/* * Copyright (C) 1994 Linus Torvalds * * Pentium III FXSR, SSE support * General FPU state handling cleanups * Gareth Hughes <gareth@valinux.com>, May 2000 * x86-64 work by Andi Kleen 2002 */ #ifndef _FPU_INTERNAL_H #define _FPU_INTERNAL_H #include <linux/kernel_stat.h> #include <linux/regset.h> #include <linux/compat.h> #include <linux/slab.h> #include <asm/asm.h> #include <asm/cpufeature.h> #include <asm/processor.h> #include <asm/sigcontext.h> #include <asm/user.h> #include <asm/uaccess.h> #include <asm/xsave.h> #include <asm/smap.h> #ifdef CONFIG_X86_64 # include <asm/sigcontext32.h> # include <asm/user32.h> struct ksignal; int ia32_setup_rt_frame(int sig, struct ksignal *ksig, compat_sigset_t *set, struct pt_regs *regs); int ia32_setup_frame(int sig, struct ksignal *ksig, compat_sigset_t *set, struct pt_regs *regs); #else # define user_i387_ia32_struct user_i387_struct # define user32_fxsr_struct user_fxsr_struct # define ia32_setup_frame __setup_frame # define ia32_setup_rt_frame __setup_rt_frame #endif extern unsigned int mxcsr_feature_mask; extern void fpu_init(void); extern void eager_fpu_init(void); DECLARE_PER_CPU(struct task_struct *, fpu_owner_task); extern void convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk); extern void convert_to_fxsr(struct task_struct *tsk, const struct user_i387_ia32_struct *env); extern user_regset_active_fn fpregs_active, xfpregs_active; extern user_regset_get_fn fpregs_get, xfpregs_get, fpregs_soft_get, xstateregs_get; extern user_regset_set_fn fpregs_set, xfpregs_set, fpregs_soft_set, xstateregs_set; /* * xstateregs_active == fpregs_active. Please refer to the comment * at the definition of fpregs_active. */ #define xstateregs_active fpregs_active #ifdef CONFIG_MATH_EMULATION extern void finit_soft_fpu(struct i387_soft_struct *soft); #else static inline void finit_soft_fpu(struct i387_soft_struct *soft) {} #endif /* * Must be run with preemption disabled: this clears the fpu_owner_task, * on this CPU. * * This will disable any lazy FPU state restore of the current FPU state, * but if the current thread owns the FPU, it will still be saved by. */ static inline void __cpu_disable_lazy_restore(unsigned int cpu) { per_cpu(fpu_owner_task, cpu) = NULL; } /* * Used to indicate that the FPU state in memory is newer than the FPU * state in registers, and the FPU state should be reloaded next time the * task is run. Only safe on the current task, or non-running tasks. */ static inline void task_disable_lazy_fpu_restore(struct task_struct *tsk) { tsk->thread.fpu.last_cpu = ~0; } static inline int fpu_lazy_restore(struct task_struct *new, unsigned int cpu) { return new == this_cpu_read_stable(fpu_owner_task) && cpu == new->thread.fpu.last_cpu; } static inline int is_ia32_compat_frame(void) { return config_enabled(CONFIG_IA32_EMULATION) && test_thread_flag(TIF_IA32); } static inline int is_ia32_frame(void) { return config_enabled(CONFIG_X86_32) || is_ia32_compat_frame(); } static inline int is_x32_frame(void) { return config_enabled(CONFIG_X86_X32_ABI) && test_thread_flag(TIF_X32); } #define X87_FSW_ES (1 << 7) /* Exception Summary */ static __always_inline __pure bool use_eager_fpu(void) { return static_cpu_has_safe(X86_FEATURE_EAGER_FPU); } static __always_inline __pure bool use_xsaveopt(void) { return static_cpu_has_safe(X86_FEATURE_XSAVEOPT); } static __always_inline __pure bool use_xsave(void) { return static_cpu_has_safe(X86_FEATURE_XSAVE); } static __always_inline __pure bool use_fxsr(void) { return static_cpu_has_safe(X86_FEATURE_FXSR); } static inline void fx_finit(struct i387_fxsave_struct *fx) { fx->cwd = 0x37f; fx->mxcsr = MXCSR_DEFAULT; } extern void __sanitize_i387_state(struct task_struct *); static inline void sanitize_i387_state(struct task_struct *tsk) { if (!use_xsaveopt()) return; __sanitize_i387_state(tsk); } #define