linux/arch/arm64/kernel/fpsimd.c
Linus Torvalds 426ee5196d sysctl-6.7-rc1
To help make the move of sysctls out of kernel/sysctl.c not incur a size
 penalty sysctl has been changed to allow us to not require the sentinel, the
 final empty element on the sysctl array. Joel Granados has been doing all this
 work. On the v6.6 kernel we got the major infrastructure changes required to
 support this. For v6.7-rc1 we have all arch/ and drivers/ modified to remove
 the sentinel. Both arch and driver changes have been on linux-next for a bit
 less than a month. It is worth re-iterating the value:
 
   - this helps reduce the overall build time size of the kernel and run time
      memory consumed by the kernel by about ~64 bytes per array
   - the extra 64-byte penalty is no longer inncurred now when we move sysctls
     out from kernel/sysctl.c to their own files
 
 For v6.8-rc1 expect removal of all the sentinels and also then the unneeded
 check for procname == NULL.
 
 The last 2 patches are fixes recently merged by Krister Johansen which allow
 us again to use softlockup_panic early on boot. This used to work but the
 alias work broke it. This is useful for folks who want to detect softlockups
 super early rather than wait and spend money on cloud solutions with nothing
 but an eventual hung kernel. Although this hadn't gone through linux-next it's
 also a stable fix, so we might as well roll through the fixes now.
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Merge tag 'sysctl-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

Pull sysctl updates from Luis Chamberlain:
 "To help make the move of sysctls out of kernel/sysctl.c not incur a
  size penalty sysctl has been changed to allow us to not require the
  sentinel, the final empty element on the sysctl array. Joel Granados
  has been doing all this work. On the v6.6 kernel we got the major
  infrastructure changes required to support this. For v6.7-rc1 we have
  all arch/ and drivers/ modified to remove the sentinel. Both arch and
  driver changes have been on linux-next for a bit less than a month. It
  is worth re-iterating the value:

   - this helps reduce the overall build time size of the kernel and run
     time memory consumed by the kernel by about ~64 bytes per array

   - the extra 64-byte penalty is no longer inncurred now when we move
     sysctls out from kernel/sysctl.c to their own files

  For v6.8-rc1 expect removal of all the sentinels and also then the
  unneeded check for procname == NULL.

  The last two patches are fixes recently merged by Krister Johansen
  which allow us again to use softlockup_panic early on boot. This used
  to work but the alias work broke it. This is useful for folks who want
  to detect softlockups super early rather than wait and spend money on
  cloud solutions with nothing but an eventual hung kernel. Although
  this hadn't gone through linux-next it's also a stable fix, so we
  might as well roll through the fixes now"

* tag 'sysctl-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux: (23 commits)
  watchdog: move softlockup_panic back to early_param
  proc: sysctl: prevent aliased sysctls from getting passed to init
  intel drm: Remove now superfluous sentinel element from ctl_table array
  Drivers: hv: Remove now superfluous sentinel element from ctl_table array
  raid: Remove now superfluous sentinel element from ctl_table array
  fw loader: Remove the now superfluous sentinel element from ctl_table array
  sgi-xp: Remove the now superfluous sentinel element from ctl_table array
  vrf: Remove the now superfluous sentinel element from ctl_table array
  char-misc: Remove the now superfluous sentinel element from ctl_table array
  infiniband: Remove the now superfluous sentinel element from ctl_table array
  macintosh: Remove the now superfluous sentinel element from ctl_table array
  parport: Remove the now superfluous sentinel element from ctl_table array
  scsi: Remove now superfluous sentinel element from ctl_table array
  tty: Remove now superfluous sentinel element from ctl_table array
  xen: Remove now superfluous sentinel element from ctl_table array
  hpet: Remove now superfluous sentinel element from ctl_table array
  c-sky: Remove now superfluous sentinel element from ctl_talbe array
  powerpc: Remove now superfluous sentinel element from ctl_table arrays
  riscv: Remove now superfluous sentinel element from ctl_table array
  x86/vdso: Remove now superfluous sentinel element from ctl_table array
  ...
2023-11-01 20:51:41 -10:00

2094 lines
56 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* FP/SIMD context switching and fault handling
*
* Copyright (C) 2012 ARM Ltd.
* Author: Catalin Marinas <catalin.marinas@arm.com>
*/
#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/bottom_half.h>
#include <linux/bug.h>
#include <linux/cache.h>
#include <linux/compat.h>
#include <linux/compiler.h>
#include <linux/cpu.h>
#include <linux/cpu_pm.h>
#include <linux/ctype.h>
#include <linux/kernel.h>
#include <linux/linkage.h>
#include <linux/irqflags.h>
#include <linux/init.h>
#include <linux/percpu.h>
#include <linux/prctl.h>
#include <linux/preempt.h>
#include <linux/ptrace.h>
#include <linux/sched/signal.h>
#include <linux/sched/task_stack.h>
#include <linux/signal.h>
#include <linux/slab.h>
#include <linux/stddef.h>
#include <linux/sysctl.h>
#include <linux/swab.h>
#include <asm/esr.h>
#include <asm/exception.h>
#include <asm/fpsimd.h>
#include <asm/cpufeature.h>
#include <asm/cputype.h>
#include <asm/neon.h>
#include <asm/processor.h>
#include <asm/simd.h>
#include <asm/sigcontext.h>
#include <asm/sysreg.h>
#include <asm/traps.h>
#include <asm/virt.h>
#define FPEXC_IOF (1 << 0)
#define FPEXC_DZF (1 << 1)
#define FPEXC_OFF (1 << 2)
#define FPEXC_UFF (1 << 3)
#define FPEXC_IXF (1 << 4)
#define FPEXC_IDF (1 << 7)
/*
* (Note: in this discussion, statements about FPSIMD apply equally to SVE.)
*
* In order to reduce the number of times the FPSIMD state is needlessly saved
* and restored, we need to keep track of two things:
* (a) for each task, we need to remember which CPU was the last one to have
* the task's FPSIMD state loaded into its FPSIMD registers;
* (b) for each CPU, we need to remember which task's userland FPSIMD state has
* been loaded into its FPSIMD registers most recently, or whether it has
* been used to perform kernel mode NEON in the meantime.
