[compiler-rt] r302112 - [XRay][compiler-rt] Support patching/unpatching specific functions
Dean Michael Berris via llvm-commits
llvm-commits at lists.llvm.org
Wed May 3 21:59:21 PDT 2017
Author: dberris
Date: Wed May 3 23:59:20 2017
New Revision: 302112
URL: http://llvm.org/viewvc/llvm-project?rev=302112&view=rev
Log:
[XRay][compiler-rt] Support patching/unpatching specific functions
Summary:
This change allows us to patch/unpatch specific functions using the
function ID. This is useful in cases where implementations might want to
do coverage-style, or more fine-grained control of which functions to
patch or un-patch at runtime.
Depends on D32693.
Reviewers: dblaikie, echristo, kpw
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32695
Added:
compiler-rt/trunk/test/xray/TestCases/Linux/coverage-sample.cc
Modified:
compiler-rt/trunk/include/xray/xray_interface.h
compiler-rt/trunk/lib/xray/xray_init.cc
compiler-rt/trunk/lib/xray/xray_interface.cc
compiler-rt/trunk/lib/xray/xray_interface_internal.h
Modified: compiler-rt/trunk/include/xray/xray_interface.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/include/xray/xray_interface.h?rev=302112&r1=302111&r2=302112&view=diff
==============================================================================
--- compiler-rt/trunk/include/xray/xray_interface.h (original)
+++ compiler-rt/trunk/include/xray/xray_interface.h Wed May 3 23:59:20 2017
@@ -67,6 +67,14 @@ extern XRayPatchingStatus __xray_patch()
// result values.
extern XRayPatchingStatus __xray_unpatch();
+// This patches a specific function id. See XRayPatchingStatus for possible
+// result values.
+extern XRayPatchingStatus __xray_patch_function(int32_t FuncId);
+
+// This unpatches a specific function id. See XRayPatchingStatus for possible
+// result values.
+extern XRayPatchingStatus __xray_unpatch_function(int32_t FuncId);
+
// Use XRay to log the first argument of each (instrumented) function call.
// When this function exits, all threads will have observed the effect and
// start logging their subsequent affected function calls (if patched).
Modified: compiler-rt/trunk/lib/xray/xray_init.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/xray/xray_init.cc?rev=302112&r1=302111&r2=302112&view=diff
==============================================================================
--- compiler-rt/trunk/lib/xray/xray_init.cc (original)
+++ compiler-rt/trunk/lib/xray/xray_init.cc Wed May 3 23:59:20 2017
@@ -25,6 +25,8 @@ extern "C" {
void __xray_init();
extern const XRaySledEntry __start_xray_instr_map[] __attribute__((weak));
extern const XRaySledEntry __stop_xray_instr_map[] __attribute__((weak));
+extern const XRayFunctionSledIndex __start_xray_fn_idx[] __attribute__((weak));
+extern const XRayFunctionSledIndex __stop_xray_fn_idx[] __attribute__((weak));
}
using namespace __xray;
@@ -55,6 +57,8 @@ void __xray_init() XRAY_NEVER_INSTRUMENT
__sanitizer::SpinMutexLock Guard(&XRayInstrMapMutex);
XRayInstrMap.Sleds = __start_xray_instr_map;
XRayInstrMap.Entries = __stop_xray_instr_map - __start_xray_instr_map;
+ XRayInstrMap.SledsIndex = __start_xray_fn_idx;
+ XRayInstrMap.Functions = __stop_xray_fn_idx - __start_xray_fn_idx;
}
__sanitizer::atomic_store(&XRayInitialized, true,
__sanitizer::memory_order_release);
Modified: compiler-rt/trunk/lib/xray/xray_interface.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/xray/xray_interface.cc?rev=302112&r1=302111&r2=302112&view=diff
==============================================================================
--- compiler-rt/trunk/lib/xray/xray_interface.cc (original)
+++ compiler-rt/trunk/lib/xray/xray_interface.cc Wed May 3 23:59:20 2017
@@ -132,12 +132,48 @@ CleanupInvoker<Function> scopeCleanup(Fu
return CleanupInvoker<Function>{Fn};
}
+inline bool patchSled(const XRaySledEntry &Sled, bool Enable,
+ int32_t FuncId) XRAY_NEVER_INSTRUMENT {
+ // While we're here, we should patch the nop sled. To do that we mprotect
+ // the page containing the function to be writeable.
