW reserved portion of the fxsave memory layout, indicating
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* the presence of the extended state information in the memory layout
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* pointed by the fpstate pointer in the sigcontext.
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* This will be saved when ever the FP and extended state context is
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* saved on the user stack during the signal handler delivery to the user.
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*/
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static void prepare_fx_sw_frame(void)
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{
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int fsave_header_size = sizeof(struct i387_fsave_struct);
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int size = xstate_size + FP_XSTATE_MAGIC2_SIZE;
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if (config_enabled(CONFIG_X86_32))
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size += fsave_header_size;
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fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
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fx_sw_reserved.extended_size = size;
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fx_sw_reserved.xstate_bv = pcntxt_mask;
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fx_sw_reserved.xstate_size = xstate_size;
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if (config_enabled(CONFIG_IA32_EMULATION)) {
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fx_sw_reserved_ia32 = fx_sw_reserved;
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fx_sw_reserved_ia32.extended_size += fsave_header_size;
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}
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}
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/*
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* Enable the extended processor state save/restore feature
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*/
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static inline void xstate_enable(void)
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{
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set_in_cr4(X86_CR4_OSXSAVE);
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xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask);
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}
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/*
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* Record the offsets and sizes of different state managed by the xsave
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* memory layout.
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*/
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static void __init setup_xstate_features(void)
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{
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int eax, ebx, ecx, edx, leaf = 0x2;
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xstate_features = fls64(pcntxt_mask);
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xstate_offsets = alloc_bootmem(xstate_features * sizeof(int));
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xstate_sizes = alloc_bootmem(xstate_features * sizeof(int));
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do {
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cpuid_count(XSTATE_CPUID, leaf, &eax, &ebx, &ecx, &edx);
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if (eax == 0)
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break;
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xstate_offsets[leaf] = ebx;
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xstate_sizes[leaf] = eax;
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leaf++;
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} while (1);
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}
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/*
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* This function sets up offsets and sizes of all extended states in
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* xsave area. This supports both standard format and compacted format
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* of the xsave aread.
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*
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|
* Input: void
|
|
* Output: void
|
|
*/
|
|
void setup_xstate_comp(void)
|
|
{
|
|
unsigned int xstate_comp_sizes[sizeof(pcntxt_mask)*8];
|
|
int i;
|
|
|
|
/*
|
|
* The FP xstates and SSE xstates are legacy states. They are always
|
|
* in the fixed offsets in the xsave area in either compacted form
|
|
* or standard form.
|
|
*/
|
|
xstate_comp_offsets[0] = 0;
|
|
xstate_comp_offsets[1] = offsetof(struct i387_fxsave_struct, xmm_space);
|
|
|
|
if (!cpu_has_xsaves) {
|
|
for (i = 2; i < xstate_features; i++) {
|
|
if (test_bit(i, (unsigned long *)&pcntxt_mask)) {
|
|
xstate_comp_offsets[i] = xstate_offsets[i];
|
|
xstate_comp_sizes[i] = xstate_sizes[i];
|
|
}
|
|
}
|
|
return;
|
|
}
|
|
|
|
xstate_comp_offsets[2] = FXSAVE_SIZE + XSAVE_HDR_SIZE;
|
|
|
|
for (i = 2; i < xstate_features; i++) {
|
|
if (test_bit(i, (unsigned long *)&pcntxt_mask))
|
|
xstate_comp_sizes[i] = xstate_sizes[i];
|
|
else
|
|
xstate_comp_sizes[i] = 0;
|
|
|
|
if (i > 2)
|
|
xstate_comp_offsets[i] = xstate_comp_offsets[i-1]
|
|
+ xstate_comp_sizes[i-1];
|
|
|
|
}
|
|
}
|
|
|
|
/*
|
|
* setup the xstate image representing the init state
|
|
*/
|
|
static void __init setup_init_fpu_buf(void)
|
|
{
|
|
/*
|
|
* Setup init_xstate_buf to represent the init state of
|
|
* all the features managed by the xsave
|
|
*/
|
|
init_xstate_buf = alloc_bootmem_align(xstate_size,
|
|
__alignof__(struct xsave_struct));
|
|
fx_finit(&init_xstate_buf->i387);
|
|
|
|
if (!cpu_has_xsave)
|
|
return;
|
|
|
|
setup_xstate_features();
|
|
|
|
if (cpu_has_xsaves) {
|
|
init_xstate_buf->xsave_hdr.xcomp_bv =
|
|
(u64)1 << 63 | pcntxt_mask;
|
|
init_xstate_buf->xsave_hdr.xstate_bv = pcntxt_mask;
|
|
}
|
|
|
|
/*
|
|
* Init all the features state with header_bv being 0x0
|
|
*/
|
|
xrstor_state_booting(init_xstate_buf, -1);
|
|
/*
|
|
* Dump the init state again. This is to identify the init state
|
|
* of any feature which is not represented by all zero's.
