| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * Copyright (c) 2018 Jan Stancek. All rights reserved. |
| */ |
| /* |
| * Test: Spawn 2 threads. First thread maps, writes and unmaps |
| * an area. Second thread tries to read from it. Second thread |
| * races against first thread. There is no synchronization |
| * between threads, but each mmap/munmap increases a counter |
| * that is checked to determine when has read occurred. If a read |
| * hit SIGSEGV in between mmap/munmap it is a failure. If a read |
| * between mmap/munmap worked, then its value must match expected |
| * value. |
| */ |
| #include <errno.h> |
| #include <float.h> |
| #include <pthread.h> |
| #include <sched.h> |
| #include <setjmp.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include "tst_test.h" |
| #include "tst_safe_pthread.h" |
| |
| #define DISTANT_MMAP_SIZE (64*1024*1024) |
| #define TEST_FILENAME "ashfile" |
| |
| /* seconds remaining before reaching timeout */ |
| #define STOP_THRESHOLD 10 |
| |
| #define PROGRESS_SEC 3 |
| |
| static int file_size = 1024; |
| static int num_iter = 5000; |
| static float exec_time = 0.05; /* default is 3 min */ |
| |
| static void *distant_area; |
| static char *str_exec_time; |
| static jmp_buf jmpbuf; |
| static volatile unsigned char *map_address; |
| static unsigned long page_sz; |
| |
| static unsigned long mapped_sigsegv_count; |
| static unsigned long map_count; |
| static unsigned long threads_spawned; |
| static unsigned long data_matched; |
| static unsigned long repeated_reads; |
| |
| /* sequence id for each map/unmap performed */ |
| static int mapcnt, unmapcnt; |
| /* stored sequence id before making read attempt */ |
| static int br_map, br_unmap; |
| |
| static struct tst_option options[] = { |
| {"x:", &str_exec_time, "Exec time (hours)"}, |
| {NULL, NULL, NULL} |
| }; |
| |
| /* compare "before read" counters with "after read" counters */ |
| static inline int was_area_mapped(int br_m, int br_u, int ar_m, int ar_u) |
| { |
| return (br_m == ar_m && br_u == ar_u && br_m > br_u); |
| } |
| |
| static void sig_handler(int signal, siginfo_t *info, |
| LTP_ATTRIBUTE_UNUSED void *ut) |
| { |
| int ar_m, ar_u; |
| |
| switch (signal) { |
| case SIGSEGV: |
| /* if we hit SIGSEGV between map/unmap, something is wrong */ |
| ar_u = tst_atomic_load(&unmapcnt); |
| ar_m = tst_atomic_load(&mapcnt); |
| if (was_area_mapped(br_map, br_unmap, ar_m, ar_u)) { |
| tst_res(TFAIL, "got sigsegv while mapped"); |
| _exit(TFAIL); |
| } |
| |
| mapped_sigsegv_count++; |
| longjmp(jmpbuf, 1); |
| break; |
| default: |
| tst_res(TFAIL, "Unexpected signal - %d, addr: %p, exiting\n", |
| signal, info->si_addr); |
| _exit(TBROK); |
| } |
| } |
| |
| void *map_write_unmap(void *ptr) |
| { |
| int *fd = ptr; |
| void *tmp; |
| int i, j; |
| |
| for (i = 0; i < num_iter; i++) { |
| map_address = SAFE_MMAP(distant_area, |
| (size_t) file_size, PROT_WRITE | PROT_READ, |
| MAP_SHARED, *fd, 0); |
| tst_atomic_inc(&mapcnt); |
| |
| for (j = 0; j < file_size; j++) |
| map_address[j] = 'b'; |
| |
| tmp = (void *)map_address; |
| tst_atomic_inc(&unmapcnt); |
| SAFE_MUNMAP(tmp, file_size); |
| |
| map_count++; |
| } |
| |
| return NULL; |
| } |
| |
| void *read_mem(LTP_ATTRIBUTE_UNUSED void *ptr) |
| { |
| volatile int i; /* longjmp could clobber i */ |