*
* For (a), we add a fpsimd_cpu field to thread_struct, which gets updated to
* the id of the current CPU every time the state is loaded onto a CPU. For (b),
* we add the per-cpu variable 'fpsimd_last_state' (below), which contains the
* address of the userland FPSIMD state of the task that was loaded onto the CPU
* the most recently, or NULL if kernel mode NEON has been performed after that.
*
* With this in place, we no longer have to restore the next FPSIMD state right
* when switching between tasks. Instead, we can defer this check to userland
* resume, at which time we verify whether the CPU's fpsimd_last_state and the
* task's fpsimd_cpu are still mutually in sync. If this is the case, we
* can omit the FPSIMD restore.
*
* As an optimization, we use the thread_info flag TIF_FOREIGN_FPSTATE to
* indicate whether or not the userland FPSIMD state of the current task is
* present in the registers. The flag is set unless the FPSIMD registers of this
* CPU currently contain the most recent userland FPSIMD state of the current
* task. If the task is behaving as a VMM, then this is will be managed by
* KVM which will clear it to indicate that the vcpu FPSIMD state is currently
* loaded on the CPU, allowing the state to be saved if a FPSIMD-aware
* 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.
*
* For a certain task, the sequence may look something like this:
* - the task gets scheduled in; if both the task's fpsimd_cpu field
* contains the id of the current CPU, and the CPU's fpsimd_last_state per-cpu
* variable points to the task's fpsimd_state, the TIF_FOREIGN_FPSTATE flag is
* cleared, otherwise it is set;
*
* - the task returns to userland; if TIF_FOREIGN_FPSTATE is set, the task's
* userland FPSIMD state is copied from memory to the registers, the task's
* fpsimd_cpu field is set to the id of the current CPU, the current
* CPU's fpsimd_last_state pointer is set to this task's fpsimd_state and the
* TIF_FOREIGN_FPSTATE flag is cleared;
*
* - the task executes an ordinary syscall; upon return to userland, the
* TIF_FOREIGN_FPSTATE flag will still be cleared, so no FPSIMD state is
* restored;
*
* - the task executes a syscall which executes some NEON instructions; this is
* preceded by a call to kernel_neon_begin(), which copies the task's FPSIMD
* register contents to memory, clears the fpsimd_last_state per-cpu variable
* and sets the TIF_FOREIGN_FPSTATE flag;
*
* - the task gets preempted after kernel_neon_end() is called; as we have not
* 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.
*/
static 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
[ARM64_VEC_SVE] = {
.type = ARM64_VEC_SVE,
.name = "SVE",
.min_vl = SVE_VL_MIN,
.max_vl = SVE_VL_MIN,
.max_virtualisable_vl = SVE_VL_MIN,
},
#endif
#ifdef CONFIG_ARM64_SME
[ARM64_VEC_SME] = {
.type = ARM64_VEC_SME,
.name = "SME",
},
#endif
};
static unsigned int vec_vl_inherit_flag(enum vec_type type)
{
switch (type) {
case ARM64_VEC_SVE:
return TIF_SVE_VL_INHERIT;
case ARM64_VEC_SME:
return TIF_SME_VL_INHERIT;
default:
WARN_ON_ONCE(1);
return 0;
}
}
struct vl_config {
int __default_vl; /* Default VL for tasks */
};
static struct vl_config vl_config[ARM64_VEC_MAX];
static inline int get_default_vl(enum vec_type type)
{
return READ_ONCE(vl_config[type].__default_vl);
}
#ifdef CONFIG_ARM64_SVE
static inline int get_sve_default_vl(void)
{
return get_default_vl(ARM64_VEC_SVE);
}
static inline void set_default_vl(enum vec_type type, int val)
{
WRITE_ONCE(vl_config[type].__default_vl, val);
}
static inline void set_sve_default_vl(int val)
{
set_default_vl(ARM64_VEC_SVE, val);
}
static void __percpu *efi_sve_state;
#else /* ! CONFIG_ARM64_SVE */
/* Dummy declaration for code that will be optimised out: */
extern void __percpu *efi_sve_state;
#endif /* ! CONFIG_ARM64_SVE */
#ifdef CONFIG_ARM64_SME
static int get_sme_default_vl(void)
{
return get_default_vl(ARM64_VEC_SME);
}
static void set_sme_default_vl(int val)
{
set_default_vl(ARM64_VEC_SME, val);
}
static void sme_free(struct task_struct *);
#else
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
* half processing is always in thread context on RT kernels so it
* implicitly prevents bottom half processing as well.
*/
static void get_cpu_fpsimd_context(void)
{
if (!IS_ENABLED(CONFIG_PREEMPT_RT))
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()? */
}
/*
* Release the CPU FPSIMD context.
*
* Must be called from a context in which get_cpu_fpsimd_context() was
* previously called, with no call to put_cpu_fpsimd_context() in the
* meantime.
*/
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];
}
void task_set_vl(struct task_struct *task, enum vec_type type,
unsigned long vl)
{
task->thread.vl[type] = vl;
}
unsigned int task_get_vl_onexec(const struct task_struct *task,
enum vec_type type)
{
return task->thread.vl_onexec[type];
}
void task_set_vl_onexec(struct task_struct *task, enum vec_type type,
unsigned long vl)
{
task->thread.vl_onexec[type] = vl;
}
/*
* TIF_SME controls whether a task can use SME without trapping while
* in userspace, when TIF_SME is set then we must have storage
* 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
* may disable TIF_SME and reenable traps.
*/
/*
* TIF_SVE controls whether a task can use SVE without trapping while
* in userspace, and also (together with TIF_SME) the way a task's
* FPSIMD/SVE state is stored in thread_struct.
*
* The kernel uses this flag to track whether a user task is actively
* using SVE, and therefore whether full SVE register state needs to
* be tracked. If not, the cheaper FPSIMD context handling code can
* be used instead of the more costly SVE equivalents.
*
* * TIF_SVE or SVCR.SM set:
*
* The task can execute SVE instructions while in userspace without
* trapping to the kernel.
*
* During any syscall, the kernel may optionally clear TIF_SVE and
* discard the vector state except for the FPSIMD subset.
*
* * TIF_SVE clear:
*
* An attempt by the user task to execute an SVE instruction causes
* do_sve_acc() to be called, which does some preparation and then
* sets TIF_SVE.
*
* 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
* view. For hygiene purposes, the kernel zeroes them on next use,
* 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 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
* not vector length dependent.
*/
/*
* Update current's FPSIMD/SVE registers from thread_struct.
