diff options
38 files changed, 105 insertions, 547 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index c57316f230de..4e2373e0c0cb 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1079,12 +1079,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted. nopku [X86] Disable Memory Protection Keys CPU feature found in some Intel CPUs. - eagerfpu= [X86] - on enable eager fpu restore - off disable eager fpu restore - auto selects the default scheme, which automatically - enables eagerfpu restore for xsaveopt. - module.async_probe [KNL] Enable asynchronous probe on this module. diff --git a/arch/x86/crypto/crc32c-intel_glue.c b/arch/x86/crypto/crc32c-intel_glue.c index 0857b1a1de3b..c194d5717ae5 100644 --- a/arch/x86/crypto/crc32c-intel_glue.c +++ b/arch/x86/crypto/crc32c-intel_glue.c @@ -48,26 +48,13 @@ #ifdef CONFIG_X86_64 /* * use carryless multiply version of crc32c when buffer - * size is >= 512 (when eager fpu is enabled) or - * >= 1024 (when eager fpu is disabled) to account + * size is >= 512 to account * for fpu state save/restore overhead. */ -#define CRC32C_PCL_BREAKEVEN_EAGERFPU 512 -#define CRC32C_PCL_BREAKEVEN_NOEAGERFPU 1024 +#define CRC32C_PCL_BREAKEVEN 512 asmlinkage unsigned int crc_pcl(const u8 *buffer, int len, unsigned int crc_init); -static int crc32c_pcl_breakeven = CRC32C_PCL_BREAKEVEN_EAGERFPU; -#if defined(X86_FEATURE_EAGER_FPU) -#define set_pcl_breakeven_point() \ -do { \ - if (!use_eager_fpu()) \ - crc32c_pcl_breakeven = CRC32C_PCL_BREAKEVEN_NOEAGERFPU; \ -} while (0) -#else -#define set_pcl_breakeven_point() \ - (crc32c_pcl_breakeven = CRC32C_PCL_BREAKEVEN_NOEAGERFPU) -#endif #endif /* CONFIG_X86_64 */ static u32 crc32c_intel_le_hw_byte(u32 crc, unsigned char const *data, size_t length) @@ -190,7 +177,7 @@ static int crc32c_pcl_intel_update(struct shash_desc *desc, const u8 *data, * use faster PCL version if datasize is large enough to * overcome kernel fpu state save/restore overhead */ - if (len >= crc32c_pcl_breakeven && irq_fpu_usable()) { + if (len >= CRC32C_PCL_BREAKEVEN && irq_fpu_usable()) { kernel_fpu_begin(); *crcp = crc_pcl(data, len, *crcp); kernel_fpu_end(); @@ -202,7 +189,7 @@ static int crc32c_pcl_intel_update(struct shash_desc *desc, const u8 *data, static int __crc32c_pcl_intel_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out) { - if (len >= crc32c_pcl_breakeven && irq_fpu_usable()) { + if (len >= CRC32C_PCL_BREAKEVEN && irq_fpu_usable()) { kernel_fpu_begin(); *(__le32 *)out = ~cpu_to_le32(crc_pcl(data, len, *crcp)); kernel_fpu_end(); @@ -261,7 +248,6 @@ static int __init crc32c_intel_mod_init(void) alg.update = crc32c_pcl_intel_update; alg.finup = crc32c_pcl_intel_finup; alg.digest = crc32c_pcl_intel_digest; - set_pcl_breakeven_point(); } #endif return crypto_register_shash(&alg); diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index 4dba597c5807..e83f972b0a14 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -104,7 +104,6 @@ #define X86_FEATURE_EXTD_APICID ( 3*32+26) /* has extended APICID (8 bits) */ #define X86_FEATURE_AMD_DCM ( 3*32+27) /* multi-node processor */ #define X86_FEATURE_APERFMPERF ( 3*32+28) /* APERFMPERF */ -#define X86_FEATURE_EAGER_FPU ( 3*32+29) /* "eagerfpu" Non lazy FPU restore */ #define X86_FEATURE_NONSTOP_TSC_S3 ( 3*32+30) /* TSC doesn't stop in S3 state */ /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */ diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h index 1429a7c736db..0877ae018fc9 100644 --- a/arch/x86/include/asm/fpu/api.h +++ b/arch/x86/include/asm/fpu/api.h @@ -27,16 +27,6 @@ extern void kernel_fpu_end(void); extern