blob: 41eea90dc5999423d82d8b948d98184adda05a8d [file] [log] [blame]
// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/allocation.h"
#include "vm/globals.h"
#if defined(HOST_OS_LINUX)
#include <signal.h> // NOLINT
#include <ucontext.h> // NOLINT
#elif defined(HOST_OS_ANDROID)
#include <signal.h> // NOLINT
#if !defined(__BIONIC_HAVE_UCONTEXT_T)
#include <asm/sigcontext.h> // NOLINT
// If ucontext_t is not defined on Android, define it here.
typedef struct sigcontext mcontext_t;
typedef struct ucontext {
uint32_t uc_flags;
struct ucontext* uc_link;
stack_t uc_stack;
struct sigcontext uc_mcontext;
uint32_t uc_sigmask;
} ucontext_t;
#endif // !defined(__BIONIC_HAVE_UCONTEXT_T)
#elif defined(HOST_OS_MACOS)
#include <signal.h> // NOLINT
#include <sys/ucontext.h> // NOLINT
#elif defined(HOST_OS_WINDOWS)
// Stub out for windows.
struct siginfo_t;
struct mcontext_t;
struct sigset_t {};
#elif defined(HOST_OS_FUCHSIA)
#include <signal.h> // NOLINT
#include <ucontext.h> // NOLINT
// Old linux kernels on ARM might require a trampoline to
// work around incorrect Thumb -> ARM transitions. See SignalHandlerTrampoline
// below for more details.
#if defined(HOST_ARCH_ARM) && \
(defined(HOST_OS_LINUX) || defined(HOST_OS_ANDROID)) && \
namespace dart {
typedef void (*SignalAction)(int signal, siginfo_t* info, void* context);
class SignalHandler : public AllStatic {
template <SignalAction action>
static void Install() {
static void Remove();
static uintptr_t GetProgramCounter(const mcontext_t& mcontext);
static uintptr_t GetFramePointer(const mcontext_t& mcontext);
static uintptr_t GetCStackPointer(const mcontext_t& mcontext);
static uintptr_t GetDartStackPointer(const mcontext_t& mcontext);
static uintptr_t GetLinkRegister(const mcontext_t& mcontext);
static void InstallImpl(SignalAction action);
// Work around for a bug in old kernels (only fixed in 3.18 Android kernel):
// Kernel does not clear If-Then execution state bits when entering ARM signal
// handler which violates requirements imposed by ARM architecture reference.
// Some CPUs look at these bits even while in ARM mode which causes them
// to skip some instructions in the prologue of the signal handler.
// To work around the issue we insert enough NOPs in the prologue to ensure
// that no actual instructions are skipped and then branch to the actual
// signal handler.
// For the kernel patch that fixes the issue see:
// Note: this function is marked "naked" because we must guarantee that
// our NOPs occur before any compiler generated prologue.
template <SignalAction action>
static __attribute__((naked)) void SignalHandlerTrampoline(int signal,
siginfo_t* info,
void* context_) {
// IT (If-Then) instruction makes up to four instructions that follow it
// conditional.
// Note: clobber all register so that compiler does not attempt to hoist
// anything from the next assembly block past this one.
asm volatile("nop; nop; nop; nop;"
: "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9",
"r10", "r11", "r12", "r13", "r14", "memory");
// Tail-call into the actual signal handler.
// Note: this code is split into a separate inline assembly block because
// any code that compiler generates to satisfy register constraints must
// be generated after four NOPs.
// Note: there is no portable way to specify that we want to have
// signal, info and context_ in r0 - r2 respectively. So we just mark them
// as clobbered and hope that compiler does not emit any code that uses
// these registers to satisfy action constraint (we tested on clang and
// the generated code looks like one would expect).
asm volatile("bx %0;" : : "r"(action) : "r0", "r1", "r2", "memory");
} // namespace dart