drm/rockchip: Don't change hdmi reference clock rate

[drm/drm-misc.git] / arch / arm64 / kernel / signal.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Based on arch/arm/kernel/signal.c
 *
 * Copyright (C) 1995-2009 Russell King
 * Copyright (C) 2012 ARM Ltd.
 */

#include <linux/cache.h>
#include <linux/compat.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/freezer.h>
#include <linux/stddef.h>
#include <linux/uaccess.h>
#include <linux/sizes.h>
#include <linux/string.h>
#include <linux/ratelimit.h>
#include <linux/rseq.h>
#include <linux/syscalls.h>
#include <linux/pkeys.h>

#include <asm/daifflags.h>
#include <asm/debug-monitors.h>
#include <asm/elf.h>
#include <asm/exception.h>
#include <asm/cacheflush.h>
#include <asm/gcs.h>
#include <asm/ucontext.h>
#include <asm/unistd.h>
#include <asm/fpsimd.h>
#include <asm/ptrace.h>
#include <asm/syscall.h>
#include <asm/signal32.h>
#include <asm/traps.h>
#include <asm/vdso.h>

#ifdef CONFIG_ARM64_GCS
#define GCS_SIGNAL_CAP(addr) (((unsigned long)addr) & GCS_CAP_ADDR_MASK)

static bool gcs_signal_cap_valid(u64 addr, u64 val)
{
        return val == GCS_SIGNAL_CAP(addr);
}
#endif

/*
 * Do a signal return; undo the signal stack. These are aligned to 128-bit.
 */
struct rt_sigframe {
        struct siginfo info;
        struct ucontext uc;
};

struct rt_sigframe_user_layout {
        struct rt_sigframe __user *sigframe;
        struct frame_record __user *next_frame;

        unsigned long size;     /* size of allocated sigframe data */
        unsigned long limit;    /* largest allowed size */

        unsigned long fpsimd_offset;
        unsigned long esr_offset;
        unsigned long gcs_offset;
        unsigned long sve_offset;
        unsigned long tpidr2_offset;
        unsigned long za_offset;
        unsigned long zt_offset;
        unsigned long fpmr_offset;
        unsigned long poe_offset;
        unsigned long extra_offset;
        unsigned long end_offset;
};

/*
 * Holds any EL0-controlled state that influences unprivileged memory accesses.
 * This includes both accesses done in userspace and uaccess done in the kernel.
 *
 * This state needs to be carefully managed to ensure that it doesn't cause
 * uaccess to fail when setting up the signal frame, and the signal handler
 * itself also expects a well-defined state when entered.
 */
struct user_access_state {
        u64 por_el0;
};

#define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
#define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)

/*
 * Save the user access state into ua_state and reset it to disable any
 * restrictions.
 */
static void save_reset_user_access_state(struct user_access_state *ua_state)
{
        if (system_supports_poe()) {
                u64 por_enable_all = 0;

                for (int pkey = 0; pkey < arch_max_pkey(); pkey++)
                        por_enable_all |= POE_RXW << (pkey * POR_BITS_PER_PKEY);

                ua_state->por_el0 = read_sysreg_s(SYS_POR_EL0);
                write_sysreg_s(por_enable_all, SYS_POR_EL0);
                /* Ensure that any subsequent uaccess observes the updated value */
                isb();
        }
}

/*
 * Set the user access state for invoking the signal handler.
 *
 * No uaccess should be done after that function is called.
 */
static void set_handler_user_access_state(void)
{
        if (system_supports_poe())
                write_sysreg_s(POR_EL0_INIT, SYS_POR_EL0);
}

/*
 * Restore the user access state to the values saved in ua_state.
 *
 * No uaccess should be done after that function is called.
 */
static void restore_user_access_state(const struct user_access_state *ua_state)
{
        if (system_supports_poe())
                write_sysreg_s(ua_state->por_el0, SYS_POR_EL0);
}

static void init_user_layout(struct rt_sigframe_user_layout *user)
{
        const size_t reserved_size =
                sizeof(user->sigframe->uc.uc_mcontext.__reserved);

        memset(user, 0, sizeof(*user));
        user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved);

        user->limit = user->size + reserved_size;

        user->limit -= TERMINATOR_SIZE;
        user->limit -= EXTRA_CONTEXT_SIZE;
        /* Reserve space for extension and terminator ^ */
}

static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
{
        return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
}

/*
 * Sanity limit on the approximate maximum size of signal frame we'll
 * try to generate.  Stack alignment padding and the frame record are
 * not taken into account.  This limit is not a guarantee and is
 * NOT ABI.
 */
#define SIGFRAME_MAXSZ SZ_256K

static int __sigframe_alloc(struct rt_sigframe_user_layout *user,
                            unsigned long *offset, size_t size, bool extend)
{
        size_t padded_size = round_up(size, 16);

        if (padded_size > user->limit - user->size &&
            !user->extra_offset &&
            extend) {
                int ret;

                user->limit += EXTRA_CONTEXT_SIZE;
                ret = __sigframe_alloc(user, &user->extra_offset,
                                       sizeof(struct extra_context), false);
                if (ret) {
                        user->limit -= EXTRA_CONTEXT_SIZE;
                        return ret;
                }

                /* Reserve space for the __reserved[] terminator */
                user->size += TERMINATOR_SIZE;

                /*
                 * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for
                 * the terminator:
                 */
                user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE;
        }

        /* Still not enough space?  Bad luck! */
        if (padded_size > user->limit - user->size)
                return -ENOMEM;

        *offset = user->size;
        user->size += padded_size;

        return 0;
}

/*
 * Allocate space for an optional record of <size> bytes in the user
 * signal frame.  The offset from the signal frame base address to the
 * allocated block is assigned to *offset.
 */
static int sigframe_alloc(struct rt_sigframe_user_layout *user,
                          unsigned long *offset, size_t size)
{
        return __sigframe_alloc(user, offset, size, true);
}

/* Allocate the null terminator record and prevent further allocations */
static int sigframe_alloc_end(struct rt_sigframe_user_layout *user)
{
        int ret;

        /* Un-reserve the space reserved for the terminator: */
        user->limit += TERMINATOR_SIZE;

        ret = sigframe_alloc(user, &user->end_offset,
                             sizeof(struct _aarch64_ctx));
        if (ret)
                return ret;

