selftest/sigaltstack: Use the AT_MINSIGSTKSZ aux vector if available
The SIGSTKSZ constant may not represent enough stack size in some architectures as the hardware state size grows. Use getauxval(AT_MINSIGSTKSZ) to increase the stack size. Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Len Brown <len.brown@intel.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20210518200320.17239-5-chang.seok.bae@intel.com
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@ -17,6 +17,7 @@
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#include <string.h>
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#include <assert.h>
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#include <errno.h>
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#include <sys/auxv.h>
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#include "../kselftest.h"
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@ -24,6 +25,11 @@
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#define SS_AUTODISARM (1U << 31)
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#endif
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#ifndef AT_MINSIGSTKSZ
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#define AT_MINSIGSTKSZ 51
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#endif
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static unsigned int stack_size;
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static void *sstack, *ustack;
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static ucontext_t uc, sc;
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static const char *msg = "[OK]\tStack preserved";
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@ -47,7 +53,7 @@ void my_usr1(int sig, siginfo_t *si, void *u)
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#endif
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if (sp < (unsigned long)sstack ||
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sp >= (unsigned long)sstack + SIGSTKSZ) {
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sp >= (unsigned long)sstack + stack_size) {
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ksft_exit_fail_msg("SP is not on sigaltstack\n");
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}
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/* put some data on stack. other sighandler will try to overwrite it */
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@ -108,6 +114,10 @@ int main(void)
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stack_t stk;
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int err;
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/* Make sure more than the required minimum. */
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stack_size = getauxval(AT_MINSIGSTKSZ) + SIGSTKSZ;
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ksft_print_msg("[NOTE]\tthe stack size is %lu\n", stack_size);
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ksft_print_header();
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ksft_set_plan(3);
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@ -117,7 +127,7 @@ int main(void)
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sigaction(SIGUSR1, &act, NULL);
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act.sa_sigaction = my_usr2;
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sigaction(SIGUSR2, &act, NULL);
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sstack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
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sstack = mmap(NULL, stack_size, PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
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if (sstack == MAP_FAILED) {
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ksft_exit_fail_msg("mmap() - %s\n", strerror(errno));
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@ -139,7 +149,7 @@ int main(void)
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}
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stk.ss_sp = sstack;
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stk.ss_size = SIGSTKSZ;
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stk.ss_size = stack_size;
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stk.ss_flags = SS_ONSTACK | SS_AUTODISARM;
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err = sigaltstack(&stk, NULL);
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if (err) {
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@ -161,7 +171,7 @@ int main(void)
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}
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}
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ustack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
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ustack = mmap(NULL, stack_size, PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
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if (ustack == MAP_FAILED) {
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ksft_exit_fail_msg("mmap() - %s\n", strerror(errno));
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@ -170,7 +180,7 @@ int main(void)
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getcontext(&uc);
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uc.uc_link = NULL;
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uc.uc_stack.ss_sp = ustack;
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uc.uc_stack.ss_size = SIGSTKSZ;
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uc.uc_stack.ss_size = stack_size;
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makecontext(&uc, switch_fn, 0);
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raise(SIGUSR1);
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