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Diffstat (limited to 'arch/x86/include/asm/fpu/internal.h')
| -rw-r--r-- | arch/x86/include/asm/fpu/internal.h | 694 |
1 files changed, 694 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..3c3550c3a4a3 --- /dev/null +++ b/arch/x86/include/asm/fpu/internal.h @@ -0,0 +1,694 @@ +/* + * 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 _ASM_X86_FPU_INTERNAL_H +#define _ASM_X86_FPU_INTERNAL_H + +#include <linux/compat.h> +#include <linux/sched.h> +#include <linux/slab.h> + +#include <asm/user.h> +#include <asm/fpu/api.h> +#include <asm/fpu/xstate.h> + +/* + * High level FPU state handling functions: + */ +extern void fpu__activate_curr(struct fpu *fpu); +extern void fpu__activate_fpstate_read(struct fpu *fpu); +extern void fpu__activate_fpstate_write(struct fpu *fpu); +extern void fpu__save(struct fpu *fpu); +extern void fpu__restore(struct fpu *fpu); +extern int fpu__restore_sig(void __user *buf, int ia32_frame); +extern void fpu__drop(struct fpu *fpu); +extern int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu); +extern void fpu__clear(struct fpu *fpu); +extern int fpu__exception_code(struct fpu *fpu, int trap_nr); +extern int dump_fpu(struct pt_regs *ptregs, struct user_i387_struct *fpstate); + +/* + * Boot time FPU initialization functions: + */ +extern void fpu__init_cpu(void); +extern void fpu__init_system_xstate(void); +extern void fpu__init_cpu_xstate(void); +extern void fpu__init_system(struct cpuinfo_x86 *c); +extern void fpu__init_check_bugs(void); +extern void fpu__resume_cpu(void); + +/* + * Debugging facility: + */ +#ifdef CONFIG_X86_DEBUG_FPU +# define WARN_ON_FPU(x) WARN_ON_ONCE(x) +#else +# define WARN_ON_FPU(x) ({ (void)(x); 0; }) +#endif + +/* + * FPU related CPU feature flag helper routines: + */ +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); +} + +/* + * fpstate handling functions: + */ + +extern union fpregs_state init_fpstate; + +extern void fpstate_init(union fpregs_state *state); +#ifdef CONFIG_MATH_EMULATION +extern void fpstate_init_soft(struct swregs_state *soft); +#else +static inline void fpstate_init_soft(struct swregs_state *soft) {} +#endif +static inline void fpstate_init_fxstate(struct fxregs_state *fx) +{ + fx->cwd = 0x37f; + fx->mxcsr = MXCSR_DEFAULT; +} +extern void fpstate_sanitize_xstate(struct fpu *fpu); + +#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 copy_fregs_to_user(struct fregs_state __user *fx) +{ + return user_insn(fnsave %[fx]; fwait, [fx] "=m" (*fx), "m" (*fx)); +} + +static inline int copy_fxregs_to_user(struct fxregs_state __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 copy_fxregs_to_kernel() below. */ + return user_insn(rex64/fxsave (%[fx]), "=m" (*fx), [fx] "R" (fx)); +} + +static inline void copy_kernel_to_fxregs(struct fxregs_state *fx) +{ + int err; + + if (config_enabled(CONFIG_X86_32)) { + err = check_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx)); + } else { + if (config_enabled(CONFIG_AS_FXSAVEQ)) { + err = check_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx)); + } else { + /* See comment in copy_fxregs_to_kernel() below. */ + err = check_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx), "m" (*fx)); + } + } + /* Copying from a kernel buffer to FPU registers should never fail: */ + WARN_ON_FPU(err); +} + +static inline int copy_user_to_fxregs(struct fxregs_state __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 copy_fxregs_to_kernel() below. */ + return