user_insn(insn, output, input...) \ ({ \ int err; \ asm volatile(ASM_STAC "\n" \ "1:" #insn "\n\t" \ "2: " ASM_CLAC "\n" \ ".section .fixup,\"ax\"\n" \ "3: movl $-1,%[err]\n" \ " jmp 2b\n" \ ".previous\n" \ _ASM_EXTABLE(1b, 3b) \ : [err] "=r" (err), output \ : "0"(0), input); \ err; \ }) #define check_insn(insn, output, input...) \ ({ \ int err; \ asm volatile("1:" #insn "\n\t" \ "2:\n" \ ".section .fixup,\"ax\"\n" \ "3: movl $-1,%[err]\n" \ " jmp 2b\n" \ ".previous\n" \ _ASM_EXTABLE(1b, 3b) \ : [err] "=r" (err), output \ : "0"(0), input); \ err; \ }) static inline int fsave_user(struct i387_fsave_struct __user *fx) { return user_insn(fnsave %[fx]; fwait, [fx] "=m" (*fx), "m" (*fx)); } static inline int fxsave_user(struct i387_fxsave_struct __user *fx) { if (config_enabled(CONFIG_X86_32)) return user_insn(fxsave %[fx], [fx] "=m" (*fx), "m" (*fx)); else if (config_enabled(CONFIG_AS_FXSAVEQ)) return user_insn(fxsaveq %[fx], [fx] "=m" (*fx), "m" (*fx)); /* See comment in fpu_fxsave() below. */ return user_insn(rex64/fxsave (%[fx]), "=m" (*fx), [fx] "R" (fx)); } static inline int fxrstor_checking(struct i387_fxsave_struct *fx) { if (config_enabled(CONFIG_X86_32)) return check_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx)); else if (config_enabled(CONFIG_AS_FXSAVEQ)) return check_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx)); /* See comment in fpu_fxsave() below. */ return check_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx), "m" (*fx)); } static inline int fxrstor_user(struct i387_fxsave_struct __user *fx) { if (config_enabled(CONFIG_X86_32)) return user_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx)); else if (config_enabled(CONFIG_AS_FXSAVEQ)) return user_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx)); /* See comment in fpu_fxsave() below. */ return user_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx), "m" (*fx)); } static inline int frstor_checking(struct i387_fsave_struct *fx) { return check_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx)); } static inline int frstor_user(struct i387_fsave_struct __user *fx) { return user_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx)); } static inline void fpu_fxsave(struct fpu *fpu) { if (config_enabled(CONFIG_X86_32)) asm volatile( "fxsave %[fx]" : [fx] "=m" (fpu->state->fxsave)); else if (config_enabled(CONFIG_AS_FXSAVEQ)) asm volatile("fxsaveq %[fx]" : [fx] "=m" (fpu->state->fxsave)); else { /* Using "rex64; fxsave %0" is broken because, if the memory * operand uses any extended registers for addressing, a second * REX prefix will be generated (to the assembler, rex64 * followed by semicolon is a separate instruction), and hence * the 64-bitness is lost. * * Using "fxsaveq %0" would be the ideal choice, but is only * supported starting with gas 2.16. * * Using, as a workaround, the properly prefixed form below * isn't accepted by any binutils version so far released, * complaining that the same type of prefix is used twice if * an extended register is needed for addressing (fix submitted * to mainline 2005-11-21). * * asm volatile("rex64/fxsave %0" : "=m" (fpu->state->fxsave)); * * This, however, we can work around by forcing the compiler to * select an addressing mode that doesn't require extended * registers. */ asm volatile( "rex64/fxsave (%[fx])" : "=m" (fpu->state->fxsave) : [fx] "R" (&fpu->state->fxsave)); } } /* * These must be called with preempt disabled. Returns * 'true' if the FPU state is still intact. */ static inline int fpu_save_init(struct fpu *fpu) { if (use_xsave()) { fpu_xsave(fpu); /* * xsave header may indicate the init state of the FP. */ if (!