aboutsummaryrefslogtreecommitdiffstats
path: root/lib/xray/xray_interface.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'lib/xray/xray_interface.cpp')
-rw-r--r--lib/xray/xray_interface.cpp480
1 files changed, 480 insertions, 0 deletions
diff --git a/lib/xray/xray_interface.cpp b/lib/xray/xray_interface.cpp
new file mode 100644
index 000000000000..0d22893eb30f
--- /dev/null
+++ b/lib/xray/xray_interface.cpp
@@ -0,0 +1,480 @@
+//===-- xray_interface.cpp --------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of XRay, a dynamic runtime instrumentation system.
+//
+// Implementation of the API functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "xray_interface_internal.h"
+
+#include <cstdint>
+#include <cstdio>
+#include <errno.h>
+#include <limits>
+#include <string.h>
+#include <sys/mman.h>
+
+#if SANITIZER_FUCHSIA
+#include <zircon/process.h>
+#include <zircon/sanitizer.h>
+#include <zircon/status.h>
+#include <zircon/syscalls.h>
+#endif
+
+#include "sanitizer_common/sanitizer_addrhashmap.h"
+#include "sanitizer_common/sanitizer_common.h"
+
+#include "xray_defs.h"
+#include "xray_flags.h"
+
+extern __sanitizer::SpinMutex XRayInstrMapMutex;
+extern __sanitizer::atomic_uint8_t XRayInitialized;
+extern __xray::XRaySledMap XRayInstrMap;
+
+namespace __xray {
+
+#if defined(__x86_64__)
+static const int16_t cSledLength = 12;
+#elif defined(__aarch64__)
+static const int16_t cSledLength = 32;
+#elif defined(__arm__)
+static const int16_t cSledLength = 28;
+#elif SANITIZER_MIPS32
+static const int16_t cSledLength = 48;
+#elif SANITIZER_MIPS64
+static const int16_t cSledLength = 64;
+#elif defined(__powerpc64__)
+static const int16_t cSledLength = 8;
+#else
+#error "Unsupported CPU Architecture"
+#endif /* CPU architecture */
+
+// This is the function to call when we encounter the entry or exit sleds.
+atomic_uintptr_t XRayPatchedFunction{0};
+
+// This is the function to call from the arg1-enabled sleds/trampolines.
+atomic_uintptr_t XRayArgLogger{0};
+
+// This is the function to call when we encounter a custom event log call.
+atomic_uintptr_t XRayPatchedCustomEvent{0};
+
+// This is the function to call when we encounter a typed event log call.
+atomic_uintptr_t XRayPatchedTypedEvent{0};
+
+// This is the global status to determine whether we are currently
+// patching/unpatching.
+atomic_uint8_t XRayPatching{0};
+
+struct TypeDescription {
+ uint32_t type_id;
+ std::size_t description_string_length;
+};
+
+using TypeDescriptorMapType = AddrHashMap<TypeDescription, 11>;
+// An address map from immutable descriptors to type ids.
+TypeDescriptorMapType TypeDescriptorAddressMap{};
+
+atomic_uint32_t TypeEventDescriptorCounter{0};
+
+// MProtectHelper is an RAII wrapper for calls to mprotect(...) that will
+// undo any successful mprotect(...) changes. This is used to make a page
+// writeable and executable, and upon destruction if it was successful in
+// doing so returns the page into a read-only and executable page.
+//
+// This is only used specifically for runtime-patching of the XRay
+// instrumentation points. This assumes that the executable pages are
+// originally read-and-execute only.
