Source code
Revision control
Copy as Markdown
Other Tools
/*
* Copyright 2018 WebAssembly Community Group participants
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "wasm-rt-impl.h"
#include <assert.h>
#include <math.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#if WASM_RT_INSTALL_SIGNAL_HANDLER && !defined(_WIN32)
#include <signal.h>
#include <unistd.h>
#endif
#ifdef _WIN32
#include <windows.h>
#else
#include <sys/mman.h>
#endif
#define PAGE_SIZE 65536
#if WASM_RT_INSTALL_SIGNAL_HANDLER
static bool g_signal_handler_installed = false;
#ifdef _WIN32
static void* g_sig_handler_handle = 0;
#else
static char* g_alt_stack = 0;
#endif
#endif
#if WASM_RT_USE_STACK_DEPTH_COUNT
WASM_RT_THREAD_LOCAL uint32_t wasm_rt_call_stack_depth;
WASM_RT_THREAD_LOCAL uint32_t wasm_rt_saved_call_stack_depth;
#endif
WASM_RT_THREAD_LOCAL wasm_rt_jmp_buf g_wasm_rt_jmp_buf;
#ifdef WASM_RT_TRAP_HANDLER
extern void WASM_RT_TRAP_HANDLER(wasm_rt_trap_t code);
#endif
#ifdef WASM_RT_GROW_FAILED_HANDLER
extern void WASM_RT_GROW_FAILED_HANDLER();
#endif
void wasm_rt_trap(wasm_rt_trap_t code) {
assert(code != WASM_RT_TRAP_NONE);
#if WASM_RT_USE_STACK_DEPTH_COUNT
wasm_rt_call_stack_depth = wasm_rt_saved_call_stack_depth;
#endif
#ifdef WASM_RT_TRAP_HANDLER
WASM_RT_TRAP_HANDLER(code);
wasm_rt_unreachable();
#else
WASM_RT_LONGJMP(g_wasm_rt_jmp_buf, code);
#endif
}
#ifdef _WIN32
static void* os_mmap(size_t size) {
void* ret = VirtualAlloc(NULL, size, MEM_RESERVE, PAGE_NOACCESS);
return ret;
}
static int os_munmap(void* addr, size_t size) {
// Windows can only unmap the whole mapping
(void)size; /* unused */
BOOL succeeded = VirtualFree(addr, 0, MEM_RELEASE);
return succeeded ? 0 : -1;
}
static int os_mprotect(void* addr, size_t size) {
if (size == 0) {
return 0;
}
void* ret = VirtualAlloc(addr, size, MEM_COMMIT, PAGE_READWRITE);
if (ret == addr) {
return 0;
}
VirtualFree(addr, 0, MEM_RELEASE);
return -1;
}
static void os_print_last_error(const char* msg) {
DWORD errorMessageID = GetLastError();
if (errorMessageID != 0) {
LPSTR messageBuffer = 0;
// The api creates the buffer that holds the message
size_t size = FormatMessageA(
FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
FORMAT_MESSAGE_IGNORE_INSERTS,
NULL, errorMessageID, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
(LPSTR)&messageBuffer, 0, NULL);
(void)size;
printf("%s. %s\n", msg, messageBuffer);
LocalFree(messageBuffer);
} else {
printf("%s. No error code.\n", msg);
}
}
#if WASM_RT_INSTALL_SIGNAL_HANDLER
static LONG os_signal_handler(PEXCEPTION_POINTERS info) {
if (info->ExceptionRecord->ExceptionCode == EXCEPTION_ACCESS_VIOLATION) {
wasm_rt_trap(WASM_RT_TRAP_OOB);
} else if (info->ExceptionRecord->ExceptionCode == EXCEPTION_STACK_OVERFLOW) {
wasm_rt_trap(WASM_RT_TRAP_EXHAUSTION);
}
return EXCEPTION_CONTINUE_SEARCH;
}
static void os_install_signal_handler(void) {
g_sig_handler_handle =
AddVectoredExceptionHandler(1 /* CALL_FIRST */, os_signal_handler);
}
static void os_cleanup_signal_handler(void) {
RemoveVectoredExceptionHandler(g_sig_handler_handle);
}
#endif
#else
static void* os_mmap(size_t size) {
int map_prot = PROT_NONE;
int map_flags = MAP_ANONYMOUS | MAP_PRIVATE;
uint8_t* addr = mmap(NULL, size, map_prot, map_flags, -1, 0);
if (addr == MAP_FAILED)
