2019-08-14 10:47:11 +02:00
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//===-- sanitizer_stoptheworld_netbsd_libcdep.cpp -------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// See sanitizer_stoptheworld.h for details.
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// This implementation was inspired by Markus Gutschke's linuxthreads.cc.
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//
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// This is a NetBSD variation of Linux stoptheworld implementation
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// See sanitizer_stoptheworld_linux_libcdep.cpp for code comments.
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//
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//===----------------------------------------------------------------------===//
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#include "sanitizer_platform.h"
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#if SANITIZER_NETBSD
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#include "sanitizer_stoptheworld.h"
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#include "sanitizer_atomic.h"
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#include "sanitizer_platform_limits_posix.h"
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#include <sys/types.h>
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#include <sys/ptrace.h>
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#include <sys/uio.h>
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#include <sys/wait.h>
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#include <machine/reg.h>
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#include <elf.h>
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#include <errno.h>
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#include <sched.h>
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#include <signal.h>
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#include <stddef.h>
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#define internal_sigaction_norestorer internal_sigaction
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#include "sanitizer_common.h"
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#include "sanitizer_flags.h"
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#include "sanitizer_libc.h"
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#include "sanitizer_linux.h"
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#include "sanitizer_mutex.h"
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#include "sanitizer_placement_new.h"
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namespace __sanitizer {
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2020-11-13 17:03:23 +01:00
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class SuspendedThreadsListNetBSD final : public SuspendedThreadsList {
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2019-08-14 10:47:11 +02:00
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public:
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SuspendedThreadsListNetBSD() { thread_ids_.reserve(1024); }
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tid_t GetThreadID(uptr index) const;
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uptr ThreadCount() const;
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bool ContainsTid(tid_t thread_id) const;
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void Append(tid_t tid);
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2020-10-16 10:03:04 +02:00
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PtraceRegistersStatus GetRegistersAndSP(uptr index,
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InternalMmapVector<uptr> *buffer,
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2019-08-14 10:47:11 +02:00
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uptr *sp) const;
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private:
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InternalMmapVector<tid_t> thread_ids_;
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};
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struct TracerThreadArgument {
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StopTheWorldCallback callback;
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void *callback_argument;
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BlockingMutex mutex;
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atomic_uintptr_t done;
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uptr parent_pid;
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};
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class ThreadSuspender {
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public:
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explicit ThreadSuspender(pid_t pid, TracerThreadArgument *arg)
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: arg(arg), pid_(pid) {
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CHECK_GE(pid, 0);
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}
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bool SuspendAllThreads();
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void ResumeAllThreads();
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void KillAllThreads();
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SuspendedThreadsListNetBSD &suspended_threads_list() {
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return suspended_threads_list_;
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}
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TracerThreadArgument *arg;
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private:
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SuspendedThreadsListNetBSD suspended_threads_list_;
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pid_t pid_;
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};
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void ThreadSuspender::ResumeAllThreads() {
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int pterrno;
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if (!internal_iserror(internal_ptrace(PT_DETACH, pid_, (void *)(uptr)1, 0),
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&pterrno)) {
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VReport(2, "Detached from process %d.\n", pid_);
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} else {
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VReport(1, "Could not detach from process %d (errno %d).\n", pid_, pterrno);
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}
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}
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void ThreadSuspender::KillAllThreads() {
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internal_ptrace(PT_KILL, pid_, nullptr, 0);
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}
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bool ThreadSuspender::SuspendAllThreads() {
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int pterrno;
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if (internal_iserror(internal_ptrace(PT_ATTACH, pid_, nullptr, 0),
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&pterrno)) {
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Printf("Could not attach to process %d (errno %d).\n", pid_, pterrno);
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return false;
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}
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int status;
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uptr waitpid_status;
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HANDLE_EINTR(waitpid_status, internal_waitpid(pid_, &status, 0));
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VReport(2, "Attached to process %d.\n", pid_);
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2020-06-01 21:15:18 +02:00
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#ifdef PT_LWPNEXT
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struct ptrace_lwpstatus pl;
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int op = PT_LWPNEXT;
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#else
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2019-08-14 10:47:11 +02:00
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struct ptrace_lwpinfo pl;
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2020-06-01 21:15:18 +02:00
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int op = PT_LWPINFO;
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#endif
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2019-08-14 10:47:11 +02:00
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pl.pl_lwpid = 0;
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2020-06-01 21:15:18 +02:00
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int val;
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2020-10-16 10:03:04 +02:00
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while ((val = internal_ptrace(op, pid_, (void *)&pl, sizeof(pl))) != -1 &&
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2019-08-14 10:47:11 +02:00
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pl.pl_lwpid != 0) {
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suspended_threads_list_.Append(pl.pl_lwpid);
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VReport(2, "Appended thread %d in process %d.\n", pl.pl_lwpid, pid_);
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}
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return true;
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}
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// Pointer to the ThreadSuspender instance for use in signal handler.