*
* This function should be called only when the FPSIMD/SVE state in
* thread_struct is known to be up to date, when preparing to enter
* userspace.
*/
static void task_fpsimd_load(void)
{
bool restore_sve_regs = false;
bool restore_ffr;
WARN_ON(!system_supports_fpsimd());
WARN_ON(!have_cpu_fpsimd_context());
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. */
if (test_and_clear_thread_flag(TIF_SVE))
sve_user_disable();
break;
case FP_STATE_SVE:
if (!thread_sm_enabled(&current->thread) &&
!WARN_ON_ONCE(!test_and_set_thread_flag(TIF_SVE)))
sve_user_enable();
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() or memory corruption, we
* should always record an explicit format
* when we save. We always at least have the
* memory allocated for FPSMID 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 */
if (system_supports_sme()) {
unsigned long sme_vl = task_get_sme_vl(current);
/* Ensure VL is set up for restoring data */
if (test_thread_flag(TIF_SME))
sme_set_vq(sve_vq_from_vl(sme_vl) - 1);
write_sysreg_s(current->thread.svcr, SYS_SVCR);
if (thread_za_enabled(&current->thread))
sme_load_state(current->thread.sme_state,
system_supports_sme2());
if (thread_sm_enabled(&current->thread))
restore_ffr = system_supports_fa64();
}
if (restore_sve_regs) {
WARN_ON_ONCE(current->thread.fp_type != FP_STATE_SVE);
sve_load_state(sve_pffr(&current->thread),
&current->thread.uw.fpsimd_state.fpsr,
restore_ffr);
} else {
WARN_ON_ONCE(current->thread.fp_type != FP_STATE_FPSIMD);
fpsimd_load_state(&current->thread.uw.fpsimd_state);
}
}
/*
* Ensure FPSIMD/SVE storage in memory for the loaded context is up to
* date with respect to the CPU registers. Note carefully that the
* current context is the context last bound to the CPU stored in
* 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, 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)
{
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;
bool save_ffr;
unsigned int vl;
WARN_ON(!system_supports_fpsimd());
WARN_ON(!have_cpu_fpsimd_context());
if (test_thread_flag(TIF_FOREIGN_FPSTATE))
return;
/*
* If a task is in a syscall the ABI allows us to only
* preserve the state shared with FPSIMD so don't bother
* saving the full SVE state in that case.
*/
if ((last->to_save == FP_STATE_CURRENT && test_thread_flag(TIF_SVE) &&
!in_syscall(current_pt_regs())) ||
last->to_save == FP_STATE_SVE) {
save_sve_regs = true;
save_ffr = true;
vl = last->sve_vl;
}
if (system_supports_sme()) {
u64 *svcr = last->svcr;
*svcr = read_sysreg_s(SYS_SVCR);
if (*svcr & SVCR_ZA_MASK)
sme_save_state(last->sme_state,
system_supports_sme2());
/* If we are in streaming mode override regular SVE. */
if (*svcr & SVCR_SM_MASK) {
save_sve_regs = true;
save_ffr = system_supports_fa64();
vl = last->sme_vl;
}
}
if (IS_ENABLED(CONFIG_ARM64_SVE) && save_sve_regs) {
/* Get the configured VL from RDVL, will account for SM */
if (WARN_ON(sve_get_vl() != vl)) {
/*
* Can't save the user regs, so current would
* re-enter user with corrupt state.
* There's no way to recover, so kill it:
*/
force_signal_inject(SIGKILL, SI_KERNEL, 0, 0);
return;
}
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;
}
}
/*
* All vector length selection from userspace comes through here.
* We're on a slow path, so some sanity-checks are included.
* If things go wrong there's a bug somewhere, but try to fall back to a
* safe choice.
*/
static unsigned int find_supported_vector_length(enum vec_type type,
unsigned int vl)
{
struct vl_info *info = &vl_info[type];
int bit;
int max_vl = info->max_vl;
if (WARN_ON(!sve_vl_valid(vl)))
vl = info->min_vl;
if (WARN_ON(!sve_vl_valid(max_vl)))
max_vl = info->min_vl;
if (vl > max_vl)
vl = max_vl;
if (vl < info->min_vl)
vl = info->min_vl;
bit = find_next_bit(info->vq_map, SVE_VQ_MAX,
__vq_to_bit(sve_vq_from_vl(vl)));
return sve_vl_from_vq(__bit_to_vq(bit));
}
#if defined(CONFIG_ARM64_SVE) && defined(CONFIG_SYSCTL)
static int vec_proc_do_default_vl(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
struct vl_info *info = table->extra1;
enum vec_type type = info->type;
int ret;
int vl = get_default_vl(type);
struct ctl_table tmp_table = {
.data = &vl,
.maxlen = sizeof(vl),
};
ret = proc_dointvec(&tmp_table, write, buffer, lenp, ppos);
if (ret || !write)
return ret;
/* Writing -1 has the special meaning "set to max": */
if (vl == -1)
vl = info->max_vl;
if (!sve_vl_valid(vl))
return -EINVAL;
set_default_vl(type, find_supported_vector_length(type, vl));
return 0;
}
static 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)
{
if (system_supports_sve())
if (!register_sysctl("abi", sve_default_vl_table))
return -EINVAL;
return 0;
}
#else /* ! (CONFIG_ARM64_SVE && CONFIG_SYSCTL) */
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[] = {
{
.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)
{
if (system_supports_sme())
if (!register_sysctl("abi", sme_default_vl_table))
return -EINVAL;
return 0;
}
#else /* ! (CONFIG_ARM64_SME && CONFIG_SYSCTL) */
static int __init sme_sysctl_init(void) { return 0; }
#endif /* ! (CONFIG_ARM64_SME && CONFIG_SYSCTL) */
#define ZREG(sve_state, vq, n) ((char *)(sve_state) + \
(SVE_SIG_ZREG_OFFSET(vq, n) - SVE_SIG_REGS_OFFSET))
#ifdef CONFIG_CPU_BIG_ENDIAN
static __uint128_t arm64_cpu_to_le128(__uint128_t x)
{
u64 a = swab64(x);
u64 b = swab64(x >> 64);
return ((__uint128_t)a << 64) | b;
}
#else
static __uint128_t arm64_cpu_to_le128(__uint128_t x)
{
return x;
}
#endif
#define arm64_le128_to_cpu(x) arm64_cpu_to_le128(x)
static void __fpsimd_to_sve(void *sst, struct user_fpsimd_state const *fst,
unsigned int vq)
{
unsigned int i;
__uint128_t *p;
for (i = 0; i < SVE_NUM_ZREGS; ++i) {
p = (__uint128_t *)ZREG(sst, vq, i);
*p = arm64_cpu_to_le128(fst->vregs[i]);
}
}
/*
* Transfer the FPSIMD state in task->thread.uw.fpsimd_state to
* task->thread.sve_state.
