/*-
 * Copyright (c) 2014 Andrew Turner
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/exec.h>
#include <sys/imgact.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/ptrace.h>
#include <sys/reg.h>
#include <sys/rwlock.h>
#include <sys/signalvar.h>
#include <sys/syscallsubr.h>
#include <sys/sysent.h>
#include <sys/sysproto.h>
#include <sys/ucontext.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>

#include <machine/armreg.h>
#include <machine/elf.h>
#include <machine/kdb.h>
#include <machine/md_var.h>
#include <machine/pcb.h>

#ifdef VFP
#include <machine/vfp.h>
#endif

#define CTX_SIZE_SVE(buf_size)                                  \
    roundup2(sizeof(struct sve_context) + (buf_size),           \
      _Alignof(struct sve_context))

_Static_assert(sizeof(mcontext_t) == 880, "mcontext_t size incorrect");
_Static_assert(sizeof(ucontext_t) == 960, "ucontext_t size incorrect");
_Static_assert(sizeof(siginfo_t) == 80, "siginfo_t size incorrect");

static void get_fpcontext(struct thread *td, mcontext_t *mcp);
static void set_fpcontext(struct thread *td, mcontext_t *mcp);

int
fill_regs(struct thread *td, struct reg *regs)
{
        struct trapframe *frame;

        frame = td->td_frame;
        regs->sp = frame->tf_sp;
        regs->lr = frame->tf_lr;
        regs->elr = frame->tf_elr;
        regs->spsr = frame->tf_spsr;

        memcpy(regs->x, frame->tf_x, sizeof(regs->x));

#ifdef COMPAT_FREEBSD32
        /*
         * We may be called here for a 32bits process, if we're using a
         * 64bits debugger. If so, put PC and SPSR where it expects it.
         */
        if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
                regs->x[15] = frame->tf_elr;
                regs->x[16] = frame->tf_spsr;
        }
#endif
        return (0);
}

int
set_regs(struct thread *td, struct reg *regs)
{
        struct trapframe *frame;

        frame = td->td_frame;
        frame->tf_sp = regs->sp;
        frame->tf_lr = regs->lr;

        memcpy(frame->tf_x, regs->x, sizeof(frame->tf_x));

#ifdef COMPAT_FREEBSD32
        if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
                /*
                 * We may be called for a 32bits process if we're using
                 * a 64bits debugger. If so, get PC and SPSR from where
                 * it put it.
                 */
                frame->tf_elr = regs->x[15];
                frame->tf_spsr &= ~PSR_SETTABLE_32;
                frame->tf_spsr |= regs->x[16] & PSR_SETTABLE_32;
                /* Don't allow userspace to ask to continue single stepping.
                 * The SPSR.SS field doesn't exist when the EL1 is AArch32.
                 * As the SPSR.DIT field has moved in its place don't
                 * allow userspace to set the SPSR.SS field.
                 */
        } else
#endif
        {
                frame->tf_elr = regs->elr;
                /*
                 * frame->tf_spsr and regs->spsr on FreeBSD 13 was 32-bit
                 * where from 14 they are 64 bit. As PSR_SETTABLE_64 clears
                 * the upper 32 bits no compatibility handling is needed,
                 * however if this is ever not the case we will need to add
                 * these, similar to how it is done in set_mcontext.
                 */
                frame->tf_spsr &= ~PSR_SETTABLE_64;
                frame->tf_spsr |= regs->spsr & PSR_SETTABLE_64;
                /* Enable single stepping if userspace asked fot it */
                if ((frame->tf_spsr & PSR_SS) != 0) {
                        td->td_pcb->pcb_flags |= PCB_SINGLE_STEP;

                        WRITE_SPECIALREG(mdscr_el1,
                            READ_SPECIALREG(mdscr_el1) | MDSCR_SS);
                        isb();
                }
        }
        return (0);
}

int
fill_fpregs(struct thread *td, struct fpreg *regs)
{
#ifdef VFP
        struct pcb *pcb;

        pcb = td->td_pcb;
        if ((pcb->pcb_fpflags & PCB_FP_STARTED) != 0) {
                /*
                 * If we have just been running VFP instructions we will
                 * need to save the state to memcpy it below.
                 */
                if (td == curthread)
                        vfp_save_state(td, pcb);
        }