bool irq_fpu_usable(void); /* - * Some instructions like VIA's padlock instructions generate a spurious - * DNA fault but don't modify SSE registers. And these instructions - * get used from interrupt context as well. To prevent these kernel instructions - * in interrupt context interacting wrongly with other user/kernel fpu usage, we - * should use them only in the context of irq_ts_save/restore() - */ -extern int irq_ts_save(void); -extern void irq_ts_restore(int TS_state); - -/* * Query the presence of one or more xfeatures. Works on any legacy CPU as well. * * If 'feature_name' is set then put a human-readable description of diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h index 2737366ea583..d4a684997497 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -60,11 +60,6 @@ extern u64 fpu__get_supported_xfeatures_mask(void); /* * FPU related CPU feature flag helper routines: */ -static __always_inline __pure bool use_eager_fpu(void) -{ - return static_cpu_has(X86_FEATURE_EAGER_FPU); -} - static __always_inline __pure bool use_xsaveopt(void) { return static_cpu_has(X86_FEATURE_XSAVEOPT); @@ -484,42 +479,42 @@ extern int copy_fpstate_to_sigframe(void __user *buf, void __user *fp, int size) 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. + * The in-register FPU state for an FPU context on a CPU is assumed to be + * valid if the fpu->last_cpu matches the CPU, and the fpu_fpregs_owner_ctx + * matches the FPU. * - * 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. + * If the FPU register state is valid, the kernel can skip restoring the + * FPU state from memory. + * + * Any code that clobbers the FPU registers or updates the in-memory + * FPU state for a task MUST let the rest of the kernel know that the + * FPU registers are no longer valid for this task. + * + * Either one of these invalidation functions is enough. Invalidate + * a resource you control: CPU if using the CPU for something else + * (with preemption disabled), FPU for the current task, or a task that + * is prevented from running by the current task. */ -static inline void __cpu_disable_lazy_restore(unsigned int cpu) +static inline void __cpu_invalidate_fpregs_state(void) { - per_cpu(fpu_fpregs_owner_ctx, cpu) = NULL; + __this_cpu_write(fpu_fpregs_owner_ctx, 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) +static inline void __fpu_invalidate_fpregs_state(struct fpu *fpu) { - if (!use_eager_fpu()) - clts(); + fpu->last_cpu = -1; } -static inline void __fpregs_deactivate_hw(void) +static inline int fpregs_state_valid(struct fpu *fpu, unsigned int cpu) { - if (!use_eager_fpu()) - stts(); + return fpu == this_cpu_read_stable(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu; } -/* Must be paired with an 'stts' (fpregs_deactivate_hw()) after! */ -static inline void __fpregs_deactivate(struct fpu *fpu) +/* + * These generally need preemption protection to work, + * do try to avoid using these on their own: + */ +static inline void fpregs_deactivate(struct fpu *fpu) { WARN_ON_FPU(!fpu->fpregs_active); @@ -528,8 +523,7 @@ static inline void __fpregs_deactivate(struct fpu *fpu) trace_x86_fpu_regs_deactivated(fpu); } -/* Must be paired with a 'clts' (fpregs_activate_hw()) before! */ -static inline void __fpregs_activate(struct fpu *fpu) +static inline void fpregs_activate(struct fpu *fpu) { WARN_ON_FPU(fpu->fpregs_active); @@ -554,51 +548,19 @@ static inline int fpregs_active(void) } /* - * 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_prepare() saves the old state. + * 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) +static