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322 lines
8.9 KiB
322 lines
8.9 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef __X86_KERNEL_FPU_XSTATE_H |
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#define __X86_KERNEL_FPU_XSTATE_H |
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#include <asm/cpufeature.h> |
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#include <asm/fpu/xstate.h> |
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#include <asm/fpu/xcr.h> |
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#ifdef CONFIG_X86_64 |
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DECLARE_PER_CPU(u64, xfd_state); |
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#endif |
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static inline void xstate_init_xcomp_bv(struct xregs_state *xsave, u64 mask) |
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{ |
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/* |
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* XRSTORS requires these bits set in xcomp_bv, or it will |
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* trigger #GP: |
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*/ |
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if (cpu_feature_enabled(X86_FEATURE_XSAVES)) |
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xsave->header.xcomp_bv = mask | XCOMP_BV_COMPACTED_FORMAT; |
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} |
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static inline u64 xstate_get_group_perm(bool guest) |
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{ |
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struct fpu *fpu = ¤t->group_leader->thread.fpu; |
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struct fpu_state_perm *perm; |
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/* Pairs with WRITE_ONCE() in xstate_request_perm() */ |
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perm = guest ? &fpu->guest_perm : &fpu->perm; |
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return READ_ONCE(perm->__state_perm); |
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} |
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static inline u64 xstate_get_host_group_perm(void) |
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{ |
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return xstate_get_group_perm(false); |
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} |
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enum xstate_copy_mode { |
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XSTATE_COPY_FP, |
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XSTATE_COPY_FX, |
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XSTATE_COPY_XSAVE, |
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}; |
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struct membuf; |
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extern void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate, |
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u32 pkru_val, enum xstate_copy_mode copy_mode); |
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extern void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk, |
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enum xstate_copy_mode mode); |
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extern int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf); |
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extern int copy_sigframe_from_user_to_xstate(struct fpstate *fpstate, const void __user *ubuf); |
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extern void fpu__init_cpu_xstate(void); |
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extern void fpu__init_system_xstate(unsigned int legacy_size); |
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extern void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr); |
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static inline u64 xfeatures_mask_supervisor(void) |
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{ |
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return fpu_kernel_cfg.max_features & XFEATURE_MASK_SUPERVISOR_SUPPORTED; |
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} |
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static inline u64 xfeatures_mask_independent(void) |
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{ |
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if (!cpu_feature_enabled(X86_FEATURE_ARCH_LBR)) |
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return XFEATURE_MASK_INDEPENDENT & ~XFEATURE_MASK_LBR; |
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return XFEATURE_MASK_INDEPENDENT; |
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} |
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/* XSAVE/XRSTOR wrapper functions */ |
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#ifdef CONFIG_X86_64 |
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#define REX_PREFIX "0x48, " |
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#else |
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#define REX_PREFIX |
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#endif |
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/* These macros all use (%edi)/(%rdi) as the single memory argument. */ |
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#define XSAVE ".byte " REX_PREFIX "0x0f,0xae,0x27" |
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#define XSAVEOPT ".byte " REX_PREFIX "0x0f,0xae,0x37" |
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#define XSAVES ".byte " REX_PREFIX "0x0f,0xc7,0x2f" |
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#define XRSTOR ".byte " REX_PREFIX "0x0f,0xae,0x2f" |
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#define XRSTORS ".byte " REX_PREFIX "0x0f,0xc7,0x1f" |
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/* |
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* After this @err contains 0 on success or the trap number when the |
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* operation raises an exception. |
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*/ |
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#define XSTATE_OP(op, st, lmask, hmask, err) \ |
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asm volatile("1:" op "\n\t" \ |
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"xor %[err], %[err]\n" \ |
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"2:\n\t" \ |
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_ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_FAULT_MCE_SAFE) \ |
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: [err] "=a" (err) \ |
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: "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ |
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: "memory") |
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/* |
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* If XSAVES is enabled, it replaces XSAVEOPT because it supports a compact |
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* format and supervisor states in addition to modified optimization in |
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* XSAVEOPT. |
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* |
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* Otherwise, if XSAVEOPT is enabled, XSAVEOPT replaces XSAVE because XSAVEOPT |
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* supports modified optimization which is not supported by XSAVE. |
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* |
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* We use XSAVE as a fallback. |