        KASSERT(pcb->pcb_fpusaved == &pcb->pcb_fpustate,
            ("Called fill_fpregs while the kernel is using the VFP"));
        memcpy(regs->fp_q, pcb->pcb_fpustate.vfp_regs,
            sizeof(regs->fp_q));
        regs->fp_cr = pcb->pcb_fpustate.vfp_fpcr;
        regs->fp_sr = pcb->pcb_fpustate.vfp_fpsr;
#else
        memset(regs, 0, sizeof(*regs));
#endif
        return (0);
}

int
set_fpregs(struct thread *td, struct fpreg *regs)
{
#ifdef VFP
        struct pcb *pcb;

        pcb = td->td_pcb;
        KASSERT(pcb->pcb_fpusaved == &pcb->pcb_fpustate,
            ("Called set_fpregs while the kernel is using the VFP"));
        memcpy(pcb->pcb_fpustate.vfp_regs, regs->fp_q, sizeof(regs->fp_q));
        pcb->pcb_fpustate.vfp_fpcr = regs->fp_cr;
        pcb->pcb_fpustate.vfp_fpsr = regs->fp_sr;
#endif
        return (0);
}

int
fill_dbregs(struct thread *td, struct dbreg *regs)
{
        struct debug_monitor_state *monitor;
        uint64_t dfr0;
        int i;
        uint8_t debug_ver, nbkpts, nwtpts;

        memset(regs, 0, sizeof(*regs));

        /*
         * Read these the Debug Feature Register 0 to get info we need.
         * It will be identical on FreeBSD and Linux, so there is no need
         * to check which the target is.
         */
        if (!get_user_reg(ID_AA64DFR0_EL1, &dfr0, true)) {
                debug_ver = ID_AA64DFR0_DebugVer_8;
                nbkpts = 0;
                nwtpts = 0;
        } else {
                debug_ver = ID_AA64DFR0_DebugVer_VAL(dfr0) >>
                    ID_AA64DFR0_DebugVer_SHIFT;
                nbkpts = ID_AA64DFR0_BRPs_VAL(dfr0) >> ID_AA64DFR0_BRPs_SHIFT;
                nwtpts = ID_AA64DFR0_WRPs_VAL(dfr0) >> ID_AA64DFR0_WRPs_SHIFT;
        }

        /*
         * The BRPs field contains the number of breakpoints - 1. Armv8-A
         * allows the hardware to provide 2-16 breakpoints so this won't
         * overflow an 8 bit value. The same applies to the WRPs field.
         */
        nbkpts++;
        nwtpts++;

        regs->db_debug_ver = debug_ver;
        regs->db_nbkpts = nbkpts;
        regs->db_nwtpts = nwtpts;

        monitor = &td->td_pcb->pcb_dbg_regs;
        if ((monitor->dbg_flags & DBGMON_ENABLED) != 0) {
                for (i = 0; i < nbkpts; i++) {
                        regs->db_breakregs[i].dbr_addr = monitor->dbg_bvr[i];
                        regs->db_breakregs[i].dbr_ctrl = monitor->dbg_bcr[i];
                }
                for (i = 0; i < nwtpts; i++) {
                        regs->db_watchregs[i].dbw_addr = monitor->dbg_wvr[i];
                        regs->db_watchregs[i].dbw_ctrl = monitor->dbg_wcr[i];
                }
        }

        return (0);
}

int
set_dbregs(struct thread *td, struct dbreg *regs)
{
        struct debug_monitor_state *monitor;
        uint64_t addr;
        uint32_t ctrl;
        int i;

        monitor = &td->td_pcb->pcb_dbg_regs;
        monitor->dbg_enable_count = 0;

        for (i = 0; i < DBG_BRP_MAX; i++) {
                addr = regs->db_breakregs[i].dbr_addr;
                ctrl = regs->db_breakregs[i].dbr_ctrl;

                /*
                 * Don't let the user set a breakpoint on a kernel or
                 * non-canonical user address.
                 */
                if (addr >= VM_MAXUSER_ADDRESS)
                        return (EINVAL);

                /*
                 * The lowest 2 bits are ignored, so record the effective
                 * address.
                 */
                addr = rounddown2(addr, 4);