+class MProtectHelper {
+ void *PageAlignedAddr;
+ std::size_t MProtectLen;
+ bool MustCleanup;
+
+public:
+ explicit MProtectHelper(void *PageAlignedAddr,
+ std::size_t MProtectLen,
+ std::size_t PageSize) XRAY_NEVER_INSTRUMENT
+ : PageAlignedAddr(PageAlignedAddr),
+ MProtectLen(MProtectLen),
+ MustCleanup(false) {
+#if SANITIZER_FUCHSIA
+ MProtectLen = RoundUpTo(MProtectLen, PageSize);
+#endif
+ }
+
+ int MakeWriteable() XRAY_NEVER_INSTRUMENT {
+#if SANITIZER_FUCHSIA
+ auto R = __sanitizer_change_code_protection(
+ reinterpret_cast<uintptr_t>(PageAlignedAddr), MProtectLen, true);
+ if (R != ZX_OK) {
+ Report("XRay: cannot change code protection: %s\n",
+ _zx_status_get_string(R));
+ return -1;
+ }
+ MustCleanup = true;
+ return 0;
+#else
+ auto R = mprotect(PageAlignedAddr, MProtectLen,
+ PROT_READ | PROT_WRITE | PROT_EXEC);
+ if (R != -1)
+ MustCleanup = true;
+ return R;
+#endif
+ }
+
+ ~MProtectHelper() XRAY_NEVER_INSTRUMENT {
+ if (MustCleanup) {
+#if SANITIZER_FUCHSIA
+ auto R = __sanitizer_change_code_protection(
+ reinterpret_cast<uintptr_t>(PageAlignedAddr), MProtectLen, false);
+ if (R != ZX_OK) {
+ Report("XRay: cannot change code protection: %s\n",
+ _zx_status_get_string(R));
+ }
+#else
+ mprotect(PageAlignedAddr, MProtectLen, PROT_READ | PROT_EXEC);
+#endif
+ }
+ }
+};
+
+namespace {
+
+bool patchSled(const XRaySledEntry &Sled, bool Enable,
+ int32_t FuncId) XRAY_NEVER_INSTRUMENT {
+ bool Success = false;
+ switch (Sled.Kind) {
+ case XRayEntryType::ENTRY:
+ Success = patchFunctionEntry(Enable, FuncId, Sled, __xray_FunctionEntry);
+ break;
+ case XRayEntryType::EXIT:
+ Success = patchFunctionExit(Enable, FuncId, Sled);
+ break;
+ case XRayEntryType::TAIL:
+ Success = patchFunctionTailExit(Enable, FuncId, Sled);
+ break;
+ case XRayEntryType::LOG_ARGS_ENTRY:
+ Success = patchFunctionEntry(Enable, FuncId, Sled, __xray_ArgLoggerEntry);
+ break;
+ case XRayEntryType::CUSTOM_EVENT:
+ Success = patchCustomEvent(Enable, FuncId, Sled);
+ break;
+ case XRayEntryType::TYPED_EVENT:
+ Success = patchTypedEvent(Enable, FuncId, Sled);
+ break;
+ default:
+ Report("Unsupported sled kind '%d' @%04x\n", Sled.Address, int(Sled.Kind));
+ return false;
+ }
+ return Success;
+}
+
+XRayPatchingStatus patchFunction(int32_t FuncId,
+ bool Enable) XRAY_NEVER_INSTRUMENT {
+ if (!atomic_load(&XRayInitialized,
+ memory_order_acquire))
+ return XRayPatchingStatus::NOT_INITIALIZED; // Not initialized.
+
+ uint8_t NotPatching = false;
+ if (!atomic_compare_exchange_strong(
+ &XRayPatching, &NotPatching, true, memory_order_acq_rel))
+ return XRayPatchingStatus::ONGOING; // Already patching.
+
+ // Next, we look for the function index.
+ XRaySledMap InstrMap;
+ {
+ SpinMutexLock Guard(&XRayInstrMapMutex);
+ InstrMap = XRayInstrMap;
+ }
+
+ // If we don't have an index, we can't patch individual functions.
+ if (InstrMap.Functions == 0)
+ return XRayPatchingStatus::NOT_INITIALIZED;
+
+ // FuncId must be a positive number, less than the number of functions
+ // instrumented.
+ if (FuncId <= 0 || static_cast<size_t>(FuncId) > InstrMap.Functions) {
+ Report("Invalid function id provided: %d\n", FuncId);
+ return XRayPatchingStatus::FAILED;
+ }
+
+ // Now we patch ths sleds for this specific function.
+ auto SledRange = InstrMap.SledsIndex[FuncId - 1];
+ auto *f = SledRange.Begin;
+ auto *e = SledRange.End;
+
+ bool SucceedOnce = false;
+ while (f != e)
+ SucceedOnce |= patchSled(*f++, Enable, FuncId);
+
+ atomic_store(&XRayPatching, false,
+ memory_order_release);
+
+ if (!SucceedOnce) {
+ Report("Failed patching any sled for function '%d'.", FuncId);
+ return XRayPatchingStatus::FAILED;
+ }
+
+ return XRayPatchingStatus::SUCCESS;
+}
+
+// controlPatching implements the common internals of the patching/unpatching
+// implementation. |Enable| defines whether we're enabling or disabling the
+// runtime XRay instrumentation.
+XRayPatchingStatus controlPatching(bool Enable) XRAY_NEVER_INSTRUMENT {
+ if (!atomic_load(&XRayInitialized,
+ memory_order_acquire))
+ return XRayPatchingStatus::NOT_INITIALIZED; // Not initialized.
+
+ uint8_t NotPatching = false;
+ if (!atomic_compare_exchange_strong(
+ &XRayPatching, &NotPatching, true, memory_order_acq_rel))
+ return XRayPatchingStatus::ONGOING; // Already patching.