+ const uint64_t PageSize = GetPageSizeCached();
+ void *PageAlignedAddr =
+ reinterpret_cast<void *>(Sled.Address & ~(PageSize - 1));
+ std::size_t MProtectLen = (Sled.Address + cSledLength) -
+ reinterpret_cast<uint64_t>(PageAlignedAddr);
+ MProtectHelper Protector(PageAlignedAddr, MProtectLen);
+ if (Protector.MakeWriteable() == -1) {
+ printf("Failed mprotect: %d\n", errno);
+ return XRayPatchingStatus::FAILED;
+ }
+
+ 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;
+ default:
+ Report("Unsupported sled kind '%d' @%04x\n", Sled.Address, int(Sled.Kind));
+ return false;
+ }
+ return 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 (!__sanitizer::atomic_load(&XRayInitialized,
- __sanitizer::memory_order_acquire))
+ __sanitizer::memory_order_acquire))
return XRayPatchingStatus::NOT_INITIALIZED; // Not initialized.
uint8_t NotPatching = false;
@@ -179,38 +215,7 @@ XRayPatchingStatus controlPatching(bool
++FuncId;
CurFun = F;
}
-
- // While we're here, we should patch the nop sled. To do that we mprotect
- // the page containing the function to be writeable.
- void *PageAlignedAddr =
- reinterpret_cast<void *>(Sled.Address & ~(PageSize - 1));
- std::size_t MProtectLen = (Sled.Address + cSledLength) -
- reinterpret_cast<uint64_t>(PageAlignedAddr);
- MProtectHelper Protector(PageAlignedAddr, MProtectLen);
- if (Protector.MakeWriteable() == -1) {
- printf("Failed mprotect: %d\n", errno);
- return XRayPatchingStatus::FAILED;
- }
-
- 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;
- default:
- Report("Unsupported sled kind: %d\n", int(Sled.Kind));
- continue;
- }
- (void)Success;
+ patchSled(Sled, Enable, FuncId);
}
__sanitizer::atomic_store(&XRayPatching, false,
__sanitizer::memory_order_release);
@@ -226,6 +231,64 @@ XRayPatchingStatus __xray_unpatch() XRAY
return controlPatching(false);
}
+XRayPatchingStatus patchFunction(int32_t FuncId,
+ bool Enable) XRAY_NEVER_INSTRUMENT {
+ if (!__sanitizer::atomic_load(&XRayInitialized,
+ __sanitizer::memory_order_acquire))
+ return XRayPatchingStatus::NOT_INITIALIZED; // Not initialized.
+
+ uint8_t NotPatching = false;
+ if (!__sanitizer::atomic_compare_exchange_strong(
+ &XRayPatching, &NotPatching, true, __sanitizer::memory_order_acq_rel))
+ return XRayPatchingStatus::ONGOING; // Already patching.
+
+ // Next, we look for the function index.
+ XRaySledMap InstrMap;
+ {
+ __sanitizer::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);
+
+ __sanitizer::atomic_store(&XRayPatching, false,
+ __sanitizer::memory_order_release);
+
+ if (!SucceedOnce) {
+ Report("Failed patching any sled for function '%d'.", FuncId);
+ return XRayPatchingStatus::FAILED;
+ }
+
+ return XRayPatchingStatus::SUCCESS;
+}
+
+XRayPatchingStatus __xray_patch_function(int32_t FuncId) XRAY_NEVER_INSTRUMENT {
+ return patchFunction(FuncId, true);
+}
+
+XRayPatchingStatus
+__xray_unpatch_function(int32_t FuncId) XRAY_NEVER_INSTRUMENT {
+ return patchFunction(FuncId, false);
+}
+
int __xray_set_handler_arg1(void (*Handler)(int32_t, XRayEntryType, uint64_t)) {
if (!__sanitizer::atomic_load(&XRayInitialized,
__sanitizer::memory_order_acquire))
Modified: compiler-rt/trunk/lib/xray/xray_interface_internal.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/xray/xray_interface_internal.h?rev=302112&r1=302111&r2=302112&view=diff
==============================================================================
--- compiler-rt/trunk/lib/xray/xray_interface_internal.h (original)
+++ compiler-rt/trunk/lib/xray/xray_interface_internal.h Wed May 3 23:59:20 2017
@@ -39,6 +39,11 @@ struct XRaySledEntry {
#error "Unsupported word size."