                /*
                 * Some control fields are ignored, and other bits reserved.
                 * Only unlinked, address-matching breakpoints are supported.
                 *
                 * XXX: fields that appear unvalidated, such as BAS, have
                 * constrained undefined behaviour. If the user mis-programs
                 * these, there is no risk to the system.
                 */
                ctrl &= DBGBCR_EN | DBGBCR_PMC | DBGBCR_BAS;
                if ((ctrl & DBGBCR_EN) != 0) {
                        /* Only target EL0. */
                        if ((ctrl & DBGBCR_PMC) != DBGBCR_PMC_EL0)
                                return (EINVAL);

                        monitor->dbg_enable_count++;
                }

                monitor->dbg_bvr[i] = addr;
                monitor->dbg_bcr[i] = ctrl;
        }

        for (i = 0; i < DBG_WRP_MAX; i++) {
                addr = regs->db_watchregs[i].dbw_addr;
                ctrl = regs->db_watchregs[i].dbw_ctrl;

                /*
                 * Don't let the user set a watchpoint on a kernel or
                 * non-canonical user address.
                 */
                if (addr >= VM_MAXUSER_ADDRESS)
                        return (EINVAL);

                /*
                 * Some control fields are ignored, and other bits reserved.
                 * Only unlinked watchpoints are supported.
                 */
                ctrl &= DBGWCR_EN | DBGWCR_PAC | DBGWCR_LSC | DBGWCR_BAS |
                    DBGWCR_MASK;

                if ((ctrl & DBGWCR_EN) != 0) {
                        /* Only target EL0. */
                        if ((ctrl & DBGWCR_PAC) != DBGWCR_PAC_EL0)
                                return (EINVAL);

                        /* Must set at least one of the load/store bits. */
                        if ((ctrl & DBGWCR_LSC) == 0)
                                return (EINVAL);

                        /*
                         * When specifying the address range with BAS, the MASK
                         * field must be zero.
                         */
                        if ((ctrl & DBGWCR_BAS) != DBGWCR_BAS &&
                            (ctrl & DBGWCR_MASK) != 0)
                                return (EINVAL);

                        monitor->dbg_enable_count++;
                }
                monitor->dbg_wvr[i] = addr;
                monitor->dbg_wcr[i] = ctrl;
        }

        if (monitor->dbg_enable_count > 0)
                monitor->dbg_flags |= DBGMON_ENABLED;

        return (0);
}

#ifdef COMPAT_FREEBSD32
int
fill_regs32(struct thread *td, struct reg32 *regs)
{
        int i;
        struct trapframe *tf;

        tf = td->td_frame;
        for (i = 0; i < 13; i++)
                regs->r[i] = tf->tf_x[i];
        /* For arm32, SP is r13 and LR is r14 */
        regs->r_sp = tf->tf_x[13];
        regs->r_lr = tf->tf_x[14];
        regs->r_pc = tf->tf_elr;
        regs->r_cpsr = tf->tf_spsr;

        return (0);
}

int
set_regs32(struct thread *td, struct reg32 *regs)
{
        int i;
        struct trapframe *tf;

        tf = td->td_frame;
        for (i = 0; i < 13; i++)
                tf->tf_x[i] = regs->r[i];
        /* For arm 32, SP is r13 an LR is r14 */
        tf->tf_x[13] = regs->r_sp;
        tf->tf_x[14] = regs->r_lr;
        tf->tf_elr = regs->r_pc;
        tf->tf_spsr &= ~PSR_SETTABLE_32;
        tf->tf_spsr |= regs->r_cpsr & PSR_SETTABLE_32;

        return (0);
}

/* XXX fill/set dbregs/fpregs are stubbed on 32-bit arm. */
int
fill_fpregs32(struct thread *td, struct fpreg32 *regs)
{

        memset(regs, 0, sizeof(*regs));
        return (0);
}

int
set_fpregs32(struct thread *td, struct fpreg32 *regs)
{

        return (0);
}

int
fill_dbregs32(struct thread *td, struct dbreg32 *regs)
{

        memset(regs, 0, sizeof(*regs));
        return (0);
}

int
set_dbregs32(struct thread *td, struct dbreg32 *regs)
{

        return (0);
}
#endif

void
exec_setregs(struct thread *td, struct image_params *imgp, uintptr_t stack)
{
        struct trapframe *tf = td->td_frame;
        struct pcb *pcb = td->td_pcb;
        uint64_t new_tcr, tcr;