        /* Prevent further allocation: */
        user->limit = user->size;
        return 0;
}

static void __user *apply_user_offset(
        struct rt_sigframe_user_layout const *user, unsigned long offset)
{
        char __user *base = (char __user *)user->sigframe;

        return base + offset;
}

struct user_ctxs {
        struct fpsimd_context __user *fpsimd;
        u32 fpsimd_size;
        struct sve_context __user *sve;
        u32 sve_size;
        struct tpidr2_context __user *tpidr2;
        u32 tpidr2_size;
        struct za_context __user *za;
        u32 za_size;
        struct zt_context __user *zt;
        u32 zt_size;
        struct fpmr_context __user *fpmr;
        u32 fpmr_size;
        struct poe_context __user *poe;
        u32 poe_size;
        struct gcs_context __user *gcs;
        u32 gcs_size;
};

static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
{
        struct user_fpsimd_state const *fpsimd =
                &current->thread.uw.fpsimd_state;
        int err;

        /* copy the FP and status/control registers */
        err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
        __put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
        __put_user_error(fpsimd->fpcr, &ctx->fpcr, err);

        /* copy the magic/size information */
        __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
        __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);

        return err ? -EFAULT : 0;
}

static int restore_fpsimd_context(struct user_ctxs *user)
{
        struct user_fpsimd_state fpsimd;
        int err = 0;

        /* check the size information */
        if (user->fpsimd_size != sizeof(struct fpsimd_context))
                return -EINVAL;

        /* copy the FP and status/control registers */
        err = __copy_from_user(fpsimd.vregs, &(user->fpsimd->vregs),
                               sizeof(fpsimd.vregs));
        __get_user_error(fpsimd.fpsr, &(user->fpsimd->fpsr), err);
        __get_user_error(fpsimd.fpcr, &(user->fpsimd->fpcr), err);

        clear_thread_flag(TIF_SVE);
        current->thread.fp_type = FP_STATE_FPSIMD;

        /* load the hardware registers from the fpsimd_state structure */
        if (!err)
                fpsimd_update_current_state(&fpsimd);

        return err ? -EFAULT : 0;
}

static int preserve_fpmr_context(struct fpmr_context __user *ctx)
{
        int err = 0;

        current->thread.uw.fpmr = read_sysreg_s(SYS_FPMR);

        __put_user_error(FPMR_MAGIC, &ctx->head.magic, err);
        __put_user_error(sizeof(*ctx), &ctx->head.size, err);
        __put_user_error(current->thread.uw.fpmr, &ctx->fpmr, err);

        return err;
}

static int restore_fpmr_context(struct user_ctxs *user)
{
        u64 fpmr;
        int err = 0;

        if (user->fpmr_size != sizeof(*user->fpmr))
                return -EINVAL;

        __get_user_error(fpmr, &user->fpmr->fpmr, err);
        if (!err)
                write_sysreg_s(fpmr, SYS_FPMR);

        return err;
}

static int preserve_poe_context(struct poe_context __user *ctx,
                                const struct user_access_state *ua_state)
{
        int err = 0;

        __put_user_error(POE_MAGIC, &ctx->head.magic, err);
        __put_user_error(sizeof(*ctx), &ctx->head.size, err);
        __put_user_error(ua_state->por_el0, &ctx->por_el0, err);

        return err;
}

static int restore_poe_context(struct user_ctxs *user,
                               struct user_access_state *ua_state)
{
        u64 por_el0;
        int err = 0;

        if (user->poe_size != sizeof(*user->poe))
                return -EINVAL;

        __get_user_error(por_el0, &(user->poe->por_el0), err);
        if (!err)
                ua_state->por_el0 = por_el0;

        return err;
}

#ifdef CONFIG_ARM64_SVE

static int preserve_sve_context(struct sve_context __user *ctx)
{
        int err = 0;
        u16 reserved[ARRAY_SIZE(ctx->__reserved)];
        u16 flags = 0;
        unsigned int vl = task_get_sve_vl(current);
        unsigned int vq = 0;

        if (thread_sm_enabled(&current->thread)) {
                vl = task_get_sme_vl(current);
                vq = sve_vq_from_vl(vl);
                flags |= SVE_SIG_FLAG_SM;
        } else if (current->thread.fp_type == FP_STATE_SVE) {
                vq = sve_vq_from_vl(vl);
        }

        memset(reserved, 0, sizeof(reserved));

        __put_user_error(SVE_MAGIC, &ctx->head.magic, err);
        __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16),
                         &ctx->head.size, err);
        __put_user_error(vl, &ctx->vl, err);
        __put_user_error(flags, &ctx->flags, err);
        BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
        err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));

        if (vq) {
                /*
                 * This assumes that the SVE state has already been saved to
                 * the task struct by calling the function
                 * fpsimd_signal_preserve_current_state().
                 */
                err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
                                      current->thread.sve_state,
                                      SVE_SIG_REGS_SIZE(vq));
        }

        return err ? -EFAULT : 0;
}

static int restore_sve_fpsimd_context(struct user_ctxs *user)
{
        int err = 0;
        unsigned int vl, vq;
        struct user_fpsimd_state fpsimd;
        u16 user_vl, flags;

        if (user->sve_size < sizeof(*user->sve))
                return -EINVAL;

        __get_user_error(user_vl, &(user->sve->vl), err);
        __get_user_error(flags, &(user->sve->flags), err);
        if (err)
                return err;

        if (flags & SVE_SIG_FLAG_SM) {
                if (!system_supports_sme())
                        return -EINVAL;

                vl = task_get_sme_vl(current);
        } else {
                /*
                 * A SME only system use SVE for streaming mode so can
                 * have a SVE formatted context with a zero VL and no
                 * payload data.
                 */
                if (!system_supports_sve() && !system_supports_sme())
                        return -EINVAL;

                vl = task_get_sve_vl(current);
        }

        if (user_vl != vl)
                return -EINVAL;

        if (user->sve_size == sizeof(*user->sve)) {
                clear_thread_flag(TIF_SVE);
                current->thread.svcr &= ~SVCR_SM_MASK;
                current->thread.fp_type = FP_STATE_FPSIMD;
                goto fpsimd_only;
        }

        vq = sve_vq_from_vl(vl);

        if (user->sve_size < SVE_SIG_CONTEXT_SIZE(vq))
                return -EINVAL;

