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Diffstat (limited to 'arch/x86/include/asm/fpu-internal.h')
| -rw-r--r-- | arch/x86/include/asm/fpu-internal.h | 520 |
1 files changed, 520 insertions, 0 deletions
diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h new file mode 100644 index 000000000000..4fa88154e4de --- /dev/null +++ b/arch/x86/include/asm/fpu-internal.h @@ -0,0 +1,520 @@ +/* + * 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/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> + +extern unsigned int sig_xstate_size; +extern void fpu_init(void); + +DECLARE_PER_CPU(struct task_struct *, fpu_owner_task); + +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 + +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); +extern int restore_i387_xstate_ia32(void __user *buf); +#endif + +#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 + +#define X87_FSW_ES (1 << 7) /* Exception Summary */ + +static __always_inline __pure bool use_xsaveopt(void) +{ + return static_cpu_has(X86_FEATURE_XSAVEOPT); +} + +static __always_inline __pure bool use_xsave(void) +{ + return static_cpu_has(X86_FEATURE_XSAVE); +} + +static __always_inline __pure bool use_fxsr(void) +{ + return static_cpu_has(X86_FEATURE_FXSR); +} + +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); +} + +#ifdef CONFIG_X86_64 +static inline int fxrstor_checking(struct i387_fxsave_struct *fx) +{ + int err; + + /* See comment in fxsave() below. */ +#ifdef CONFIG_AS_FXSAVEQ + asm volatile("1: fxrstorq %[fx]\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) + : [fx] "m" (*fx), "0" (0)); +#else + asm volatile("1: rex64/fxrstor (%[fx])\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) + : [fx] "R" (fx), "m" (*fx), "0" (0)); +#endif + return err; +} + +static inline int fxsave_user(struct i387_fxsave_struct __user *fx) +{ + int err; + + /* + * Clear the bytes not touched by the fxsave and reserved + * for the SW usage. + */ + err = __clear_user(&fx->sw_reserved, + sizeof(struct _fpx_sw_bytes)); + if (unlikely(err)) + return -EFAULT; + + /* See comment in fxsave() below. */ +#ifdef CONFIG_AS_FXSAVEQ + asm volatile("1: fxsaveq %[fx]\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), [fx] "=m" (*fx) + : "0" (0)); +#else + asm volatile("1: rex64/fxsave (%[fx])\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), "=m" (*fx) + : [fx] "R" (fx), "0" (0)); +#endif + if (unlikely(err) && + __clear_user(fx, sizeof(struct i387_fxsave_struct))) + err = -EFAULT; + /* No need to clear here because the caller clears USED_MATH */ + return err; +} + +static inline void fpu_fxsave(struct fpu *fpu) +{ + /* 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. */ + +#ifdef CONFIG_AS_FXSAVEQ + /* Using "fxsaveq %0" would be the ideal choice, but is only supported + starting with gas 2.16. */ + __asm__ __volatile__("fxsaveq %0" + : "=m" (fpu->state->fxsave)); +#else + /* 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)); +#endif +} + +#else /* CONFIG_X86_32 */ + +/* perform fxrstor iff the processor has extended states, otherwise frstor */ +static inline int fxrstor_checking(struct i387_fxsave_struct *fx) +{ + /* + * The "nop" is needed to make the instructions the same + * length. + */ + alternative_input( + "nop ; frstor %1", + "fxrstor %1", + X86_FEATURE_FXSR, + "m" (*fx)); + + return 0; +} + +static inline void fpu_fxsave(struct fpu *fpu) +{ + asm volatile("fxsave %[fx]" + : [fx] "=m" (fpu->state->fxsave)); +} + +#endif /* CONFIG_X86_64 */ + +/* + * 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_fxrstor_checking(struct fpu *fpu) +{ + return fxrstor_checking(&fpu->state->fxsave); +} + +static inline int fpu_restore_checking(struct fpu *fpu) +{ + if (use_xsave()) + return fpu_xrstor_checking(fpu); + else + return fpu_fxrstor_checking(fpu); +} + +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 */ + alternative_input( + ASM_NOP8 ASM_NOP2, + "emms\n\t" /* clear stack tags */ + "fildl %P[addr]", /* set F?P to defined value */ + X86_FEATURE_FXSAVE_LEAK, + [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; + percpu_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; + percpu_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); + stts(); +} + +static inline void __thread_fpu_begin(struct task_struct *tsk) +{ + clts(); + __thread_set_has_fpu(tsk); +} + +/* + * 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; + +/* + * FIXME! We could do a totally lazy restore, but we need to + * add a per-cpu "this was the task that last touched the FPU + * on this CPU" variable, and the task needs to have a "I last + * touched the FPU on this CPU" and check them. + * + * We don't do that yet, so "fpu_lazy_restore()" always returns + * false, but some day.. + */ +static inline int fpu_lazy_restore(struct task_struct *new, unsigned int cpu) +{ + return new == percpu_read_stable(fpu_owner_task) && + cpu == new->thread.fpu.last_cpu; +} + +static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct task_struct *new, int cpu) +{ + fpu_switch_t fpu; + + fpu.preload = tsk_used_math(new) && new->fpu_counter > 5; + if (__thread_has_fpu(old)) { + if (!__save_init_fpu(old)) + cpu = ~0; + old->thread.fpu.last_cpu = cpu; + old->thread.fpu.has_fpu = 0; /* But leave fpu_owner_task! */ + + /* Don't change CR0.TS if we just switch! */ + if (fpu.preload) { + new->fpu_counter++; + __thread_set_has_fpu(new); + prefetch(new->thread.fpu.state); + } else + stts(); + } else { + old->fpu_counter = 0; + old->thread.fpu.last_cpu = ~0; + if (fpu.preload) { + new->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))) + __thread_fpu_end(new); + } +} + +/* + * Signal frame handlers... + */ +extern int save_i387_xstate(void __user *buf); +extern int restore_i387_xstate(void __user *buf); + +static inline void __clear_fpu(struct task_struct *tsk) +{ + 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); + } +} + +/* + * The actual user_fpu_begin/end() functions + * need to be preemption-safe. + * + * NOTE! user_fpu_end() must be used only after you + * have saved the FP state, and user_fpu_begin() must + * be used only immediately before restoring it. + * These functions do not do any save/restore on + * their own. + */ +static inline void user_fpu_end(void) +{ + preempt_disable(); + __thread_fpu_end(current); + preempt_enable(); +} + +static inline void user_fpu_begin(void) +{ + preempt_disable(); + if (!user_has_fpu()) + __thread_fpu_begin(current); + preempt_enable(); +} + +/* + * These disable preemption on their own and are safe + */ +static inline void save_init_fpu(struct task_struct *tsk) +{ + WARN_ON_ONCE(!__thread_has_fpu(tsk)); + preempt_disable(); + __save_init_fpu(tsk); + __thread_fpu_end(tsk); + preempt_enable(); +} + +static inline void clear_fpu(struct task_struct *tsk) +{ + preempt_disable(); + __clear_fpu(tsk); + preempt_enable(); +} + +/* + * 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 fpu *dst, struct fpu *src) +{ + memcpy(dst->state, src->state, xstate_size); +} + +extern void fpu_finit(struct fpu *fpu); + +#endif |