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static ThreadSuspender *thread_suspender_instance = nullptr;
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// Synchronous signals that should not be blocked.
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static const int kSyncSignals[] = {SIGABRT, SIGILL, SIGFPE, SIGSEGV,
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SIGBUS, SIGXCPU, SIGXFSZ};
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static void TracerThreadDieCallback() {
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ThreadSuspender *inst = thread_suspender_instance;
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if (inst && stoptheworld_tracer_pid == internal_getpid()) {
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inst->KillAllThreads();
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thread_suspender_instance = nullptr;
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}
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}
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// Signal handler to wake up suspended threads when the tracer thread dies.
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static void TracerThreadSignalHandler(int signum, __sanitizer_siginfo *siginfo,
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void *uctx) {
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SignalContext ctx(siginfo, uctx);
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Printf("Tracer caught signal %d: addr=0x%zx pc=0x%zx sp=0x%zx\n", signum,
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ctx.addr, ctx.pc, ctx.sp);
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ThreadSuspender *inst = thread_suspender_instance;
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if (inst) {
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if (signum == SIGABRT)
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inst->KillAllThreads();
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else
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inst->ResumeAllThreads();
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RAW_CHECK(RemoveDieCallback(TracerThreadDieCallback));
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thread_suspender_instance = nullptr;
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atomic_store(&inst->arg->done, 1, memory_order_relaxed);
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}
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internal__exit((signum == SIGABRT) ? 1 : 2);
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}
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// Size of alternative stack for signal handlers in the tracer thread.
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static const int kHandlerStackSize = 8192;
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// This function will be run as a cloned task.
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static int TracerThread(void *argument) {
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TracerThreadArgument *tracer_thread_argument =
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(TracerThreadArgument *)argument;
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// Check if parent is already dead.
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if (internal_getppid() != tracer_thread_argument->parent_pid)
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internal__exit(4);
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// Wait for the parent thread to finish preparations.
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tracer_thread_argument->mutex.Lock();
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tracer_thread_argument->mutex.Unlock();
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RAW_CHECK(AddDieCallback(TracerThreadDieCallback));
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ThreadSuspender thread_suspender(internal_getppid(), tracer_thread_argument);
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// Global pointer for the signal handler.
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thread_suspender_instance = &thread_suspender;
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// Alternate stack for signal handling.
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InternalMmapVector<char> handler_stack_memory(kHandlerStackSize);
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stack_t handler_stack;
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internal_memset(&handler_stack, 0, sizeof(handler_stack));
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handler_stack.ss_sp = handler_stack_memory.data();
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handler_stack.ss_size = kHandlerStackSize;
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internal_sigaltstack(&handler_stack, nullptr);
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// Install our handler for synchronous signals. Other signals should be
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// blocked by the mask we inherited from the parent thread.
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for (uptr i = 0; i < ARRAY_SIZE(kSyncSignals); i++) {
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__sanitizer_sigaction act;
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internal_memset(&act, 0, sizeof(act));
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act.sigaction = TracerThreadSignalHandler;
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act.sa_flags = SA_ONSTACK | SA_SIGINFO;
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internal_sigaction_norestorer(kSyncSignals[i], &act, 0);
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}
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int exit_code = 0;
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if (!thread_suspender.SuspendAllThreads()) {
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VReport(1, "Failed suspending threads.\n");
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exit_code = 3;
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} else {
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tracer_thread_argument->callback(thread_suspender.suspended_threads_list(),
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tracer_thread_argument->callback_argument);
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thread_suspender.ResumeAllThreads();
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exit_code = 0;
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}
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RAW_CHECK(RemoveDieCallback(TracerThreadDieCallback));
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thread_suspender_instance = nullptr;
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atomic_store(&tracer_thread_argument->done, 1, memory_order_relaxed);
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return exit_code;
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}
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class ScopedStackSpaceWithGuard {
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public:
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explicit ScopedStackSpaceWithGuard(uptr stack_size) {
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stack_size_ = stack_size;
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guard_size_ = GetPageSizeCached();
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// FIXME: Omitting MAP_STACK here works in current kernels but might break
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// in the future.