        /*
         * Careful: we are about __copy_from_user() directly into
         * thread.sve_state with preemption enabled, so protection is
         * needed to prevent a racing context switch from writing stale
         * registers back over the new data.
         */

        fpsimd_flush_task_state(current);
        /* From now, fpsimd_thread_switch() won't touch thread.sve_state */

        sve_alloc(current, true);
        if (!current->thread.sve_state) {
                clear_thread_flag(TIF_SVE);
                return -ENOMEM;
        }

        err = __copy_from_user(current->thread.sve_state,
                               (char __user const *)user->sve +
                                        SVE_SIG_REGS_OFFSET,
                               SVE_SIG_REGS_SIZE(vq));
        if (err)
                return -EFAULT;

        if (flags & SVE_SIG_FLAG_SM)
                current->thread.svcr |= SVCR_SM_MASK;
        else
                set_thread_flag(TIF_SVE);
        current->thread.fp_type = FP_STATE_SVE;

fpsimd_only:
        /* copy the FP and status/control registers */
        /* restore_sigframe() already checked that user->fpsimd != NULL. */
        err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs,
                               sizeof(fpsimd.vregs));
        __get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err);
        __get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err);

        /* load the hardware registers from the fpsimd_state structure */
        if (!err)
                fpsimd_update_current_state(&fpsimd);

        return err ? -EFAULT : 0;
}

#else /* ! CONFIG_ARM64_SVE */

static int restore_sve_fpsimd_context(struct user_ctxs *user)
{
        WARN_ON_ONCE(1);
        return -EINVAL;
}

/* Turn any non-optimised out attempts to use this into a link error: */
extern int preserve_sve_context(void __user *ctx);

#endif /* ! CONFIG_ARM64_SVE */

#ifdef CONFIG_ARM64_SME

static int preserve_tpidr2_context(struct tpidr2_context __user *ctx)
{
        int err = 0;

        current->thread.tpidr2_el0 = read_sysreg_s(SYS_TPIDR2_EL0);

        __put_user_error(TPIDR2_MAGIC, &ctx->head.magic, err);
        __put_user_error(sizeof(*ctx), &ctx->head.size, err);
        __put_user_error(current->thread.tpidr2_el0, &ctx->tpidr2, err);

        return err;
}

static int restore_tpidr2_context(struct user_ctxs *user)
{
        u64 tpidr2_el0;
        int err = 0;

        if (user->tpidr2_size != sizeof(*user->tpidr2))
                return -EINVAL;

        __get_user_error(tpidr2_el0, &user->tpidr2->tpidr2, err);
        if (!err)
                write_sysreg_s(tpidr2_el0, SYS_TPIDR2_EL0);

        return err;
}

static int preserve_za_context(struct za_context __user *ctx)
{
        int err = 0;
        u16 reserved[ARRAY_SIZE(ctx->__reserved)];
        unsigned int vl = task_get_sme_vl(current);
        unsigned int vq;

        if (thread_za_enabled(&current->thread))
                vq = sve_vq_from_vl(vl);
        else
                vq = 0;

        memset(reserved, 0, sizeof(reserved));

        __put_user_error(ZA_MAGIC, &ctx->head.magic, err);
        __put_user_error(round_up(ZA_SIG_CONTEXT_SIZE(vq), 16),
                         &ctx->head.size, err);
        __put_user_error(vl, &ctx->vl, err);
        BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
        err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));

        if (vq) {
                /*
                 * This assumes that the ZA state has already been saved to
                 * the task struct by calling the function
                 * fpsimd_signal_preserve_current_state().
                 */
                err |= __copy_to_user((char __user *)ctx + ZA_SIG_REGS_OFFSET,
                                      current->thread.sme_state,
                                      ZA_SIG_REGS_SIZE(vq));
        }

        return err ? -EFAULT : 0;
}

static int restore_za_context(struct user_ctxs *user)
{
        int err = 0;
        unsigned int vq;
        u16 user_vl;

        if (user->za_size < sizeof(*user->za))
                return -EINVAL;

        __get_user_error(user_vl, &(user->za->vl), err);
        if (err)
                return err;

        if (user_vl != task_get_sme_vl(current))
                return -EINVAL;

        if (user->za_size == sizeof(*user->za)) {
                current->thread.svcr &= ~SVCR_ZA_MASK;
                return 0;
        }

        vq = sve_vq_from_vl(user_vl);

        if (user->za_size < ZA_SIG_CONTEXT_SIZE(vq))
                return -EINVAL;

        /*
         * Careful: we are about __copy_from_user() directly into
         * thread.sme_state with preemption enabled, so protection is
         * needed to prevent a racing context switch from writing stale
         * registers back over the new data.
         */

        fpsimd_flush_task_state(current);
        /* From now, fpsimd_thread_switch() won't touch thread.sve_state */

        sme_alloc(current, true);
        if (!current->thread.sme_state) {
                current->thread.svcr &= ~SVCR_ZA_MASK;
                clear_thread_flag(TIF_SME);
                return -ENOMEM;
        }

        err = __copy_from_user(current->thread.sme_state,
                               (char __user const *)user->za +
                                        ZA_SIG_REGS_OFFSET,
                               ZA_SIG_REGS_SIZE(vq));
        if (err)
                return -EFAULT;

        set_thread_flag(TIF_SME);
        current->thread.svcr |= SVCR_ZA_MASK;

        return 0;
}

static int preserve_zt_context(struct zt_context __user *ctx)
{
        int err = 0;
        u16 reserved[ARRAY_SIZE(ctx->__reserved)];

        if (WARN_ON(!thread_za_enabled(&current->thread)))
                return -EINVAL;

        memset(reserved, 0, sizeof(reserved));

        __put_user_error(ZT_MAGIC, &ctx->head.magic, err);
        __put_user_error(round_up(ZT_SIG_CONTEXT_SIZE(1), 16),
                         &ctx->head.size, err);
        __put_user_error(1, &ctx->nregs, err);
        BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
        err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));

        /*
         * This assumes that the ZT state has already been saved to
         * the task struct by calling the function
         * fpsimd_signal_preserve_current_state().
         */
        err |= __copy_to_user((char __user *)ctx + ZT_SIG_REGS_OFFSET,
                              thread_zt_state(&current->thread),
                              ZT_SIG_REGS_SIZE(1));

        return err ? -EFAULT : 0;
}

static int restore_zt_context(struct user_ctxs *user)
{
        int err;
        u16 nregs;

