x86, xsave: save/restore the extended state context in sigframe
On cpu's supporting xsave/xrstor, fpstate pointer in the sigcontext, will include the extended state information along with fpstate information. Presence of extended state information is indicated by the presence of FP_XSTATE_MAGIC1 at fpstate.sw_reserved.magic1 and FP_XSTATE_MAGIC2 at fpstate + (fpstate.sw_reserved.extended_size - FP_XSTATE_MAGIC2_SIZE). Extended feature bit mask that is saved in the memory layout is represented by the fpstate.sw_reserved.xstate_bv For RT signal frames, UC_FP_XSTATE in the uc_flags also indicate the presence of extended state information in the sigcontext's fpstate pointer. 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>
This commit is contained in:
Suresh Siddha
Ingo Molnar
parent
bdd8caba5e
commit
c37b5efea4
8 changed files with 264 additions and 22 deletions
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@ -544,7 +544,10 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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goto give_sigsegv;
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/* Create the ucontext. */
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err |= __put_user(0, &frame->uc.uc_flags);
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if (cpu_has_xsave)
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err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
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else
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err |= __put_user(0, &frame->uc.uc_flags);
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err |= __put_user(0, &frame->uc.uc_link);
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err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
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err |= __put_user(sas_ss_flags(regs->sp),
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@ -26,6 +26,7 @@
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# define _fpstate_ia32 _fpstate
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# define _xstate_ia32 _xstate
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# define sig_xstate_ia32_size sig_xstate_size
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# define fx_sw_reserved_ia32 fx_sw_reserved
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# define user_i387_ia32_struct user_i387_struct
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# define user32_fxsr_struct user_fxsr_struct
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#endif
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@ -447,12 +448,30 @@ static int save_i387_fxsave(struct _fpstate_ia32 __user *buf)
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if (err)
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return -1;
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if (__copy_to_user(&buf->_fxsr_env[0], fx,
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sizeof(struct i387_fxsave_struct)))
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if (__copy_to_user(&buf->_fxsr_env[0], fx, xstate_size))
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return -1;
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return 1;
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}
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static int save_i387_xsave(void __user *buf)
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{
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struct _fpstate_ia32 __user *fx = buf;
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int err = 0;
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if (save_i387_fxsave(fx) < 0)
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return -1;
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err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved_ia32,
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sizeof(struct _fpx_sw_bytes));
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err |= __put_user(FP_XSTATE_MAGIC2,
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(__u32 __user *) (buf + sig_xstate_ia32_size
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- FP_XSTATE_MAGIC2_SIZE));
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if (err)
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return -1;
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return 1;
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}
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int save_i387_xstate_ia32(void __user *buf)
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{
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struct _fpstate_ia32 __user *fp = (struct _fpstate_ia32 __user *) buf;
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@ -477,6 +496,8 @@ int save_i387_xstate_ia32(void __user *buf)
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unlazy_fpu(tsk);
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if (cpu_has_xsave)
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return save_i387_xsave(fp);
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if (cpu_has_fxsr)
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return save_i387_fxsave(fp);
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else
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@ -491,14 +512,15 @@ static inline int restore_i387_fsave(struct _fpstate_ia32 __user *buf)
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sizeof(struct i387_fsave_struct));
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}
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static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf)
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static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf,
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unsigned int size)
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{
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struct task_struct *tsk = current;
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struct user_i387_ia32_struct env;
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int err;
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err = __copy_from_user(&tsk->thread.xstate->fxsave, &buf->_fxsr_env[0],
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sizeof(struct i387_fxsave_struct));
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size);
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/* mxcsr reserved bits must be masked to zero for security reasons */
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tsk->thread.xstate->fxsave.mxcsr &= mxcsr_feature_mask;
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if (err || __copy_from_user(&env, buf, sizeof(env)))
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@ -508,6 +530,51 @@ static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf)
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return 0;
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}
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static int restore_i387_xsave(void __user *buf)
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{
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struct _fpx_sw_bytes fx_sw_user;
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struct _fpstate_ia32 __user *fx_user =
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((struct _fpstate_ia32 __user *) buf);
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struct i387_fxsave_struct __user *fx =
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(struct i387_fxsave_struct __user *) &fx_user->_fxsr_env[0];
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struct xsave_hdr_struct *xsave_hdr =
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¤t->thread.xstate->xsave.xsave_hdr;
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unsigned int lmask, hmask;
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int err;
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if (check_for_xstate(fx, buf, &fx_sw_user))
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goto fx_only;
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lmask = fx_sw_user.xstate_bv;
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hmask = fx_sw_user.xstate_bv >> 32;
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err = restore_i387_fxsave(buf, fx_sw_user.xstate_size);
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xsave_hdr->xstate_bv &= (pcntxt_lmask | (((u64) pcntxt_hmask) << 32));
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/*
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* These bits must be zero.
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*/
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xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0;
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/*
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* Init the state that is not present in the memory layout
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* and enabled by the OS.