user_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx), + "m" (*fx)); +} + +static inline void copy_kernel_to_fregs(struct fregs_state *fx) +{ + int err = check_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx)); + + WARN_ON_FPU(err); +} + +static inline int copy_user_to_fregs(struct fregs_state __user *fx) +{ + return user_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx)); +} + +static inline void copy_fxregs_to_kernel(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 macros all use (%edi)/(%rdi) as the single memory argument. */ +#define XSAVE ".byte " REX_PREFIX "0x0f,0xae,0x27" +#define XSAVEOPT ".byte " REX_PREFIX "0x0f,0xae,0x37" +#define XSAVES ".byte " REX_PREFIX "0x0f,0xc7,0x2f" +#define XRSTOR ".byte " REX_PREFIX "0x0f,0xae,0x2f" +#define XRSTORS ".byte " REX_PREFIX "0x0f,0xc7,0x1f" + +/* xstate instruction fault handler: */ +#define xstate_fault(__err) \ + \ + ".section .fixup,\"ax\"\n" \ + \ + "3: movl $-2,%[_err]\n" \ + " jmp 2b\n" \ + \ + ".previous\n" \ + \ + _ASM_EXTABLE(1b, 3b) \ + : [_err] "=r" (__err) + +/* + * This function is called only during boot time when x86 caps are not set + * up and alternative can not be used yet. + */ +static inline void copy_xregs_to_kernel_booting(struct xregs_state *xstate) +{ + u64 mask = -1; + u32 lmask = mask; + u32 hmask = mask >> 32; + int err = 0; + + WARN_ON(system_state != SYSTEM_BOOTING); + + if (boot_cpu_has(X86_FEATURE_XSAVES)) + asm volatile("1:"XSAVES"\n\t" + "2:\n\t" + xstate_fault(err) + : "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err) + : "memory"); + else + asm volatile("1:"XSAVE"\n\t" + "2:\n\t" + xstate_fault(err) + : "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err) + : "memory"); + + /* We should never fault when copying to a kernel buffer: */ + WARN_ON_FPU(err); +} + +/* + * This function is called only during boot time when x86 caps are not set + * up and alternative can not be used yet. + */ +static inline void copy_kernel_to_xregs_booting(struct xregs_state *xstate) +{ + u64 mask = -1; + u32 lmask = mask; + u32 hmask = mask >> 32; + int err = 0; + + WARN_ON(system_state != SYSTEM_BOOTING); + + if (boot_cpu_has(X86_FEATURE_XSAVES)) + asm volatile("1:"XRSTORS"\n\t" + "2:\n\t" + xstate_fault(err) + : "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err) + : "memory"); + else + asm volatile("1:"XRSTOR"\n\t" + "2:\n\t" + xstate_fault(err) + : "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask), "0" (err) + : "memory"); + + /* We should never fault when copying from a kernel buffer: */ + WARN_ON_FPU(err); +} + +/* + * Save processor xstate to xsave area. + */ +static inline void copy_xregs_to_kernel(struct xregs_state *xstate) +{ + u64 mask = -1; + u32 lmask = mask; + u32 hmask = mask >> 32; + int err = 0; + + WARN_ON(!alternatives_patched); + + /* + * If xsaves is enabled, xsaves replaces xsaveopt because + * it supports compact format and supervisor states in addition to + * modified optimization in xsaveopt. + * + * Otherwise, if xsaveopt is enabled, xsaveopt replaces xsave + * because xsaveopt supports modified optimization which is not + * supported by xsave. + * + * If none of xsaves and xsaveopt is enabled, use xsave. + */ + alternative_input_2( + "1:"XSAVE, + XSAVEOPT, + X86_FEATURE_XSAVEOPT, + XSAVES, + X86_FEATURE_XSAVES, + [xstate] "D" (xstate), "a" (lmask), "d" (hmask) : + "memory"); + asm volatile("2:\n\t" + xstate_fault(err) + : "0" (err) + : "memory"); + + /* We should never fault when copying to a kernel buffer: */ + WARN_ON_FPU(err); +} + +/* + * Restore processor xstate from xsave