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-rw-r--r--absl/base/BUILD.bazel1
-rw-r--r--absl/base/internal/spinlock_akaros.inc35
-rw-r--r--absl/base/internal/spinlock_wait.cc2
-rw-r--r--absl/base/internal/sysinfo.cc24
-rw-r--r--absl/base/macros.h1
-rw-r--r--absl/debugging/internal/elf_mem_image.cc5
-rw-r--r--absl/debugging/internal/elf_mem_image.h7
-rw-r--r--absl/debugging/internal/stacktrace_x86-inl.inc4
-rw-r--r--absl/debugging/internal/vdso_support.cc73
9 files changed, 119 insertions, 33 deletions
diff --git a/absl/base/BUILD.bazel b/absl/base/BUILD.bazel
index d68448da..e68c4500 100644
--- a/absl/base/BUILD.bazel
+++ b/absl/base/BUILD.bazel
@@ -28,6 +28,7 @@ licenses(["notice"]) # Apache 2.0
cc_library(
name = "spinlock_wait",
srcs = [
+ "internal/spinlock_akaros.inc",
"internal/spinlock_posix.inc",
"internal/spinlock_wait.cc",
"internal/spinlock_win32.inc",
diff --git a/absl/base/internal/spinlock_akaros.inc b/absl/base/internal/spinlock_akaros.inc
new file mode 100644
index 00000000..051c8cf8
--- /dev/null
+++ b/absl/base/internal/spinlock_akaros.inc
@@ -0,0 +1,35 @@
+// Copyright 2017 The Abseil Authors.
+//
+// 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
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// 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.
+//
+// This file is an Akaros-specific part of spinlock_wait.cc
+
+#include <atomic>
+
+#include "absl/base/internal/scheduling_mode.h"
+
+extern "C" {
+
+ABSL_ATTRIBUTE_WEAK void AbslInternalSpinLockDelay(
+ std::atomic<uint32_t>* /* lock_word */, uint32_t /* value */,
+ int /* loop */, absl::base_internal::SchedulingMode /* mode */) {
+ // In Akaros, one must take care not to call anything that could cause a
+ // malloc(), a blocking system call, or a uthread_yield() while holding a
+ // spinlock. Our callers assume will not call into libraries or other
+ // arbitrary code.
+}
+
+ABSL_ATTRIBUTE_WEAK void AbslInternalSpinLockWake(
+ std::atomic<uint32_t>* /* lock_word */, bool /* all */) {}
+
+} // extern "C"
diff --git a/absl/base/internal/spinlock_wait.cc b/absl/base/internal/spinlock_wait.cc
index 0fd36286..8f951b66 100644
--- a/absl/base/internal/spinlock_wait.cc
+++ b/absl/base/internal/spinlock_wait.cc
@@ -23,6 +23,8 @@
#if defined(_WIN32)
#include "absl/base/internal/spinlock_win32.inc"
+#elif defined(__akaros__)
+#include "absl/base/internal/spinlock_akaros.inc"
#else
#include "absl/base/internal/spinlock_posix.inc"
#endif
diff --git a/absl/base/internal/sysinfo.cc b/absl/base/internal/sysinfo.cc
index 9e0140fa..00e98b66 100644
--- a/absl/base/internal/sysinfo.cc
+++ b/absl/base/internal/sysinfo.cc
@@ -284,6 +284,30 @@ pid_t GetTID() {
return syscall(SYS_gettid);
}
+#elif defined(__akaros__)
+
+pid_t GetTID() {
+ // Akaros has a concept of "vcore context", which is the state the program
+ // is forced into when we need to make a user-level scheduling decision, or
+ // run a signal handler. This is analogous to the interrupt context that a
+ // CPU might enter if it encounters some kind of exception.
+ //
+ // There is no current thread context in vcore context, but we need to give
+ // a reasonable answer if asked for a thread ID (e.g., in a signal handler).
+ // Thread 0 always exists, so if we are in vcore context, we return that.
+ //
+ // Otherwise, we know (since we are using pthreads) that the uthread struct
+ // current_uthread is pointing to is the first element of a
+ // struct pthread_tcb, so we extract and return the thread ID from that.
+ //
+ // TODO(dcross): Akaros anticipates moving the thread ID to the uthread
+ // structure at some point. We should modify this code to remove the cast
+ // when that happens.
