// Copyright 2015 The Crashpad Authors. All rights reserved. // // 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. #include "util/win/capture_context.h" #include #include #include #include "base/macros.h" #include "build/build_config.h" #include "gtest/gtest.h" namespace crashpad { namespace test { namespace { // If the context structure has fields that tell whether it’s valid, such as // magic numbers or size fields, sanity-checks those fields for validity with // fatal gtest assertions. For other fields, where it’s possible to reason about // their validity based solely on their contents, sanity-checks via nonfatal // gtest assertions. void SanityCheckContext(const CONTEXT& context) { #if defined(ARCH_CPU_X86) const uint32_t must_have = CONTEXT_i386 | CONTEXT_CONTROL | CONTEXT_INTEGER | CONTEXT_SEGMENTS | CONTEXT_FLOATING_POINT; ASSERT_EQ(must_have, context.ContextFlags & must_have); const uint32_t may_have = CONTEXT_EXTENDED_REGISTERS; ASSERT_EQ(0, context.ContextFlags & ~(must_have | may_have)); #elif defined(ARCH_CPU_X86_64) ASSERT_EQ(CONTEXT_AMD64 | CONTEXT_CONTROL | CONTEXT_INTEGER | CONTEXT_SEGMENTS | CONTEXT_FLOATING_POINT, context.ContextFlags); #endif #if defined(ARCH_CPU_X86_FAMILY) // Many bit positions in the flags register are reserved and will always read // a known value. Most reserved bits are always 0, but bit 1 is always 1. // Check that the reserved bits are all set to their expected values. Note // that the set of reserved bits may be relaxed over time with newer CPUs, and // that this test may need to be changed to reflect these developments. The // current set of reserved bits are 1, 3, 5, 15, and 22 and higher. See Intel // Software Developer’s Manual, Volume 1: Basic Architecture (253665-055), // 3.4.3 “EFLAGS Register”, and AMD Architecture Programmer’s Manual, Volume // 2: System Programming (24593-3.25), 3.1.6 “RFLAGS Register”. EXPECT_EQ(2u, context.EFlags & 0xffc0802a); // CaptureContext() doesn’t capture debug registers, so make sure they read 0. EXPECT_EQ(0, context.Dr0); EXPECT_EQ(0, context.Dr1); EXPECT_EQ(0, context.Dr2); EXPECT_EQ(0, context.Dr3); EXPECT_EQ(0, context.Dr6); EXPECT_EQ(0, context.Dr7); #endif #if defined(ARCH_CPU_X86) // fxsave doesn’t write these bytes. for (size_t i = 464; i < arraysize(context.ExtendedRegisters); ++i) { SCOPED_TRACE(i); EXPECT_EQ(0, context.ExtendedRegisters[i]); } #elif defined(ARCH_CPU_X86_64) // mxcsr shows up twice in the context structure. Make sure the values are // identical. EXPECT_EQ(context.MxCsr, context.FltSave.MxCsr); // fxsave doesn’t write these bytes. for (size_t i = 0; i < arraysize(context.FltSave.Reserved4); ++i) { SCOPED_TRACE(i); EXPECT_EQ(0, context.FltSave.Reserved4[i]); } // CaptureContext() doesn’t use these fields. EXPECT_EQ(0, context.P1Home); EXPECT_EQ(0, context.P2Home); EXPECT_EQ(0, context.P3Home); EXPECT_EQ(0, context.P4Home); EXPECT_EQ(0, context.P5Home); EXPECT_EQ(0, context.P6Home); for (size_t i = 0; i < arraysize(context.VectorRegister); ++i) { SCOPED_TRACE(i); EXPECT_EQ(0, context.VectorRegister[i].Low); EXPECT_EQ(0, context.VectorRegister[i].High); } EXPECT_EQ(0, context.VectorControl); EXPECT_EQ(0, context.DebugControl); EXPECT_EQ(0, context.LastBranchToRip); EXPECT_EQ(0, context.LastBranchFromRip); EXPECT_EQ(0, context.LastExceptionToRip); EXPECT_EQ(0, context.LastExceptionFromRip); #endif } // A CPU-independent function to return the program counter. uintptr_t ProgramCounterFromContext(const CONTEXT& context) { #if defined(ARCH_CPU_X86) return context.Eip; #elif defined(ARCH_CPU_X86_64) return context.Rip; #endif } // A CPU-independent function to return the stack pointer. uintptr_t StackPointerFromContext(const CONTEXT& context) { #if defined(ARCH_CPU_X86) return context.Esp; #elif defined(ARCH_CPU_X86_64) return context.Rsp; #endif } void TestCaptureContext() { CONTEXT context_1; CaptureContext(&context_1); { SCOPED_TRACE("context_1"); ASSERT_NO_FATAL_FAILURE(SanityCheckContext(context_1)); } // The program counter reference value is this function’s address. The // captured program counter should be slightly greater than or equal to the // reference program counter. uintptr_t pc = ProgramCounterFromContext(context_1); // Declare sp and context_2 here because all local variables need to be // declared before computing the stack pointer reference value, so that the // reference value can be the lowest value possible. uintptr_t sp; CONTEXT context_2; // The stack pointer reference value is the lowest address of a local variable // in this function. The captured program counter will be slightly less than // or equal to the reference stack pointer. const uintptr_t kReferenceSP = std::min(std::min(reinterpret_cast(&context_1), reinterpret_cast(&context_2)), std::min(reinterpret_cast(&pc), reinterpret_cast(&sp))); sp = StackPointerFromContext(context_1); EXPECT_LT(kReferenceSP - sp, 512u); // Capture the context again, expecting that the stack pointer stays the same // and the program counter increases. Strictly speaking, there’s no guarantee // that these conditions will hold, although they do for known compilers even // under typical optimization. CaptureContext(&context_2); { SCOPED_TRACE("context_2"); ASSERT_NO_FATAL_FAILURE(SanityCheckContext(context_2)); } EXPECT_EQ(sp, StackPointerFromContext(context_2)); EXPECT_GT(ProgramCounterFromContext(context_2), pc); } TEST(CaptureContextWin, CaptureContext) { ASSERT_NO_FATAL_FAILURE(TestCaptureContext()); } } // namespace } // namespace test } // namespace crashpad