area. + */ +static inline void copy_kernel_to_xregs(struct xregs_state *xstate, u64 mask) +{ + u32 lmask = mask; + u32 hmask = mask >> 32; + int err = 0; + + /* + * Use xrstors to restore context if it is enabled. xrstors supports + * compacted format of xsave area which is not supported by xrstor. + */ + alternative_input( + "1: " XRSTOR, + XRSTORS, + X86_FEATURE_XSAVES, + "D" (xstate), "m" (*xstate), "a" (lmask), "d" (hmask) + : "memory"); + + asm volatile("2:\n" + xstate_fault(err) + : "0" (err) + : "memory"); + + /* We should never fault when copying from a kernel buffer: */ + WARN_ON_FPU(err); +} + +/* + * Save xstate to user space xsave area. + * + * We don't use modified optimization because xrstor/xrstors might track + * a different application. + * + * We don't use compacted format xsave area for + * backward compatibility for old applications which don't understand + * compacted format of xsave area. + */ +static inline int copy_xregs_to_user(struct xregs_state __user *buf) +{ + int err; + + /* + * Clear the xsave header first, so that reserved fields are + * initialized to zero. + */ + err = __clear_user(&buf->header, sizeof(buf->header)); + if (unlikely(err)) + return -EFAULT; + + __asm__ __volatile__(ASM_STAC "\n" + "1:"XSAVE"\n" + "2: " ASM_CLAC "\n" + xstate_fault(err) + : "D" (buf), "a" (-1), "d" (-1), "0" (err) + : "memory"); + return err; +} + +/* + * Restore xstate from user space xsave area. + */ +static inline int copy_user_to_xregs(struct xregs_state __user *buf, u64 mask) +{ + struct xregs_state *xstate = ((__force struct xregs_state *)buf); + u32 lmask = mask; + u32 hmask = mask >> 32; + int err = 0; + + __asm__ __volatile__(ASM_STAC "\n" + "1:"XRSTOR"\n" + "2: " ASM_CLAC "\n" + xstate_fault(err) + : "D" (xstate), "a" (lmask), "d" (hmask), "0" (err) + : "memory"); /* memory required? */ + return err; +} + +/* + * These must be called with preempt disabled. Returns + * 'true' if the FPU state is still intact and we can + * keep registers active. + * + * The legacy FNSAVE instruction cleared all FPU state + * unconditionally, so registers are essentially destroyed. + * Modern FPU state can be kept in registers, if there are + * no pending FP exceptions. + */ +static inline int copy_fpregs_to_fpstate(struct fpu *fpu) +{ + if (likely(use_xsave())) { + copy_xregs_to_kernel(&fpu->state.xsave); + return 1; + } + + if (likely(use_fxsr())) { + copy_fxregs_to_kernel(fpu); + return 1; + } + + /* + * Legacy FPU register saving, FNSAVE always clears FPU registers, + * so we have to mark them inactive: + */ + asm volatile("fnsave %[fp]; fwait" : [fp] "=m" (fpu->state.fsave)); + + return 0; +} + +static inline void __copy_kernel_to_fpregs(union fpregs_state *fpstate) +{ + if (use_xsave()) { + copy_kernel_to_xregs(&fpstate->xsave, -1); + } else { + if (use_fxsr()) + copy_kernel_to_fxregs(&fpstate->fxsave); + else + copy_kernel_to_fregs(&fpstate->fsave); + } +} + +static inline void copy_kernel_to_fpregs(union fpregs_state *fpstate) +{ + /* + * 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" (fpstate)); + } + + __copy_kernel_to_fpregs(fpstate); +} + +extern int copy_fpstate_to_sigframe(void __user *buf, void __user *fp, int size); + +/* + * FPU context switch related helper methods: + */ + +DECLARE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx); + +/* + * Must be run with preemption disabled: this clears the fpu_fpregs_owner_ctx, + * 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_fpregs_owner_ctx, cpu) = NULL; +} + +static inline int