inline void +switch_fpu_prepare(struct fpu *old_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 = static_cpu_has(X86_FEATURE_FPU) && - 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; @@ -608,29 +570,8 @@ switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu) /* But leave fpu_fpregs_owner_ctx! */ old_fpu->fpregs_active = 0; trace_x86_fpu_regs_deactivated(old_fpu); - - /* Don't change CR0.TS if we just switch! */ - if (fpu.preload) { - new_fpu->counter++; - __fpregs_activate(new_fpu); - trace_x86_fpu_regs_activated(new_fpu); - prefetch(&new_fpu->state); - } else { - __fpregs_deactivate_hw(); - } - } else { - old_fpu->counter = 0; + } else 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; } /* @@ -638,15 +579,19 @@ switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu) */ /* - * 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. + * Set up the userspace FPU context for the new task, if the task + * has used the FPU. */ -static inline void switch_fpu_finish(struct fpu *new_fpu, fpu_switch_t fpu_switch) +static inline void switch_fpu_finish(struct fpu *new_fpu, int cpu) { - if (fpu_switch.preload) - copy_kernel_to_fpregs(&new_fpu->state); + bool preload = static_cpu_has(X86_FEATURE_FPU) && + new_fpu->fpstate_active; + + if (preload) { + if (!fpregs_state_valid(new_fpu, cpu)) + copy_kernel_to_fpregs(&new_fpu->state); + fpregs_activate(new_fpu); + } } /* diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h index 48df486b02f9..3c80f5b9c09d 100644 --- a/arch/x86/include/asm/fpu/types.h +++ b/arch/x86/include/asm/fpu/types.h @@ -322,17 +322,6 @@ struct fpu { unsigned char fpregs_active; /* - * @counter: - * - * This counter contains the number of consecutive context switches - * during which the FPU stays used. If this is over a threshold, the - * lazy FPU restore logic becomes eager, to save the trap overhead. - * This is an unsigned char so that after 256 iterations the counter - * wraps and the context switch behavior turns lazy again; this is to - * deal with bursty apps that only use the FPU for a short time: - */ - unsigned char counter; - /* * @state: * * In-memory copy of all FPU registers that we save/restore @@ -340,29 +329,6 @@ struct fpu { * the registers in the FPU are more recent than this state * copy. If the task context-switches away then they get * saved here and represent the FPU state. - * - * After context switches there may be a (short) time period - * during which the in-FPU hardware registers are unchanged - * and still perfectly match this state, if the tasks - * scheduled afterwards are not using the FPU. - * - * This is the 'lazy restore' window of optimization, which - * we track though 'fpu_fpregs_owner_ctx' and 'fpu->last_cpu'. - * - * We detect whether a subsequent task uses the FPU via setting - * CR0::TS to 1, which causes any FPU use to raise a #NM fault. - * - * During this window, if the task gets scheduled again, we - * might be able to skip having to do a restore from this - * memory buffer to the hardware registers - at the cost of - * incurring the overhead of #NM fault traps. - * - * Note that on modern CPUs that support the XSAVEOPT (or other - * optimized XSAVE instructions), we don't use #NM traps anymore, - * as the hardware can track whether FPU registers need saving - * or not. On such CPUs we activate the non-lazy ('eagerfpu') - * logic, which unconditionally saves/restores all FPU state - * across context switches. (if FPU state exists.) */ union fpregs_state state; /* diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index 430bacf73074..1b2799e0699a 