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*/
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lmask = ~(pcntxt_lmask & ~lmask);
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hmask = ~(pcntxt_hmask & ~hmask);
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xsave_hdr->xstate_bv &= (lmask | (((u64) hmask) << 32));
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return err;
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fx_only:
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/*
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* Couldn't find the extended state information in the memory
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* layout. Restore the FP/SSE and init the other extended state
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* enabled by the OS.
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*/
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xsave_hdr->xstate_bv = XSTATE_FPSSE;
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return restore_i387_fxsave(buf, sizeof(struct i387_fxsave_struct));
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}
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int restore_i387_xstate_ia32(void __user *buf)
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{
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int err;
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@ -535,8 +602,11 @@ int restore_i387_xstate_ia32(void __user *buf)
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}
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if (HAVE_HWFP) {
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if (cpu_has_fxsr)
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err = restore_i387_fxsave(fp);
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if (cpu_has_xsave)
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err = restore_i387_xsave(buf);
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else if (cpu_has_fxsr)
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err = restore_i387_fxsave(fp, sizeof(struct
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i387_fxsave_struct));
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else
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err = restore_i387_fsave(fp);
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} else {
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@ -441,7 +441,10 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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goto give_sigsegv;
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/* Create the ucontext. */
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err |= __put_user(0, &frame->uc.uc_flags);
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if (cpu_has_xsave)
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err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
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else
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err |= __put_user(0, &frame->uc.uc_flags);
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err |= __put_user(0, &frame->uc.uc_link);
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err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
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err |= __put_user(sas_ss_flags(regs->sp),
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@ -192,7 +192,7 @@ get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size)
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sp = current->sas_ss_sp + current->sas_ss_size;
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}
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return (void __user *)round_down(sp - size, 16);
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return (void __user *)round_down(sp - size, 64);
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}
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static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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@ -226,7 +226,10 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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}
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/* Create the ucontext. */
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err |= __put_user(0, &frame->uc.uc_flags);
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if (cpu_has_xsave)
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err |= __put_user(UC_FP_XSTATE, &frame->uc.uc_flags);
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else
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err |= __put_user(0, &frame->uc.uc_flags);
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err |= __put_user(0, &frame->uc.uc_link);
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err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
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err |= __put_user(sas_ss_flags(regs->sp),
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@ -6,12 +6,68 @@
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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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#ifdef CONFIG_IA32_EMULATION
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#include <asm/sigcontext32.h>
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#endif
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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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struct _fpx_sw_bytes fx_sw_reserved;
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#ifdef CONFIG_IA32_EMULATION
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struct _fpx_sw_bytes fx_sw_reserved_ia32;
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#endif
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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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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_user)
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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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int err;
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err = __copy_from_user(fx_sw_user, &buf->sw_reserved[0],
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sizeof(struct _fpx_sw_bytes));
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if (err)
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return err;
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/*
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* First Magic check failed.
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*/
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if (fx_sw_user->magic1 != FP_XSTATE_MAGIC1)
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return -1;
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/*
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* Check for error scenarios.
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*/
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if (fx_sw_user->xstate_size < min_xstate_size ||
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fx_sw_user->xstate_size > xstate_size ||
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fx_sw_user->xstate_size > fx_sw_user->extended_size)
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return -1;
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err = __get_user(magic2, (__u32 *) (((void *)fpstate) +
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fx_sw_user->extended_size -
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FP_XSTATE_MAGIC2_SIZE));
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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 (err || magic2 != FP_XSTATE_MAGIC2)
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return -1;
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return 0;
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}
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#ifdef CONFIG_X86_64
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/*
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* Signal frame handlers.
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@ -28,15 +84,18 @@ int save_i387_xstate(void __user *buf)
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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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if ((unsigned long)buf % 64)
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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 (task_thread_info(tsk)->status & TS_XSAVE)
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err = xsave_user(buf);
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else
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err = fxsave_user(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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@ -46,23 +105,77 @@ int save_i387_xstate(void __user *buf)
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xstate_size))
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return -1;
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}
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if (task_thread_info(tsk)->status & TS_XSAVE) {
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struct _fpstate __user *fx = buf;
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err = __copy_to_user(&fx->sw_reserved, &fx_sw_reserved,
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sizeof(struct _fpx_sw_bytes));
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err |= __put_user(FP_XSTATE_MAGIC2,
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(__u32 __user *) (buf + sig_xstate_size
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- FP_XSTATE_MAGIC2_SIZE));
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}
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return 1;
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}
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/*
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* Restore the extended state if present. Otherwise, restore the FP/SSE
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* state.
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*/
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int restore_user_xstate(void __user *buf)
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{
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struct _fpx_sw_bytes fx_sw_user;
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unsigned int lmask, hmask;
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int err;
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if (((unsigned long)buf % 64) ||
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check_for_xstate(buf, buf, &fx_sw_user))
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goto fx_only;
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lmask = fx_sw_user.xstate_bv;
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hmask = fx_sw_user.xstate_bv >> 32;
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/*
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* restore the state passed by the user.
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*/
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err = xrestore_user(buf, lmask, hmask);
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if (err)
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return err;
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/*
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* init the state skipped by the user.