        memset(tf, 0, sizeof(struct trapframe));

        tf->tf_x[0] = stack;
        tf->tf_sp = STACKALIGN(stack);
        tf->tf_lr = imgp->entry_addr;
        tf->tf_elr = imgp->entry_addr;

        td->td_pcb->pcb_tpidr_el0 = 0;
        td->td_pcb->pcb_tpidrro_el0 = 0;
        WRITE_SPECIALREG(tpidrro_el0, 0);
        WRITE_SPECIALREG(tpidr_el0, 0);

#ifdef VFP
        vfp_reset_state(td, pcb);
#endif

        /*
         * Clear debug register state. It is not applicable to the new process.
         */
        bzero(&pcb->pcb_dbg_regs, sizeof(pcb->pcb_dbg_regs));

        /* If the process is new enough enable TBI */
        if (td->td_proc->p_osrel >= TBI_VERSION)
                new_tcr = TCR_TBI0;
        else
                new_tcr = 0;
        td->td_proc->p_md.md_tcr = new_tcr;

        /* TODO: should create a pmap function for this... */
        tcr = READ_SPECIALREG(tcr_el1);
        if ((tcr & MD_TCR_FIELDS) != new_tcr) {
                uint64_t asid;

                tcr &= ~MD_TCR_FIELDS;
                tcr |= new_tcr;
                WRITE_SPECIALREG(tcr_el1, tcr);
                isb();

                /*
                 * TCR_EL1.TBI0 is permitted to be cached in the TLB, so
                 * we need to perform a TLB invalidation.
                 */
                asid = READ_SPECIALREG(ttbr0_el1) & TTBR_ASID_MASK;
                __asm __volatile(
                    "tlbi aside1is, %0          \n"
                    "dsb ish                    \n"
                    "isb                        \n"
                    : : "r" (asid));
        }

        /* Generate new pointer authentication keys */
        ptrauth_exec(td);
}

/* Sanity check these are the same size, they will be memcpy'd to and from */
CTASSERT(sizeof(((struct trapframe *)0)->tf_x) ==
    sizeof((struct gpregs *)0)->gp_x);
CTASSERT(sizeof(((struct trapframe *)0)->tf_x) ==
    sizeof((struct reg *)0)->x);

int
get_mcontext(struct thread *td, mcontext_t *mcp, int clear_ret)
{
        struct trapframe *tf = td->td_frame;

        if (clear_ret & GET_MC_CLEAR_RET) {
                mcp->mc_gpregs.gp_x[0] = 0;
                mcp->mc_gpregs.gp_spsr = tf->tf_spsr & ~PSR_C;
        } else {
                mcp->mc_gpregs.gp_x[0] = tf->tf_x[0];
                mcp->mc_gpregs.gp_spsr = tf->tf_spsr;
        }

        memcpy(&mcp->mc_gpregs.gp_x[1], &tf->tf_x[1],
            sizeof(mcp->mc_gpregs.gp_x[1]) * (nitems(mcp->mc_gpregs.gp_x) - 1));

        mcp->mc_gpregs.gp_sp = tf->tf_sp;
        mcp->mc_gpregs.gp_lr = tf->tf_lr;
        mcp->mc_gpregs.gp_elr = tf->tf_elr;
        get_fpcontext(td, mcp);

        return (0);
}

int
set_mcontext(struct thread *td, mcontext_t *mcp)
{
#define PSR_13_MASK     0xfffffffful
        struct arm64_reg_context ctx;
        struct trapframe *tf = td->td_frame;
        struct pcb *pcb;
        uint64_t spsr;
        vm_offset_t addr;
        int error, seen_types;
        bool done;

        spsr = mcp->mc_gpregs.gp_spsr;
#ifdef COMPAT_FREEBSD13
        if (td->td_proc->p_osrel < P_OSREL_ARM64_SPSR) {
                /*
                 * Before FreeBSD 14 gp_spsr was 32 bit. The size of mc_gpregs
                 * was identical because of padding so mask of the upper bits
                 * that may be invalid on earlier releases.
                 */
                spsr &= PSR_13_MASK;
        }
#endif

