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/*
* Minimal user-environment for testing BTI.
*
* Normal libc is not (yet) built with BTI support enabled,
* and so could generate a BTI TRAP before ever reaching main.
*/
#include <stdlib.h>
#include <signal.h>
#include <ucontext.h>
#include <asm/unistd.h>
int main(void);
void _start(void)
{
exit(main());
}
void exit(int ret)
{
register int x0 __asm__("x0") = ret;
register int x8 __asm__("x8") = __NR_exit;
asm volatile("svc #0" : : "r"(x0), "r"(x8));
__builtin_unreachable();
}
/*
* Irritatingly, the user API struct sigaction does not match the
* kernel API struct sigaction. So for simplicity, isolate the
* kernel ABI here, and make this act like signal.
*/
void signal_info(int sig, void (*fn)(int, siginfo_t *, ucontext_t *))
{
struct kernel_sigaction {
void (*handler)(int, siginfo_t *, ucontext_t *);
unsigned long flags;
unsigned long restorer;
unsigned long mask;
} sa = { fn, SA_SIGINFO, 0, 0 };
register int x0 __asm__("x0") = sig;
register void *x1 __asm__("x1") = &sa;
register void *x2 __asm__("x2") = 0;
register int x3 __asm__("x3") = sizeof(unsigned long);
register int x8 __asm__("x8") = __NR_rt_sigaction;
asm volatile("svc #0"
: : "r"(x0), "r"(x1), "r"(x2), "r"(x3), "r"(x8) : "memory");
}
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