| int j, ar_map, ar_unmap; |
| unsigned char c; |
| |
| for (i = 0; i < num_iter; i++) { |
| if (setjmp(jmpbuf) == 1) |
| continue; |
| |
| for (j = 0; j < file_size; j++) { |
| read_again: |
| br_map = tst_atomic_load(&mapcnt); |
| br_unmap = tst_atomic_load(&unmapcnt); |
| |
| c = map_address[j]; |
| |
| ar_unmap = tst_atomic_load(&unmapcnt); |
| ar_map = tst_atomic_load(&mapcnt); |
| |
| /* |
| * Read above is racing against munmap and mmap |
| * in other thread. While the address might be valid |
| * the mapping could be in various stages of being |
| * 'ready'. We only check the value, if we can be sure |
| * read hapenned in between single mmap and munmap as |
| * observed by first thread. |
| */ |
| if (was_area_mapped(br_map, br_unmap, ar_map, |
| ar_unmap)) { |
| switch (c) { |
| case 'a': |
| repeated_reads++; |
| goto read_again; |
| case 'b': |
| data_matched++; |
| break; |
| default: |
| tst_res(TFAIL, "value[%d] is %c", j, c); |
| break; |
| } |
| } |
| } |
| } |
| |
| return NULL; |
| } |
| |
| int mkfile(int size) |
| { |
| int fd, i; |
| |
| fd = SAFE_OPEN(TEST_FILENAME, O_RDWR | O_CREAT, 0600); |
| SAFE_UNLINK(TEST_FILENAME); |
| |
| for (i = 0; i < size; i++) |
| SAFE_WRITE(1, fd, "a", 1); |
| SAFE_WRITE(1, fd, "\0", 1); |
| |
| if (fsync(fd) == -1) |
| tst_brk(TBROK | TERRNO, "fsync()"); |
| |
| return fd; |
| } |
| |
| static void setup(void) |
| { |
| struct sigaction sigptr; |
| |
| page_sz = getpagesize(); |
| |
| /* |
| * Used as hint for mmap thread, so it doesn't interfere |
| * with other potential (temporary) mappings from libc |
| */ |
| distant_area = SAFE_MMAP(0, DISTANT_MMAP_SIZE, PROT_WRITE | PROT_READ, |
| MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); |
| SAFE_MUNMAP(distant_area, (size_t)DISTANT_MMAP_SIZE); |
| distant_area += DISTANT_MMAP_SIZE / 2; |
| |
| if (tst_parse_float(str_exec_time, &exec_time, 0, FLT_MAX)) { |
| tst_brk(TBROK, "Invalid number for exec_time '%s'", |
| str_exec_time); |
| } |
| |
| sigptr.sa_sigaction = sig_handler; |
| sigemptyset(&sigptr.sa_mask); |
| sigptr.sa_flags = SA_SIGINFO | SA_NODEFER; |
| SAFE_SIGACTION(SIGSEGV, &sigptr, NULL); |
| |
| tst_set_timeout((int)(exec_time * 3600)); |
| } |
| |
| static void run(void) |
| { |
| pthread_t thid[2]; |
| int remaining = tst_timeout_remaining(); |
| int elapsed = 0; |
| |
| while (tst_timeout_remaining() > STOP_THRESHOLD) { |
| int fd = mkfile(file_size); |
| |
| tst_atomic_store(0, &mapcnt); |
| tst_atomic_store(0, &unmapcnt); |
| |
| SAFE_PTHREAD_CREATE(&thid[0], NULL, map_write_unmap, &fd); |
| SAFE_PTHREAD_CREATE(&thid[1], NULL, read_mem, &fd); |
| threads_spawned += 2; |
| |
| SAFE_PTHREAD_JOIN(thid[0], NULL); |
| SAFE_PTHREAD_JOIN(thid[1], NULL); |
| |
| close(fd); |
| |
| if (remaining - tst_timeout_remaining() > PROGRESS_SEC) { |
| remaining = tst_timeout_remaining(); |
| elapsed += PROGRESS_SEC; |
| tst_res(TINFO, "[%d] mapped: %lu, sigsegv hit: %lu, " |
| "threads spawned: %lu", elapsed, map_count, |
| mapped_sigsegv_count, threads_spawned); |
| tst_res(TINFO, "[%d] repeated_reads: %ld, " |
| "data_matched: %lu", elapsed, repeated_reads, |
| data_matched); |
| } |
| } |
| tst_res(TPASS, "System survived."); |
| } |
| |
| static struct tst_test test = { |
| .test_all = run, |
| .setup = setup, |
| .options = options, |
| .needs_tmpdir = 1, |
| }; |