        if ((spsr & PSR_M_MASK) != PSR_M_EL0t ||
            (spsr & PSR_AARCH32) != 0 ||
            (spsr & PSR_DAIF) != (td->td_frame->tf_spsr & PSR_DAIF))
                return (EINVAL); 

        memcpy(tf->tf_x, mcp->mc_gpregs.gp_x, sizeof(tf->tf_x));

        tf->tf_sp = mcp->mc_gpregs.gp_sp;
        tf->tf_lr = mcp->mc_gpregs.gp_lr;
        tf->tf_elr = mcp->mc_gpregs.gp_elr;
#ifdef COMPAT_FREEBSD13
        if (td->td_proc->p_osrel < P_OSREL_ARM64_SPSR) {
                /* Keep the upper 32 bits of spsr on older releases */
                tf->tf_spsr &= ~PSR_13_MASK;
                tf->tf_spsr |= spsr;
        } else
#endif
                tf->tf_spsr = spsr;
        if ((tf->tf_spsr & PSR_SS) != 0) {
                td->td_pcb->pcb_flags |= PCB_SINGLE_STEP;

                WRITE_SPECIALREG(mdscr_el1,
                    READ_SPECIALREG(mdscr_el1) | MDSCR_SS);
                isb();
        }

        set_fpcontext(td, mcp);

        /* Read any register contexts we find */
        if (mcp->mc_ptr != 0) {
                addr = mcp->mc_ptr;
                pcb = td->td_pcb;

#define CTX_TYPE_FLAG_SVE       (1 << 0)

                seen_types = 0;
                done = false;
                do {
                        if (!__is_aligned(addr,
                            _Alignof(struct arm64_reg_context)))
                                return (EINVAL);

                        error = copyin((const void *)addr, &ctx, sizeof(ctx));
                        if (error != 0)
                                return (error);

                        switch (ctx.ctx_id) {
#ifdef VFP
                        case ARM64_CTX_SVE: {
                                struct sve_context sve_ctx;
                                size_t buf_size;

                                if ((seen_types & CTX_TYPE_FLAG_SVE) != 0)
                                        return (EINVAL);
                                seen_types |= CTX_TYPE_FLAG_SVE;

                                if (pcb->pcb_svesaved == NULL)
                                        return (EINVAL);

                                /* XXX: Check pcb_svesaved is valid */

                                buf_size = sve_buf_size(td);
                                /* Check the size is valid */
                                if (ctx.ctx_size != CTX_SIZE_SVE(buf_size))
                                        return (EINVAL);

                                memset(pcb->pcb_svesaved, 0,
                                    sve_max_buf_size());

                                /* Copy the SVE registers from userspace */
                                if (copyin((void *)(addr + sizeof(sve_ctx)),
                                    pcb->pcb_svesaved, buf_size) != 0)
                                        return (EINVAL);

                                pcb->pcb_fpflags |= PCB_FP_SVEVALID;
                                break;
                        }
#endif
                        case ARM64_CTX_END:
                                done = true;
                                break;
                        default:
                                return (EINVAL);
                        }

                        addr += ctx.ctx_size;
                } while (!done);

#undef CTX_TYPE_FLAG_SVE
        }

        return (0);
#undef PSR_13_MASK
}

static void
get_fpcontext(struct thread *td, mcontext_t *mcp)
{
#ifdef VFP
        struct pcb *curpcb;

        MPASS(td == curthread);

        curpcb = curthread->td_pcb;
        if ((curpcb->pcb_fpflags & PCB_FP_STARTED) != 0) {
                /*
                 * If we have just been running VFP instructions we will
                 * need to save the state to memcpy it below.
                 */
                vfp_save_state(td, curpcb);
        }