*
* Task can be a non-runnable task, or current. In the latter case,
* the caller must have ownership of the cpu FPSIMD context before calling
* this function.
* task->thread.sve_state must point to at least sve_state_size(task)
* bytes of allocated kernel memory.
* task->thread.uw.fpsimd_state must be up to date before calling this
* function.
*/
static 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() && !system_supports_sme())
return;
vq = sve_vq_from_vl(thread_get_cur_vl(&task->thread));
__fpsimd_to_sve(sst, fst, vq);
}
/*
* Transfer the SVE state in task->thread.sve_state to
* task->thread.uw.fpsimd_state.
*
* Task can be a non-runnable task, or current. In the latter case,
* the caller must have ownership of the cpu FPSIMD context before calling
* this function.
* task->thread.sve_state must point to at least sve_state_size(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)
{
unsigned int vq, vl;
void const *sst = task->thread.sve_state;
struct user_fpsimd_state *fst = &task->thread.uw.fpsimd_state;
unsigned int i;
__uint128_t const *p;
if (!system_supports_sve() && !system_supports_sme())
return;
vl = thread_get_cur_vl(&task->thread);
vq = sve_vq_from_vl(vl);
for (i = 0; i < SVE_NUM_ZREGS; ++i) {
p = (__uint128_t const *)ZREG(sst, vq, i);
fst->vregs[i] = arm64_le128_to_cpu(*p);
}
}
#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)
{
kfree(task->thread.sve_state);
task->thread.sve_state = NULL;
}
static void sve_free(struct task_struct *task)
{
WARN_ON(test_tsk_thread_flag(task, TIF_SVE));
__sve_free(task);
}
/*
* 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)
{
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));
return SVE_SIG_REGS_SIZE(sve_vq_from_vl(vl));
}
/*
* Ensure that task->thread.sve_state is allocated and sufficiently large.
*
* This function should be used only in preparation for replacing
* task->thread.sve_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: except in the
* do_sve_acc() case, there is no ABI requirement to hide stale data
* written previously be task.
*/
void sve_alloc(struct task_struct *task, bool flush)
{
if (task->thread.sve_state) {
if (flush)
memset(task->thread.sve_state, 0,
sve_state_size(task));
return;
}
/* This is a small allocation (maximum ~8KB) and Should Not Fail. */
task->thread.sve_state =
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.
*
* 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.
*/
void fpsimd_sync_to_sve(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 (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.
*
* 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.
*/
void sve_sync_from_fpsimd_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) &&
!thread_sm_enabled(&task->thread))
return;
vq = sve_vq_from_vl(thread_get_cur_vl(&task->thread));
memset(sst, 0, SVE_SIG_REGS_SIZE(vq));
__fpsimd_to_sve(sst, fst, vq);
}
int vec_set_vector_length(struct task_struct *task, enum vec_type type,
unsigned long vl, unsigned long flags)
{
bool free_sme = false;
if (flags & ~(unsigned long)(PR_SVE_VL_INHERIT |
PR_SVE_SET_VL_ONEXEC))
return -EINVAL;
if (!sve_vl_valid(vl))
return -EINVAL;
/*
* Clamp to the maximum vector length that VL-agnostic code
* can work with. A flag may be assigned in the future to
* allow setting of larger vector lengths without confusing
* older software.
*/
if (vl > VL_ARCH_MAX)
vl = VL_ARCH_MAX;
vl = find_supported_vector_length(type, vl);
if (flags & (PR_SVE_VL_INHERIT |
PR_SVE_SET_VL_ONEXEC))
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);
task->thread.fp_type = FP_STATE_FPSIMD;
}
if (system_supports_sme()) {
if (type == ARM64_VEC_SME ||
!(task->thread.svcr & (SVCR_SM_MASK | SVCR_ZA_MASK))) {
/*
* We are changing the SME VL or weren't using
* SME anyway, discard the state and force a
* reallocation.
*/
task->thread.svcr &= ~(SVCR_SM_MASK |
SVCR_ZA_MASK);
clear_tsk_thread_flag(task, TIF_SME);
free_sme = true;
}
}
if (task == current)
put_cpu_fpsimd_context();
task_set_vl(task, type, vl);
/*
* Free the changed states if they are not in use, SME will be
* reallocated to the correct size on next use and we just
* allocate SVE now in case it is needed for use in streaming
* mode.
*/
if (system_supports_sve()) {
sve_free(task);
sve_alloc(task, true);
}
if (free_sme)
sme_free(task);
out:
update_tsk_thread_flag(task, vec_vl_inherit_flag(type),
flags & PR_SVE_VL_INHERIT);
return 0;
}
/*
* Encode the current vector length and flags for return.
* This is only required for prctl(): ptrace has separate fields.
* SVE and SME use the same bits for _ONEXEC and _INHERIT.
*
* flags are as for vec_set_vector_length().
