/*
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright 2026 The FreeBSD Foundation
 *
 * This software were developed by
 * Konstantin Belousov <kib@FreeBSD.org> under sponsorship from
 * the FreeBSD Foundation.
 */

#include <sys/syscall.h>
#include <err.h>
#include <signal.h>
#include <stdatomic.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#ifndef __amd64__
#error "amd64 only"
#endif

/*
 * The check to see how "INT $0x80" behaves for amd64 native ABI
 * processes.  Before bd8edba0792b71be3f8ed5dea9c22287e95c986a it
 * executed syscalls with amd64 calling conventions.  After that
 * revision, it should raise SIGBUS.
 */

static uintptr_t int0x80_loc;
static int signo;
extern char after_int0x80[];

static void
sigill_action(int signo1, siginfo_t *si __unused, void *uctxv)
{
        ucontext_t *uctx = uctxv;

        signo = signo1;
        int0x80_loc = uctx->uc_mcontext.mc_rip;
}

static int
fire(void)
{
        int res;

        res = SYS_getpid;
        asm volatile(
            ".globl\tafter_int0x80\n"
            "\tint\t$0x80\n"
            "after_int0x80:"
            : "+a" (res)
            :
            : "rdx", "memory", "cc");
        return (res);
}

int
main(void)
{
        struct sigaction sa;
        char signame[SIG2STR_MAX];
        int pid, res;

        res = 0;

        memset(&sa, 0, sizeof(sa));
        sa.sa_sigaction = sigill_action;
        sa.sa_flags = SA_SIGINFO;
        if (sigaction(SIGBUS, &sa, NULL) == -1)
                err(1, "catching SIGBUS");

        pid = fire();
        atomic_signal_fence(memory_order_seq_cst);
        if (int0x80_loc == 0) {
                printf("int $0x80 does not raise SIGBUS\n");
                if (pid == getpid())
                        printf("and syscall worked\n");
                else
                        printf("but syscall did not worked\n");
                res = 1;
        } else {
                sig2str(signo, signame);
                printf("int $0x80 raises SIG%s\n", signame);
                if (int0x80_loc == (uintptr_t)after_int0x80) {
                        printf("at expected location\n");
                } else {
                        printf("not at expected location\n");
                        res = 1;
                }
        }
        exit(res);
}