        /* ZA must be restored first for this check to be valid */
        if (!thread_za_enabled(&current->thread))
                return -EINVAL;

        if (user->zt_size != ZT_SIG_CONTEXT_SIZE(1))
                return -EINVAL;

        if (__copy_from_user(&nregs, &(user->zt->nregs), sizeof(nregs)))
                return -EFAULT;

        if (nregs != 1)
                return -EINVAL;

        /*
         * Careful: we are about __copy_from_user() directly into
         * thread.zt_state with preemption enabled, so protection is
         * needed to prevent a racing context switch from writing stale
         * registers back over the new data.
         */

        fpsimd_flush_task_state(current);
        /* From now, fpsimd_thread_switch() won't touch ZT in thread state */

        err = __copy_from_user(thread_zt_state(&current->thread),
                               (char __user const *)user->zt +
                                        ZT_SIG_REGS_OFFSET,
                               ZT_SIG_REGS_SIZE(1));
        if (err)
                return -EFAULT;

        return 0;
}

#else /* ! CONFIG_ARM64_SME */

/* Turn any non-optimised out attempts to use these into a link error: */
extern int preserve_tpidr2_context(void __user *ctx);
extern int restore_tpidr2_context(struct user_ctxs *user);
extern int preserve_za_context(void __user *ctx);
extern int restore_za_context(struct user_ctxs *user);
extern int preserve_zt_context(void __user *ctx);
extern int restore_zt_context(struct user_ctxs *user);

#endif /* ! CONFIG_ARM64_SME */

#ifdef CONFIG_ARM64_GCS

static int preserve_gcs_context(struct gcs_context __user *ctx)
{
        int err = 0;
        u64 gcspr = read_sysreg_s(SYS_GCSPR_EL0);

        /*
         * If GCS is enabled we will add a cap token to the frame,
         * include it in the GCSPR_EL0 we report to support stack
         * switching via sigreturn if GCS is enabled.  We do not allow
         * enabling via sigreturn so the token is only relevant for
         * threads with GCS enabled.
         */
        if (task_gcs_el0_enabled(current))
                gcspr -= 8;

        __put_user_error(GCS_MAGIC, &ctx->head.magic, err);
        __put_user_error(sizeof(*ctx), &ctx->head.size, err);
        __put_user_error(gcspr, &ctx->gcspr, err);
        __put_user_error(0, &ctx->reserved, err);
        __put_user_error(current->thread.gcs_el0_mode,
                         &ctx->features_enabled, err);

        return err;
}

static int restore_gcs_context(struct user_ctxs *user)
{
        u64 gcspr, enabled;
        int err = 0;

        if (user->gcs_size != sizeof(*user->gcs))
                return -EINVAL;

        __get_user_error(gcspr, &user->gcs->gcspr, err);
        __get_user_error(enabled, &user->gcs->features_enabled, err);
        if (err)
                return err;

        /* Don't allow unknown modes */
        if (enabled & ~PR_SHADOW_STACK_SUPPORTED_STATUS_MASK)
                return -EINVAL;

        err = gcs_check_locked(current, enabled);
        if (err != 0)
                return err;

        /* Don't allow enabling */
        if (!task_gcs_el0_enabled(current) &&
            (enabled & PR_SHADOW_STACK_ENABLE))
                return -EINVAL;

        /* If we are disabling disable everything */
        if (!(enabled & PR_SHADOW_STACK_ENABLE))
                enabled = 0;

        current->thread.gcs_el0_mode = enabled;

        /*
         * We let userspace set GCSPR_EL0 to anything here, we will
         * validate later in gcs_restore_signal().
         */
        write_sysreg_s(gcspr, SYS_GCSPR_EL0);

        return 0;
}

#else /* ! CONFIG_ARM64_GCS */

/* Turn any non-optimised out attempts to use these into a link error: */
extern int preserve_gcs_context(void __user *ctx);
extern int restore_gcs_context(struct user_ctxs *user);

#endif /* ! CONFIG_ARM64_GCS */

static int parse_user_sigframe(struct user_ctxs *user,
                               struct rt_sigframe __user *sf)
{
        struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
        struct _aarch64_ctx __user *head;
        char __user *base = (char __user *)&sc->__reserved;
        size_t offset = 0;
        size_t limit = sizeof(sc->__reserved);
        bool have_extra_context = false;
        char const __user *const sfp = (char const __user *)sf;

        user->fpsimd = NULL;
        user->sve = NULL;
        user->tpidr2 = NULL;
        user->za = NULL;
        user->zt = NULL;
        user->fpmr = NULL;
        user->poe = NULL;
        user->gcs = NULL;

        if (!IS_ALIGNED((unsigned long)base, 16))
                goto invalid;

        while (1) {
                int err = 0;
                u32 magic, size;
                char const __user *userp;
                struct extra_context const __user *extra;
                u64 extra_datap;
                u32 extra_size;
                struct _aarch64_ctx const __user *end;
                u32 end_magic, end_size;

                if (limit - offset < sizeof(*head))
                        goto invalid;

                if (!IS_ALIGNED(offset, 16))
                        goto invalid;

                head = (struct _aarch64_ctx __user *)(base + offset);
                __get_user_error(magic, &head->magic, err);
                __get_user_error(size, &head->size, err);
                if (err)
                        return err;

                if (limit - offset < size)
                        goto invalid;

                switch (magic) {
                case 0:
                        if (size)
                                goto invalid;

                        goto done;

                case FPSIMD_MAGIC:
                        if (!system_supports_fpsimd())
                                goto invalid;
                        if (user->fpsimd)
                                goto invalid;

                        user->fpsimd = (struct fpsimd_context __user *)head;
                        user->fpsimd_size = size;
                        break;

                case ESR_MAGIC:
                        /* ignore */
                        break;

                case POE_MAGIC:
                        if (!system_supports_poe())
                                goto invalid;

                        if (user->poe)
                                goto invalid;

                        user->poe = (struct poe_context __user *)head;
                        user->poe_size = size;
                        break;

                case SVE_MAGIC:
                        if (!system_supports_sve() && !system_supports_sme())
                                goto invalid;

                        if (user->sve)
                                goto invalid;

                        user->sve = (struct sve_context __user *)head;
                        user->sve_size = size;
                        break;

                case TPIDR2_MAGIC:
                        if (!system_supports_tpidr2())
                                goto invalid;

                        if (user->tpidr2)
                                goto invalid;

