diff options
Diffstat (limited to 'arch/arm64/kernel/fpsimd.c')
| -rw-r--r-- | arch/arm64/kernel/fpsimd.c | 929 |
1 files changed, 483 insertions, 446 deletions
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index dd63ffc3a2fa..c37f02d7194e 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -85,13 +85,13 @@ * softirq kicks in. Upon vcpu_put(), KVM will save the vcpu FP state and * flag the register state as invalid. * - * In order to allow softirq handlers to use FPSIMD, kernel_neon_begin() may - * save the task's FPSIMD context back to task_struct from softirq context. - * To prevent this from racing with the manipulation of the task's FPSIMD state - * from task context and thereby corrupting the state, it is necessary to - * protect any manipulation of a task's fpsimd_state or TIF_FOREIGN_FPSTATE - * flag with {, __}get_cpu_fpsimd_context(). This will still allow softirqs to - * run but prevent them to use FPSIMD. + * In order to allow softirq handlers to use FPSIMD, kernel_neon_begin() may be + * called from softirq context, which will save the task's FPSIMD context back + * to task_struct. To prevent this from racing with the manipulation of the + * task's FPSIMD state from task context and thereby corrupting the state, it + * is necessary to protect any manipulation of a task's fpsimd_state or + * TIF_FOREIGN_FPSTATE flag with get_cpu_fpsimd_context(), which will suspend + * softirq servicing entirely until put_cpu_fpsimd_context() is called. * * For a certain task, the sequence may look something like this: * - the task gets scheduled in; if both the task's fpsimd_cpu field @@ -118,16 +118,8 @@ * returned from the 2nd syscall yet, TIF_FOREIGN_FPSTATE is still set so * whatever is in the FPSIMD registers is not saved to memory, but discarded. */ -struct fpsimd_last_state_struct { - struct user_fpsimd_state *st; - void *sve_state; - void *za_state; - u64 *svcr; - unsigned int sve_vl; - unsigned int sme_vl; -}; -static DEFINE_PER_CPU(struct fpsimd_last_state_struct, fpsimd_last_state); +DEFINE_PER_CPU(struct cpu_fp_state, fpsimd_last_state); __ro_after_init struct vl_info vl_info[ARM64_VEC_MAX] = { #ifdef CONFIG_ARM64_SVE @@ -188,12 +180,12 @@ static inline void set_sve_default_vl(int val) set_default_vl(ARM64_VEC_SVE, val); } -static void __percpu *efi_sve_state; +static u8 *efi_sve_state; #else /* ! CONFIG_ARM64_SVE */ /* Dummy declaration for code that will be optimised out: */ -extern void __percpu *efi_sve_state; +extern u8 *efi_sve_state; #endif /* ! CONFIG_ARM64_SVE */ @@ -217,27 +209,14 @@ static inline void sme_free(struct task_struct *t) { } #endif -DEFINE_PER_CPU(bool, fpsimd_context_busy); -EXPORT_PER_CPU_SYMBOL(fpsimd_context_busy); - static void fpsimd_bind_task_to_cpu(void); -static void __get_cpu_fpsimd_context(void) -{ - bool busy = __this_cpu_xchg(fpsimd_context_busy, true); - - WARN_ON(busy); -} - /* * Claim ownership of the CPU FPSIMD context for use by the calling context. * * The caller may freely manipulate the FPSIMD context metadata until * put_cpu_fpsimd_context() is called. * - * The double-underscore version must only be called if you know the task - * can't be preempted. - * * On RT kernels local_bh_disable() is not sufficient because it only * serializes soft interrupt related sections via a local lock, but stays * preemptible. Disabling preemption is the right choice here as bottom @@ -250,14 +229,6 @@ static void get_cpu_fpsimd_context(void) local_bh_disable(); else preempt_disable(); - __get_cpu_fpsimd_context(); -} - -static void __put_cpu_fpsimd_context(void) -{ - bool busy = __this_cpu_xchg(fpsimd_context_busy, false); - - WARN_ON(!busy); /* No matching get_cpu_fpsimd_context()? */ } /* @@ -269,18 +240,12 @@ static void __put_cpu_fpsimd_context(void) */ static void put_cpu_fpsimd_context(void) { - __put_cpu_fpsimd_context(); if (!IS_ENABLED(CONFIG_PREEMPT_RT)) local_bh_enable(); else preempt_enable(); } -static bool have_cpu_fpsimd_context(void) -{ - return !preemptible() && __this_cpu_read(fpsimd_context_busy); -} - unsigned int task_get_vl(const struct task_struct *task, enum vec_type type) { return task->thread.vl[type]; @@ -307,7 +272,7 @@ void task_set_vl_onexec(struct task_struct *task, enum vec_type type, /* * TIF_SME controls whether a task can use SME without trapping while * in userspace, when TIF_SME is set then we must have storage - * alocated in sve_state and za_state to store the contents of both ZA + * allocated in sve_state and sme_state to store the contents of both ZA * and the SVE registers for both streaming and non-streaming modes. * * If both SVCR.ZA and SVCR.SM are disabled then at any point we @@ -330,15 +295,6 @@ void task_set_vl_onexec(struct task_struct *task, enum vec_type type, * The task can execute SVE instructions while in userspace without * trapping to the kernel. * - * When stored, Z0-Z31 (incorporating Vn in bits[127:0] or the - * corresponding Zn), P0-P15 and FFR are encoded in - * task->thread.sve_state, formatted appropriately for vector - * length task->thread.sve_vl or, if SVCR.SM is set, - * task->thread.sme_vl. - * - * task->thread.sve_state must point to a valid buffer at least - * sve_state_size(task) bytes in size. - * * During any syscall, the kernel may optionally clear TIF_SVE and * discard the vector state except for the FPSIMD subset. * @@ -348,7 +304,15 @@ void task_set_vl_onexec(struct task_struct *task, enum vec_type type, * do_sve_acc() to be called, which does some preparation and then * sets TIF_SVE. * - * When stored, FPSIMD registers V0-V31 are encoded in + * During any syscall, the kernel may optionally clear TIF_SVE and + * discard the vector state except for the FPSIMD subset. + * + * The data will be stored in one of two formats: + * + * * FPSIMD only - FP_STATE_FPSIMD: + * + * When the FPSIMD only state stored task->thread.fp_type is set to + * FP_STATE_FPSIMD, the FPSIMD registers V0-V31 are encoded in * task->thread.uw.fpsimd_state; bits [max : 128] for each of Z0-Z31 are * logically