(fpu->state->xsave.xsave_hdr.xstate_bv & XSTATE_FP)) return 1; } else if (use_fxsr()) { fpu_fxsave(fpu); } else { asm volatile("fnsave %[fx]; fwait" : [fx] "=m" (fpu->state->fsave)); return 0; } /* * If exceptions are pending, we need to clear them so * that we don't randomly get exceptions later. * * FIXME! Is this perhaps only true for the old-style * irq13 case? Maybe we could leave the x87 state * intact otherwise? */ if (unlikely(fpu->state->fxsave.swd & X87_FSW_ES)) { asm volatile("fnclex"); return 0; } return 1; } static inline int __save_init_fpu(struct task_struct *tsk) { return fpu_save_init(&tsk->thread.fpu); } static inline int fpu_restore_checking(struct fpu *fpu) { if (use_xsave()) return fpu_xrstor_checking(&fpu->state->xsave); else if (use_fxsr()) return fxrstor_checking(&fpu->state->fxsave); else return frstor_checking(&fpu->state->fsave); } static inline int restore_fpu_checking(struct task_struct *tsk) { /* * AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception is * pending. Clear the x87 state here by setting it to fixed values. * "m" is a random variable that should be in L1. */ if (unlikely(static_cpu_has_bug_safe(X86_BUG_FXSAVE_LEAK))) { asm volatile( "fnclex\n\t" "emms\n\t" "fildl %P[addr]" /* set F?P to defined value */ : : [addr] "m" (tsk->thread.fpu.has_fpu)); } return fpu_restore_checking(&tsk->thread.fpu); } /* * Software FPU state helpers. Careful: these need to * be preemption protection *and* they need to be * properly paired with the CR0.TS changes! */ static inline int __thread_has_fpu(struct task_struct *tsk) { return tsk->thread.fpu.has_fpu; } /* Must be paired with an 'stts' after! */ static inline void __thread_clear_has_fpu(struct task_struct *tsk) { tsk->thread.fpu.has_fpu = 0; this_cpu_write(fpu_owner_task, NULL); } /* Must be paired with a 'clts' before! */ static inline void __thread_set_has_fpu(struct task_struct *tsk) { tsk->thread.fpu.has_fpu = 1; this_cpu_write(fpu_owner_task, tsk); } /* * Encapsulate the CR0.TS handling together with the * software flag. * * These generally need preemption protection to work, * do try to avoid using these on their own. */ static inline void __thread_fpu_end(struct task_struct *tsk) { __thread_clear_has_fpu(tsk); if (!use_eager_fpu()) stts(); } static inline void __thread_fpu_begin(struct task_struct *tsk) { if (!use_eager_fpu()) clts(); __thread_set_has_fpu(tsk); } static inline void drop_fpu(struct task_struct *tsk) { /* * Forget coprocessor state.. */ preempt_disable(); tsk->thread.fpu_counter = 0; if (__thread_has_fpu(tsk)) { /* Ignore delayed exceptions from user space */ asm volatile("1: fwait\n" "2:\n" _ASM_EXTABLE(1b, 2b)); __thread_fpu_end(tsk); } clear_stopped_child_used_math(tsk); preempt_enable(); } static inline void restore_init_xstate(void) { if (use_xsave()) xrstor_state(init_xstate_buf, -1); else fxrstor_checking(&init_xstate_buf->i387); } /* * Reset the FPU state in the eager case and drop it in the lazy case (later use * will reinit it). */ static inline void fpu_reset_state(struct task_struct *tsk) { if (!use_eager_fpu()) drop_fpu(tsk); else restore_init_xstate(); } /* * FPU state switching for scheduling. * * This is a two-stage process: * * - switch_fpu_prepare() saves the old state and * sets the new state of the CR0.TS bit. This is * done within the context of the old process. * * - switch_fpu_finish() restores the new state as * necessary. */ typedef struct { int preload; } fpu_switch_t; static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct task_struct *new, int cpu) { fpu_switch_t fpu; /* * If the task has used the math, pre-load the FPU on xsave processors * or if the past 5 consecutive context-switches used math. */ fpu.preload = tsk_used_math(new) && (use_eager_fpu() || new->thread.fpu_counter > 5); if (__thread_has_fpu(old)) { if (!