+
+ uint8_t PatchingSuccess = false;
+ auto XRayPatchingStatusResetter =
+ at_scope_exit([&PatchingSuccess] {
+ if (!PatchingSuccess)
+ atomic_store(&XRayPatching, false,
+ memory_order_release);
+ });
+
+ XRaySledMap InstrMap;
+ {
+ SpinMutexLock Guard(&XRayInstrMapMutex);
+ InstrMap = XRayInstrMap;
+ }
+ if (InstrMap.Entries == 0)
+ return XRayPatchingStatus::NOT_INITIALIZED;
+
+ uint32_t FuncId = 1;
+ uint64_t CurFun = 0;
+
+ // First we want to find the bounds for which we have instrumentation points,
+ // and try to get as few calls to mprotect(...) as possible. We're assuming
+ // that all the sleds for the instrumentation map are contiguous as a single
+ // set of pages. When we do support dynamic shared object instrumentation,
+ // we'll need to do this for each set of page load offsets per DSO loaded. For
+ // now we're assuming we can mprotect the whole section of text between the
+ // minimum sled address and the maximum sled address (+ the largest sled
+ // size).
+ auto MinSled = InstrMap.Sleds[0];
+ auto MaxSled = InstrMap.Sleds[InstrMap.Entries - 1];
+ for (std::size_t I = 0; I < InstrMap.Entries; I++) {
+ const auto &Sled = InstrMap.Sleds[I];
+ if (Sled.Address < MinSled.Address)
+ MinSled = Sled;
+ if (Sled.Address > MaxSled.Address)
+ MaxSled = Sled;
+ }
+
+ const size_t PageSize = flags()->xray_page_size_override > 0
+ ? flags()->xray_page_size_override
+ : GetPageSizeCached();
+ if ((PageSize == 0) || ((PageSize & (PageSize - 1)) != 0)) {
+ Report("System page size is not a power of two: %lld\n", PageSize);
+ return XRayPatchingStatus::FAILED;
+ }
+
+ void *PageAlignedAddr =
+ reinterpret_cast<void *>(MinSled.Address & ~(PageSize - 1));
+ size_t MProtectLen =
+ (MaxSled.Address - reinterpret_cast<uptr>(PageAlignedAddr)) + cSledLength;
+ MProtectHelper Protector(PageAlignedAddr, MProtectLen, PageSize);
+ if (Protector.MakeWriteable() == -1) {
+ Report("Failed mprotect: %d\n", errno);
+ return XRayPatchingStatus::FAILED;
+ }
+
+ for (std::size_t I = 0; I < InstrMap.Entries; ++I) {
+ auto &Sled = InstrMap.Sleds[I];
+ auto F = Sled.Function;
+ if (CurFun == 0)
+ CurFun = F;
+ if (F != CurFun) {
+ ++FuncId;
+ CurFun = F;
+ }
+ patchSled(Sled, Enable, FuncId);
+ }
+ atomic_store(&XRayPatching, false,
+ memory_order_release);
+ PatchingSuccess = true;
+ return XRayPatchingStatus::SUCCESS;
+}
+
+XRayPatchingStatus mprotectAndPatchFunction(int32_t FuncId,
+ bool Enable) XRAY_NEVER_INSTRUMENT {
+ XRaySledMap InstrMap;
+ {
+ SpinMutexLock Guard(&XRayInstrMapMutex);
+ InstrMap = XRayInstrMap;
+ }
+
+ // FuncId must be a positive number, less than the number of functions
+ // instrumented.
+ if (FuncId <= 0 || static_cast<size_t>(FuncId) > InstrMap.Functions) {
+ Report("Invalid function id provided: %d\n", FuncId);
+ return XRayPatchingStatus::FAILED;
+ }
+
+ const size_t PageSize = flags()->xray_page_size_override > 0
+ ? flags()->xray_page_size_override
+ : GetPageSizeCached();
+ if ((PageSize == 0) || ((PageSize & (PageSize - 1)) != 0)) {
+ Report("Provided page size is not a power of two: %lld\n", PageSize);
+ return XRayPatchingStatus::FAILED;
+ }
+
+ // Here we compute the minumum sled and maximum sled associated with a
+ // particular function ID.
+ auto SledRange = InstrMap.SledsIndex[FuncId - 1];
+ auto *f = SledRange.Begin;
+ auto *e = SledRange.End;
+ auto MinSled = *f;
+ auto MaxSled = *(SledRange.End - 1);
+ while (f != e) {
+ if (f->Address < MinSled.Address)
+ MinSled = *f;
+ if (f->Address > MaxSled.Address)
+ MaxSled = *f;
+ ++f;
+ }
+
+ void *PageAlignedAddr =
+ reinterpret_cast<void *>(MinSled.Address & ~(PageSize - 1));
+ size_t MProtectLen =
+ (MaxSled.Address - reinterpret_cast<uptr>(PageAlignedAddr)) + cSledLength;
+ MProtectHelper Protector(PageAlignedAddr, MProtectLen, PageSize);
+ if (Protector.MakeWriteable() == -1) {
+ Report("Failed mprotect: %d\n", errno);
+ return XRayPatchingStatus::FAILED;
+ }
+ return patchFunction(FuncId, Enable);
+}
+
+} // namespace
+
+} // namespace __xray
+
+using namespace __xray;
+
+// The following functions are declared `extern "C" {...}` in the header, hence
+// they're defined in the global namespace.
