diff options
| -rw-r--r-- | js/src/jsnativestack.cpp | 68 |
1 files changed, 65 insertions, 3 deletions
diff --git a/js/src/jsnativestack.cpp b/js/src/jsnativestack.cpp index 05928ea3df..166a5a4f77 100644 --- a/js/src/jsnativestack.cpp +++ b/js/src/jsnativestack.cpp @@ -21,6 +21,18 @@ # include <unistd.h> # endif +# if defined(XP_LINUX) && !defined(ANDROID) && defined(__GLIBC__) +# include <dlfcn.h> +# include <sys/syscall.h> +# include <sys/types.h> +# include <unistd.h> +static pid_t +gettid() +{ + return syscall(__NR_gettid); +} +# endif + #else # error "Unsupported platform" @@ -88,6 +100,52 @@ js::GetNativeStackBaseImpl() context.uc_stack.ss_size; } +#elif defined(XP_LINUX) && !defined(ANDROID) && defined(__GLIBC__) +void* +js::GetNativeStackBaseImpl() +{ + // On the main thread, get stack base from glibc's __libc_stack_end rather than pthread APIs + // to avoid filesystem calls /proc/self/maps. Non-main threads spawned with pthreads can read + // this information directly from their pthread struct, but when using the pthreads API, the + // main thread must go parse /proc/self/maps to figure the mapped stack address space ranges. + // We want to avoid reading from /proc/ so that the application can run in restricted + // environments where /proc may not be mounted (e.g. chroot). + if (gettid() == getpid()) { + void** pLibcStackEnd = (void**)dlsym(RTLD_DEFAULT, "__libc_stack_end"); + + // If __libc_stack_end is not found, architecture specific frame pointer hopping will need + // to be implemented. + MOZ_RELEASE_ASSERT(pLibcStackEnd, "__libc_stack_end unavailable, unable to setup stack range for JS."); + void* stackBase = *pLibcStackEnd; + MOZ_RELEASE_ASSERT(stackBase, "Invalid stack base, unable to setup stack range for JS."); + + // We don't need to fix stackBase, as it already roughly points to beginning of the stack. + return stackBase; + } + + // Non-main threads have the required info stored in memory, so no filesystem calls are made. + pthread_t thread = pthread_self(); + pthread_attr_t sattr; + pthread_attr_init(&sattr); + pthread_getattr_np(thread, &sattr); + + // stackBase will be the *lowest* address on all architectures. + void* stackBase = nullptr; + size_t stackSize = 0; + int rc = pthread_attr_getstack(&sattr, &stackBase, &stackSize); + if (rc) { + MOZ_CRASH("Call to pthread_attr_getstack failed, unable to setup stack range for JS."); + } + MOZ_RELEASE_ASSERT(stackBase, "Invalid stack base, unable to setup stack range for JS."); + pthread_attr_destroy(&sattr); + +# if JS_STACK_GROWTH_DIRECTION > 0 + return stackBase; +# else + return static_cast<char*>(stackBase) + stackSize; +# endif +} + #else /* XP_UNIX */ void* @@ -156,11 +214,15 @@ js::GetNativeStackBaseImpl() // the truth. rc = pthread_attr_getstack(&sattr, &stackBase, &stackSize); # else + // Use the default pthread_attr_getstack() call. Note that this function + // differs between libc implementations and could imply /proc access etc. + // which may not work in restricted environments. rc = pthread_attr_getstack(&sattr, &stackBase, &stackSize); # endif - if (rc) - MOZ_CRASH(); - MOZ_ASSERT(stackBase); + if (rc) { + MOZ_CRASH("Call to pthread_attr_getstack failed, unable to setup stack range for JS."); + } + MOZ_RELEASE_ASSERT(stackBase, "Invalid stack base, unable to setup stack range for JS."); pthread_attr_destroy(&sattr); # if JS_STACK_GROWTH_DIRECTION > 0 |