*/
static int vec_prctl_status(enum vec_type type, unsigned long flags)
{
int ret;
if (flags & PR_SVE_SET_VL_ONEXEC)
ret = task_get_vl_onexec(current, type);
else
ret = task_get_vl(current, type);
if (test_thread_flag(vec_vl_inherit_flag(type)))
ret |= PR_SVE_VL_INHERIT;
return ret;
}
/* PR_SVE_SET_VL */
int sve_set_current_vl(unsigned long arg)
{
unsigned long vl, flags;
int ret;
vl = arg & PR_SVE_VL_LEN_MASK;
flags = arg & ~vl;
if (!system_supports_sve() || is_compat_task())
return -EINVAL;
ret = vec_set_vector_length(current, ARM64_VEC_SVE, vl, flags);
if (ret)
return ret;
return vec_prctl_status(ARM64_VEC_SVE, flags);
}
/* PR_SVE_GET_VL */
int sve_get_current_vl(void)
{
if (!system_supports_sve() || is_compat_task())
return -EINVAL;
return vec_prctl_status(ARM64_VEC_SVE, 0);
}
#ifdef CONFIG_ARM64_SME
/* PR_SME_SET_VL */
int sme_set_current_vl(unsigned long arg)
{
unsigned long vl, flags;
int ret;
vl = arg & PR_SME_VL_LEN_MASK;
flags = arg & ~vl;
if (!system_supports_sme() || is_compat_task())
return -EINVAL;
ret = vec_set_vector_length(current, ARM64_VEC_SME, vl, flags);
if (ret)
return ret;
return vec_prctl_status(ARM64_VEC_SME, flags);
}
/* PR_SME_GET_VL */
int sme_get_current_vl(void)
{
if (!system_supports_sme() || is_compat_task())
return -EINVAL;
return vec_prctl_status(ARM64_VEC_SME, 0);
}
#endif /* CONFIG_ARM64_SME */
static void vec_probe_vqs(struct vl_info *info,
DECLARE_BITMAP(map, SVE_VQ_MAX))
{
unsigned int vq, vl;
bitmap_zero(map, SVE_VQ_MAX);
for (vq = SVE_VQ_MAX; vq >= SVE_VQ_MIN; --vq) {
write_vl(info->type, vq - 1); /* self-syncing */
switch (info->type) {
case ARM64_VEC_SVE:
vl = sve_get_vl();
break;
case ARM64_VEC_SME:
vl = sme_get_vl();
break;
default:
vl = 0;
break;
}
/* Minimum VL identified? */
if (sve_vq_from_vl(vl) > vq)
break;
vq = sve_vq_from_vl(vl); /* skip intervening lengths */
set_bit(__vq_to_bit(vq), map);
}
}
/*
* Initialise the set of known supported VQs for the boot CPU.
* This is called during kernel boot, before secondary CPUs are brought up.
*/
void __init vec_init_vq_map(enum vec_type type)
{
struct vl_info *info = &vl_info[type];
vec_probe_vqs(info, info->vq_map);
bitmap_copy(info->vq_partial_map, info->vq_map, SVE_VQ_MAX);
}
/*
* If we haven't committed to the set of supported VQs yet, filter out
* those not supported by the current CPU.
* This function is called during the bring-up of early secondary CPUs only.
*/
void vec_update_vq_map(enum vec_type type)
{
struct vl_info *info = &vl_info[type];
DECLARE_BITMAP(tmp_map, SVE_VQ_MAX);
vec_probe_vqs(info, tmp_map);
bitmap_and(info->vq_map, info->vq_map, tmp_map, SVE_VQ_MAX);
bitmap_or(info->vq_partial_map, info->vq_partial_map, tmp_map,
SVE_VQ_MAX);
}
/*
* Check whether the current CPU supports all VQs in the committed set.
* This function is called during the bring-up of late secondary CPUs only.
*/
int vec_verify_vq_map(enum vec_type type)
{
struct vl_info *info = &vl_info[type];
DECLARE_BITMAP(tmp_map, SVE_VQ_MAX);
unsigned long b;
vec_probe_vqs(info, tmp_map);
bitmap_complement(tmp_map, tmp_map, SVE_VQ_MAX);
if (bitmap_intersects(tmp_map, info->vq_map, SVE_VQ_MAX)) {
pr_warn("%s: cpu%d: Required vector length(s) missing\n",
info->name, smp_processor_id());
return -EINVAL;
}
if (!IS_ENABLED(CONFIG_KVM) || !is_hyp_mode_available())
return 0;
/*
* For KVM, it is necessary to ensure that this CPU doesn't
* support any vector length that guests may have probed as
* unsupported.
*/
/* Recover the set of supported VQs: */
bitmap_complement(tmp_map, tmp_map, SVE_VQ_MAX);
/* Find VQs supported that are not globally supported: */
bitmap_andnot(tmp_map, tmp_map, info->vq_map, SVE_VQ_MAX);
/* Find the lowest such VQ, if any: */
b = find_last_bit(tmp_map, SVE_VQ_MAX);
if (b >= SVE_VQ_MAX)
return 0; /* no mismatches */
/*
* Mismatches above sve_max_virtualisable_vl are fine, since
* no guest is allowed to configure ZCR_EL2.LEN to exceed this:
*/
if (sve_vl_from_vq(__bit_to_vq(b)) <= info->max_virtualisable_vl) {
pr_warn("%s: cpu%d: Unsupported vector length(s) present\n",
info->name, smp_processor_id());
return -EINVAL;
}
return 0;
}
static void __init sve_efi_setup(void)
{
int max_vl = 0;
int i;
if (!IS_ENABLED(CONFIG_EFI))
return;
for (i = 0; i < ARRAY_SIZE(vl_info); i++)
max_vl = max(vl_info[i].max_vl, max_vl);
/*
* alloc_percpu() warns and prints a backtrace if this goes wrong.
* This is evidence of a crippled system and we are returning void,
* so no attempt is made to handle this situation here.
*/
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);
if (!efi_sve_state)
goto fail;
return;
fail:
panic("Cannot allocate percpu memory for EFI SVE save/restore");
}
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();
}
void __init sve_setup(void)
{
struct vl_info *info = &vl_info[ARM64_VEC_SVE];
DECLARE_BITMAP(tmp_map, SVE_VQ_MAX);
unsigned long b;
int max_bit;
if (!cpus_have_cap(ARM64_SVE))
return;
/*
* The SVE architecture mandates support for 128-bit vectors,
* so sve_vq_map must have at least SVE_VQ_MIN set.
* If something went wrong, at least try to patch it up:
*/
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);
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.
* VL == 64 is guaranteed not to grow the signal frame.
*/
set_sve_default_vl(find_supported_vector_length(ARM64_VEC_SVE, 64));
bitmap_andnot(tmp_map, info->vq_partial_map, info->vq_map,
SVE_VQ_MAX);
b = find_last_bit(tmp_map, SVE_VQ_MAX);
if (b >= SVE_VQ_MAX)
/* No non-virtualisable VLs found */
info->max_virtualisable_vl = SVE_VQ_MAX;
else if (WARN_ON(b == SVE_VQ_MAX - 1))
/* No virtualisable VLs? This is architecturally forbidden. */
info->max_virtualisable_vl = SVE_VQ_MIN;
else /* b + 1 < SVE_VQ_MAX */
info->max_virtualisable_vl = sve_vl_from_vq(__bit_to_vq(b + 1));
if (info->max_virtualisable_vl > info->max_vl)
info->max_virtualisable_vl = info->max_vl;
pr_info("%s: maximum available vector length %u bytes per vector\n",
info->name, info->max_vl);
pr_info("%s: default vector length %u bytes per vector\n",
info->name, get_sve_default_vl());
/* KVM decides whether to support mismatched systems. Just warn here: */
if (sve_max_virtualisable_vl() < sve_max_vl())
pr_warn("%s: unvirtualisable vector lengths present\n",
info->name);
sve_efi_setup();
}
/*
* Called from the put_task_struct() path, which cannot get here
* unless dead_task is really dead and not schedulable.