+
+int __xray_set_handler(void (*entry)(int32_t,
+ XRayEntryType)) XRAY_NEVER_INSTRUMENT {
+ if (atomic_load(&XRayInitialized,
+ memory_order_acquire)) {
+
+ atomic_store(&__xray::XRayPatchedFunction,
+ reinterpret_cast<uintptr_t>(entry),
+ memory_order_release);
+ return 1;
+ }
+ return 0;
+}
+
+int __xray_set_customevent_handler(void (*entry)(void *, size_t))
+ XRAY_NEVER_INSTRUMENT {
+ if (atomic_load(&XRayInitialized,
+ memory_order_acquire)) {
+ atomic_store(&__xray::XRayPatchedCustomEvent,
+ reinterpret_cast<uintptr_t>(entry),
+ memory_order_release);
+ return 1;
+ }
+ return 0;
+}
+
+int __xray_set_typedevent_handler(void (*entry)(
+ uint16_t, const void *, size_t)) XRAY_NEVER_INSTRUMENT {
+ if (atomic_load(&XRayInitialized,
+ memory_order_acquire)) {
+ atomic_store(&__xray::XRayPatchedTypedEvent,
+ reinterpret_cast<uintptr_t>(entry),
+ memory_order_release);
+ return 1;
+ }
+ return 0;
+}
+
+int __xray_remove_handler() XRAY_NEVER_INSTRUMENT {
+ return __xray_set_handler(nullptr);
+}
+
+int __xray_remove_customevent_handler() XRAY_NEVER_INSTRUMENT {
+ return __xray_set_customevent_handler(nullptr);
+}
+
+int __xray_remove_typedevent_handler() XRAY_NEVER_INSTRUMENT {
+ return __xray_set_typedevent_handler(nullptr);
+}
+
+uint16_t __xray_register_event_type(
+ const char *const event_type) XRAY_NEVER_INSTRUMENT {
+ TypeDescriptorMapType::Handle h(&TypeDescriptorAddressMap, (uptr)event_type);
+ if (h.created()) {
+ h->type_id = atomic_fetch_add(
+ &TypeEventDescriptorCounter, 1, memory_order_acq_rel);
+ h->description_string_length = strnlen(event_type, 1024);
+ }
+ return h->type_id;
+}
+
+XRayPatchingStatus __xray_patch() XRAY_NEVER_INSTRUMENT {
+ return controlPatching(true);
+}
+
+XRayPatchingStatus __xray_unpatch() XRAY_NEVER_INSTRUMENT {
+ return controlPatching(false);
+}
+
+XRayPatchingStatus __xray_patch_function(int32_t FuncId) XRAY_NEVER_INSTRUMENT {
+ return mprotectAndPatchFunction(FuncId, true);
+}
+
+XRayPatchingStatus
+__xray_unpatch_function(int32_t FuncId) XRAY_NEVER_INSTRUMENT {
+ return mprotectAndPatchFunction(FuncId, false);
+}
+
+int __xray_set_handler_arg1(void (*entry)(int32_t, XRayEntryType, uint64_t)) {
+ if (!atomic_load(&XRayInitialized,
+ memory_order_acquire))
+ return 0;
+
+ // A relaxed write might not be visible even if the current thread gets
+ // scheduled on a different CPU/NUMA node. We need to wait for everyone to
+ // have this handler installed for consistency of collected data across CPUs.
+ atomic_store(&XRayArgLogger, reinterpret_cast<uint64_t>(entry),
+ memory_order_release);
+ return 1;
+}
+
+int __xray_remove_handler_arg1() { return __xray_set_handler_arg1(nullptr); }
+
+uintptr_t __xray_function_address(int32_t FuncId) XRAY_NEVER_INSTRUMENT {
+ SpinMutexLock Guard(&XRayInstrMapMutex);
+ if (FuncId <= 0 || static_cast<size_t>(FuncId) > XRayInstrMap.Functions)
+ return 0;
+ return XRayInstrMap.SledsIndex[FuncId - 1].Begin->Function
+// On PPC, function entries are always aligned to 16 bytes. The beginning of a
+// sled might be a local entry, which is always +8 based on the global entry.
+// Always return the global entry.
+#ifdef __PPC__
+ & ~0xf
+#endif
+ ;
+}
+
+size_t __xray_max_function_id() XRAY_NEVER_INSTRUMENT {
+ SpinMutexLock Guard(&XRayInstrMapMutex);
+ return XRayInstrMap.Functions;
+}