#endif
};
+
+struct XRayFunctionSledIndex {
+ const XRaySledEntry* Begin;
+ const XRaySledEntry* End;
+};
}
namespace __xray {
@@ -46,6 +51,8 @@ namespace __xray {
struct XRaySledMap {
const XRaySledEntry *Sleds;
size_t Entries;
+ const XRayFunctionSledIndex *SledsIndex;
+ size_t Functions;
};
bool patchFunctionEntry(bool Enable, uint32_t FuncId,
Added: compiler-rt/trunk/test/xray/TestCases/Linux/coverage-sample.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/xray/TestCases/Linux/coverage-sample.cc?rev=302112&view=auto
==============================================================================
--- compiler-rt/trunk/test/xray/TestCases/Linux/coverage-sample.cc (added)
+++ compiler-rt/trunk/test/xray/TestCases/Linux/coverage-sample.cc Wed May 3 23:59:20 2017
@@ -0,0 +1,88 @@
+// Check that we can patch and unpatch specific function ids.
+//
+// RUN: %clangxx_xray -std=c++11 %s -o %t
+// RUN: XRAY_OPTIONS="patch_premain=false xray_naive_log=false" %run %t | FileCheck %s
+
+#include "xray/xray_interface.h"
+
+#include <set>
+#include <cstdio>
+
+std::set<int32_t> function_ids;
+
+[[clang::xray_never_instrument]] void coverage_handler(int32_t fid,
+ XRayEntryType) {
+ thread_local bool patching = false;
+ if (patching) return;
+ patching = true;
+ function_ids.insert(fid);
+ __xray_unpatch_function(fid);
+ patching = false;
+}
+
+[[clang::xray_always_instrument]] void baz() {
+ // do nothing!
+}
+
+[[clang::xray_always_instrument]] void bar() {
+ baz();
+}
+
+[[clang::xray_always_instrument]] void foo() {
+ bar();
+}
+
+[[clang::xray_always_instrument]] int main(int argc, char *argv[]) {
+ __xray_set_handler(coverage_handler);
+ __xray_patch();
+ foo();
+ __xray_unpatch();
+
+ // print out the function_ids.
+ printf("first pass.\n");
+ for (const auto id : function_ids)
+ printf("patched: %d\n", id);
+
+ // CHECK-LABEL: first pass.
+ // CHECK-DAG: patched: [[F1:.*]]
+ // CHECK-DAG: patched: [[F2:.*]]
+ // CHECK-DAG: patched: [[F3:.*]]
+
+ // make a copy of the function_ids, then patch them later.
+ auto called_fns = function_ids;
+
+ // clear the function_ids.
+ function_ids.clear();
+
+ // patch the functions we've called before.
+ for (const auto id : called_fns)
+ __xray_patch_function(id);
+
+ // then call them again.
+ foo();
+ __xray_unpatch();
+
+ // confirm that we've seen the same functions again.
+ printf("second pass.\n");
+ for (const auto id : function_ids)
+ printf("patched: %d\n", id);
+ // CHECK-LABEL: second pass.
+ // CHECK-DAG: patched: [[F1]]
+ // CHECK-DAG: patched: [[F2]]
+ // CHECK-DAG: patched: [[F3]]
+
+ // Now we want to make sure that if we unpatch one, that we're only going to
+ // see two calls of the coverage_handler.
+ function_ids.clear();
+ __xray_patch();
+ __xray_unpatch_function(1);
+ foo();
+ __xray_unpatch();
+
+ // confirm that we don't see function id one called anymore.
+ printf("missing 1.\n");
+ for (const auto id : function_ids)
+ printf("patched: %d\n", id);
+ // CHECK-LABEL: missing 1.
+ // CHECK-NOT: patched: 1
+}
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