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*/
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lmask = pcntxt_lmask & ~lmask;
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hmask = pcntxt_hmask & ~hmask;
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xrstor_state(init_xstate_buf, lmask, hmask);
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return 0;
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fx_only:
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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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xrstor_state(init_xstate_buf, pcntxt_lmask & ~XSTATE_FPSSE,
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pcntxt_hmask);
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return fxrstor_checking((__force struct i387_fxsave_struct *)buf);
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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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int err = 0;
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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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if (used_math())
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goto clear;
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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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@ -78,12 +191,17 @@ int restore_i387_xstate(void __user *buf)
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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 (task_thread_info(tsk)->status & TS_XSAVE)
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err = restore_user_xstate(buf);
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else
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err = fxrstor_checking((__force struct i387_fxsave_struct *)
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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:
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clear_fpu(tsk);
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clear_used_math();
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}
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@ -91,6 +209,38 @@ int restore_i387_xstate(void __user *buf)
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}
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#endif
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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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void prepare_fx_sw_frame(void)
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{
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int size_extended = (xstate_size - sizeof(struct i387_fxsave_struct)) +
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FP_XSTATE_MAGIC2_SIZE;
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sig_xstate_size = sizeof(struct _fpstate) + size_extended;
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#ifdef CONFIG_IA32_EMULATION
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sig_xstate_ia32_size = sizeof(struct _fpstate_ia32) + size_extended;
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#endif
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memset(&fx_sw_reserved, 0, sizeof(fx_sw_reserved));
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fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
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fx_sw_reserved.extended_size = sig_xstate_size;
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fx_sw_reserved.xstate_bv = pcntxt_lmask |
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(((u64) (pcntxt_hmask)) << 32);
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fx_sw_reserved.xstate_size = xstate_size;
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#ifdef CONFIG_IA32_EMULATION
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memcpy(&fx_sw_reserved_ia32, &fx_sw_reserved,
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sizeof(struct _fpx_sw_bytes));
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fx_sw_reserved_ia32.extended_size = sig_xstate_ia32_size;
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#endif
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}
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/*
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* Represents init state for the supported extended state.
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*/
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@ -162,6 +312,8 @@ void __init xsave_cntxt_init(void)
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xstate_size = ebx;
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prepare_fx_sw_frame();
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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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@ -31,8 +31,10 @@ extern user_regset_active_fn fpregs_active, xfpregs_active;
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extern user_regset_get_fn fpregs_get, xfpregs_get, fpregs_soft_get;
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||||
extern user_regset_set_fn fpregs_set, xfpregs_set, fpregs_soft_set;
|
||||
|
||||
extern struct _fpx_sw_bytes fx_sw_reserved;
|
||||
#ifdef CONFIG_IA32_EMULATION
|
||||
extern unsigned int sig_xstate_ia32_size;
|
||||
extern struct _fpx_sw_bytes fx_sw_reserved_ia32;
|
||||
struct _fpstate_ia32;
|
||||
struct _xstate_ia32;
|
||||
extern int save_i387_xstate_ia32(void __user *buf);
|
||||
|
|
@ -104,7 +106,7 @@ static inline void clear_fpu_state(struct task_struct *tsk)
|
|||
X86_FEATURE_FXSAVE_LEAK);
|
||||
}
|
||||
|
||||
static inline int save_i387_checking(struct i387_fxsave_struct __user *fx)
|
||||
static inline int fxsave_user(struct i387_fxsave_struct __user *fx)
|
||||
{
|
||||
int err;
|
||||
|
||||
|
|
|
|||
|
|
@ -1,6 +1,12 @@
|
|||
#ifndef ASM_X86__UCONTEXT_H
|
||||
#define ASM_X86__UCONTEXT_H
|
||||
|
||||
#define UC_FP_XSTATE 0x1 /* indicates the presence of extended state
|
||||
* information in the memory layout pointed
|
||||
* by the fpstate pointer in the ucontext's
|
||||
* sigcontext struct (uc_mcontext).
|
||||
*/
|
||||
|
||||
struct ucontext {
|
||||
unsigned long uc_flags;
|
||||
struct ucontext *uc_link;
|
||||
|
|
|
|||
|
|
@ -29,6 +29,9 @@ extern struct xsave_struct *init_xstate_buf;
|
|||
extern void xsave_cntxt_init(void);
|
||||
extern void xsave_init(void);
|
||||
extern int init_fpu(struct task_struct *child);
|
||||
extern int check_for_xstate(struct i387_fxsave_struct __user *buf,
|
||||
void __user *fpstate,
|
||||
struct _fpx_sw_bytes *sw);
|
||||
|
||||
static inline int xrstor_checking(struct xsave_struct *fx)
|
||||
{
|
||||
|
|
@ -48,7 +51,7 @@ static inline int xrstor_checking(struct xsave_struct *fx)
|
|||
return err;
|
||||
}
|
||||
|
||||
static inline int xsave_check(struct xsave_struct __user *buf)
|
||||
static inline int xsave_user(struct xsave_struct __user *buf)
|
||||
{
|
||||
int err;
|
||||
__asm__ __volatile__("1: .byte " REX_PREFIX "0x0f,0xae,0x27\n"
|
||||
|
|
|
|||
Loading…
Reference in a new issue