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guard_start_ =
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(uptr)MmapOrDie(stack_size_ + guard_size_, "ScopedStackWithGuard");
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CHECK(MprotectNoAccess((uptr)guard_start_, guard_size_));
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}
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~ScopedStackSpaceWithGuard() {
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UnmapOrDie((void *)guard_start_, stack_size_ + guard_size_);
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}
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void *Bottom() const {
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return (void *)(guard_start_ + stack_size_ + guard_size_);
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}
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private:
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uptr stack_size_;
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uptr guard_size_;
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uptr guard_start_;
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};
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static __sanitizer_sigset_t blocked_sigset;
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static __sanitizer_sigset_t old_sigset;
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struct ScopedSetTracerPID {
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explicit ScopedSetTracerPID(uptr tracer_pid) {
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stoptheworld_tracer_pid = tracer_pid;
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stoptheworld_tracer_ppid = internal_getpid();
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}
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~ScopedSetTracerPID() {
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stoptheworld_tracer_pid = 0;
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stoptheworld_tracer_ppid = 0;
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}
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};
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void StopTheWorld(StopTheWorldCallback callback, void *argument) {
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// Prepare the arguments for TracerThread.
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struct TracerThreadArgument tracer_thread_argument;
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tracer_thread_argument.callback = callback;
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tracer_thread_argument.callback_argument = argument;
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tracer_thread_argument.parent_pid = internal_getpid();
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atomic_store(&tracer_thread_argument.done, 0, memory_order_relaxed);
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const uptr kTracerStackSize = 2 * 1024 * 1024;
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ScopedStackSpaceWithGuard tracer_stack(kTracerStackSize);
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tracer_thread_argument.mutex.Lock();
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internal_sigfillset(&blocked_sigset);
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for (uptr i = 0; i < ARRAY_SIZE(kSyncSignals); i++)
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internal_sigdelset(&blocked_sigset, kSyncSignals[i]);
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int rv = internal_sigprocmask(SIG_BLOCK, &blocked_sigset, &old_sigset);
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CHECK_EQ(rv, 0);
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uptr tracer_pid = internal_clone(TracerThread, tracer_stack.Bottom(),
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CLONE_VM | CLONE_FS | CLONE_FILES,
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&tracer_thread_argument);
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internal_sigprocmask(SIG_SETMASK, &old_sigset, 0);
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int local_errno = 0;
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if (internal_iserror(tracer_pid, &local_errno)) {
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VReport(1, "Failed spawning a tracer thread (errno %d).\n", local_errno);
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tracer_thread_argument.mutex.Unlock();
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} else {
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ScopedSetTracerPID scoped_set_tracer_pid(tracer_pid);
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tracer_thread_argument.mutex.Unlock();
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while (atomic_load(&tracer_thread_argument.done, memory_order_relaxed) == 0)
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sched_yield();
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for (;;) {
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uptr waitpid_status = internal_waitpid(tracer_pid, nullptr, __WALL);
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if (!internal_iserror(waitpid_status, &local_errno))
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break;
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if (local_errno == EINTR)
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continue;
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VReport(1, "Waiting on the tracer thread failed (errno %d).\n",
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local_errno);
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break;
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}
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}
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}
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tid_t SuspendedThreadsListNetBSD::GetThreadID(uptr index) const {
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CHECK_LT(index, thread_ids_.size());
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return thread_ids_[index];
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}
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uptr SuspendedThreadsListNetBSD::ThreadCount() const {
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return thread_ids_.size();
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}
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bool SuspendedThreadsListNetBSD::ContainsTid(tid_t thread_id) const {
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for (uptr i = 0; i < thread_ids_.size(); i++) {
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if (thread_ids_[i] == thread_id)
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return true;
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}
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return false;
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}
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void SuspendedThreadsListNetBSD::Append(tid_t tid) {
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thread_ids_.push_back(tid);
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}
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PtraceRegistersStatus SuspendedThreadsListNetBSD::GetRegistersAndSP(
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2020-10-16 10:03:04 +02:00
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uptr index, InternalMmapVector<uptr> *buffer, uptr *sp) const {
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2019-08-14 10:47:11 +02:00
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lwpid_t tid = GetThreadID(index);
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pid_t ppid = internal_getppid();
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struct reg regs;
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int pterrno;
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bool isErr =
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internal_iserror(internal_ptrace(PT_GETREGS, ppid, ®s, tid), &pterrno);
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if (isErr) {
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VReport(1,
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"Could not get registers from process %d thread %d (errno %d).\n",
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ppid, tid, pterrno);
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return pterrno == ESRCH ? REGISTERS_UNAVAILABLE_FATAL
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: REGISTERS_UNAVAILABLE;
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}
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*sp = PTRACE_REG_SP(®s);
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2020-10-16 10:03:04 +02:00
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buffer->resize(RoundUpTo(sizeof(regs), sizeof(uptr)) / sizeof(uptr));
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|
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internal_memcpy(buffer->data(), ®s, sizeof(regs));
|
2019-08-14 10:47:11 +02:00
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return REGISTERS_AVAILABLE;
|
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|
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}
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} // namespace __sanitizer
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#endif
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