|
|
*/
|
|
xsave_state_booting(init_xstate_buf, -1);
|
|
}
|
|
|
|
static enum { AUTO, ENABLE, DISABLE } eagerfpu = AUTO;
|
|
static int __init eager_fpu_setup(char *s)
|
|
{
|
|
if (!strcmp(s, "on"))
|
|
eagerfpu = ENABLE;
|
|
else if (!strcmp(s, "off"))
|
|
eagerfpu = DISABLE;
|
|
else if (!strcmp(s, "auto"))
|
|
eagerfpu = AUTO;
|
|
return 1;
|
|
}
|
|
__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.
|
|
*/
|
|
static void __init xstate_enable_boot_cpu(void)
|
|
{
|
|
unsigned int eax, ebx, ecx, edx;
|
|
|
|
if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
|
|
WARN(1, KERN_ERR "XSTATE_CPUID missing\n");
|
|
return;
|
|
}
|
|
|
|
cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
|
|
pcntxt_mask = eax + ((u64)edx << 32);
|
|
|
|
if ((pcntxt_mask & XSTATE_FPSSE) != XSTATE_FPSSE) {
|
|
pr_err("FP/SSE not shown under xsave features 0x%llx\n",
|
|
pcntxt_mask);
|
|
BUG();
|
|
}
|
|
|
|
/*
|
|
* Support only the state known to OS.
|
|
*/
|
|
pcntxt_mask = pcntxt_mask & XCNTXT_MASK;
|
|
|
|
xstate_enable();
|
|
|
|
/*
|
|
* Recompute the context size for enabled features
|
|
*/
|
|
init_xstate_size();
|
|
|
|
update_regset_xstate_info(xstate_size, pcntxt_mask);
|
|
prepare_fx_sw_frame();
|
|
setup_init_fpu_buf();
|
|
|
|
/* Auto enable eagerfpu for xsaveopt */
|
|
if (cpu_has_xsaveopt && eagerfpu != DISABLE)
|
|
eagerfpu = ENABLE;
|
|
|
|
if (pcntxt_mask & XSTATE_EAGER) {
|
|
if (eagerfpu == DISABLE) {
|
|
pr_err("eagerfpu not present, disabling some xstate features: 0x%llx\n",
|
|
pcntxt_mask & XSTATE_EAGER);
|
|
pcntxt_mask &= ~XSTATE_EAGER;
|
|
} else {
|
|
eagerfpu = ENABLE;
|
|
}
|
|
}
|
|
|
|
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");
|
|
}
|
|
|
|
/*
|
|
* For the very first instance, this calls xstate_enable_boot_cpu();
|
|
* for all subsequent instances, this calls xstate_enable().
|
|
*
|
|
* This is somewhat obfuscated due to the lack of powerful enough
|
|
* overrides for the section checks.
|
|
*/
|
|
void xsave_init(void)
|
|
{
|
|
static __refdata void (*next_func)(void) = xstate_enable_boot_cpu;
|
|
void (*this_func)(void);
|
|
|
|
if (!cpu_has_xsave)
|
|
return;
|
|
|
|
this_func = next_func;
|
|
next_func = xstate_enable;
|
|
this_func();
|
|
}
|
|
|
|
static inline void __init eager_fpu_init_bp(void)
|
|
{
|
|
current->thread.fpu.state =
|
|
alloc_bootmem_align(xstate_size, __alignof__(struct xsave_struct));
|
|
if (!init_xstate_buf)
|
|
setup_init_fpu_buf();
|
|
}
|
|
|
|
void eager_fpu_init(void)
|
|
{
|
|
static __refdata void (*boot_func)(void) = eager_fpu_init_bp;
|
|
|
|
clear_used_math();
|
|
current_thread_info()->status = 0;
|
|
|
|
if (eagerfpu == ENABLE)
|
|
setup_force_cpu_cap(X86_FEATURE_EAGER_FPU);
|
|
|
|
if (!cpu_has_eager_fpu) {
|
|
stts();
|
|
return;
|
|
}
|
|
|
|
if (boot_func) {
|
|
boot_func();
|
|
boot_func = NULL;
|
|
}
|
|
|
|
/*
|
|
* This is same as math_state_restore(). But use_xsave() is
|
|
* not yet patched to use math_state_restore().
|
|
*/
|
|
init_fpu(current);
|
|
__thread_fpu_begin(current);
|
|
if (cpu_has_xsave)
|
|
xrstor_state(init_xstate_buf, -1);
|
|
else
|
|
fxrstor_checking(&init_xstate_buf->i387);
|
|
}
|
|
|
|
/*
|
|
* Given the xsave area and a state inside, this function returns the
|
|
* address of the state.
|
|
*
|
|
* This is the API that is called to get xstate address in either
|
|
* standard format or compacted format of xsave area.
|
|
*
|
|
* Inputs:
|
|
* xsave: base address of the xsave area;
|
|
* xstate: state which is defined in xsave.h (e.g. XSTATE_FP, XSTATE_SSE,
|
|
* etc.)
|
|
* Output:
|
|
* address of the state in the xsave area.
|
|
*/
|
|
void *get_xsave_addr(struct xsave_struct *xsave, int xstate)
|
|
{
|
|
int feature = fls64(xstate) - 1;
|
|
if (!test_bit(feature, (unsigned long *)&pcntxt_mask))
|
|
return NULL;
|
|
|
|
return (void *)xsave + xstate_comp_offsets[feature];
|
|
}
|