[compiler-rt] r302112 - [XRay][compiler-rt] Support patching/unpatching specific functions
Dean Michael Berris via llvm-commits
llvm-commits at lists.llvm.org
Thu May 4 19:19:42 PDT 2017
In the meantime, I think it's fine if we XFAIL this for now on powerpc,
while Tim has a look.
Cheers
On Fri, May 5, 2017 at 9:36 AM Dean Michael Berris <dberris at google.com>
wrote:
> Huh. +Tim Shen <timshen at google.com> -- any ideas why the recursion guard
> in the example wouldn't work?
>
> Bill, do you think the fact that the set is a global, that we're running
> into weird init/destruction issues on ppc?
>
> On Fri, May 5, 2017 at 2:18 AM Bill Seurer <seurer at linux.vnet.ibm.com>
> wrote:
>
>> The new test case doesn't work on powerpc64le:
>>
>>
>> http://lab.llvm.org:8011/builders/clang-ppc64le-linux/builds/6031/steps/ninja%20check%201/logs/FAIL%3A%20XRay-powerpc64le-linux%3A%3Acoverage-sample.cc
>>
>> When I run it locally it segfaults.
>>
>> Program received signal SIGSEGV, Segmentation fault.
>> 0x00003fffb7e39868 in std::_Rb_tree_insert_and_rebalance
>> (__insert_left=<optimized out>, __x=<optimized out>, __p=<optimized
>> out>, __header=...)
>> at /home/seurer/gcc/gcc-6.2.0/libstdc++-v3/src/c++98/tree.cc:282
>> 282 __root->_M_color = _S_black;
>> (gdb) where
>> #0 0x00003fffb7e39868 in std::_Rb_tree_insert_and_rebalance
>> (__insert_left=<optimized out>, __x=<optimized out>, __p=<optimized
>> out>, __header=...)
>> at /home/seurer/gcc/gcc-6.2.0/libstdc++-v3/src/c++98/tree.cc:282
>> #1 0x000000001003644c in std::_Rb_tree<int, int, std::_Identity<int>,
>> std::less<int>, std::allocator<int> >::_M_insert_<int const&,
>> std::_Rb_tree<int, int, std::_Identity<int>, std::less<int>,
>> std::allocator<int> >::_Alloc_node> (this=0x10ab48a0 <function_ids>,
>> __x=0x0, __p=0x3fffffffef60, __v=@0x3ffffffff104: 3, __node_gen=...)
>> at
>>
>> /home/seurer/gcc/install/gcc-6.2.0/lib/gcc/powerpc64le-unknown-linux-gnu/6.1.1/../../../../include/c++/6.1.1/bits/stl_tree.h:1512
>> #2 0x0000000010035f4c in std::_Rb_tree<int, int, std::_Identity<int>,
>> std::less<int>, std::allocator<int> >::_M_insert_unique<int const&>
>> (this=0x10ab48a0 <function_ids>,
>> __v=@0x3ffffffff104: 3) at
>>
>> /home/seurer/gcc/install/gcc-6.2.0/lib/gcc/powerpc64le-unknown-linux-gnu/6.1.1/../../../../include/c++/6.1.1/bits/stl_tree.h:1869
>> #3 0x00000000100353dc in std::set<int, std::less<int>,
>> std::allocator<int> >::insert (this=0x10ab48a0 <function_ids>,
>> __x=@0x3ffffffff104: 3)
>> at
>>
>> /home/seurer/gcc/install/gcc-6.2.0/lib/gcc/powerpc64le-unknown-linux-gnu/6.1.1/../../../../include/c++/6.1.1/bits/stl_set.h:483
>> #4 0x0000000010034d50 in coverage_handler (fid=3) at
>>
>> /home/seurer/llvm/llvm-test/projects/compiler-rt/test/xray/TestCases/Linux/coverage-sample.cc:18
>> #5 0x000000001002db78 in __xray::CallXRayPatchedFunction
>> (FuncId=<optimized out>, Type=<optimized out>)
>> at
>>
>> /home/seurer/llvm/llvm-test/projects/compiler-rt/lib/xray/xray_trampoline_powerpc64.cc:12
>> #6 0x000000001002dca8 in __xray_FunctionEntry () at
>>
>> /home/seurer/llvm/llvm-test/projects/compiler-rt/lib/xray/xray_trampoline_powerpc64_asm.S:75
>>
>>
>> On 05/03/2017 11:59 PM, Dean Michael Berris via llvm-commits wrote:
>> > 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
>> > +}
>> >
>> >
>> > _______________________________________________
>> > llvm-commits mailing list
>> > llvm-commits at lists.llvm.org
>> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>> >
>>
>>
>> --
>>
>> -Bill Seurer
>>
>>
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