+ if (in_vcore_context())
+ return 0;
+ return reinterpret_cast<struct pthread_tcb *>(current_uthread)->id;
+}
+
#else
// Fallback implementation of GetTID using pthread_getspecific.
diff --git a/absl/base/macros.h b/absl/base/macros.h
index 31d1c02e..d4140872 100644
--- a/absl/base/macros.h
+++ b/absl/base/macros.h
@@ -29,6 +29,7 @@
#ifndef ABSL_BASE_MACROS_H_
#define ABSL_BASE_MACROS_H_
+#include <cassert>
#include <cstddef>
#include "absl/base/port.h"
diff --git a/absl/debugging/internal/elf_mem_image.cc b/absl/debugging/internal/elf_mem_image.cc
index f6c6bc07..3dfef5e8 100644
--- a/absl/debugging/internal/elf_mem_image.cc
+++ b/absl/debugging/internal/elf_mem_image.cc
@@ -75,8 +75,9 @@ const T *GetTableElement(const ElfW(Ehdr) * ehdr, ElfW(Off) table_offset,
} // namespace
-const void *const ElfMemImage::kInvalidBase =
- reinterpret_cast<const void *>(~0L);
+// The value of this variable doesn't matter; it's used only for its
+// unique address.
+const int ElfMemImage::kInvalidBaseSentinel = 0;
ElfMemImage::ElfMemImage(const void *base) {
ABSL_RAW_CHECK(base != kInvalidBase, "bad pointer");
diff --git a/absl/debugging/internal/elf_mem_image.h b/absl/debugging/internal/elf_mem_image.h
index 7f3dbb97..20a32a49 100644
--- a/absl/debugging/internal/elf_mem_image.h
+++ b/absl/debugging/internal/elf_mem_image.h
@@ -43,9 +43,14 @@ namespace debug_internal {
// An in-memory ELF image (may not exist on disk).
class ElfMemImage {
+ private:
+ // Sentinel: there could never be an elf image at &kInvalidBaseSentinel.
+ static const int kInvalidBaseSentinel;
+
public:
// Sentinel: there could never be an elf image at this address.
- static const void *const kInvalidBase;
+ static constexpr const void *const kInvalidBase =
+ static_cast<const void*>(&kInvalidBaseSentinel);
// Information about a single vdso symbol.
// All pointers are into .dynsym, .dynstr, or .text of the VDSO.
diff --git a/absl/debugging/internal/stacktrace_x86-inl.inc b/absl/debugging/internal/stacktrace_x86-inl.inc
index 6e1af017..9bdaa542 100644
--- a/absl/debugging/internal/stacktrace_x86-inl.inc
+++ b/absl/debugging/internal/stacktrace_x86-inl.inc
@@ -114,7 +114,9 @@ static const int kMaxFrameBytes = 100000;
// vuc is a ucontext_t *. We use void* to avoid the use
// of ucontext_t on non-POSIX systems.
static uintptr_t GetFP(const void *vuc) {
-#if defined(__linux__)
+#if !defined(__linux__)
+ static_cast<void>(vuc); // Avoid an unused argument compiler warning.
+#else
if (vuc != nullptr) {
auto *uc = reinterpret_cast<const ucontext_t *>(vuc);
#if defined(__i386__)
diff --git a/absl/debugging/internal/vdso_support.cc b/absl/debugging/internal/vdso_support.cc
index 5026e1c1..815e702f 100644
--- a/absl/debugging/internal/vdso_support.cc
+++ b/absl/debugging/internal/vdso_support.cc
@@ -20,10 +20,15 @@
#ifdef ABSL_HAVE_VDSO_SUPPORT // defined in vdso_support.h
+#include <errno.h>
#include <fcntl.h>
#include <sys/syscall.h>
#include <unistd.h>
+#if __GLIBC_PREREQ(2, 16) // GLIBC-2.16 implements getauxval.
