cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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stack_expansion_signal.c (2310B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Test that signal delivery is able to expand the stack segment without
      4 * triggering a SEGV.
      5 *
      6 * Based on test code by Tom Lane.
      7 */
      8
      9#include <err.h>
     10#include <stdio.h>
     11#include <stdlib.h>
     12#include <signal.h>
     13#include <sys/types.h>
     14#include <unistd.h>
     15
     16#include "../pmu/lib.h"
     17#include "utils.h"
     18
     19#define _KB (1024)
     20#define _MB (1024 * 1024)
     21
     22static char *stack_base_ptr;
     23static char *stack_top_ptr;
     24
     25static volatile sig_atomic_t sig_occurred = 0;
     26
     27static void sigusr1_handler(int signal_arg)
     28{
     29	sig_occurred = 1;
     30}
     31
     32static int consume_stack(unsigned int stack_size, union pipe write_pipe)
     33{
     34	char stack_cur;
     35
     36	if ((stack_base_ptr - &stack_cur) < stack_size)
     37		return consume_stack(stack_size, write_pipe);
     38	else {
     39		stack_top_ptr = &stack_cur;
     40
     41		FAIL_IF(notify_parent(write_pipe));
     42
     43		while (!sig_occurred)
     44			barrier();
     45	}
     46
     47	return 0;
     48}
     49
     50static int child(unsigned int stack_size, union pipe write_pipe)
     51{
     52	struct sigaction act;
     53	char stack_base;
     54
     55	act.sa_handler = sigusr1_handler;
     56	sigemptyset(&act.sa_mask);
     57	act.sa_flags = 0;
     58	if (sigaction(SIGUSR1, &act, NULL) < 0)
     59		err(1, "sigaction");
     60
     61	stack_base_ptr = (char *) (((size_t) &stack_base + 65535) & ~65535UL);
     62
     63	FAIL_IF(consume_stack(stack_size, write_pipe));
     64
     65	printf("size 0x%06x: OK, stack base %p top %p (%zx used)\n",
     66		stack_size, stack_base_ptr, stack_top_ptr,
     67		stack_base_ptr - stack_top_ptr);
     68
     69	return 0;
     70}
     71
     72static int test_one_size(unsigned int stack_size)
     73{
     74	union pipe read_pipe, write_pipe;
     75	pid_t pid;
     76
     77	FAIL_IF(pipe(read_pipe.fds) == -1);
     78	FAIL_IF(pipe(write_pipe.fds) == -1);
     79
     80	pid = fork();
     81	if (pid == 0) {
     82		close(read_pipe.read_fd);
     83		close(write_pipe.write_fd);
     84		exit(child(stack_size, read_pipe));
     85	}
     86
     87	close(read_pipe.write_fd);
     88	close(write_pipe.read_fd);
     89	FAIL_IF(sync_with_child(read_pipe, write_pipe));
     90
     91	kill(pid, SIGUSR1);
     92
     93	FAIL_IF(wait_for_child(pid));
     94
     95	close(read_pipe.read_fd);
     96	close(write_pipe.write_fd);
     97
     98	return 0;
     99}
    100
    101int test(void)
    102{
    103	unsigned int i, size;
    104
    105	// Test with used stack from 1MB - 64K to 1MB + 64K
    106	// Increment by 64 to get more coverage of odd sizes
    107	for (i = 0; i < (128 * _KB); i += 64) {
    108		size = i + (1 * _MB) - (64 * _KB);
    109		FAIL_IF(test_one_size(size));
    110	}
    111
    112	return 0;
    113}
    114
    115int main(void)
    116{
    117	return test_harness(test, "stack_expansion_signal");
    118}