[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 16:36:04 PDT 2017
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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