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* |
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* The 661 label is defined in the ALTERNATIVE* macros as the address of the |
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* original instruction which gets replaced. We need to use it here as the |
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* address of the instruction where we might get an exception at. |
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*/ |
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#define XSTATE_XSAVE(st, lmask, hmask, err) \ |
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asm volatile(ALTERNATIVE_2(XSAVE, \ |
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XSAVEOPT, X86_FEATURE_XSAVEOPT, \ |
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XSAVES, X86_FEATURE_XSAVES) \ |
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"\n" \ |
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"xor %[err], %[err]\n" \ |
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"3:\n" \ |
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_ASM_EXTABLE_TYPE_REG(661b, 3b, EX_TYPE_EFAULT_REG, %[err]) \ |
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: [err] "=r" (err) \ |
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: "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ |
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: "memory") |
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/* |
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* Use XRSTORS to restore context if it is enabled. XRSTORS supports compact |
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* XSAVE area format. |
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*/ |
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#define XSTATE_XRESTORE(st, lmask, hmask) \ |
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asm volatile(ALTERNATIVE(XRSTOR, \ |
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XRSTORS, X86_FEATURE_XSAVES) \ |
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"\n" \ |
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"3:\n" \ |
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_ASM_EXTABLE_TYPE(661b, 3b, EX_TYPE_FPU_RESTORE) \ |
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: \ |
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: "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \ |
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: "memory") |
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#if defined(CONFIG_X86_64) && defined(CONFIG_X86_DEBUG_FPU) |
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extern void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor); |
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#else |
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static inline void xfd_validate_state(struct fpstate *fpstate, u64 mask, bool rstor) { } |
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#endif |
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#ifdef CONFIG_X86_64 |
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static inline void xfd_update_state(struct fpstate *fpstate) |
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{ |
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if (fpu_state_size_dynamic()) { |
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u64 xfd = fpstate->xfd; |
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if (__this_cpu_read(xfd_state) != xfd) { |
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wrmsrl(MSR_IA32_XFD, xfd); |
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__this_cpu_write(xfd_state, xfd); |
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} |
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} |
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} |
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extern int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu); |
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#else |
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static inline void xfd_update_state(struct fpstate *fpstate) { } |
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static inline int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu) { |
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return -EPERM; |
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} |
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#endif |
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/* |
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* Save processor xstate to xsave area. |
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* |
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* Uses either XSAVE or XSAVEOPT or XSAVES depending on the CPU features |
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* and command line options. The choice is permanent until the next reboot. |
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*/ |
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static inline void os_xsave(struct fpstate *fpstate) |
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{ |
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u64 mask = fpstate->xfeatures; |
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u32 lmask = mask; |
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u32 hmask = mask >> 32; |
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int err; |
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WARN_ON_FPU(!alternatives_patched); |
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xfd_validate_state(fpstate, mask, false); |
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XSTATE_XSAVE(&fpstate->regs.xsave, lmask, hmask, err); |
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/* We should never fault when copying to a kernel buffer: */ |
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WARN_ON_FPU(err); |
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} |
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/* |
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* Restore processor xstate from xsave area. |
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* |
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* Uses XRSTORS when XSAVES is used, XRSTOR otherwise. |
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*/ |
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static inline void os_xrstor(struct fpstate *fpstate, u64 mask) |
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{ |
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u32 lmask = mask; |
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u32 hmask = mask >> 32; |
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xfd_validate_state(fpstate, mask, true); |
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XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask); |
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} |
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/* Restore of supervisor state. Does not require XFD */ |
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static inline void os_xrstor_supervisor(struct fpstate *fpstate) |
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{ |
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u64 mask = xfeatures_mask_supervisor(); |
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u32 lmask = mask; |
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u32 hmask = mask >> 32; |
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XSTATE_XRESTORE(&fpstate->regs.xsave, lmask, hmask); |
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} |
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/* |
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* XSAVE itself always writes all requested xfeatures. Removing features |