                        user->tpidr2 = (struct tpidr2_context __user *)head;
                        user->tpidr2_size = size;
                        break;

                case ZA_MAGIC:
                        if (!system_supports_sme())
                                goto invalid;

                        if (user->za)
                                goto invalid;

                        user->za = (struct za_context __user *)head;
                        user->za_size = size;
                        break;

                case ZT_MAGIC:
                        if (!system_supports_sme2())
                                goto invalid;

                        if (user->zt)
                                goto invalid;

                        user->zt = (struct zt_context __user *)head;
                        user->zt_size = size;
                        break;

                case FPMR_MAGIC:
                        if (!system_supports_fpmr())
                                goto invalid;

                        if (user->fpmr)
                                goto invalid;

                        user->fpmr = (struct fpmr_context __user *)head;
                        user->fpmr_size = size;
                        break;

                case GCS_MAGIC:
                        if (!system_supports_gcs())
                                goto invalid;

                        if (user->gcs)
                                goto invalid;

                        user->gcs = (struct gcs_context __user *)head;
                        user->gcs_size = size;
                        break;

                case EXTRA_MAGIC:
                        if (have_extra_context)
                                goto invalid;

                        if (size < sizeof(*extra))
                                goto invalid;

                        userp = (char const __user *)head;

                        extra = (struct extra_context const __user *)userp;
                        userp += size;

                        __get_user_error(extra_datap, &extra->datap, err);
                        __get_user_error(extra_size, &extra->size, err);
                        if (err)
                                return err;

                        /* Check for the dummy terminator in __reserved[]: */

                        if (limit - offset - size < TERMINATOR_SIZE)
                                goto invalid;

                        end = (struct _aarch64_ctx const __user *)userp;
                        userp += TERMINATOR_SIZE;

                        __get_user_error(end_magic, &end->magic, err);
                        __get_user_error(end_size, &end->size, err);
                        if (err)
                                return err;

                        if (end_magic || end_size)
                                goto invalid;

                        /* Prevent looping/repeated parsing of extra_context */
                        have_extra_context = true;

                        base = (__force void __user *)extra_datap;
                        if (!IS_ALIGNED((unsigned long)base, 16))
                                goto invalid;

                        if (!IS_ALIGNED(extra_size, 16))
                                goto invalid;

                        if (base != userp)
                                goto invalid;

                        /* Reject "unreasonably large" frames: */
                        if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
                                goto invalid;

                        /*
                         * Ignore trailing terminator in __reserved[]
                         * and start parsing extra data:
                         */
                        offset = 0;
                        limit = extra_size;

                        if (!access_ok(base, limit))
                                goto invalid;

                        continue;

                default:
                        goto invalid;
                }

                if (size < sizeof(*head))
                        goto invalid;

                if (limit - offset < size)
                        goto invalid;

                offset += size;
        }

done:
        return 0;

invalid:
        return -EINVAL;
}

static int restore_sigframe(struct pt_regs *regs,
                            struct rt_sigframe __user *sf,
                            struct user_access_state *ua_state)
{
        sigset_t set;
        int i, err;
        struct user_ctxs user;

        err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
        if (err == 0)
                set_current_blocked(&set);

        for (i = 0; i < 31; i++)
                __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
                                 err);
        __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
        __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
        __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);

        /*
         * Avoid sys_rt_sigreturn() restarting.
         */
        forget_syscall(regs);

        err |= !valid_user_regs(&regs->user_regs, current);
        if (err == 0)
                err = parse_user_sigframe(&user, sf);

        if (err == 0 && system_supports_fpsimd()) {
                if (!user.fpsimd)
                        return -EINVAL;

                if (user.sve)
                        err = restore_sve_fpsimd_context(&user);
                else
                        err = restore_fpsimd_context(&user);
        }

        if (err == 0 && system_supports_gcs() && user.gcs)
                err = restore_gcs_context(&user);

        if (err == 0 && system_supports_tpidr2() && user.tpidr2)
                err = restore_tpidr2_context(&user);

        if (err == 0 && system_supports_fpmr() && user.fpmr)
                err = restore_fpmr_context(&user);

        if (err == 0 && system_supports_sme() && user.za)
                err = restore_za_context(&user);

        if (err == 0 && system_supports_sme2() && user.zt)
                err = restore_zt_context(&user);

        if (err == 0 && system_supports_poe() && user.poe)
                err = restore_poe_context(&user, ua_state);

        return err;
}

#ifdef CONFIG_ARM64_GCS
static int gcs_restore_signal(void)
{
        unsigned long __user *gcspr_el0;
        u64 cap;
        int ret;

        if (!system_supports_gcs())
                return 0;

        if (!(current->thread.gcs_el0_mode & PR_SHADOW_STACK_ENABLE))
                return 0;

        gcspr_el0 = (unsigned long __user *)read_sysreg_s(SYS_GCSPR_EL0);

        /*
         * Ensure that any changes to the GCS done via GCS operations
         * are visible to the normal reads we do to validate the
         * token.
         */
        gcsb_dsync();

        /*
         * GCSPR_EL0 should be pointing at a capped GCS, read the cap.
         * We don't enforce that this is in a GCS page, if it is not
         * then faults will be generated on GCS operations - the main
         * concern is to protect GCS pages.
         */
        ret = copy_from_user(&cap, gcspr_el0, sizeof(cap));
        if (ret)
                return -EFAULT;

        /*
         * Check that the cap is the actual GCS before replacing it.
         */
        if (!gcs_signal_cap_valid((u64)gcspr_el0, cap))
                return -EINVAL;

        /* Invalidate the token to prevent reuse */
        put_user_gcs(0, (__user void*)gcspr_el0, &ret);
        if (ret != 0)
                return -EFAULT;

        write_sysreg_s(gcspr_el0 + 1, SYS_GCSPR_EL0);

        return 0;
}

#else
static int gcs_restore_signal(void) { return 0; }
#endif

SYSCALL_DEFINE0(rt_sigreturn)
{
        struct pt_regs *regs = current_pt_regs();
        struct rt_sigframe __user *frame;
        struct user_access_state ua_state;

        /* Always make any pending restarted system calls return -EINTR */
        current->restart_block.fn = do_no_restart_syscall;