+#include <sys/auxv.h>
+#endif
+
#include "absl/base/dynamic_annotations.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/base/port.h"
@@ -35,8 +40,10 @@
namespace absl {
namespace debug_internal {
+ABSL_CONST_INIT
std::atomic<const void *> VDSOSupport::vdso_base_(
debug_internal::ElfMemImage::kInvalidBase);
+
std::atomic<VDSOSupport::GetCpuFn> VDSOSupport::getcpu_fn_(&InitAndGetCPU);
VDSOSupport::VDSOSupport()
// If vdso_base_ is still set to kInvalidBase, we got here
@@ -56,37 +63,44 @@ VDSOSupport::VDSOSupport()
// Finally, even if there is a race here, it is harmless, because
// the operation should be idempotent.
const void *VDSOSupport::Init() {
- if (vdso_base_.load(std::memory_order_relaxed) ==
- debug_internal::ElfMemImage::kInvalidBase) {
- {
- // Valgrind zaps AT_SYSINFO_EHDR and friends from the auxv[]
- // on stack, and so glibc works as if VDSO was not present.
- // But going directly to kernel via /proc/self/auxv below bypasses
- // Valgrind zapping. So we check for Valgrind separately.
- if (RunningOnValgrind()) {
- vdso_base_.store(nullptr, std::memory_order_relaxed);
- getcpu_fn_.store(&GetCPUViaSyscall, std::memory_order_relaxed);
- return nullptr;
- }
- int fd = open("/proc/self/auxv", O_RDONLY);
- if (fd == -1) {
- // Kernel too old to have a VDSO.
- vdso_base_.store(nullptr, std::memory_order_relaxed);
- getcpu_fn_.store(&GetCPUViaSyscall, std::memory_order_relaxed);
- return nullptr;
- }
- ElfW(auxv_t) aux;
- while (read(fd, &aux, sizeof(aux)) == sizeof(aux)) {
- if (aux.a_type == AT_SYSINFO_EHDR) {
- vdso_base_.store(reinterpret_cast<void *>(aux.a_un.a_val),
- std::memory_order_relaxed);
- break;
- }
+ const auto kInvalidBase = debug_internal::ElfMemImage::kInvalidBase;
+#if __GLIBC_PREREQ(2, 16)
+ if (vdso_base_.load(std::memory_order_relaxed) == kInvalidBase) {
+ errno = 0;
+ const void *const sysinfo_ehdr =
+ reinterpret_cast<const void *>(getauxval(AT_SYSINFO_EHDR));
+ if (errno == 0) {
+ vdso_base_.store(sysinfo_ehdr, std::memory_order_relaxed);
+ }
+ }
+#endif // __GLIBC_PREREQ(2, 16)
+ if (vdso_base_.load(std::memory_order_relaxed) == kInvalidBase) {
+ // Valgrind zaps AT_SYSINFO_EHDR and friends from the auxv[]
+ // on stack, and so glibc works as if VDSO was not present.
+ // But going directly to kernel via /proc/self/auxv below bypasses
+ // Valgrind zapping. So we check for Valgrind separately.
+ if (RunningOnValgrind()) {
+ vdso_base_.store(nullptr, std::memory_order_relaxed);
+ getcpu_fn_.store(&GetCPUViaSyscall, std::memory_order_relaxed);
+ return nullptr;
+ }
+ int fd = open("/proc/self/auxv", O_RDONLY);
+ if (fd == -1) {
+ // Kernel too old to have a VDSO.
+ vdso_base_.store(nullptr, std::memory_order_relaxed);
+ getcpu_fn_.store(&GetCPUViaSyscall, std::memory_order_relaxed);
+ return nullptr;
+ }
+ ElfW(auxv_t) aux;
+ while (read(fd, &aux, sizeof(aux)) == sizeof(aux)) {
+ if (aux.a_type == AT_SYSINFO_EHDR) {
+ vdso_base_.store(reinterpret_cast<void *>(aux.a_un.a_val),
+ std::memory_order_relaxed);
+ break;
}
- close(fd);
}
- if (vdso_base_.load(std::memory_order_relaxed) ==
- debug_internal::ElfMemImage::kInvalidBase) {
+ close(fd);
+ if (vdso_base_.load(std::memory_order_relaxed) == kInvalidBase) {
// Didn't find AT_SYSINFO_EHDR in auxv[].
vdso_base_.store(nullptr, std::memory_order_relaxed);
}
@@ -135,6 +149,7 @@ long VDSOSupport::GetCPUViaSyscall(unsigned *cpu, // NOLINT(runtime/int)
return syscall(SYS_getcpu, cpu, nullptr, nullptr);
#else
// x86_64 never implemented sys_getcpu(), except as a VDSO call.
+ static_cast<void>(cpu); // Avoid an unused argument compiler warning.
errno = ENOSYS;
return -1;
#endif
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-22 01:52:24 +0000