*/
void fpsimd_release_task(struct task_struct *dead_task)
{
__sve_free(dead_task);
sme_free(dead_task);
}
#endif /* CONFIG_ARM64_SVE */
#ifdef CONFIG_ARM64_SME
/*
* Ensure that task->thread.sme_state is allocated and sufficiently large.
*
* This function should be used only in preparation for replacing
* 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, bool flush)
{
if (task->thread.sme_state && flush) {
memset(task->thread.sme_state, 0, sme_state_size(task));
return;
}
/* This could potentially be up to 64K. */
task->thread.sme_state =
kzalloc(sme_state_size(task), GFP_KERNEL);
}
static void sme_free(struct task_struct *task)
{
kfree(task->thread.sme_state);
task->thread.sme_state = NULL;
}
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,
SYS_SMPRI_EL1);
/* Allow SME in kernel */
write_sysreg(read_sysreg(CPACR_EL1) | CPACR_EL1_SMEN_EL1EN, CPACR_EL1);
isb();
/* Allow EL0 to access TPIDR2 */
write_sysreg(read_sysreg(SCTLR_EL1) | SCTLR_ELx_ENTP2, SCTLR_EL1);
isb();
}
void cpu_enable_sme2(const struct arm64_cpu_capabilities *__always_unused p)
{
/* 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);
}
void cpu_enable_fa64(const struct arm64_cpu_capabilities *__always_unused p)
{
/* This must be enabled after SME */
BUILD_BUG_ON(ARM64_SME_FA64 <= ARM64_SME);
/* Allow use of FA64 */
write_sysreg_s(read_sysreg_s(SYS_SMCR_EL1) | SMCR_ELx_FA64_MASK,
SYS_SMCR_EL1);
}
void __init sme_setup(void)
{
struct vl_info *info = &vl_info[ARM64_VEC_SME];
int min_bit, max_bit;
if (!cpus_have_cap(ARM64_SME))
return;
/*
* 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. 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));
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);
/*
* For the default VL, pick the maximum supported value <= 32
* (256 bits) if there is one since this is guaranteed not to
* grow the signal frame when in streaming mode, otherwise the
* minimum available VL will be used.
*/
set_sme_default_vl(find_supported_vector_length(ARM64_VEC_SME, 32));
pr_info("SME: minimum available vector length %u bytes per vector\n",
info->min_vl);
pr_info("SME: maximum available vector length %u bytes per vector\n",
info->max_vl);
pr_info("SME: default vector length %u bytes per vector\n",
get_sme_default_vl());
}
#endif /* CONFIG_ARM64_SME */
static void sve_init_regs(void)
{
/*
* Convert the FPSIMD state to SVE, zeroing all the state that
* is not shared with FPSIMD. If (as is likely) the current
* state is live in the registers then do this there and
* update our metadata for the current task including
* disabling the trap, otherwise update our in-memory copy.
* We are guaranteed to not be in streaming mode, we can only
* take a SVE trap when not in streaming mode and we can't be
* in streaming mode when taking a SME trap.
*/
if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {
unsigned long vq_minus_one =
sve_vq_from_vl(task_get_sve_vl(current)) - 1;
sve_set_vq(vq_minus_one);
sve_flush_live(true, vq_minus_one);
fpsimd_bind_task_to_cpu();
} else {
fpsimd_to_sve(current);
current->thread.fp_type = FP_STATE_SVE;
}
}
/*
* Trapped SVE access
*
* Storage is allocated for the full SVE state, the current FPSIMD
* register contents are migrated across, and the access trap is
* disabled.
*
* TIF_SVE should be clear on entry: otherwise, fpsimd_restore_current_state()
* would have disabled the SVE access trap for userspace during
* ret_to_user, making an SVE access trap impossible in that case.
*/
void do_sve_acc(unsigned long esr, struct pt_regs *regs)
{
/* Even if we chose not to use SVE, the hardware could still trap: */
if (unlikely(!system_supports_sve()) || WARN_ON(is_compat_task())) {
force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
return;
}
sve_alloc(current, true);
if (!current->thread.sve_state) {
force_sig(SIGKILL);
return;
}
get_cpu_fpsimd_context();
if (test_and_set_thread_flag(TIF_SVE))
WARN_ON(1); /* SVE access shouldn't have trapped */
/*
* Even if the task can have used streaming mode we can only
* generate SVE access traps in normal SVE mode and
* transitioning out of streaming mode may discard any
* streaming mode state. Always clear the high bits to avoid
* any potential errors tracking what is properly initialised.
*/
sve_init_regs();
put_cpu_fpsimd_context();
}
/*
* Trapped SME access
*
* Storage is allocated for the full SVE and SME state, the current
* FPSIMD register contents are migrated to SVE if SVE is not already
* active, and the access trap is disabled.
*
* 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 SME access trap impossible in that case.
*/
void do_sme_acc(unsigned long esr, struct pt_regs *regs)
{
/* Even if we chose not to use SME, the hardware could still trap: */
if (unlikely(!system_supports_sme()) || WARN_ON(is_compat_task())) {
force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
return;
}
/*
* 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) {
force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
return;
}
sve_alloc(current, false);
sme_alloc(current, true);
if (!current->thread.sve_state || !current->thread.sme_state) {
force_sig(SIGKILL);
return;
}
get_cpu_fpsimd_context();
/* With TIF_SME userspace shouldn't generate any traps */
if (test_and_set_thread_flag(TIF_SME))
WARN_ON(1);
if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {
unsigned long vq_minus_one =
sve_vq_from_vl(task_get_sme_vl(current)) - 1;
sme_set_vq(vq_minus_one);
fpsimd_bind_task_to_cpu();
}
put_cpu_fpsimd_context();
}
/*
* Trapped FP/ASIMD access.
*/
void do_fpsimd_acc(unsigned long esr, struct pt_regs *regs)
{
/* 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();
}
/*
* Raise a SIGFPE for the current process.