zero but not stored anywhere; P0-P15 and FFR are not * stored and have unspecified values from userspace's point of @@ -356,7 +320,23 @@ void task_set_vl_onexec(struct task_struct *task, enum vec_type type, * but userspace is discouraged from relying on this. * * task->thread.sve_state does not need to be non-NULL, valid or any - * particular size: it must not be dereferenced. + * particular size: it must not be dereferenced and any data stored + * there should be considered stale and not referenced. + * + * * SVE state - FP_STATE_SVE: + * + * When the full SVE state is stored task->thread.fp_type is set to + * FP_STATE_SVE and Z0-Z31 (incorporating Vn in bits[127:0] or the + * corresponding Zn), P0-P15 and FFR are encoded in in + * task->thread.sve_state, formatted appropriately for vector + * length task->thread.sve_vl or, if SVCR.SM is set, + * task->thread.sme_vl. The storage for the vector registers in + * task->thread.uw.fpsimd_state should be ignored. + * + * task->thread.sve_state must point to a valid buffer at least + * sve_state_size(task) bytes in size. The data stored in + * task->thread.uw.fpsimd_state.vregs should be considered stale + * and not referenced. * * * FPSR and FPCR are always stored in task->thread.uw.fpsimd_state * irrespective of whether TIF_SVE is clear or set, since these are @@ -376,13 +356,38 @@ static void task_fpsimd_load(void) bool restore_ffr; WARN_ON(!system_supports_fpsimd()); - WARN_ON(!have_cpu_fpsimd_context()); + WARN_ON(preemptible()); + WARN_ON(test_thread_flag(TIF_KERNEL_FPSTATE)); + + if (system_supports_sve() || system_supports_sme()) { + switch (current->thread.fp_type) { + case FP_STATE_FPSIMD: + /* Stop tracking SVE for this task until next use. */ + clear_thread_flag(TIF_SVE); + break; + case FP_STATE_SVE: + if (!thread_sm_enabled(¤t->thread)) + WARN_ON_ONCE(!test_and_set_thread_flag(TIF_SVE)); - /* Check if we should restore SVE first */ - if (IS_ENABLED(CONFIG_ARM64_SVE) && test_thread_flag(TIF_SVE)) { - sve_set_vq(sve_vq_from_vl(task_get_sve_vl(current)) - 1); - restore_sve_regs = true; - restore_ffr = true; + if (test_thread_flag(TIF_SVE)) + sve_set_vq(sve_vq_from_vl(task_get_sve_vl(current)) - 1); + + restore_sve_regs = true; + restore_ffr = true; + break; + default: + /* + * This indicates either a bug in + * fpsimd_save_user_state() or memory corruption, we + * should always record an explicit format + * when we save. We always at least have the + * memory allocated for FPSIMD registers so + * try that and hope for the best. + */ + WARN_ON_ONCE(1); + clear_thread_flag(TIF_SVE); + break; + } } /* Restore SME, override SVE register configuration if needed */ @@ -396,20 +401,25 @@ static void task_fpsimd_load(void) write_sysreg_s(current->thread.svcr, SYS_SVCR); if (thread_za_enabled(¤t->thread)) - za_load_state(current->thread.za_state); + sme_load_state(current->thread.sme_state, + system_supports_sme2()); - if (thread_sm_enabled(¤t->thread)) { - restore_sve_regs = true; + if (thread_sm_enabled(¤t->thread)) restore_ffr = system_supports_fa64(); - } } - if (restore_sve_regs) + if (system_supports_fpmr()) + write_sysreg_s(current->thread.uw.fpmr, SYS_FPMR); + + if (restore_sve_regs) { + WARN_ON_ONCE(current->thread.fp_type != FP_STATE_SVE); sve_load_state(sve_pffr(¤t->thread), ¤t->thread.uw.fpsimd_state.fpsr, restore_ffr); - else + } else { + WARN_ON_ONCE(current->thread.fp_type != FP_STATE_FPSIMD); fpsimd_load_state(¤t->thread.uw.fpsimd_state); + } } /* @@ -419,12 +429,12 @@ static void task_fpsimd_load(void) * last, if KVM is involved this may be the guest VM context rather * than the host thread for the VM pointed to by current. This means * that we must always reference the state storage via last rather - * than via current, other than the TIF_ flags which KVM will - * carefully maintain for us. + * than via current, if we are saving KVM state then it will have + * ensured that the type of registers to save is set in last->to_save. */ -static void fpsimd_save(void) +static void fpsimd_save_user_state(void) { - struct fpsimd_last_state_struct const *last = + struct cpu_fp_state const *last = this_cpu_ptr(&fpsimd_last_state); /* set by fpsimd_bind_task_to_cpu() or fpsimd_bind_state_to_cpu() */ bool save_sve_regs = false; @@ -432,12 +442,25 @@ static void fpsimd_save(void) unsigned int vl; WARN_ON(!system_supports_fpsimd()); - WARN_ON(!have_cpu_fpsimd_context()); + WARN_ON(preemptible()); if (test_thread_flag(TIF_FOREIGN_FPSTATE)) return; - if (test_thread_flag(TIF_SVE)) { + if (system_supports_fpmr()) + *(last->fpmr) = read_sysreg_s(SYS_FPMR); + + /* + * Save SVE state if it is live. + * + * The syscall ABI discards live SVE state at syscall entry. When + * entering a syscall, fpsimd_syscall_enter() sets to_save to + * FP_STATE_FPSIMD to allow the SVE state to be lazily discarded until + * either new SVE state is loaded+bound or fpsimd_syscall_exit() is + * called prior to a return to userspace. + */ + if ((last->to_save == FP_STATE_CURRENT && test_thread_flag(TIF_SVE)) || + last->to_save == FP_STATE_SVE) { save_sve_regs = true; save_ffr = true; vl = last->sve_vl; @@ -449,7 +472,8 @@ static void fpsimd_save(void) *svcr = read_sysreg_s(SYS_SVCR); if (*svcr & SVCR_ZA_MASK) - za_save_state(last->za_state); + sme_save_state(last->sme_state, + system_supports_sme2()); /* If we are in streaming mode override regular SVE. */ if (*svcr & SVCR_SM_MASK) { @@ -474,8 +498,10 @@ static void fpsimd_save(void) sve_save_state((char *)last->sve_state + sve_ffr_offset(vl), &last->st->fpsr, save_ffr); + *last->fp_type = FP_STATE_SVE; } else { fpsimd_save_state(last->st); + *last->fp_type = FP_STATE_FPSIMD; } } @@ -510,7 +536,7 @@ static unsigned int find_supported_vector_length(enum vec_type type, #if defined(CONFIG_ARM64_SVE) && defined(CONFIG_SYSCTL) -static int vec_proc_do_default_vl(struct ctl_table *table, int write, +static int vec_proc_do_default_vl(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { struct vl_info *info = table->extra1; @@ -537,14 +563,13 @@ static int vec_proc_do_default_vl(struct ctl_table *table, int write, return 0; } -static struct ctl_table sve_default_vl_table[] = { +static const struct ctl_table sve_default_vl_table[] = { { .procname = "sve_default_vector_length", .mode = 0644, .proc_handler = vec_proc_do_default_vl, .extra1 = &vl_info[ARM64_VEC_SVE], }, - { } }; static int __init sve_sysctl_init(void) @@ -561,14 +586,13 @@ static int __init sve_sysctl_init(void) { return 0; } #endif /* ! (CONFIG_ARM64_SVE && CONFIG_SYSCTL) */ #if defined(CONFIG_ARM64_SME) && defined(CONFIG_SYSCTL) -static struct ctl_table sme_default_vl_table[] = { +static const struct ctl_table sme_default_vl_table[] = { { .procname = "sme_default_vector_length", .mode = 0644, .proc_handler = vec_proc_do_default_vl, .extra1 = &vl_info[ARM64_VEC_SME], }, - { } }; static int __init sme_sysctl_init(void) @@ -628,13 +652,13 @@ static void __fpsimd_to_sve(void *sst, struct user_fpsimd_state const *fst, * task->thread.uw.fpsimd_state must be up to date before calling this * function. */ -static void fpsimd_to_sve(struct task_struct *task) +static inline void fpsimd_to_sve(struct task_struct *task) { unsigned int vq; void *sst = task->thread.sve_state; struct user_fpsimd_state const *fst = &task->thread.uw.fpsimd_state; - if (!system_supports_sve()) + if (!system_supports_sve() && !system_supports_sme()) return; vq = sve_vq_from_vl(thread_get_cur_vl(&task->thread)); @@ -652,7 +676,7 @@ static void fpsimd_to_sve(struct task_struct *task) * bytes of allocated kernel memory. * task->thread.sve_state must be up to date before calling this function. */ -static void sve_to_fpsimd(struct task_struct *task) +static inline void sve_to_fpsimd(struct task_struct *task) { unsigned int vq, vl; void const *sst = task->thread.sve_state; @@ -660,7 +684,7 @@ static void sve_to_fpsimd(struct task_struct *task) unsigned int i; __uint128_t const *p; - if (!system_supports_sve()) + if (!system_supports_sve() && !system_supports_sme()) return; vl = thread_get_cur_vl(&task->thread); @@ -671,38 +695,39 @@ static void sve_to_fpsimd(struct task_struct *task) } } -#ifdef CONFIG_ARM64_SVE -/* - * Call __sve_free() directly only if you know task can't be scheduled - * or preempted. - */ -static void __sve_free(struct task_struct *task) +static inline void __fpsimd_zero_vregs(struct user_fpsimd_state *fpsimd) { - kfree(task->thread.sve_state); - task->thread.sve_state = NULL; + memset(&fpsimd->vregs, 0, sizeof(fpsimd->vregs)); } -static void sve_free(struct task_struct *task) +/* + * Simulate the effects of an SMSTOP SM instruction. + */ +void task_smstop_sm(struct task_struct *task) { - WARN_ON(test_tsk_thread_flag(task, TIF_SVE)); + if (!thread_sm_enabled(&task->thread)) + return; + + __fpsimd_zero_vregs(&task->thread.uw.fpsimd_state); + task->thread.uw.fpsimd_state.fpsr = 0x0800009f; + if (system_supports_fpmr()) + task->thread.uw.fpmr = 0; - __sve_free(task); + task->thread.svcr &= ~SVCR_SM_MASK; + task->thread.fp_type = FP_STATE_FPSIMD; } -/* - * Return how many bytes of memory are required to store the full SVE - * state for task, given task's currently configured vector length. - */ -size_t sve_state_size(struct task_struct const *task) +void cpu_enable_fpmr(const struct arm64_cpu_capabilities *__always_unused p) { - unsigned int vl = 0; - - if (system_supports_sve()) - vl = task_get_sve_vl(task); - if (system_supports_sme()) - vl = max(vl, task_get_sme_vl(task)); + write_sysreg_s(read_sysreg_s(SYS_SCTLR_EL1) | SCTLR_EL1_EnFPM_MASK, + SYS_SCTLR_EL1); +} - return SVE_SIG_REGS_SIZE(sve_vq_from_vl(vl)); +#ifdef CONFIG_ARM64_SVE +static void sve_free(struct task_struct *task) +{ + kfree(task->thread.sve_state); + task->thread.sve_state = NULL; } /* @@ -715,10 +740,12 @@ size_t sve_state_size(struct task_struct const *task) * do_sve_acc() case, there is no ABI requirement to hide stale data * written previously be task. */ -void sve_alloc(struct task_struct *task) +void sve_alloc(struct task_struct *task, bool flush) { if (task->thread.sve_state) { - memset(task->thread.sve_state, 0, sve_state_size(task)); + if (flush) + memset(task->thread.sve_state, 0, + sve_state_size(task)); return; } @@ -727,69 +754,34 @@ void sve_alloc(struct task_struct *task) kzalloc(sve_state_size(task), GFP_KERNEL); } - /* - * Force the FPSIMD state shared with SVE to be updated in the SVE state - * even if the SVE state is the current active state. + * Ensure that task->thread.uw.fpsimd_state is up to date with respect to the + * task's currently effective FPSIMD/SVE state. * - * This should only be called by ptrace. task must be non-runnable. - * task->thread.sve_state must point to at least sve_state_size(task) - * bytes of allocated kernel memory. - */ -void fpsimd_force_sync_to_sve(struct task_struct *task) -{ - fpsimd_to_sve(task); -} - -/* - * Ensure that task->thread.sve_state is up to date with respect to - * the user task, irrespective of when SVE is in use or not. - * - * This should only be called by ptrace. task must be non-runnable. - * task->thread.sve_state must point to at least sve_state_size(task) - * bytes of allocated kernel memory. + * The task's FPSIMD/SVE/SME state must not be subject to concurrent + * manipulation. */ -void fpsimd_sync_to_sve(struct task_struct *task) +void fpsimd_sync_from_effective_state(struct task_struct *task) { - if (!test_tsk_thread_flag(task, TIF_SVE) && - !thread_sm_enabled(&task->thread)) - fpsimd_to_sve(task); -} - -/* - * Ensure that task->thread.uw.fpsimd_state is up to date with respect to - * the user task, irrespective of whether SVE is in use or not. - * - * This should only be called by ptrace. task must be non-runnable. - * task->thread.sve_state must point to at least sve_state_size(task) - * bytes of allocated kernel memory. - */ -void sve_sync_to_fpsimd(struct task_struct *task) -{ - if (test_tsk_thread_flag(task, TIF_SVE) || - thread_sm_enabled(&task->thread)) + if (task->thread.fp_type == FP_STATE_SVE) sve_to_fpsimd(task); } /* - * Ensure