// Copyright 2020 the V8 project authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #include "src/d8/cov.h" #include <fcntl.h> #include <inttypes.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/mman.h> #include <sys/stat.h> #include <sys/wait.h> #include <unistd.h> #include "src/base/platform/wrappers.h" #define SHM_SIZE 0x100000 #define MAX_EDGES ((SHM_SIZE - 4) * 8) struct shmem_data { uint32_t num_edges; unsigned char edges[]; }; struct shmem_data* shmem; uint32_t *edges_start, *edges_stop; uint32_t builtins_start; uint32_t builtins_edge_count; void sanitizer_cov_reset_edgeguards() { uint32_t N = 0; for (uint32_t* x = edges_start; x < edges_stop && N < MAX_EDGES; x++) *x = ++N; } extern "C" void __sanitizer_cov_trace_pc_guard_init(uint32_t* start, uint32_t* stop) { // Map the shared memory region const char* shm_key = getenv("SHM_ID"); if (!shm_key) { puts("[COV] no shared memory bitmap available, skipping"); shmem = (struct shmem_data*)v8::base::Malloc(SHM_SIZE); } else { int fd = shm_open(shm_key, O_RDWR, S_IREAD | S_IWRITE); if (fd <= -1) { fprintf(stderr, "[COV] Failed to open shared memory region\n"); _exit(-1); } shmem = (struct shmem_data*)mmap(0, SHM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if (shmem == MAP_FAILED) { fprintf(stderr, "[COV] Failed to mmap shared memory region\n"); _exit(-1); } } edges_start = start; edges_stop = stop; sanitizer_cov_reset_edgeguards(); shmem->num_edges = static_cast<uint32_t>(stop - start); builtins_start = 1 + shmem->num_edges; printf("[COV] edge counters initialized. Shared memory: %s with %u edges\n", shm_key, shmem->num_edges); } uint32_t sanitizer_cov_count_discovered_edges() { uint32_t on_edges_counter = 0; for (uint32_t i = 1; i < builtins_start; ++i) { // TODO(ralbovsky): Can be optimized for fewer divisions. if (shmem->edges[i / 8] & (1 << (i % 8))) { ++on_edges_counter; } } return on_edges_counter; } extern "C" void __sanitizer_cov_trace_pc_guard(uint32_t* guard) { // There's a small race condition here: if this function executes in two // threads for the same edge at the same time, the first thread might disable // the edge (by setting the guard to zero) before the second thread fetches // the guard value (and thus the index). However, our instrumentation ignores // the first edge (see libcoverage.c) and so the race is unproblematic. uint32_t index = *guard; shmem->edges[index / 8] |= 1 << (index % 8); *guard = 0; } void cov_init_builtins_edges(uint32_t num_edges) { if (num_edges + shmem->num_edges > MAX_EDGES) { printf( "[COV] Error: Insufficient amount of edges left for builtins " "coverage.\n"); exit(-1); } builtins_edge_count = num_edges; builtins_start = 1 + shmem->num_edges; shmem->num_edges += builtins_edge_count; printf("[COV] Additional %d edges for builtins initialized.\n", num_edges); } // This function is ran once per REPRL loop. In case of crash the coverage of // crash will not be stored in shared memory. Therefore, it would be useful, if // we could store these coverage information into shared memory in real time. void cov_update_builtins_basic_block_coverage( const std::vector<bool>& cov_map) { if (cov_map.size() != builtins_edge_count) { printf("[COV] Error: Size of builtins cov map changed.\n"); exit(-1); } for (uint32_t i = 0; i < cov_map.size(); ++i) { if (cov_map[i]) { // TODO(ralbovsky): Can be optimized for fewer divisions. shmem->edges[(i + builtins_start) / 8] |= (1 << ((i + builtins_start) % 8)); } } }