*/
void do_fpsimd_exc(unsigned long esr, struct pt_regs *regs)
{
unsigned int si_code = FPE_FLTUNK;
if (esr & ESR_ELx_FP_EXC_TFV) {
if (esr & FPEXC_IOF)
si_code = FPE_FLTINV;
else if (esr & FPEXC_DZF)
si_code = FPE_FLTDIV;
else if (esr & FPEXC_OFF)
si_code = FPE_FLTOVF;
else if (esr & FPEXC_UFF)
si_code = FPE_FLTUND;
else if (esr & FPEXC_IXF)
si_code = FPE_FLTRES;
}
send_sig_fault(SIGFPE, si_code,
(void __user *)instruction_pointer(regs),
current);
}
void fpsimd_thread_switch(struct task_struct *next)
{
bool wrong_task, wrong_cpu;
if (!system_supports_fpsimd())
return;
__get_cpu_fpsimd_context();
/* 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();
update_tsk_thread_flag(next, TIF_FOREIGN_FPSTATE,
wrong_task || wrong_cpu);
__put_cpu_fpsimd_context();
}
static void fpsimd_flush_thread_vl(enum vec_type type)
{
int vl, supported_vl;
/*
* Reset the task vector length as required. This is where we
* ensure that all user tasks have a valid vector length
* configured: no kernel task can become a user task without
* an exec and hence a call to this function. By the time the
* first call to this function is made, all early hardware
* probing is complete, so __sve_default_vl should be valid.
* If a bug causes this to go wrong, we make some noise and
* try to fudge thread.sve_vl to a safe value here.
*/
vl = task_get_vl_onexec(current, type);
if (!vl)
vl = get_default_vl(type);
if (WARN_ON(!sve_vl_valid(vl)))
vl = vl_info[type].min_vl;
supported_vl = find_supported_vector_length(type, vl);
if (WARN_ON(supported_vl != vl))
vl = supported_vl;
task_set_vl(current, type, vl);
/*
* If the task is not set to inherit, ensure that the vector
* length will be reset by a subsequent exec:
*/
if (!test_thread_flag(vec_vl_inherit_flag(type)))
task_set_vl_onexec(current, type, 0);
}
void fpsimd_flush_thread(void)
{
void *sve_state = NULL;
void *sme_state = NULL;
if (!system_supports_fpsimd())
return;
get_cpu_fpsimd_context();
fpsimd_flush_task_state(current);
memset(&current->thread.uw.fpsimd_state, 0,
sizeof(current->thread.uw.fpsimd_state));
if (system_supports_sve()) {
clear_thread_flag(TIF_SVE);
/* Defer kfree() while in atomic context */
sve_state = current->thread.sve_state;
current->thread.sve_state = NULL;
fpsimd_flush_thread_vl(ARM64_VEC_SVE);
}
if (system_supports_sme()) {
clear_thread_flag(TIF_SME);
/* Defer kfree() while in atomic context */
sme_state = current->thread.sme_state;
current->thread.sme_state = NULL;
fpsimd_flush_thread_vl(ARM64_VEC_SME);
current->thread.svcr = 0;
}
current->thread.fp_type = FP_STATE_FPSIMD;
put_cpu_fpsimd_context();
kfree(sve_state);
kfree(sme_state);
}
/*
* Save the userland FPSIMD state of 'current' to memory, but only if the state
* currently held in the registers does in fact belong to 'current'
*/
void fpsimd_preserve_current_state(void)
{
if (!system_supports_fpsimd())
return;
get_cpu_fpsimd_context();
fpsimd_save();
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);
}
/*
* Called by KVM when entering the guest.
*/
void fpsimd_kvm_prepare(void)
{
if (!system_supports_sve())
return;
/*
* KVM does not save host SVE state since we can only enter
* the guest from a syscall so the ABI means that only the
* non-saved SVE state needs to be saved. If we have left
* SVE enabled for performance reasons then update the task
* state to be FPSIMD only.
*/
get_cpu_fpsimd_context();
if (test_and_clear_thread_flag(TIF_SVE)) {
sve_to_fpsimd(current);
current->thread.fp_type = FP_STATE_FPSIMD;
}
put_cpu_fpsimd_context();
}
/*
* 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 cpu_fp_state *last = this_cpu_ptr(&fpsimd_last_state);
WARN_ON(!system_supports_fpsimd());
last->st = &current->thread.uw.fpsimd_state;
last->sve_state = current->thread.sve_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 = &current->thread.svcr;
last->fp_type = &current->thread.fp_type;
last->to_save = FP_STATE_CURRENT;
current->thread.fpsimd_cpu = smp_processor_id();
/*
* Toggle SVE and SME trapping for userspace if needed, these
* are serialsied by ret_to_user().
*/
if (system_supports_sme()) {
if (test_thread_flag(TIF_SME))
sme_user_enable();
else
sme_user_disable();
}
if (system_supports_sve()) {
if (test_thread_flag(TIF_SVE))
sve_user_enable();
else
sve_user_disable();
}
}
void fpsimd_bind_state_to_cpu(struct cpu_fp_state *state)
{
struct cpu_fp_state *last = this_cpu_ptr(&fpsimd_last_state);
WARN_ON(!system_supports_fpsimd());
WARN_ON(!in_softirq() && !irqs_disabled());
*last = *state;
}
/*
* Load the userland FPSIMD state of 'current' from memory, but only if the
* FPSIMD state already held in the registers is /not/ the most recent FPSIMD
* state of 'current'. This is called when we are preparing to return to
* userspace to ensure that userspace sees a good register state.
*/
void fpsimd_restore_current_state(void)
{
/*
* 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);
return;
}
get_cpu_fpsimd_context();
if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
task_fpsimd_load();
fpsimd_bind_task_to_cpu();
}
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))
fpsimd_to_sve(current);
task_fpsimd_load();
fpsimd_bind_task_to_cpu();
clear_thread_flag(TIF_FOREIGN_FPSTATE);
put_cpu_fpsimd_context();
}
/*
* Invalidate live CPU copies of task t's FPSIMD state
*
* This function may be called with preemption enabled. The barrier()
* ensures that the assignment to fpsimd_cpu is visible to any
* preemption/softirq that could race with set_tsk_thread_flag(), so
* that TIF_FOREIGN_FPSTATE cannot be spuriously re-cleared.
*
* The final barrier ensures that TIF_FOREIGN_FPSTATE is seen set by any
* subsequent code.