that task->thread.sve_state is up to date with respect to - * the task->thread.uw.fpsimd_state. + * Ensure that the task's currently effective FPSIMD/SVE state is up to date + * with respect to task->thread.uw.fpsimd_state, zeroing any effective + * non-FPSIMD (S)SVE state. * - * This should only be called by ptrace to merge new FPSIMD register - * values into a task for which SVE is currently active. - * task must be non-runnable. - * task->thread.sve_state must point to at least sve_state_size(task) - * bytes of allocated kernel memory. - * task->thread.uw.fpsimd_state must already have been initialised with - * the new FPSIMD register values to be merged in. + * The task's FPSIMD/SVE/SME state must not be subject to concurrent + * manipulation. */ -void sve_sync_from_fpsimd_zeropad(struct task_struct *task) +void fpsimd_sync_to_effective_state_zeropad(struct task_struct *task) { unsigned int vq; void *sst = task->thread.sve_state; struct user_fpsimd_state const *fst = &task->thread.uw.fpsimd_state; - if (!test_tsk_thread_flag(task, TIF_SVE)) + if (task->thread.fp_type != FP_STATE_SVE) return; vq = sve_vq_from_vl(thread_get_cur_vl(&task->thread)); @@ -798,9 +790,74 @@ void sve_sync_from_fpsimd_zeropad(struct task_struct *task) __fpsimd_to_sve(sst, fst, vq); } +static int change_live_vector_length(struct task_struct *task, + enum vec_type type, + unsigned long vl) +{ + unsigned int sve_vl = task_get_sve_vl(task); + unsigned int sme_vl = task_get_sme_vl(task); + void *sve_state = NULL, *sme_state = NULL; + + if (type == ARM64_VEC_SME) + sme_vl = vl; + else + sve_vl = vl; + + /* + * Allocate the new sve_state and sme_state before freeing the old + * copies so that allocation failure can be handled without needing to + * mutate the task's state in any way. + * + * Changes to the SVE vector length must not discard live ZA state or + * clear PSTATE.ZA, as userspace code which is unaware of the AAPCS64 + * ZA lazy saving scheme may attempt to change the SVE vector length + * while unsaved/dormant ZA state exists. + */ + sve_state = kzalloc(__sve_state_size(sve_vl, sme_vl), GFP_KERNEL); + if (!sve_state) + goto out_mem; + + if (type == ARM64_VEC_SME) { + sme_state = kzalloc(__sme_state_size(sme_vl), GFP_KERNEL); + if (!sme_state) + goto out_mem; + } + + if (task == current) + fpsimd_save_and_flush_current_state(); + else + fpsimd_flush_task_state(task); + + /* + * Always preserve PSTATE.SM and the effective FPSIMD state, zeroing + * other SVE state. + */ + fpsimd_sync_from_effective_state(task); + task_set_vl(task, type, vl); + kfree(task->thread.sve_state); + task->thread.sve_state = sve_state; + fpsimd_sync_to_effective_state_zeropad(task); + + if (type == ARM64_VEC_SME) { + task->thread.svcr &= ~SVCR_ZA_MASK; + kfree(task->thread.sme_state); + task->thread.sme_state = sme_state; + } + + return 0; + +out_mem: + kfree(sve_state); + kfree(sme_state); + return -ENOMEM; +} + int vec_set_vector_length(struct task_struct *task, enum vec_type type, unsigned long vl, unsigned long flags) { + bool onexec = flags & PR_SVE_SET_VL_ONEXEC; + bool inherit = flags & PR_SVE_VL_INHERIT; + if (flags & ~(unsigned long)(PR_SVE_VL_INHERIT | PR_SVE_SET_VL_ONEXEC)) return -EINVAL; @@ -819,56 +876,17 @@ int vec_set_vector_length(struct task_struct *task, enum vec_type type, vl = find_supported_vector_length(type, vl); - if (flags & (PR_SVE_VL_INHERIT | - PR_SVE_SET_VL_ONEXEC)) + if (!onexec && vl != task_get_vl(task, type)) { + if (change_live_vector_length(task, type, vl)) + return -ENOMEM; + } + + if (onexec || inherit) task_set_vl_onexec(task, type, vl); else /* Reset VL to system default on next exec: */ task_set_vl_onexec(task, type, 0); - /* Only actually set the VL if not deferred: */ - if (flags & PR_SVE_SET_VL_ONEXEC) - goto out; - - if (vl == task_get_vl(task, type)) - goto out; - - /* - * To ensure the FPSIMD bits of the SVE vector registers are preserved, - * write any live register state back to task_struct, and convert to a - * regular FPSIMD thread. - */ - if (task == current) { - get_cpu_fpsimd_context(); - - fpsimd_save(); - } - - fpsimd_flush_task_state(task); - if (test_and_clear_tsk_thread_flag(task, TIF_SVE) || - thread_sm_enabled(&task->thread)) - sve_to_fpsimd(task); - - if (system_supports_sme() && type == ARM64_VEC_SME) { - task->thread.svcr &= ~(SVCR_SM_MASK | - SVCR_ZA_MASK); - clear_thread_flag(TIF_SME); - } - - if (task == current) - put_cpu_fpsimd_context(); - - /* - * Force reallocation of task SVE and SME state to the correct - * size on next use: - */ - sve_free(task); - if (system_supports_sme() && type == ARM64_VEC_SME) - sme_free(task); - - task_set_vl(task, type, vl); - -out: update_tsk_thread_flag(task, vec_vl_inherit_flag(type), flags & PR_SVE_VL_INHERIT); @@ -1083,60 +1101,31 @@ static void __init sve_efi_setup(void) if (!sve_vl_valid(max_vl)) goto fail; - efi_sve_state = __alloc_percpu( - SVE_SIG_REGS_SIZE(sve_vq_from_vl(max_vl)), SVE_VQ_BYTES); + efi_sve_state = kmalloc(SVE_SIG_REGS_SIZE(sve_vq_from_vl(max_vl)), + GFP_KERNEL); if (!efi_sve_state) goto fail; return; fail: - panic("Cannot allocate percpu memory for EFI SVE save/restore"); + panic("Cannot allocate memory for EFI SVE save/restore"); } -/* - * Enable SVE for EL1. - * Intended for use by the cpufeatures code during CPU boot. - */ -void sve_kernel_enable(const struct arm64_cpu_capabilities *__always_unused p) +void cpu_enable_sve(const struct arm64_cpu_capabilities *__always_unused p) { write_sysreg(read_sysreg(CPACR_EL1) | CPACR_EL1_ZEN_EL1EN, CPACR_EL1); isb(); -} - -/* - * Read the pseudo-ZCR used by cpufeatures to identify the supported SVE - * vector length. - * - * Use only if SVE is present. - * This function clobbers the SVE vector length. - */ -u64 read_zcr_features(void) -{ - u64 zcr; - unsigned int vq_max; - /* - * Set the maximum possible VL, and write zeroes to all other - * bits to see if they stick. - */ - sve_kernel_enable(NULL); - write_sysreg_s(ZCR_ELx_LEN_MASK, SYS_ZCR_EL1); - - zcr = read_sysreg_s(SYS_ZCR_EL1); - zcr &= ~(u64)ZCR_ELx_LEN_MASK; /* find sticky 1s outside LEN field */ - vq_max = sve_vq_from_vl(sve_get_vl()); - zcr |= vq_max - 1; /* set LEN field to maximum effective value */ - - return zcr; + write_sysreg_s(0, SYS_ZCR_EL1); } void __init sve_setup(void) { struct vl_info *info = &vl_info[ARM64_VEC_SVE]; - u64 zcr; DECLARE_BITMAP(tmp_map, SVE_VQ_MAX); unsigned long b; + int max_bit; if (!system_supports_sve()) return; @@ -1149,17 +1138,8 @@ void __init sve_setup(void) if (WARN_ON(!test_bit(__vq_to_bit(SVE_VQ_MIN), info->vq_map))) set_bit(__vq_to_bit(SVE_VQ_MIN), info->vq_map); - zcr = read_sanitised_ftr_reg(SYS_ZCR_EL1); - info->max_vl = sve_vl_from_vq((zcr & ZCR_ELx_LEN_MASK) + 1); - - /* - * Sanity-check that the max VL we determined through CPU features - * corresponds properly to sve_vq_map. If not, do our best: - */ - if (WARN_ON(info->max_vl != find_supported_vector_length(ARM64_VEC_SVE, - info->max_vl))) - info->max_vl = find_supported_vector_length(ARM64_VEC_SVE, - info->max_vl); + max_bit = find_first_bit(info->vq_map, SVE_VQ_MAX); + info->max_vl = sve_vl_from_vq(__bit_to_vq(max_bit)); /* * For the default VL, pick the maximum supported value <= 64. @@ -1202,7 +1182,7 @@ void __init sve_setup(void) */ void fpsimd_release_task(struct task_struct *dead_task) { - __sve_free(dead_task); + sve_free(dead_task); sme_free(dead_task); } @@ -1211,33 +1191,35 @@ void fpsimd_release_task(struct task_struct *dead_task) #ifdef CONFIG_ARM64_SME /* - * Ensure that task->thread.za_state is allocated and sufficiently large. + * Ensure that task->thread.sme_state is allocated and sufficiently large. * * This function should be used only in preparation for replacing - * task->thread.za_state with new data. The memory is always zeroed + * task->thread.sme_state with new data. The memory is always zeroed * here to prevent stale data from showing through: this is done in * the interest of testability and predictability, the architecture * guarantees that when ZA is enabled it will be zeroed. */ -void sme_alloc(struct task_struct *task) +void sme_alloc(struct task_struct *task, bool flush) { - if (task->thread.za_state) { - memset(task->thread.za_state, 0, za_state_size(task)); + if (task->thread.sme_state) { + if (flush) + memset(task->thread.sme_state, 0, + sme_state_size(task)); return; } /* This could potentially be up to 64K. */ - task->thread.za_state = - kzalloc(za_state_size(task), GFP_KERNEL); + task->thread.sme_state = + kzalloc(sme_state_size(task), GFP_KERNEL); } static void sme_free(struct task_struct *task) { - kfree(task->thread.za_state); - task->thread.za_state = NULL; + kfree(task->thread.sme_state); + task->thread.sme_state = NULL; } -void sme_kernel_enable(const struct arm64_cpu_capabilities *__always_unused p) +void cpu_enable_sme(const struct arm64_cpu_capabilities *__always_unused p) { /* Set priority for all PEs to architecturally defined minimum */ write_sysreg_s(read_sysreg_s(SYS_SMPRI_EL1) & ~SMPRI_EL1_PRIORITY_MASK, @@ -1247,58 +1229,38 @@ void sme_kernel_enable(const struct arm64_cpu_capabilities *__always_unused p) write_sysreg(read_sysreg(CPACR_EL1) | CPACR_EL1_SMEN_EL1EN, CPACR_EL1); isb(); + /* Ensure all bits in SMCR are set to known values */ + write_sysreg_s(0, SYS_SMCR_EL1); + /* Allow EL0 to access TPIDR2 */ write_sysreg(read_sysreg(SCTLR_EL1) | SCTLR_ELx_ENTP2, SCTLR_EL1); isb(); } -/* - * This must be called after sme_kernel_enable(), we rely on the - * feature table being sorted to ensure this. - */ -void fa64_kernel_enable(const struct arm64_cpu_capabilities *__always_unused p) +void cpu_enable_sme2(const struct arm64_cpu_capabilities *__always_unused p) { - /* Allow use of FA64 */ - write_sysreg_s(read_sysreg_s(SYS_SMCR_EL1) | SMCR_ELx_FA64_MASK, + /* This must be enabled after SME */ + BUILD_BUG_ON(ARM64_SME2 <= ARM64_SME); + + /* Allow use of ZT0 */ + write_sysreg_s(read_sysreg_s(SYS_SMCR_EL1) | SMCR_ELx_EZT0_MASK, SYS_SMCR_EL1); } -/* - * Read the pseudo-SMCR used by cpufeatures to identify the supported - * vector length. - * - * Use only if SME is present. - * This function clobbers the SME vector length. - */ -u64 read_smcr_features(void) +void cpu_enable_fa64(const struct arm64_cpu_capabilities *__always_unused p) { - u64 smcr; - unsigned int vq_max; - - sme_kernel_enable(NULL); - sme_smstart_sm(); + /* This must be enabled after SME */ + BUILD_BUG_ON(ARM64_SME_FA64 <= ARM64_SME); - /* - * Set the maximum possible VL. - */ - write_sysreg_s(read_sysreg_s(SYS_SMCR_EL1) | SMCR_ELx_LEN_MASK, + /* Allow use of FA64 */ + write_sysreg_s(read_sysreg_s(SYS_SMCR_EL1) | SMCR_ELx_FA64_MASK, SYS_SMCR_EL1); - - smcr = read_sysreg_s(SYS_SMCR_EL1); - smcr &= ~(u64)SMCR_ELx_LEN_MASK; /* Only the LEN field */ - vq_max = sve_vq_from_vl(sve_get_vl()); - smcr |= vq_max - 1; /* set LEN field to maximum effective value */ - - sme_smstop_sm(); - - return smcr; } void __init sme_setup(void) { struct vl_info *info = &vl_info[ARM64_VEC_SME]; - u64 smcr; - int min_bit; + int min_bit, max_bit; if (!system_supports_sme()) return; @@ -1307,24 +1269,16 @@ void __init sme_setup(void) * SME doesn't require any particular vector length be * supported but it does require at least one. We should have * disabled the feature entirely while bringing up CPUs but - * let's double check here. + * let's double check here. The bitmap is SVE_VQ_MAP sized for + * sharing with SVE. */ WARN_ON(bitmap_empty(info->vq_map, SVE_VQ_MAX)); min_bit = find_last_bit(info->vq_map, SVE_VQ_MAX); info->min_vl = sve_vl_from_vq(__bit_to_vq(min_bit)); - smcr = read_sanitised_ftr_reg(SYS_SMCR_EL1); - info->max_vl = sve_vl_from_vq((smcr & SMCR_ELx_LEN_MASK) + 1); - - /* - * Sanity-check that the max VL we determined through CPU features - * corresponds properly to sme_vq_map. If not, do our best: - */ - if (WARN_ON(info->max_vl != find_supported_vector_length(ARM64_VEC_SME, - info->max_vl))) - info->max_vl = find_supported_vector_length(ARM64_VEC_SME, - info->max_vl); + max_bit = find_first_bit(info->vq_map, SVE_VQ_MAX); + info->max_vl = sve_vl_from_vq(__bit_to_vq(max_bit)); WARN_ON(info->min_vl > info->max_vl); @@ -1344,6 +1298,22 @@ void __init sme_setup(void) get_sme_default_vl()); } +void sme_suspend_exit(void) +{ + u64 smcr = 0; + + if (!system_supports_sme()) + return; + + if (system_supports_fa64()) + smcr |= SMCR_ELx_FA64; + if (system_supports_sme2()) + smcr |= SMCR_ELx_EZT0; + + write_sysreg_s(smcr, SYS_SMCR_EL1); + write_sysreg_s(0, SYS_SMPRI_EL1); +} + #endif /* CONFIG_ARM64_SME */ static void sve_init_regs(void) @@ -1366,6 +1336,8 @@ static void sve_init_regs(void) fpsimd_bind_task_to_cpu(); } else { fpsimd_to_sve(current); + current->thread.fp_type = FP_STATE_SVE; + fpsimd_flush_task_state(current); } } @@ -1388,7 +1360,7 @@ void do_sve_acc(unsigned long esr, struct pt_regs *regs) return; } - sve_alloc(current); + sve_alloc(current, true); if (!current->thread.sve_state) { force_sig(SIGKILL); return; @@ -1420,7 +1392,7 @@ void do_sve_acc(unsigned long esr, struct pt_regs *regs) * * TIF_SME should be clear on entry: otherwise, fpsimd_restore_current_state() * would have disabled the SME access trap for userspace during - * ret_to_user, making an SVE access trap impossible in that case. + * ret_to_user, making an SME access trap impossible in that case. */ void do_sme_acc(unsigned long esr, struct pt_regs *regs) { @@ -1434,14 +1406,14 @@ void do_sme_acc(unsigned long esr, struct pt_regs *regs) * If this not a trap due to SME being disabled then something * is being used in the wrong mode, report as SIGILL. */ - if (ESR_ELx_ISS(esr) != ESR_ELx_SME_ISS_SME_DISABLED) { + if (ESR_ELx_SME_ISS_SMTC(esr) != ESR_ELx_SME_ISS_SMTC_SME_DISABLED) { force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); return; } - sve_alloc(current); - sme_alloc(current); - if (!current->thread.sve_state || !current->thread.za_state) { + sve_alloc(current, false); + sme_alloc(current, true); + if (!current->thread.sve_state || !current->thread.sme_state) { force_sig(SIGKILL); return; } @@ -1458,19 +1430,10 @@ void do_sme_acc(unsigned long esr, struct pt_regs *regs) sme_set_vq(vq_minus_one); fpsimd_bind_task_to_cpu(); + } else { + fpsimd_flush_task_state(current); } - /* - * If SVE was not already active initialise the SVE registers, - * any non-shared state between the streaming and regular SVE - * registers is architecturally guaranteed to be zeroed when - * we enter streaming mode. We do not need to initialize ZA - * since ZA must be disabled at this point and enabling ZA is - * architecturally defined to zero ZA. - */ - if (system_supports_sve() && !test_thread_flag(TIF_SVE)) - sve_init_regs(); - put_cpu_fpsimd_context(); } @@ -1479,8 +1442,17 @@ void do_sme_acc(unsigned long esr, struct pt_regs *regs) */ void do_fpsimd_acc(unsigned long esr, struct pt_regs *regs) { - /* TODO: implement lazy context saving/restoring */ - WARN_ON(1); + /* Even if we chose not to use FPSIMD, the hardware could still trap: */ + if (!system_supports_fpsimd()) { + force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); + return; + } + + /* + * When FPSIMD is enabled, we should never take a trap unless something + * has gone very wrong. + */ + BUG(); } /* @@ -1508,6 +1480,55 @@ void do_fpsimd_exc(unsigned long esr, struct pt_regs *regs) current); } +static void fpsimd_load_kernel_state(struct task_struct *task) +{ + struct cpu_fp_state *last = this_cpu_ptr(&fpsimd_last_state); + + /* + * Elide the load if this CPU holds the most recent kernel mode + * FPSIMD context of the current task. + */ + if (last->st == &task->thread.kernel_fpsimd_state && + task->thread.kernel_fpsimd_cpu == smp_processor_id()) + return; + + fpsimd_load_state(&task->thread.kernel_fpsimd_state); +} + +static void fpsimd_save_kernel_state(struct task_struct *task) +{ + struct cpu_fp_state cpu_fp_state = { + .st = &task->thread.kernel_fpsimd_state, + .to_save = FP_STATE_FPSIMD, + }; + + fpsimd_save_state(&task->thread.kernel_fpsimd_state); + fpsimd_bind_state_to_cpu(&cpu_fp_state); + + task->thread.kernel_fpsimd_cpu = smp_processor_id(); +} + +/* + * Invalidate any task's FPSIMD state that is present on this cpu. + * The FPSIMD context should be acquired with get_cpu_fpsimd_context() + * before calling this function. + */ +static void fpsimd_flush_cpu_state(void) +{ + WARN_ON(!system_supports_fpsimd()); + __this_cpu_write(fpsimd_last_state.st, NULL); + + /* + * Leaving streaming mode enabled will cause issues for any kernel + * NEON and leaving streaming mode or ZA enabled may increase power + * consumption. + */ + if (system_supports_sme()) + sme_smstop(); + + set_thread_flag(TIF_FOREIGN_FPSTATE); +} + void fpsimd_thread_switch(struct task_struct *next) { bool wrong_task, wrong_cpu; @@ -1515,24 +1536,31 @@ void fpsimd_thread_switch(struct task_struct *next) if (!system_supports_fpsimd()) return; - __get_cpu_fpsimd_context(); + WARN_ON_ONCE(!irqs_disabled()); /* Save unsaved fpsimd state, if any: */ - fpsimd_save(); - - /* - * Fix up TIF_FOREIGN_FPSTATE to correctly describe next's - * state. For kernel threads, FPSIMD registers are never loaded - * and wrong_task and wrong_cpu will always be true. - */ - wrong_task = __this_cpu_read(fpsimd_last_state.st) != - &next->thread.uw.fpsimd_state; - wrong_cpu = next->thread.fpsimd_cpu != smp_processor_id(); + if (test_thread_flag(TIF_KERNEL_FPSTATE)) + fpsimd_save_kernel_state(current); + else + fpsimd_save_user_state(); - update_tsk_thread_flag(next, TIF_FOREIGN_FPSTATE, - wrong_task || wrong_cpu); + if (test_tsk_thread_flag(next, TIF_KERNEL_FPSTATE)) { + fpsimd_flush_cpu_state(); + fpsimd_load_kernel_state(next); + } else { + /* + * Fix up TIF_FOREIGN_FPSTATE to correctly describe next's + * state. For kernel threads, FPSIMD registers are never + * loaded with user mode FPSIMD state and so wrong_task and + * wrong_cpu will always be true. + */ + wrong_task = __this_cpu_read(fpsimd_last_state.st) != + &next->thread.uw.fpsimd_state; + wrong_cpu = next->thread.fpsimd_cpu != smp_processor_id(); - __put_cpu_fpsimd_context(); + update_tsk_thread_flag(next, TIF_FOREIGN_FPSTATE, + wrong_task || wrong_cpu); + } } static void fpsimd_flush_thread_vl(enum vec_type type) @@ -1573,7 +1601,7 @@ static void fpsimd_flush_thread_vl(enum vec_type type) void fpsimd_flush_thread(void) { void *sve_state = NULL; - void *za_state = NULL; + void *sme_state = NULL; if (!system_supports_fpsimd()) return; @@ -1598,16 +1626,21 @@ void fpsimd_flush_thread(void) clear_thread_flag(TIF_SME); /* Defer kfree() while in atomic context */ - za_state = current->thread.za_state; - current->thread.za_state = NULL; + sme_state = current->thread.sme_state; + current->thread.sme_state = NULL; fpsimd_flush_thread_vl(ARM64_VEC_SME); current->thread.svcr = 0; } + if (system_supports_fpmr()) + current->thread.uw.fpmr = 0; + + current->thread.fp_type = FP_STATE_FPSIMD; + put_cpu_fpsimd_context(); kfree(sve_state); - kfree(za_state); + kfree(sme_state); } /* @@ -1620,39 +1653,29 @@ void fpsimd_preserve_current_state(void) return; get_cpu_fpsimd_context(); - fpsimd_save(); + fpsimd_save_user_state(); put_cpu_fpsimd_context(); } /* - * Like fpsimd_preserve_current_state(), but ensure that - * current->thread.uw.fpsimd_state is updated so that it can be copied to - * the signal frame. - */ -void fpsimd_signal_preserve_current_state(void) -{ - fpsimd_preserve_current_state(); - if (test_thread_flag(TIF_SVE)) - sve_to_fpsimd(current); -} - -/* * Associate current's FPSIMD context with this cpu * The caller must have ownership of the cpu FPSIMD context before calling * this function. */ static void fpsimd_bind_task_to_cpu(void) { - struct fpsimd_last_state_struct *last = - this_cpu_ptr(&fpsimd_last_state); + struct cpu_fp_state *last = this_cpu_ptr(&fpsimd_last_state); WARN_ON(!system_supports_fpsimd()); last->st = ¤t->thread.uw.fpsimd_state; last->sve_state = current->thread.sve_state; - last->za_state = current->thread.za_state; + last->sme_state = current->thread.sme_state; last->sve_vl = task_get_sve_vl(current); last->sme_vl = task_get_sme_vl(current); last->svcr = ¤t->thread.svcr; + last->fpmr = ¤t->thread.uw.fpmr; + last->fp_type = ¤t->thread.fp_type; + last->to_save = FP_STATE_CURRENT; current->thread.fpsimd_cpu = smp_processor_id(); /* @@ -1674,22 +1697,14 @@ static void fpsimd_bind_task_to_cpu(void) } } -void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *st, void *sve_state, - unsigned int sve_vl, void *za_state, - unsigned int sme_vl, u64 *svcr) +void fpsimd_bind_state_to_cpu(struct cpu_fp_state *state) { - struct fpsimd_last_state_struct *last = - this_cpu_ptr(&fpsimd_last_state); + struct cpu_fp_state *last = this_cpu_ptr(&fpsimd_last_state); WARN_ON(!system_supports_fpsimd()); WARN_ON(!in_softirq() && !irqs_disabled()); - last->st = st; - last->svcr = svcr; - last->sve_state = sve_state; - last->za_state = za_state; - last->sve_vl = sve_vl; - last->sme_vl = sme_vl; + *last = *state; } /* @@ -1701,13 +1716,23 @@ void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *st, void *sve_state, void fpsimd_restore_current_state(void) { /* - * For the tasks that were created before we detected the absence of - * FP/SIMD, the TIF_FOREIGN_FPSTATE could be set via fpsimd_thread_switch(), - * e.g, init. This could be then inherited by the children processes. - * If we later detect that the system doesn't support FP/SIMD, - * we must clear the flag for all the tasks to indicate that the - * FPSTATE is clean (as we can't have one) to avoid looping for ever in - * do_notify_resume(). + * TIF_FOREIGN_FPSTATE is set on the init task and copied by + * arch_dup_task_struct() regardless of whether FP/SIMD is detected. + * Thus user threads can have this set even when FP/SIMD hasn't been + * detected. + * + * When FP/SIMD is detected, begin_new_exec() will set + * TIF_FOREIGN_FPSTATE via flush_thread() -> fpsimd_flush_thread(), + * and fpsimd_thread_switch() will set TIF_FOREIGN_FPSTATE when + * switching tasks. We detect FP/SIMD before we exec the first user + * process, ensuring this has TIF_FOREIGN_FPSTATE set and + * do_notify_resume() will call fpsimd_restore_current_state() to + * install the user FP/SIMD context. + * + * When FP/SIMD is not detected, nothing else will clear or set + * TIF_FOREIGN_FPSTATE prior to the first return to userspace, and + * we must clear TIF_FOREIGN_FPSTATE to avoid do_notify_resume() + * looping forever calling fpsimd_restore_current_state(). */ if (!system_supports_fpsimd()) { clear_thread_flag(TIF_FOREIGN_FPSTATE); @@ -1724,30 +1749,14 @@ void fpsimd_restore_current_state(void) put_cpu_fpsimd_context(); } -/* - * Load an updated userland FPSIMD state for 'current' from memory and set the - * flag that indicates that the FPSIMD register contents are the most recent - * FPSIMD state of 'current'. This is used by the signal code to restore the - * register state when returning from a signal handler in FPSIMD only cases, - * any SVE context will be discarded. - */ void fpsimd_update_current_state(struct user_fpsimd_state const *state) { if (WARN_ON(!system_supports_fpsimd())) return; - get_cpu_fpsimd_context(); - current->thread.uw.fpsimd_state = *state; - if (test_thread_flag(TIF_SVE)) + if (current->thread.fp_type == FP_STATE_SVE) fpsimd_to_sve(current); - - task_fpsimd_load(); - fpsimd_bind_task_to_cpu(); - - clear_thread_flag(TIF_FOREIGN_FPSTATE); - - put_cpu_fpsimd_context(); } /* @@ -1777,25 +1786,15 @@ void fpsimd_flush_task_state(struct task_struct *t) barrier(); } -/* - * Invalidate any task's FPSIMD state that is present on this cpu. - * The FPSIMD context should be acquired with get_cpu_fpsimd_context() - * before calling this function. - */ -static void fpsimd_flush_cpu_state(void) +void fpsimd_save_and_flush_current_state(void) { - WARN_ON(!system_supports_fpsimd()); - __this_cpu_write(fpsimd_last_state.st, NULL); - - /* - * Leaving streaming mode enabled will cause issues for any kernel - * NEON and leaving streaming mode or ZA enabled may increase power - * consumption. - */ - if (system_supports_sme()) - sme_smstop(); + if (!system_supports_fpsimd()) + return; - set_thread_flag(TIF_FOREIGN_FPSTATE); + get_cpu_fpsimd_context(); + fpsimd_save_user_state(); + fpsimd_flush_task_state(current); + put_cpu_fpsimd_context(); } /* @@ -1804,13 +1803,15 @@ static void fpsimd_flush_cpu_state(void) */ void fpsimd_save_and_flush_cpu_state(void) { + unsigned long flags; + if (!system_supports_fpsimd()) return; WARN_ON(preemptible()); - __get_cpu_fpsimd_context(); - fpsimd_save(); + local_irq_save(flags); + fpsimd_save_user_state(); fpsimd_flush_cpu_state(); - __put_cpu_fpsimd_context(); + local_irq_restore(flags); } #ifdef CONFIG_KERNEL_MODE_NEON @@ -1842,12 +1843,39 @@ void kernel_neon_begin(void) get_cpu_fpsimd_context(); /* Save unsaved fpsimd state, if any: */ - fpsimd_save(); + if (test_thread_flag(TIF_KERNEL_FPSTATE)) { + BUG_ON(IS_ENABLED(CONFIG_PREEMPT_RT) || !in_serving_softirq()); + fpsimd_save_kernel_state(current); + } else { + fpsimd_save_user_state(); + + /* + * Set the thread flag so that the kernel mode FPSIMD state + * will be context switched along with the rest of the task + * state. + * + * On non-PREEMPT_RT, softirqs may interrupt task level kernel + * mode FPSIMD, but the task will not be preemptible so setting + * TIF_KERNEL_FPSTATE for those would be both wrong (as it + * would mark the task context FPSIMD state as requiring a + * context switch) and unnecessary. + * + * On PREEMPT_RT, softirqs are serviced from a separate thread, + * which is scheduled as usual, and this guarantees that these + * softirqs are not interrupting use of the FPSIMD in kernel + * mode in task context. So in this case, setting the flag here + * is always appropriate. + */ + if (IS_ENABLED(CONFIG_PREEMPT_RT) || !in_serving_softirq()) + set_thread_flag(TIF_KERNEL_FPSTATE); + } /* Invalidate any task state remaining in the fpsimd regs: */ fpsimd_flush_cpu_state(); + + put_cpu_fpsimd_context(); } -EXPORT_SYMBOL(kernel_neon_begin); +EXPORT_SYMBOL_GPL(kernel_neon_begin); /* * kernel_neon_end(): give the CPU FPSIMD registers back to the current task @@ -1863,16 +1891,25 @@ void kernel_neon_end(void) if (!system_supports_fpsimd()) return; - put_cpu_fpsimd_context(); + /* + * If we are returning from a nested use of kernel mode FPSIMD, restore + * the task context kernel mode FPSIMD state. This can only happen when + * running in softirq context on non-PREEMPT_RT. + */ + if (!IS_ENABLED(CONFIG_PREEMPT_RT) && in_serving_softirq() && + test_thread_flag(TIF_KERNEL_FPSTATE)) + fpsimd_load_kernel_state(current); + else + clear_thread_flag(TIF_KERNEL_FPSTATE); } -EXPORT_SYMBOL(kernel_neon_end); +EXPORT_SYMBOL_GPL(kernel_neon_end); #ifdef CONFIG_EFI -static DEFINE_PER_CPU(struct user_fpsimd_state, efi_fpsimd_state); -static DEFINE_PER_CPU(bool, efi_fpsimd_state_used); -static DEFINE_PER_CPU(bool, efi_sve_state_used); -static DEFINE_PER_CPU(bool, efi_sm_state); +static struct user_fpsimd_state efi_fpsimd_state; +static bool efi_fpsimd_state_used; +static bool efi_sve_state_used; +static bool efi_sm_state; /* * EFI runtime services support functions @@ -1905,18 +1942,16 @@ void __efi_fpsimd_begin(void) * If !efi_sve_state, SVE can't be in use yet and doesn't need * preserving: */ - if (system_supports_sve() && likely(efi_sve_state)) { - char *sve_state = this_cpu_ptr(efi_sve_state); + if (system_supports_sve() && efi_sve_state != NULL) { bool ffr = true; u64 svcr; - __this_cpu_write(efi_sve_state_used, true); + efi_sve_state_used = true; if (system_supports_sme()) { svcr = read_sysreg_s(SYS_SVCR); - __this_cpu_write(efi_sm_state, - svcr & SVCR_SM_MASK); + efi_sm_state = svcr & SVCR_SM_MASK; /* * Unless we have FA64 FFR does not @@ -1926,19 +1961,18 @@ void __efi_fpsimd_begin(void) ffr = !(svcr & SVCR_SM_MASK); } - sve_save_state(sve_state + sve_ffr_offset(sve_max_vl()), - &this_cpu_ptr(&efi_fpsimd_state)->fpsr, - ffr); + sve_save_state(efi_sve_state + sve_ffr_offset(sve_max_vl()), + &efi_fpsimd_state.fpsr, ffr); if (system_supports_sme()) sysreg_clear_set_s(SYS_SVCR, SVCR_SM_MASK, 0); } else { - fpsimd_save_state(this_cpu_ptr(&efi_fpsimd_state)); + fpsimd_save_state(&efi_fpsimd_state); } - __this_cpu_write(efi_fpsimd_state_used, true); + efi_fpsimd_state_used = true; } } @@ -1950,12 +1984,10 @@ void __efi_fpsimd_end(void) if (!system_supports_fpsimd()) return; - if (!__this_cpu_xchg(efi_fpsimd_state_used, false)) { + if (!efi_fpsimd_state_used) { kernel_neon_end(); } else { - if (system_supports_sve() && - likely(__this_cpu_read(efi_sve_state_used))) { - char const *sve_state = this_cpu_ptr(efi_sve_state); + if (system_supports_sve() && efi_sve_state_used) { bool ffr = true; /* @@ -1964,7 +1996,7 @@ void __efi_fpsimd_end(void) * streaming mode. */ if (system_supports_sme()) { - if (__this_cpu_read(efi_sm_state)) { + if (efi_sm_state) { sysreg_clear_set_s(SYS_SVCR, 0, SVCR_SM_MASK); @@ -1978,14 +2010,15 @@ void __efi_fpsimd_end(void) } } - sve_load_state(sve_state + sve_ffr_offset(sve_max_vl()), - &this_cpu_ptr(&efi_fpsimd_state)->fpsr, - ffr); + sve_load_state(efi_sve_state + sve_ffr_offset(sve_max_vl()), + &efi_fpsimd_state.fpsr, ffr); - __this_cpu_write(efi_sve_state_used, false); + efi_sve_state_used = false; } else { - fpsimd_load_state(this_cpu_ptr(&efi_fpsimd_state)); + fpsimd_load_state(&efi_fpsimd_state); } + + efi_fpsimd_state_used = false; } } @@ -2040,6 +2073,13 @@ static inline void fpsimd_hotplug_init(void) static inline void fpsimd_hotplug_init(void) { } #endif +void cpu_enable_fpsimd(const struct arm64_cpu_capabilities *__always_unused p) +{ + unsigned long enable = CPACR_EL1_FPEN_EL1EN | CPACR_EL1_FPEN_EL0EN; + write_sysreg(read_sysreg(CPACR_EL1) | enable, CPACR_EL1); + isb(); +} + /* * FP/SIMD support code initialisation. */ @@ -2056,9 +2096,6 @@ static int __init fpsimd_init(void) pr_notice("Advanced SIMD is not implemented\n"); - if (cpu_have_named_feature(SME) && !cpu_have_named_feature(SVE)) - pr_notice("SME is implemented but not SVE\n"); - sve_sysctl_init(); sme_sysctl_init(); |