fpu_want_lazy_restore(struct fpu *fpu, unsigned int cpu) +{ + return fpu == this_cpu_read_stable(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu; +} + + +/* + * Wrap lazy FPU TS handling in a 'hw fpregs activation/deactivation' + * idiom, which is then paired with the sw-flag (fpregs_active) later on: + */ + +static inline void __fpregs_activate_hw(void) +{ + if (!use_eager_fpu()) + clts(); +} + +static inline void __fpregs_deactivate_hw(void) +{ + if (!use_eager_fpu()) + stts(); +} + +/* Must be paired with an 'stts' (fpregs_deactivate_hw()) after! */ +static inline void __fpregs_deactivate(struct fpu *fpu) +{ + WARN_ON_FPU(!fpu->fpregs_active); + + fpu->fpregs_active = 0; + this_cpu_write(fpu_fpregs_owner_ctx, NULL); +} + +/* Must be paired with a 'clts' (fpregs_activate_hw()) before! */ +static inline void __fpregs_activate(struct fpu *fpu) +{ + WARN_ON_FPU(fpu->fpregs_active); + + fpu->fpregs_active = 1; + this_cpu_write(fpu_fpregs_owner_ctx, fpu); +} + +/* + * The question "does this thread have fpu access?" + * is slightly racy, since preemption could come in + * and revoke it immediately after the test. + * + * However, even in that very unlikely scenario, + * we can just assume we have FPU access - typically + * to save the FP state - we'll just take a #NM + * fault and get the FPU access back. + */ +static inline int fpregs_active(void) +{ + return current->thread.fpu.fpregs_active; +} + +/* + * 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 fpregs_activate(struct fpu *fpu) +{ + __fpregs_activate_hw(); + __fpregs_activate(fpu); +} + +static inline void fpregs_deactivate(struct fpu *fpu) +{ + __fpregs_deactivate(fpu); + __fpregs_deactivate_hw(); +} + +/* + * 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 fpu *old_fpu, struct fpu *new_fpu, 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 = new_fpu->fpstate_active && + (use_eager_fpu() || new_fpu->counter > 5); + + if (old_fpu->fpregs_active) { + if (!copy_fpregs_to_fpstate(old_fpu)) + old_fpu->last_cpu = -1; + else + old_fpu->last_cpu = cpu; + + /* But leave fpu_fpregs_owner_ctx! */ + old_fpu->fpregs_active = 0; + + /* Don't change CR0.TS if we just switch! */ + if (fpu.preload) { + new_fpu->counter++; + __fpregs_activate(new_fpu); + prefetch(&new_fpu->state); + } else { + __fpregs_deactivate_hw(); + } + } else { + old_fpu->counter = 0; + old_fpu->last_cpu = -1; + if (fpu.preload) { + new_fpu->counter++; + if (fpu_want_lazy_restore(new_fpu, cpu)) + fpu.preload = 0; + else + prefetch(&new_fpu->state); + fpregs_activate(new_fpu); + } + } + return fpu; +} + +/* + * Misc helper functions: + */ + +/* + * 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 fpu *new_fpu, fpu_switch_t fpu_switch) +{ + if (fpu_switch.preload) + copy_kernel_to_fpregs(&new_fpu->state); +} + +/* + * 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) +{ + struct fpu *fpu = ¤t->thread.fpu; + + preempt_disable(); + if (!fpregs_active()) + fpregs_activate(fpu); + preempt_enable(); +} + +/* + * MXCSR and XCR definitions: + */ + +extern unsigned int mxcsr_feature_mask; + +#define XCR_XFEATURE_ENABLED_MASK 0x00000000 + +static inline u64 xgetbv(u32 index) +{ + u32 eax, edx; + + asm volatile(".byte 0x0f,0x01,0xd0" /* xgetbv */ + : "=a" (eax), "=d" (edx) + : "c" (index)); + return eax + ((u64)edx << 32); +} + +static inline void xsetbv(u32 index, u64 value) +{ + u32 eax = value; + u32 edx = value >> 32; + + asm volatile(".byte 0x0f,0x01,0xd1" /* xsetbv */ + : : "a" (eax), "d" (edx), "c" (index)); +} + +#endif /* _ASM_X86_FPU_INTERNAL_H */ |