        /*
         * Since we stacked the signal on a 128-bit boundary, then 'sp' should
         * be word aligned here.
         */
        if (regs->sp & 15)
                goto badframe;

        frame = (struct rt_sigframe __user *)regs->sp;

        if (!access_ok(frame, sizeof (*frame)))
                goto badframe;

        if (restore_sigframe(regs, frame, &ua_state))
                goto badframe;

        if (gcs_restore_signal())
                goto badframe;

        if (restore_altstack(&frame->uc.uc_stack))
                goto badframe;

        restore_user_access_state(&ua_state);

        return regs->regs[0];

badframe:
        arm64_notify_segfault(regs->sp);
        return 0;
}

/*
 * Determine the layout of optional records in the signal frame
 *
 * add_all: if true, lays out the biggest possible signal frame for
 *      this task; otherwise, generates a layout for the current state
 *      of the task.
 */
static int setup_sigframe_layout(struct rt_sigframe_user_layout *user,
                                 bool add_all)
{
        int err;

        if (system_supports_fpsimd()) {
                err = sigframe_alloc(user, &user->fpsimd_offset,
                                     sizeof(struct fpsimd_context));
                if (err)
                        return err;
        }

        /* fault information, if valid */
        if (add_all || current->thread.fault_code) {
                err = sigframe_alloc(user, &user->esr_offset,
                                     sizeof(struct esr_context));
                if (err)
                        return err;
        }

#ifdef CONFIG_ARM64_GCS
        if (system_supports_gcs() && (add_all || current->thread.gcspr_el0)) {
                err = sigframe_alloc(user, &user->gcs_offset,
                                     sizeof(struct gcs_context));
                if (err)
                        return err;
        }
#endif

        if (system_supports_sve() || system_supports_sme()) {
                unsigned int vq = 0;

                if (add_all || current->thread.fp_type == FP_STATE_SVE ||
                    thread_sm_enabled(&current->thread)) {
                        int vl = max(sve_max_vl(), sme_max_vl());

                        if (!add_all)
                                vl = thread_get_cur_vl(&current->thread);

                        vq = sve_vq_from_vl(vl);
                }

                err = sigframe_alloc(user, &user->sve_offset,
                                     SVE_SIG_CONTEXT_SIZE(vq));
                if (err)
                        return err;
        }

        if (system_supports_tpidr2()) {
                err = sigframe_alloc(user, &user->tpidr2_offset,
                                     sizeof(struct tpidr2_context));
                if (err)
                        return err;
        }

        if (system_supports_sme()) {
                unsigned int vl;
                unsigned int vq = 0;

                if (add_all)
                        vl = sme_max_vl();
                else
                        vl = task_get_sme_vl(current);

                if (thread_za_enabled(&current->thread))
                        vq = sve_vq_from_vl(vl);

                err = sigframe_alloc(user, &user->za_offset,
                                     ZA_SIG_CONTEXT_SIZE(vq));
                if (err)
                        return err;
        }

        if (system_supports_sme2()) {
                if (add_all || thread_za_enabled(&current->thread)) {
                        err = sigframe_alloc(user, &user->zt_offset,
                                             ZT_SIG_CONTEXT_SIZE(1));
                        if (err)
                                return err;
                }
        }

        if (system_supports_fpmr()) {
                err = sigframe_alloc(user, &user->fpmr_offset,
                                     sizeof(struct fpmr_context));
                if (err)
                        return err;
        }

        if (system_supports_poe()) {
                err = sigframe_alloc(user, &user->poe_offset,
                                     sizeof(struct poe_context));
                if (err)
                        return err;
        }

        return sigframe_alloc_end(user);
}

static int setup_sigframe(struct rt_sigframe_user_layout *user,
                          struct pt_regs *regs, sigset_t *set,
                          const struct user_access_state *ua_state)
{
        int i, err = 0;
        struct rt_sigframe __user *sf = user->sigframe;

        /* set up the stack frame for unwinding */
        __put_user_error(regs->regs[29], &user->next_frame->fp, err);
        __put_user_error(regs->regs[30], &user->next_frame->lr, err);

        for (i = 0; i < 31; i++)
                __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
                                 err);
        __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
        __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
        __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);

        __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);

        err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));

        if (err == 0 && system_supports_fpsimd()) {
                struct fpsimd_context __user *fpsimd_ctx =
                        apply_user_offset(user, user->fpsimd_offset);
                err |= preserve_fpsimd_context(fpsimd_ctx);
        }

        /* fault information, if valid */
        if (err == 0 && user->esr_offset) {
                struct esr_context __user *esr_ctx =
                        apply_user_offset(user, user->esr_offset);

                __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
                __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
                __put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
        }

        if (system_supports_gcs() && err == 0 && user->gcs_offset) {
                struct gcs_context __user *gcs_ctx =
                        apply_user_offset(user, user->gcs_offset);
                err |= preserve_gcs_context(gcs_ctx);
        }

        /* Scalable Vector Extension state (including streaming), if present */
        if ((system_supports_sve() || system_supports_sme()) &&
            err == 0 && user->sve_offset) {
                struct sve_context __user *sve_ctx =
                        apply_user_offset(user, user->sve_offset);
                err |= preserve_sve_context(sve_ctx);
        }

        /* TPIDR2 if supported */
        if (system_supports_tpidr2() && err == 0) {
                struct tpidr2_context __user *tpidr2_ctx =
                        apply_user_offset(user, user->tpidr2_offset);
                err |= preserve_tpidr2_context(tpidr2_ctx);
        }

        /* FPMR if supported */
        if (system_supports_fpmr() && err == 0) {
                struct fpmr_context __user *fpmr_ctx =
                        apply_user_offset(user, user->fpmr_offset);
                err |= preserve_fpmr_context(fpmr_ctx);
        }

        if (system_supports_poe() && err == 0) {
                struct poe_context __user *poe_ctx =
                        apply_user_offset(user, user->poe_offset);

                err |= preserve_poe_context(poe_ctx, ua_state);
        }

        /* ZA state if present */
        if (system_supports_sme() && err == 0 && user->za_offset) {
                struct za_context __user *za_ctx =
                        apply_user_offset(user, user->za_offset);
                err |= preserve_za_context(za_ctx);
        }