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* from the request bitmap reduces the features which are written. |
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* Generate a mask of features which must be written to a sigframe. The |
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* unset features can be optimized away and not written. |
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* |
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* This optimization is user-visible. Only use for states where |
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* uninitialized sigframe contents are tolerable, like dynamic features. |
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* |
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* Users of buffers produced with this optimization must check XSTATE_BV |
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* to determine which features have been optimized out. |
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*/ |
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static inline u64 xfeatures_need_sigframe_write(void) |
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{ |
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u64 xfeaures_to_write; |
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/* In-use features must be written: */ |
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xfeaures_to_write = xfeatures_in_use(); |
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/* Also write all non-optimizable sigframe features: */ |
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xfeaures_to_write |= XFEATURE_MASK_USER_SUPPORTED & |
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~XFEATURE_MASK_SIGFRAME_INITOPT; |
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return xfeaures_to_write; |
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} |
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/* |
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* Save xstate to user space xsave area. |
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* |
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* We don't use modified optimization because xrstor/xrstors might track |
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* a different application. |
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* |
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* We don't use compacted format xsave area for backward compatibility for |
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* old applications which don't understand the compacted format of the |
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* xsave area. |
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* |
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* The caller has to zero buf::header before calling this because XSAVE* |
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* does not touch the reserved fields in the header. |
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*/ |
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static inline int xsave_to_user_sigframe(struct xregs_state __user *buf) |
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{ |
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/* |
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* Include the features which are not xsaved/rstored by the kernel |
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* internally, e.g. PKRU. That's user space ABI and also required |
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* to allow the signal handler to modify PKRU. |
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*/ |
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struct fpstate *fpstate = current->thread.fpu.fpstate; |
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u64 mask = fpstate->user_xfeatures; |
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u32 lmask; |
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u32 hmask; |
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int err; |
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/* Optimize away writing unnecessary xfeatures: */ |
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if (fpu_state_size_dynamic()) |
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mask &= xfeatures_need_sigframe_write(); |
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lmask = mask; |
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hmask = mask >> 32; |
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xfd_validate_state(fpstate, mask, false); |
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stac(); |
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XSTATE_OP(XSAVE, buf, lmask, hmask, err); |
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clac(); |
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return err; |
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} |
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/* |
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* Restore xstate from user space xsave area. |
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*/ |
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static inline int xrstor_from_user_sigframe(struct xregs_state __user *buf, u64 mask) |
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{ |
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struct xregs_state *xstate = ((__force struct xregs_state *)buf); |
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u32 lmask = mask; |
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u32 hmask = mask >> 32; |
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int err; |
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xfd_validate_state(current->thread.fpu.fpstate, mask, true); |
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stac(); |
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XSTATE_OP(XRSTOR, xstate, lmask, hmask, err); |
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clac(); |
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return err; |
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} |
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/* |
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* Restore xstate from kernel space xsave area, return an error code instead of |
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* an exception. |
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*/ |
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static inline int os_xrstor_safe(struct fpstate *fpstate, u64 mask) |
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{ |
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struct xregs_state *xstate = &fpstate->regs.xsave; |
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u32 lmask = mask; |
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u32 hmask = mask >> 32; |
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int err; |
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/* Ensure that XFD is up to date */ |
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xfd_update_state(fpstate); |
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if (cpu_feature_enabled(X86_FEATURE_XSAVES)) |
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XSTATE_OP(XRSTORS, xstate, lmask, hmask, err); |
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else |
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XSTATE_OP(XRSTOR, xstate, lmask, hmask, err); |
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return err; |
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} |
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#endif
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