return NULL;
return addr;
}
static int os_munmap(void* addr, size_t size) {
return munmap(addr, size);
}
static int os_mprotect(void* addr, size_t size) {
return mprotect(addr, size, PROT_READ | PROT_WRITE);
}
static void os_print_last_error(const char* msg) {
perror(msg);
}
#if WASM_RT_INSTALL_SIGNAL_HANDLER
static void os_signal_handler(int sig, siginfo_t* si, void* unused) {
if (si->si_code == SEGV_ACCERR) {
wasm_rt_trap(WASM_RT_TRAP_OOB);
} else {
wasm_rt_trap(WASM_RT_TRAP_EXHAUSTION);
}
}
static void os_install_signal_handler(void) {
/* Use alt stack to handle SIGSEGV from stack overflow */
g_alt_stack = malloc(SIGSTKSZ);
if (g_alt_stack == NULL) {
perror("malloc failed");
abort();
}
stack_t ss;
ss.ss_sp = g_alt_stack;
ss.ss_flags = 0;
ss.ss_size = SIGSTKSZ;
if (sigaltstack(&ss, NULL) != 0) {
perror("sigaltstack failed");
abort();
}
struct sigaction sa;
memset(&sa, '\0', sizeof(sa));
sa.sa_flags = SA_SIGINFO | SA_ONSTACK;
sigemptyset(&sa.sa_mask);
sa.sa_sigaction = os_signal_handler;
/* Install SIGSEGV and SIGBUS handlers, since macOS seems to use SIGBUS. */
if (sigaction(SIGSEGV, &sa, NULL) != 0 || sigaction(SIGBUS, &sa, NULL) != 0) {
perror("sigaction failed");
abort();
}
}
static void os_cleanup_signal_handler(void) {
/* Undo what was done in os_install_signal_handler */
struct sigaction sa;
memset(&sa, '\0', sizeof(sa));
sa.sa_handler = SIG_DFL;
if (sigaction(SIGSEGV, &sa, NULL) != 0 || sigaction(SIGBUS, &sa, NULL)) {
perror("sigaction failed");
abort();
}
if (sigaltstack(NULL, NULL) != 0) {
perror("sigaltstack failed");
abort();
}
free(g_alt_stack);
}
#endif
#endif
void wasm_rt_init(void) {
#if WASM_RT_INSTALL_SIGNAL_HANDLER
if (!g_signal_handler_installed) {
g_signal_handler_installed = true;
os_install_signal_handler();
}
#endif
}
bool wasm_rt_is_initialized(void) {
#if WASM_RT_INSTALL_SIGNAL_HANDLER
return g_signal_handler_installed;
#else
return true;
#endif
}
void wasm_rt_free(void) {
#if WASM_RT_INSTALL_SIGNAL_HANDLER
os_cleanup_signal_handler();
g_signal_handler_installed = false;
#endif
}
#if WASM_RT_USE_MMAP
static uint64_t get_allocation_size_for_mmap(wasm_rt_memory_t* memory) {
assert(!memory->is64 &&
"memory64 is not yet compatible with WASM_RT_USE_MMAP");
#if WASM_RT_MEMCHECK_GUARD_PAGES
/* Reserve 8GiB. */
const uint64_t max_size = 0x200000000ul;
return max_size;
#else
if (memory->max_pages != 0) {
const uint64_t max_size = memory->max_pages * PAGE_SIZE;
return max_size;
}
/* Reserve 4GiB. */
const uint64_t max_size = 0x100000000ul;
return max_size;
#endif
}
#endif
void wasm_rt_allocate_memory(wasm_rt_memory_t* memory,
uint64_t initial_pages,
uint64_t max_pages,
bool is64) {
uint64_t byte_length = initial_pages * PAGE_SIZE;
memory->size = byte_length;
memory->pages = initial_pages;
memory->max_pages = max_pages;
memory->is64 = is64;
#if WASM_RT_USE_MMAP
const uint64_t mmap_size = get_allocation_size_for_mmap(memory);
void* addr = os_mmap(mmap_size);
if (!addr) {
os_print_last_error("os_mmap failed.");
abort();
}
int ret = os_mprotect(addr, byte_length);
if (ret != 0) {
os_print_last_error("os_mprotect failed.");
abort();
}
memory->data = addr;
#else
memory->data = calloc(byte_length, 1);
#endif
}
static uint64_t grow_memory_impl(wasm_rt_memory_t* memory, uint64_t delta) {
