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      1 /*
      2  * Copyright (c) 2016 Richard Palethorpe <richiejp (at) f-m.fm>
      3  *
      4  * This program is free software: you can redistribute it and/or modify
      5  * it under the terms of the GNU General Public License as published by
      6  * the Free Software Foundation, either version 2 of the License, or
      7  * (at your option) any later version.
      8  *
      9  * This program is distributed in the hope that it will be useful,
     10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     12  * GNU General Public License for more details.
     13  *
     14  * You should have received a copy of the GNU General Public License
     15  * along with this program. If not, see <http://www.gnu.org/licenses/>.
     16  */
     17 
     18 /*
     19  * Check that accessing a page marked with MADV_HWPOISON results in SIGBUS.
     20  *
     21  * Test flow: create child process,
     22  *	      map and write to memory,
     23  *	      mark memory with MADV_HWPOISON,
     24  *	      access memory,
     25  *	      if SIGBUS is delivered to child the test passes else it fails
     26  *
     27  * If the underlying page type of the memory we have mapped does not support
     28  * poisoning then the test will fail. We try to map and write to the memory in
     29  * such a way that by the time madvise is called the virtual memory address
     30  * points to a supported page. However there may be some rare circumstances
     31  * where the test produces the wrong result because we have somehow obtained
     32  * an unsupported page. In such cases madvise will probably return success,
     33  * but no SIGBUS will be produced.
     34  *
     35  * For more information see <linux source>/Documentation/vm/hwpoison.txt.
     36  */
     37 
     38 #include <stdlib.h>
     39 #include <stdio.h>
     40 #include <sys/wait.h>
     41 #include <fcntl.h>
     42 #include <unistd.h>
     43 #include <signal.h>
     44 #include <errno.h>
     45 #include <string.h>
     46 
     47 #include "tst_test.h"
     48 #include "lapi/mmap.h"
     49 
     50 static void run_child(void)
     51 {
     52 	const size_t msize = getpagesize();
     53 	void *mem = NULL;
     54 
     55 	tst_res(TINFO,
     56 		"mmap(0, %zu, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0)",
     57 		msize);
     58 	mem = SAFE_MMAP(NULL,
     59 			msize,
     60 			PROT_READ | PROT_WRITE,
     61 			MAP_ANONYMOUS | MAP_PRIVATE,
     62 			-1,
     63 			0);
     64 	memset(mem, 'L', msize);
     65 
     66 	tst_res(TINFO, "madvise(%p, %zu, MADV_HWPOISON)", mem, msize);
     67 	if (madvise(mem, msize, MADV_HWPOISON) == -1) {
     68 		if (errno == EINVAL) {
     69 			tst_res(TCONF | TERRNO,
     70 				"CONFIG_MEMORY_FAILURE probably not set in kconfig");
     71 		} else {
     72 			tst_res(TFAIL | TERRNO, "Could not poison memory");
     73 		}
     74 		exit(0);
     75 	}
     76 
     77 	*((char *)mem) = 'd';
     78 
     79 	tst_res(TFAIL, "Did not receive SIGBUS on accessing poisoned page");
     80 }
     81 
     82 static void run(void)
     83 {
     84 	int status;
     85 	pid_t pid;
     86 
     87 	pid = SAFE_FORK();
     88 	if (pid == 0) {
     89 		run_child();
     90 		exit(0);
     91 	}
     92 
     93 	SAFE_WAITPID(pid, &status, 0);
     94 	if (WIFSIGNALED(status) && WTERMSIG(status) == SIGBUS) {
     95 		tst_res(TPASS, "Received SIGBUS after accessing poisoned page");
     96 		return;
     97 	}
     98 
     99 	if (WIFEXITED(status) && WEXITSTATUS(status) == 0)
    100 		return;
    101 
    102 	tst_res(TFAIL, "Child %s", tst_strstatus(status));
    103 }
    104 
    105 static struct tst_test test = {
    106 	.test_all = run,
    107 	.min_kver = "2.6.31",
    108 	.needs_root = 1,
    109 	.forks_child = 1
    110 };
    111 
    112