*/
void fpsimd_flush_task_state(struct task_struct *t)
{
t->thread.fpsimd_cpu = NR_CPUS;
/*
* If we don't support fpsimd, bail out after we have
* reset the fpsimd_cpu for this task and clear the
* FPSTATE.
*/
if (!system_supports_fpsimd())
return;
barrier();
set_tsk_thread_flag(t, TIF_FOREIGN_FPSTATE);
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)
{
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);
}
/*
* Save the FPSIMD state to memory and invalidate cpu view.
* This function must be called with preemption disabled.
*/
void fpsimd_save_and_flush_cpu_state(void)
{
if (!system_supports_fpsimd())
return;
WARN_ON(preemptible());
__get_cpu_fpsimd_context();
fpsimd_save();
fpsimd_flush_cpu_state();
__put_cpu_fpsimd_context();
}
#ifdef CONFIG_KERNEL_MODE_NEON
/*
* Kernel-side NEON support functions
*/
/*
* kernel_neon_begin(): obtain the CPU FPSIMD registers for use by the calling
* context
*
* Must not be called unless may_use_simd() returns true.
* Task context in the FPSIMD registers is saved back to memory as necessary.
*
* A matching call to kernel_neon_end() must be made before returning from the
* calling context.
*
* The caller may freely use the FPSIMD registers until kernel_neon_end() is
* called.
*/
void kernel_neon_begin(void)
{
if (WARN_ON(!system_supports_fpsimd()))
return;
BUG_ON(!may_use_simd());
get_cpu_fpsimd_context();
/* Save unsaved fpsimd state, if any: */
fpsimd_save();
/* Invalidate any task state remaining in the fpsimd regs: */
fpsimd_flush_cpu_state();
}
EXPORT_SYMBOL_GPL(kernel_neon_begin);
/*
* kernel_neon_end(): give the CPU FPSIMD registers back to the current task
*
* Must be called from a context in which kernel_neon_begin() was previously
* called, with no call to kernel_neon_end() in the meantime.
*
* The caller must not use the FPSIMD registers after this function is called,
* unless kernel_neon_begin() is called again in the meantime.
*/
void kernel_neon_end(void)
{
if (!system_supports_fpsimd())
return;
put_cpu_fpsimd_context();
}
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);
/*
* EFI runtime services support functions
*
* The ABI for EFI runtime services allows EFI to use FPSIMD during the call.
* This means that for EFI (and only for EFI), we have to assume that FPSIMD
* is always used rather than being an optional accelerator.
*
* These functions provide the necessary support for ensuring FPSIMD
* save/restore in the contexts from which EFI is used.
*
* Do not use them for any other purpose -- if tempted to do so, you are
* either doing something wrong or you need to propose some refactoring.
*/
/*
* __efi_fpsimd_begin(): prepare FPSIMD for making an EFI runtime services call
*/
void __efi_fpsimd_begin(void)
{
if (!system_supports_fpsimd())
return;
WARN_ON(preemptible());
if (may_use_simd()) {
kernel_neon_begin();
} else {
/*
* 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);
bool ffr = true;
u64 svcr;
__this_cpu_write(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);
/*
* Unless we have FA64 FFR does not
* exist in streaming mode.
*/
if (!system_supports_fa64())
ffr = !(svcr & SVCR_SM_MASK);
}
sve_save_state(sve_state + sve_ffr_offset(sve_max_vl()),
&this_cpu_ptr(&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));
}
__this_cpu_write(efi_fpsimd_state_used, true);
}
}
/*
* __efi_fpsimd_end(): clean up FPSIMD after an EFI runtime services call
*/
void __efi_fpsimd_end(void)
{
if (!system_supports_fpsimd())
return;
if (!__this_cpu_xchg(efi_fpsimd_state_used, false)) {
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);
bool ffr = true;
/*
* Restore streaming mode; EFI calls are
* normal function calls so should not return in
* streaming mode.
*/
if (system_supports_sme()) {
if (__this_cpu_read(efi_sm_state)) {
sysreg_clear_set_s(SYS_SVCR,
0,
SVCR_SM_MASK);
/*
* Unless we have FA64 FFR does not
* exist in streaming mode.
*/
if (!system_supports_fa64())
ffr = false;
}
}
sve_load_state(sve_state + sve_ffr_offset(sve_max_vl()),
&this_cpu_ptr(&efi_fpsimd_state)->fpsr,
ffr);
__this_cpu_write(efi_sve_state_used, false);
} else {
fpsimd_load_state(this_cpu_ptr(&efi_fpsimd_state));
}
}
}
#endif /* CONFIG_EFI */
#endif /* CONFIG_KERNEL_MODE_NEON */
#ifdef CONFIG_CPU_PM
static int fpsimd_cpu_pm_notifier(struct notifier_block *self,
unsigned long cmd, void *v)
{
switch (cmd) {
case CPU_PM_ENTER:
fpsimd_save_and_flush_cpu_state();
break;
case CPU_PM_EXIT:
break;
case CPU_PM_ENTER_FAILED:
default:
return NOTIFY_DONE;
}
return NOTIFY_OK;
}
static struct notifier_block fpsimd_cpu_pm_notifier_block = {
.notifier_call = fpsimd_cpu_pm_notifier,
};
static void __init fpsimd_pm_init(void)
{
cpu_pm_register_notifier(&fpsimd_cpu_pm_notifier_block);
}
#else
static inline void fpsimd_pm_init(void) { }
#endif /* CONFIG_CPU_PM */
#ifdef CONFIG_HOTPLUG_CPU
static int fpsimd_cpu_dead(unsigned int cpu)
{
per_cpu(fpsimd_last_state.st, cpu) = NULL;
return 0;
}
static inline void fpsimd_hotplug_init(void)
{
cpuhp_setup_state_nocalls(CPUHP_ARM64_FPSIMD_DEAD, "arm64/fpsimd:dead",
NULL, fpsimd_cpu_dead);
}
#else
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.
*/
static int __init fpsimd_init(void)
{
if (cpu_have_named_feature(FP)) {
fpsimd_pm_init();
fpsimd_hotplug_init();
} else {
pr_notice("Floating-point is not implemented\n");
}
if (!cpu_have_named_feature(ASIMD))
pr_notice("Advanced SIMD is not implemented\n");
sve_sysctl_init();
sme_sysctl_init();
return 0;
}
core_initcall(fpsimd_init);