100644 --- a/arch/x86/include/asm/fpu/xstate.h +++ b/arch/x86/include/asm/fpu/xstate.h @@ -21,21 +21,16 @@ /* Supervisor features */ #define XFEATURE_MASK_SUPERVISOR (XFEATURE_MASK_PT) -/* Supported features which support lazy state saving */ -#define XFEATURE_MASK_LAZY (XFEATURE_MASK_FP | \ +/* All currently supported features */ +#define XCNTXT_MASK (XFEATURE_MASK_FP | \ XFEATURE_MASK_SSE | \ XFEATURE_MASK_YMM | \ XFEATURE_MASK_OPMASK | \ XFEATURE_MASK_ZMM_Hi256 | \ - XFEATURE_MASK_Hi16_ZMM) - -/* Supported features which require eager state saving */ -#define XFEATURE_MASK_EAGER (XFEATURE_MASK_BNDREGS | \ - XFEATURE_MASK_BNDCSR | \ - XFEATURE_MASK_PKRU) - -/* All currently supported features */ -#define XCNTXT_MASK (XFEATURE_MASK_LAZY | XFEATURE_MASK_EAGER) + XFEATURE_MASK_Hi16_ZMM | \ + XFEATURE_MASK_PKRU | \ + XFEATURE_MASK_BNDREGS | \ + XFEATURE_MASK_BNDCSR) #ifdef CONFIG_X86_64 #define REX_PREFIX "0x48, " diff --git a/arch/x86/include/asm/lguest_hcall.h b/arch/x86/include/asm/lguest_hcall.h index ef01fef3eebc..6c119cfae218 100644 --- a/arch/x86/include/asm/lguest_hcall.h +++ b/arch/x86/include/asm/lguest_hcall.h @@ -9,7 +9,6 @@ #define LHCALL_FLUSH_TLB 5 #define LHCALL_LOAD_IDT_ENTRY 6 #define LHCALL_SET_STACK 7 -#define LHCALL_TS 8 #define LHCALL_SET_CLOCKEVENT 9 #define LHCALL_HALT 10 #define LHCALL_SET_PMD 13 diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index 6108b1fada2b..1eea6ca40694 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -41,11 +41,6 @@ static inline void set_debugreg(unsigned long val, int reg) PVOP_VCALL2(pv_cpu_ops.set_debugreg, reg, val); } -static inline void clts(void) -{ - PVOP_VCALL0(pv_cpu_ops.clts); -} - static inline unsigned long read_cr0(void) { return PVOP_CALL0(unsigned long, pv_cpu_ops.read_cr0); diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h index 3f2bc0f0d3e8..bb2de45a60f2 100644 --- a/arch/x86/include/asm/paravirt_types.h +++ b/arch/x86/include/asm/paravirt_types.h @@ -103,8 +103,6 @@ struct pv_cpu_ops { unsigned long (*get_debugreg)(int regno); void (*set_debugreg)(int regno, unsigned long value); - void (*clts)(void); - unsigned long (*read_cr0)(void); void (*write_cr0)(unsigned long); diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h index 19a2224f9e16..12af3e35edfa 100644 --- a/arch/x86/include/asm/special_insns.h +++ b/arch/x86/include/asm/special_insns.h @@ -6,11 +6,6 @@ #include <asm/nops.h> -static inline void native_clts(void) -{ - asm volatile("clts"); -} - /* * Volatile isn't enough to prevent the compiler from reordering the * read/write functions for the control registers and messing everything up. @@ -208,16 +203,8 @@ static inline void load_gs_index(unsigned selector) #endif -/* Clear the 'TS' bit */ -static inline void clts(void) -{ - native_clts(); -} - #endif/* CONFIG_PARAVIRT */ -#define stts() write_cr0(read_cr0() | X86_CR0_TS) - static inline void clflush(volatile void *__p) { asm volatile("clflush %0" : "+m" (*(volatile char __force *)__p)); diff --git a/arch/x86/include/asm/trace/fpu.h b/arch/x86/include/asm/trace/fpu.h index 9217ab1f5bf6..342e59789fcd 100644 --- a/arch/x86/include/asm/trace/fpu.h +++ b/arch/x86/include/asm/trace/fpu.h @@ -14,7 +14,6 @@ DECLARE_EVENT_CLASS(x86_fpu, __field(struct fpu *, fpu) __field(bool, fpregs_active) __field(bool, fpstate_active) - __field(int, counter) __field(u64, xfeatures) __field(u64, xcomp_bv) ), @@ -23,17 +22,15 @@ DECLARE_EVENT_CLASS(x86_fpu, __entry->fpu = fpu; __entry->fpregs_active = fpu->fpregs_active; __entry->fpstate_active = fpu->fpstate_active; - __entry->counter = fpu->counter; if (boot_cpu_has(X86_FEATURE_OSXSAVE)) { __entry->xfeatures = fpu->state.xsave.header.xfeatures; __entry->xcomp_bv = fpu->state.xsave.header.xcomp_bv; } ), - TP_printk("x86/fpu: %p fpregs_active: %d fpstate_active: %d counter: %d xfeatures: %llx xcomp_bv: %llx", + TP_printk("x86/fpu: %p fpregs_active: %d fpstate_active: %d xfeatures: %llx xcomp_bv: %llx", __entry->fpu, __entry->fpregs_active, __entry->fpstate_active, - __entry->counter, __entry->xfeatures, __entry->xcomp_bv ) diff --git a/arch/x86/kernel/fpu/bugs.c b/arch/x86/kernel/fpu/bugs.c index aad34aafc0e0..d913047f832c 100644 --- a/arch/x86/kernel/fpu/bugs.c +++ b/arch/x86/kernel/fpu/bugs.c @@ -23,17 +23,12 @@ static double __initdata y = 3145727.0; */ void __init fpu__init_check_bugs(void) { - u32 cr0_saved; s32 fdiv_bug; /* kernel_fpu_begin/end() relies on patched alternative instructions. */ if (!boot_cpu_has(X86_FEATURE_FPU)) return; - /* We might have CR0::TS set already, clear it: */ - cr0_saved = read_cr0(); - write_cr0(cr0_saved & ~X86_CR0_TS); - kernel_fpu_begin(); /* @@ -56,8 +51,6 @@ void __init fpu__init_check_bugs(void) kernel_fpu_end(); - write_cr0(cr0_saved); - if (fdiv_bug) { set_cpu_bug(&boot_cpu_data, X86_BUG_FDIV); pr_warn("Hmm, FPU with FDIV bug\n"); diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index ebb4e95fbd74..e4e97a5355ce 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -58,27 +58,9 @@ static bool kernel_fpu_disabled(void) return this_cpu_read(in_kernel_fpu); } -/* - * Were we in an interrupt that interrupted kernel mode? - * - * On others, we can do a kernel_fpu_begin/end() pair *ONLY* if that - * pair does nothing at all: the thread must not have fpu (so - * that we don't try to save the FPU state), and TS must - * be set (so that the clts/stts pair does nothing that is - * visible in the interrupted kernel thread). - * - * Except for the eagerfpu case when we return true; in the likely case - * the thread has FPU but we are not going to set/clear TS. - */ static bool interrupted_kernel_fpu_idle(void) { - if (kernel_fpu_disabled()) - return false; - - if (use_eager_fpu()) - return true; - - return !current->thread.fpu.fpregs_active && (read_cr0() & X86_CR0_TS); + return !kernel_fpu_disabled(); } /* @@ -125,8 +107,7 @@ void __kernel_fpu_begin(void) */ copy_fpregs_to_fpstate(fpu); } else { - this_cpu_write(fpu_fpregs_owner_ctx, NULL); - __fpregs_activate_hw(); + __cpu_invalidate_fpregs_state(); } } EXPORT_SYMBOL(__kernel_fpu_begin); @@ -137,8 +118,6 @@ void __kernel_fpu_end(void) if (fpu->fpregs_active) copy_kernel_to_fpregs(&fpu->state); - else - __fpregs_deactivate_hw(); kernel_fpu_enable(); } @@ -159,35 +138,6 @@ void kernel_fpu_end(void) EXPORT_SYMBOL_GPL(kernel_fpu_end); /* - * CR0::TS save/restore functions: - */ -int irq_ts_save(void) -{ - /* - * If in process context and not atomic, we can take a spurious DNA fault. - * Otherwise, doing clts() in process context requires disabling preemption - * or some heavy lifting like kernel_fpu_begin() - */ - if (!in_atomic()) - return 0; - - if (read_cr0() & X86_CR0_TS) { - clts(); - return 1; - } - - return 0; -} -EXPORT_SYMBOL_GPL(irq_ts_save); - -void irq_ts_restore(int TS_state) -{ - if (TS_state) - stts(); -} -EXPORT_SYMBOL_GPL(irq_ts_restore); - -/* * Save the FPU state (mark it for reload if necessary): * * This only ever gets called for the current task. @@ -200,10 +150,7 @@ void fpu__save(struct fpu *fpu) trace_x86_fpu_before_save(fpu); if (fpu->fpregs_active) { if (!copy_fpregs_to_fpstate(fpu)) { - if (use_eager_fpu()) - copy_kernel_to_fpregs(&fpu->state); - else - fpregs_deactivate(fpu); + copy_kernel_to_fpregs(&fpu->state); } } trace_x86_fpu_after_save(fpu); @@ -247,7 +194,6 @@ EXPORT_SYMBOL_GPL(fpstate_init); int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu) { - dst_fpu->counter = 0; dst_fpu->fpregs_active = 0; dst_fpu->last_cpu = -1; @@ -260,8 +206,7 @@ int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu) * Don't let 'init optimized' areas of the XSAVE area * leak into the child task: */ - if (use_eager_fpu()) - memset(&dst_fpu->state.xsave, 0, fpu_kernel_xstate_size); + memset(&dst_fpu->state.xsave, 0, fpu_kernel_xstate_size); /* * Save current FPU registers directly into the child @@ -283,10 +228,7 @@ int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu) memcpy(&src_fpu->state, &dst_fpu->state, fpu_kernel_xstate_size); - if (use_eager_fpu()) - copy_kernel_to_fpregs(&src_fpu->state); - else - fpregs_deactivate(src_fpu); + copy_kernel_to_fpregs(&src_fpu->state); } preempt_enable(); @@ -366,7 +308,7 @@ void fpu__activate_fpstate_write(struct fpu *fpu) if (fpu->fpstate_active) { /* Invalidate any lazy state: */ - fpu->last_cpu = -1; + __fpu_invalidate_fpregs_state(fpu); } else { fpstate_init(&fpu->state); trace_x86_fpu_init_state(fpu); @@ -409,7 +351,7 @@ void fpu__current_fpstate_write_begin(void) * ensures we will not be lazy and skip a XRSTOR in the * future. */ - fpu->last_cpu = -1; + __fpu_invalidate_fpregs_state(fpu); } /* @@ -459,7 +401,6 @@ void fpu__restore(struct fpu *fpu) trace_x86_fpu_before_restore(fpu); fpregs_activate(fpu); copy_kernel_to_fpregs(&fpu->state); - fpu->counter++; trace_x86_fpu_after_restore(fpu); kernel_fpu_enable(); } @@ -477,7 +418,6 @@ EXPORT_SYMBOL_GPL(fpu__restore); void fpu__drop(struct fpu *fpu) { preempt_disable(); - fpu->counter = 0; if (fpu->fpregs_active) { /* Ignore delayed exceptions from user space */ diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c index 2f2b8c7ccb85..60dece392b3a 100644 --- a/arch/x86/kernel/fpu/init.c +++ b/arch/x86/kernel/fpu/init.c @@ -10,18 +10,6 @@ #include <linux/init.h> /* - * Initialize the TS bit in CR0 according to the style of context-switches - * we are using: - */ -static void fpu__init_cpu_ctx_switch(void) -{ - if (!boot_cpu_has(X86_FEATURE_EAGER_FPU)) - stts(); - else - clts(); -} - -/* * Initialize the registers found in all CPUs, CR0 and CR4: */ static void fpu__init_cpu_generic(void) @@ -58,7 +46,6 @@ void fpu__init_cpu(void) { fpu__init_cpu_generic(); fpu__init_cpu_xstate(); - fpu__init_cpu_ctx_switch(); } /* @@ -233,82 +220,16 @@ static void __init fpu__init_system_xstate_size_legacy(void) } /* - * FPU context switching strategies: - * - * Against popular belief, we don't do lazy FPU saves, due to the - * task migration complications it brings on SMP - we only do - * lazy FPU restores. - * - * 'lazy' is the traditional strategy, which is based on setting - * CR0::TS to 1 during context-switch (instead of doing a full - * restore of the FPU state), which causes the first FPU instruction - * after the context switch (whenever it is executed) to fault - at - * which point we lazily restore the FPU state into FPU registers. - * - * Tasks are of course under no obligation to execute FPU instructions, - * so it can easily happen that another context-switch occurs without - * a single FPU instruction being executed. If we eventually switch - * back to the original task (that still owns the FPU) then we have - * not only saved the restores along the way, but we also have the - * FPU ready to be used for the original task. - * - * 'lazy' is deprecated because it's almost never a per |