        KASSERT(curpcb->pcb_fpusaved == &curpcb->pcb_fpustate,
            ("Called get_fpcontext while the kernel is using the VFP"));
        KASSERT((curpcb->pcb_fpflags & ~PCB_FP_USERMASK) == 0,
            ("Non-userspace FPU flags set in get_fpcontext"));
        memcpy(mcp->mc_fpregs.fp_q, curpcb->pcb_fpustate.vfp_regs,
            sizeof(mcp->mc_fpregs.fp_q));
        mcp->mc_fpregs.fp_cr = curpcb->pcb_fpustate.vfp_fpcr;
        mcp->mc_fpregs.fp_sr = curpcb->pcb_fpustate.vfp_fpsr;
        mcp->mc_fpregs.fp_flags = curpcb->pcb_fpflags;
        mcp->mc_flags |= _MC_FP_VALID;
#endif
}

static void
set_fpcontext(struct thread *td, mcontext_t *mcp)
{
#ifdef VFP
        struct pcb *curpcb;

        MPASS(td == curthread);
        if ((mcp->mc_flags & _MC_FP_VALID) != 0) {
                curpcb = curthread->td_pcb;

                /*
                 * Discard any vfp state for the current thread, we
                 * are about to override it.
                 */
                critical_enter();
                vfp_discard(td);
                critical_exit();

                KASSERT(curpcb->pcb_fpusaved == &curpcb->pcb_fpustate,
                    ("Called set_fpcontext while the kernel is using the VFP"));
                memcpy(curpcb->pcb_fpustate.vfp_regs, mcp->mc_fpregs.fp_q,
                    sizeof(mcp->mc_fpregs.fp_q));
                curpcb->pcb_fpustate.vfp_fpcr = mcp->mc_fpregs.fp_cr;
                curpcb->pcb_fpustate.vfp_fpsr = mcp->mc_fpregs.fp_sr;
                curpcb->pcb_fpflags = mcp->mc_fpregs.fp_flags & PCB_FP_STARTED;
        }
#endif
}

int
sys_sigreturn(struct thread *td, struct sigreturn_args *uap)
{
        ucontext_t uc;
        int error;

        if (copyin(uap->sigcntxp, &uc, sizeof(uc)))
                return (EFAULT);

        /* Stop an interrupt from causing the sve state to be dropped */
        td->td_sa.code = -1;
        error = set_mcontext(td, &uc.uc_mcontext);
        if (error != 0)
                return (error);

        /*
         * Sync the VFP and SVE registers. To be backwards compatible we
         * use the VFP registers to restore the lower bits of the SVE
         * register it aliases.
         */
        vfp_to_sve_sync(td);

        /* Restore signal mask. */
        kern_sigprocmask(td, SIG_SETMASK, &uc.uc_sigmask, NULL, 0);

        return (EJUSTRETURN);
}

static bool
sendsig_ctx_end(struct thread *td, vm_offset_t *addrp)
{
        struct arm64_reg_context end_ctx;
        vm_offset_t ctx_addr;

        *addrp -= sizeof(end_ctx);
        ctx_addr = *addrp;

        memset(&end_ctx, 0, sizeof(end_ctx));
        end_ctx.ctx_id = ARM64_CTX_END;
        end_ctx.ctx_size = sizeof(end_ctx);

        if (copyout(&end_ctx, (void *)ctx_addr, sizeof(end_ctx)) != 0)
                return (false);

        return (true);
}

static bool
sendsig_ctx_sve(struct thread *td, vm_offset_t *addrp)
{
        struct sve_context ctx;
        struct pcb *pcb;
        size_t buf_size, ctx_size;
        vm_offset_t ctx_addr;

        pcb = td->td_pcb;
        /* Do nothing if sve hasn't started */
        if (pcb->pcb_svesaved == NULL)
                return (true);

        MPASS(pcb->pcb_svesaved != NULL);

        buf_size = sve_buf_size(td);
        ctx_size = CTX_SIZE_SVE(buf_size);

        /* Address for the full context */
        *addrp -= ctx_size;
        ctx_addr = *addrp;

        memset(&ctx, 0, sizeof(ctx));
        ctx.sve_ctx.ctx_id = ARM64_CTX_SVE;
        ctx.sve_ctx.ctx_size = ctx_size;
        ctx.sve_vector_len = pcb->pcb_sve_len;
        ctx.sve_flags = 0;

