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