        /* ZT state if present */
        if (system_supports_sme2() && err == 0 && user->zt_offset) {
                struct zt_context __user *zt_ctx =
                        apply_user_offset(user, user->zt_offset);
                err |= preserve_zt_context(zt_ctx);
        }

        if (err == 0 && user->extra_offset) {
                char __user *sfp = (char __user *)user->sigframe;
                char __user *userp =
                        apply_user_offset(user, user->extra_offset);

                struct extra_context __user *extra;
                struct _aarch64_ctx __user *end;
                u64 extra_datap;
                u32 extra_size;

                extra = (struct extra_context __user *)userp;
                userp += EXTRA_CONTEXT_SIZE;

                end = (struct _aarch64_ctx __user *)userp;
                userp += TERMINATOR_SIZE;

                /*
                 * extra_datap is just written to the signal frame.
                 * The value gets cast back to a void __user *
                 * during sigreturn.
                 */
                extra_datap = (__force u64)userp;
                extra_size = sfp + round_up(user->size, 16) - userp;

                __put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
                __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
                __put_user_error(extra_datap, &extra->datap, err);
                __put_user_error(extra_size, &extra->size, err);

                /* Add the terminator */
                __put_user_error(0, &end->magic, err);
                __put_user_error(0, &end->size, err);
        }

        /* set the "end" magic */
        if (err == 0) {
                struct _aarch64_ctx __user *end =
                        apply_user_offset(user, user->end_offset);

                __put_user_error(0, &end->magic, err);
                __put_user_error(0, &end->size, err);
        }

        return err;
}

static int get_sigframe(struct rt_sigframe_user_layout *user,
                         struct ksignal *ksig, struct pt_regs *regs)
{
        unsigned long sp, sp_top;
        int err;

        init_user_layout(user);
        err = setup_sigframe_layout(user, false);
        if (err)
                return err;

        sp = sp_top = sigsp(regs->sp, ksig);

        sp = round_down(sp - sizeof(struct frame_record), 16);
        user->next_frame = (struct frame_record __user *)sp;

        sp = round_down(sp, 16) - sigframe_size(user);
        user->sigframe = (struct rt_sigframe __user *)sp;

        /*
         * Check that we can actually write to the signal frame.
         */
        if (!access_ok(user->sigframe, sp_top - sp))
                return -EFAULT;

        return 0;
}

#ifdef CONFIG_ARM64_GCS

static int gcs_signal_entry(__sigrestore_t sigtramp, struct ksignal *ksig)
{
        unsigned long __user *gcspr_el0;
        int ret = 0;

        if (!system_supports_gcs())
                return 0;

        if (!task_gcs_el0_enabled(current))
                return 0;

        /*
         * We are entering a signal handler, current register state is
         * active.
         */
        gcspr_el0 = (unsigned long __user *)read_sysreg_s(SYS_GCSPR_EL0);

        /*
         * Push a cap and the GCS entry for the trampoline onto the GCS.
         */
        put_user_gcs((unsigned long)sigtramp, gcspr_el0 - 2, &ret);
        put_user_gcs(GCS_SIGNAL_CAP(gcspr_el0 - 1), gcspr_el0 - 1, &ret);
        if (ret != 0)
                return ret;

        gcspr_el0 -= 2;
        write_sysreg_s((unsigned long)gcspr_el0, SYS_GCSPR_EL0);

        return 0;
}
#else

static int gcs_signal_entry(__sigrestore_t sigtramp, struct ksignal *ksig)
{
        return 0;
}

#endif

static int setup_return(struct pt_regs *regs, struct ksignal *ksig,
                         struct rt_sigframe_user_layout *user, int usig)
{
        __sigrestore_t sigtramp;

        regs->regs[0] = usig;
        regs->sp = (unsigned long)user->sigframe;
        regs->regs[29] = (unsigned long)&user->next_frame->fp;
        regs->pc = (unsigned long)ksig->ka.sa.sa_handler;

        /*
         * Signal delivery is a (wacky) indirect function call in
         * userspace, so simulate the same setting of BTYPE as a BLR
         * <register containing the signal handler entry point>.
         * Signal delivery to a location in a PROT_BTI guarded page
         * that is not a function entry point will now trigger a
         * SIGILL in userspace.
         *
         * If the signal handler entry point is not in a PROT_BTI
         * guarded page, this is harmless.
         */
        if (system_supports_bti()) {
                regs->pstate &= ~PSR_BTYPE_MASK;
                regs->pstate |= PSR_BTYPE_C;
        }

        /* TCO (Tag Check Override) always cleared for signal handlers */
        regs->pstate &= ~PSR_TCO_BIT;

        /* Signal handlers are invoked with ZA and streaming mode disabled */
        if (system_supports_sme()) {
                /*
                 * If we were in streaming mode the saved register
                 * state was SVE but we will exit SM and use the
                 * FPSIMD register state - flush the saved FPSIMD
                 * register state in case it gets loaded.
                 */
                if (current->thread.svcr & SVCR_SM_MASK) {
                        memset(&current->thread.uw.fpsimd_state, 0,
                               sizeof(current->thread.uw.fpsimd_state));
                        current->thread.fp_type = FP_STATE_FPSIMD;
                }

                current->thread.svcr &= ~(SVCR_ZA_MASK |
                                          SVCR_SM_MASK);
                sme_smstop();
        }

        if (ksig->ka.sa.sa_flags & SA_RESTORER)
                sigtramp = ksig->ka.sa.sa_restorer;
        else
                sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);

        regs->regs[30] = (unsigned long)sigtramp;

        return gcs_signal_entry(sigtramp, ksig);
}

static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
                          struct pt_regs *regs)
{
        struct rt_sigframe_user_layout user;
        struct rt_sigframe __user *frame;
        struct user_access_state ua_state;
        int err = 0;

        fpsimd_signal_preserve_current_state();

        if (get_sigframe(&user, ksig, regs))
                return 1;

        save_reset_user_access_state(&ua_state);
        frame = user.sigframe;

        __put_user_error(0, &frame->uc.uc_flags, err);
        __put_user_error(NULL, &frame->uc.uc_link, err);

        err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
        err |= setup_sigframe(&user, regs, set, &ua_state);
        if (err == 0) {
                err = setup_return(regs, ksig, &user, usig);
                if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
                        err |= copy_siginfo_to_user(&frame->info, &ksig->info);
                        regs->regs[1] = (unsigned long)&frame->info;
                        regs->regs[2] = (unsigned long)&frame->uc;
                }
        }

        if (err == 0)
                set_handler_user_access_state();
        else
                restore_user_access_state(&ua_state);

        return err;
}

static void setup_restart_syscall(struct pt_regs *regs)
{
        if (is_compat_task())
                compat_setup_restart_syscall(regs);
        else
                regs->regs[8] = __NR_restart_syscall;
}