        /* Copy out the header and data */
        if (copyout(&ctx, (void *)ctx_addr, sizeof(ctx)) != 0)
                return (false);
        if (copyout(pcb->pcb_svesaved, (void *)(ctx_addr + sizeof(ctx)),
            buf_size) != 0)
                return (false);

        return (true);
}

typedef bool(*ctx_func)(struct thread *, vm_offset_t *);
static const ctx_func ctx_funcs[] = {
        sendsig_ctx_end,        /* Must be first to end the linked list */
        sendsig_ctx_sve,
        NULL,
};

void
sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
{
        struct thread *td;
        struct proc *p;
        struct trapframe *tf;
        struct sigframe *fp, frame;
        struct sigacts *psp;
        vm_offset_t addr;
        int onstack, sig;

        td = curthread;
        p = td->td_proc;
        PROC_LOCK_ASSERT(p, MA_OWNED);

        sig = ksi->ksi_signo;
        psp = p->p_sigacts;
        mtx_assert(&psp->ps_mtx, MA_OWNED);

        tf = td->td_frame;
        onstack = sigonstack(tf->tf_sp);

        CTR4(KTR_SIG, "sendsig: td=%p (%s) catcher=%p sig=%d", td, p->p_comm,
            catcher, sig);

        /* Allocate and validate space for the signal handler context. */
        if ((td->td_pflags & TDP_ALTSTACK) != 0 && !onstack &&
            SIGISMEMBER(psp->ps_sigonstack, sig)) {
                addr = ((uintptr_t)td->td_sigstk.ss_sp +
                    td->td_sigstk.ss_size);
#if defined(COMPAT_43)
                td->td_sigstk.ss_flags |= SS_ONSTACK;
#endif
        } else {
                addr = td->td_frame->tf_sp;
        }

        /* Fill in the frame to copy out */
        bzero(&frame, sizeof(frame));
        get_mcontext(td, &frame.sf_uc.uc_mcontext, 0);
        frame.sf_si = ksi->ksi_info;
        frame.sf_uc.uc_sigmask = *mask;
        frame.sf_uc.uc_stack = td->td_sigstk;
        frame.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK) != 0 ?
            (onstack ? SS_ONSTACK : 0) : SS_DISABLE;
        mtx_unlock(&psp->ps_mtx);
        PROC_UNLOCK(td->td_proc);

        for (int i = 0; ctx_funcs[i] != NULL; i++) {
                if (!ctx_funcs[i](td, &addr)) {
                        /* Process has trashed its stack. Kill it. */
                        CTR4(KTR_SIG,
                            "sendsig: frame sigexit td=%p fp=%#lx func[%d]=%p",
                            td, addr, i, ctx_funcs[i]);
                        PROC_LOCK(p);
                        sigexit(td, SIGILL);
                        /* NOTREACHED */
                }
        }

        /* Point at the first context */
        frame.sf_uc.uc_mcontext.mc_ptr = addr;

        /* Make room, keeping the stack aligned */
        fp = (struct sigframe *)addr;
        fp--;
        fp = STACKALIGN(fp);

        /* Copy the sigframe out to the user's stack. */
        if (copyout(&frame, fp, sizeof(*fp)) != 0) {
                /* Process has trashed its stack. Kill it. */
                CTR2(KTR_SIG, "sendsig: sigexit td=%p fp=%p", td, fp);
                PROC_LOCK(p);
                sigexit(td, SIGILL);
        }

        tf->tf_x[0] = sig;
        tf->tf_x[1] = (register_t)&fp->sf_si;
        tf->tf_x[2] = (register_t)&fp->sf_uc;
        tf->tf_x[8] = (register_t)catcher;
        tf->tf_sp = (register_t)fp;
        tf->tf_elr = (register_t)PROC_SIGCODE(p);

        /* Clear the single step flag while in the signal handler */
        if ((td->td_pcb->pcb_flags & PCB_SINGLE_STEP) != 0) {
                td->td_pcb->pcb_flags &= ~PCB_SINGLE_STEP;
                WRITE_SPECIALREG(mdscr_el1,
                    READ_SPECIALREG(mdscr_el1) & ~MDSCR_SS);
                isb();
        }

        CTR3(KTR_SIG, "sendsig: return td=%p pc=%#x sp=%#x", td, tf->tf_elr,
            tf->tf_sp);

        PROC_LOCK(p);
        mtx_lock(&psp->ps_mtx);
}