1 /* Licensed under Apache License v2.0 - see LICENSE file for details */
13 static __thread char ebuf[ALTSTACK_ERR_MAXLEN];
14 static __thread unsigned elen;
17 (elen += snprintf(ebuf + elen, sizeof(ebuf) - elen, \
18 "%s(altstack@%d) %s%s%s", \
19 elen ? "; " : "", __LINE__, (x), \
20 errno ? ": " : "", errno ? strerror(errno) : ""))
22 void altstack_perror(void)
24 fprintf(stderr, "%s\n", ebuf);
27 char *altstack_geterr(void)
32 static __thread jmp_buf jmp;
34 static void segvjmp(int signum)
39 static __thread void *rsp_save_[2];
41 static ptrdiff_t rsp_save(unsigned i) {
43 asm volatile ("movq %%rsp, %0" : "=g" (rsp_save_[i]));
44 return (char *) rsp_save_[0] - (char *) rsp_save_[i];
47 void altstack_rsp_save(void) {
51 ptrdiff_t altstack_used(void) {
55 static __thread void *(*fn_)(void *);
56 static __thread void *arg_, *out_;
58 int altstack(rlim_t max, void *(*fn)(void *), void *arg, void **out)
60 int ret = -1, undo = 0;
62 struct rlimit rl_save;
63 struct sigaction sa_save;
66 assert(max > 0 && fn);
67 #define ok(x, y) ({ long __r = (long) (x); if (__r == -1) { bang(#x); if (y) goto out; } __r; })
72 ebuf[elen = 0] = '\0';
75 ok(getrlimit(RLIMIT_STACK, &rl_save), 1);
76 ok(setrlimit(RLIMIT_STACK, &(struct rlimit) { max, rl_save.rlim_max }), 1);
79 ok(m = mmap(0, max, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_GROWSDOWN|MAP_NORESERVE, -1, 0), 1);
82 if (setjmp(jmp) == 0) {
83 unsigned char sigstk[MINSIGSTKSZ];
84 stack_t ss = { .ss_sp = sigstk, .ss_size = sizeof(sigstk) };
85 struct sigaction sa = { .sa_handler = segvjmp, .sa_flags = SA_NODEFER|SA_RESETHAND|SA_ONSTACK };
87 ok(sigaltstack(&ss, 0), 1);
90 sigemptyset(&sa.sa_mask);
91 ok(sigaction(SIGSEGV, &sa, &sa_save), 1);
94 asm volatile ("movq %%rsp, %%r10\nmov %0, %%rsp\npush %%r10" : : "g" (m + max) : "r10");
97 asm volatile ("pop %rsp");
103 bang("SIGSEGV caught");
112 ok(sigaction(SIGSEGV, &sa_save, 0), 0);
114 ok(sigaltstack(&(stack_t) { .ss_flags = SS_DISABLE }, 0), 0);
116 ok(munmap(m, max), 0);
118 ok(setrlimit(RLIMIT_STACK, &rl_save), 0);
123 return !ret && elen ? 1 : ret;