/*
 * OK, we're invoking a handler
 */
static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
        sigset_t *oldset = sigmask_to_save();
        int usig = ksig->sig;
        int ret;

        rseq_signal_deliver(ksig, regs);

        /*
         * Set up the stack frame
         */
        if (is_compat_task()) {
                if (ksig->ka.sa.sa_flags & SA_SIGINFO)
                        ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
                else
                        ret = compat_setup_frame(usig, ksig, oldset, regs);
        } else {
                ret = setup_rt_frame(usig, ksig, oldset, regs);
        }

        /*
         * Check that the resulting registers are actually sane.
         */
        ret |= !valid_user_regs(&regs->user_regs, current);

        /* Step into the signal handler if we are stepping */
        signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
}

/*
 * Note that 'init' is a special process: it doesn't get signals it doesn't
 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 * mistake.
 *
 * Note that we go through the signals twice: once to check the signals that
 * the kernel can handle, and then we build all the user-level signal handling
 * stack-frames in one go after that.
 */
void do_signal(struct pt_regs *regs)
{
        unsigned long continue_addr = 0, restart_addr = 0;
        int retval = 0;
        struct ksignal ksig;
        bool syscall = in_syscall(regs);

        /*
         * If we were from a system call, check for system call restarting...
         */
        if (syscall) {
                continue_addr = regs->pc;
                restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
                retval = regs->regs[0];

                /*
                 * Avoid additional syscall restarting via ret_to_user.
                 */
                forget_syscall(regs);

                /*
                 * Prepare for system call restart. We do this here so that a
                 * debugger will see the already changed PC.
                 */
                switch (retval) {
                case -ERESTARTNOHAND:
                case -ERESTARTSYS:
                case -ERESTARTNOINTR:
                case -ERESTART_RESTARTBLOCK:
                        regs->regs[0] = regs->orig_x0;
                        regs->pc = restart_addr;
                        break;
                }
        }

        /*
         * Get the signal to deliver. When running under ptrace, at this point
         * the debugger may change all of our registers.
         */
        if (get_signal(&ksig)) {
                /*
                 * Depending on the signal settings, we may need to revert the
                 * decision to restart the system call, but skip this if a
                 * debugger has chosen to restart at a different PC.
                 */
                if (regs->pc == restart_addr &&
                    (retval == -ERESTARTNOHAND ||
                     retval == -ERESTART_RESTARTBLOCK ||
                     (retval == -ERESTARTSYS &&
                      !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
                        syscall_set_return_value(current, regs, -EINTR, 0);
                        regs->pc = continue_addr;
                }

                handle_signal(&ksig, regs);
                return;
        }

        /*
         * Handle restarting a different system call. As above, if a debugger
         * has chosen to restart at a different PC, ignore the restart.
         */
        if (syscall && regs->pc == restart_addr) {
                if (retval == -ERESTART_RESTARTBLOCK)
                        setup_restart_syscall(regs);
                user_rewind_single_step(current);
        }

        restore_saved_sigmask();
}

unsigned long __ro_after_init signal_minsigstksz;

/*
 * Determine the stack space required for guaranteed signal devliery.
 * This function is used to populate AT_MINSIGSTKSZ at process startup.
 * cpufeatures setup is assumed to be complete.
 */
void __init minsigstksz_setup(void)
{
        struct rt_sigframe_user_layout user;

        init_user_layout(&user);

        /*
         * If this fails, SIGFRAME_MAXSZ needs to be enlarged.  It won't
         * be big enough, but it's our best guess:
         */
        if (WARN_ON(setup_sigframe_layout(&user, true)))
                return;

        signal_minsigstksz = sigframe_size(&user) +
                round_up(sizeof(struct frame_record), 16) +
                16; /* max alignment padding */
}

/*
 * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
 * changes likely come with new fields that should be added below.
 */
static_assert(NSIGILL   == 11);
static_assert(NSIGFPE   == 15);
static_assert(NSIGSEGV  == 10);
static_assert(NSIGBUS   == 5);
static_assert(NSIGTRAP  == 6);
static_assert(NSIGCHLD  == 6);
static_assert(NSIGSYS   == 2);
static_assert(sizeof(siginfo_t) == 128);
static_assert(__alignof__(siginfo_t) == 8);
static_assert(offsetof(siginfo_t, si_signo)     == 0x00);
static_assert(offsetof(siginfo_t, si_errno)     == 0x04);
static_assert(offsetof(siginfo_t, si_code)      == 0x08);
static_assert(offsetof(siginfo_t, si_pid)       == 0x10);
static_assert(offsetof(siginfo_t, si_uid)       == 0x14);
static_assert(offsetof(siginfo_t, si_tid)       == 0x10);
static_assert(offsetof(siginfo_t, si_overrun)   == 0x14);
static_assert(offsetof(siginfo_t, si_status)    == 0x18);
static_assert(offsetof(siginfo_t, si_utime)     == 0x20);
static_assert(offsetof(siginfo_t, si_stime)     == 0x28);
static_assert(offsetof(siginfo_t, si_value)     == 0x18);
static_assert(offsetof(siginfo_t, si_int)       == 0x18);
static_assert(offsetof(siginfo_t, si_ptr)       == 0x18);
static_assert(offsetof(siginfo_t, si_addr)      == 0x10);
static_assert(offsetof(siginfo_t, si_addr_lsb)  == 0x18);
static_assert(offsetof(siginfo_t, si_lower)     == 0x20);
static_assert(offsetof(siginfo_t, si_upper)     == 0x28);
static_assert(offsetof(siginfo_t, si_pkey)      == 0x20);
static_assert(offsetof(siginfo_t, si_perf_data) == 0x18);
static_assert(offsetof(siginfo_t, si_perf_type) == 0x20);
static_assert(offsetof(siginfo_t, si_perf_flags) == 0x24);
static_assert(offsetof(siginfo_t, si_band)      == 0x10);
static_assert(offsetof(siginfo_t, si_fd)        == 0x18);
static_assert(offsetof(siginfo_t, si_call_addr) == 0x10);
static_assert(offsetof(siginfo_t, si_syscall)   == 0x18);
static_assert(offsetof(siginfo_t, si_arch)      == 0x1c);