uint64_t old_pages = memory->pages;
uint64_t new_pages = memory->pages + delta;
if (new_pages == 0) {
return 0;
}
if (new_pages < old_pages || new_pages > memory->max_pages) {
return (uint64_t)-1;
}
uint64_t old_size = old_pages * PAGE_SIZE;
uint64_t new_size = new_pages * PAGE_SIZE;
uint64_t delta_size = delta * PAGE_SIZE;
#if WASM_RT_USE_MMAP
uint8_t* new_data = memory->data;
int ret = os_mprotect(new_data + old_size, delta_size);
if (ret != 0) {
return (uint64_t)-1;
}
#else
uint8_t* new_data = realloc(memory->data, new_size);
if (new_data == NULL) {
return (uint64_t)-1;
}
#if !WABT_BIG_ENDIAN
memset(new_data + old_size, 0, delta_size);
#endif
#endif
#if WABT_BIG_ENDIAN
memmove(new_data + new_size - old_size, new_data, old_size);
memset(new_data, 0, delta_size);
#endif
memory->pages = new_pages;
memory->size = new_size;
memory->data = new_data;
return old_pages;
}
uint64_t wasm_rt_grow_memory(wasm_rt_memory_t* memory, uint64_t delta) {
uint64_t ret = grow_memory_impl(memory, delta);
#ifdef WASM_RT_GROW_FAILED_HANDLER
if (ret == -1) {
WASM_RT_GROW_FAILED_HANDLER();
}
#endif
return ret;
}
void wasm_rt_free_memory(wasm_rt_memory_t* memory) {
#if WASM_RT_USE_MMAP
const uint64_t mmap_size = get_allocation_size_for_mmap(memory);
os_munmap(memory->data, mmap_size); // ignore error
#else
free(memory->data);
#endif
}
#define DEFINE_TABLE_OPS(type) \
void wasm_rt_allocate_##type##_table(wasm_rt_##type##_table_t* table, \
uint32_t elements, \
uint32_t max_elements) { \
table->size = elements; \
table->max_size = max_elements; \
table->data = calloc(table->size, sizeof(wasm_rt_##type##_t)); \
} \
void wasm_rt_free_##type##_table(wasm_rt_##type##_table_t* table) { \
free(table->data); \
} \
uint32_t wasm_rt_grow_##type##_table(wasm_rt_##type##_table_t* table, \
uint32_t delta, \
wasm_rt_##type##_t init) { \
uint32_t old_elems = table->size; \
uint64_t new_elems = (uint64_t)table->size + delta; \
if (new_elems == 0) { \
return 0; \
} \
if ((new_elems < old_elems) || (new_elems > table->max_size)) { \
return (uint32_t)-1; \
} \
void* new_data = \
realloc(table->data, new_elems * sizeof(wasm_rt_##type##_t)); \
if (!new_data) { \
return (uint32_t)-1; \
} \
table->data = new_data; \
table->size = new_elems; \
for (uint32_t i = old_elems; i < new_elems; i++) { \
table->data[i] = init; \
} \
return old_elems; \
}
DEFINE_TABLE_OPS(funcref)
DEFINE_TABLE_OPS(externref)
const char* wasm_rt_strerror(wasm_rt_trap_t trap) {
switch (trap) {
case WASM_RT_TRAP_NONE:
return "No error";
case WASM_RT_TRAP_OOB:
#if WASM_RT_MERGED_OOB_AND_EXHAUSTION_TRAPS
return "Out-of-bounds access in linear memory or a table, or call stack "
"exhausted";
#else
return "Out-of-bounds access in linear memory or a table";
case WASM_RT_TRAP_EXHAUSTION:
return "Call stack exhausted";
#endif
case WASM_RT_TRAP_INT_OVERFLOW:
return "Integer overflow on divide or truncation";
case WASM_RT_TRAP_DIV_BY_ZERO:
return "Integer divide by zero";
case WASM_RT_TRAP_INVALID_CONVERSION:
return "Conversion from NaN to integer";
case WASM_RT_TRAP_UNREACHABLE:
return "Unreachable instruction executed";
case WASM_RT_TRAP_CALL_INDIRECT:
return "Invalid call_indirect";
case WASM_RT_TRAP_UNCAUGHT_EXCEPTION:
return "Uncaught exception";
}
return "invalid trap code";
}