__save_init_fpu(old)) task_disable_lazy_fpu_restore(old); else old->thread.fpu.last_cpu = cpu; /* But leave fpu_owner_task! */ old->thread.fpu.has_fpu = 0; /* Don't change CR0.TS if we just switch! */ if (fpu.preload) { new->thread.fpu_counter++; __thread_set_has_fpu(new); prefetch(new->thread.fpu.state); } else if (!use_eager_fpu()) stts(); } else { old->thread.fpu_counter = 0; task_disable_lazy_fpu_restore(old); if (fpu.preload) { new->thread.fpu_counter++; if (fpu_lazy_restore(new, cpu)) fpu.preload = 0; else prefetch(new->thread.fpu.state); __thread_fpu_begin(new); } } return fpu; } /* * By the time this gets called, we've already cleared CR0.TS and * given the process the FPU if we are going to preload the FPU * state - all we need to do is to conditionally restore the register * state itself. */ static inline void switch_fpu_finish(struct task_struct *new, fpu_switch_t fpu) { if (fpu.preload) { if (unlikely(restore_fpu_checking(new))) fpu_reset_state(new); } } /* * Signal frame handlers... */ extern int save_xstate_sig(void __user *buf, void __user *fx, int size); extern int __restore_xstate_sig(void __user *buf, void __user *fx, int size); static inline int xstate_sigframe_size(void) { return use_xsave() ? xstate_size + FP_XSTATE_MAGIC2_SIZE : xstate_size; } static inline int restore_xstate_sig(void __user *buf, int ia32_frame) { void __user *buf_fx = buf; int size = xstate_sigframe_size(); if (ia32_frame && use_fxsr()) { buf_fx = buf + sizeof(struct i387_fsave_struct); size += sizeof(struct i387_fsave_struct); } return __restore_xstate_sig(buf, buf_fx, size); } /* * Needs to be preemption-safe. * * NOTE! user_fpu_begin() must be used only immediately before restoring * the save state. It does not do any saving/restoring on its own. In * lazy FPU mode, it is just an optimization to avoid a #NM exception, * the task can lose the FPU right after preempt_enable(). */ static inline void user_fpu_begin(void) { preempt_disable(); if (!user_has_fpu()) __thread_fpu_begin(current); preempt_enable(); } static inline void __save_fpu(struct task_struct *tsk) { if (use_xsave()) { if (unlikely(system_state == SYSTEM_BOOTING)) xsave_state_booting(&tsk->thread.fpu.state->xsave, -1); else xsave_state(&tsk->thread.fpu.state->xsave, -1); } else fpu_fxsave(&tsk->thread.fpu); } /* * i387 state interaction */ static inline unsigned short get_fpu_cwd(struct task_struct *tsk) { if (cpu_has_fxsr) { return tsk->thread.fpu.state->fxsave.cwd; } else { return (unsigned short)tsk->thread.fpu.state->fsave.cwd; } } static inline unsigned short get_fpu_swd(struct task_struct *tsk) { if (cpu_has_fxsr) { return tsk->thread.fpu.state->fxsave.swd; } else { return (unsigned short)tsk->thread.fpu.state->fsave.swd; } } static inline unsigned short get_fpu_mxcsr(struct task_struct *tsk) { if (cpu_has_xmm) { return tsk->thread.fpu.state->fxsave.mxcsr; } else { return MXCSR_DEFAULT; } } static bool fpu_allocated(struct fpu *fpu) { return fpu->state != NULL; } static inline int fpu_alloc(struct fpu *fpu) { if (fpu_allocated(fpu)) return 0; fpu->state = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL); if (!fpu->state) return -ENOMEM; WARN_ON((unsigned long)fpu->state & 15); return 0; } static inline void fpu_free(struct fpu *fpu) { if (fpu->state) { kmem_cache_free(task_xstate_cachep, fpu->state); fpu->state = NULL; } } static inline void fpu_copy(struct task_struct *dst, struct task_struct *src) { if (use_eager_fpu()) { memset(&dst->thread.fpu.state->xsave, 0, xstate_size); __save_fpu(dst); } else { struct fpu *dfpu = &dst->thread.fpu; struct fpu *sfpu = &src->thread.fpu; unlazy_fpu(src); memcpy(dfpu->state, sfpu->state, xstate_size); } } static inline unsigned long alloc_mathframe(unsigned long sp, int ia32_frame, unsigned long *buf_fx, unsigned long *size) { unsigned long frame_size = xstate_sigframe_size(); *buf_fx = sp = round_down(sp - frame_size, 64); if (ia32_frame && use_fxsr()) { frame_size += sizeof(struct i387_fsave_struct); sp -= sizeof(struct i387_fsave_struct); } *size = frame_size; return sp; } #endif