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- // Copyright 2014 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 "client/capture_context_mac.h"
- #include <mach/mach.h>
- #include <stdint.h>
- #include <algorithm>
- #include "build/build_config.h"
- #include "gtest/gtest.h"
- #include "util/misc/address_sanitizer.h"
- #include "util/misc/implicit_cast.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 NativeCPUContext& context) {
- #if defined(ARCH_CPU_X86)
- ASSERT_EQ(implicit_cast<thread_state_flavor_t>(context.tsh.flavor),
- implicit_cast<thread_state_flavor_t>(x86_THREAD_STATE32));
- ASSERT_EQ(implicit_cast<uint32_t>(context.tsh.count),
- implicit_cast<uint32_t>(x86_THREAD_STATE32_COUNT));
- #elif defined(ARCH_CPU_X86_64)
- ASSERT_EQ(implicit_cast<thread_state_flavor_t>(context.tsh.flavor),
- implicit_cast<thread_state_flavor_t>(x86_THREAD_STATE64));
- ASSERT_EQ(implicit_cast<uint32_t>(context.tsh.count),
- implicit_cast<uint32_t>(x86_THREAD_STATE64_COUNT));
- #endif
- #if defined(ARCH_CPU_X86_FAMILY)
- // The segment registers are only capable of storing 16-bit quantities, but
- // the context structure provides native integer-width fields for them. Ensure
- // that the high bits are all clear.
- //
- // 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 (253665-051),
- // 3.4.3 “EFLAGS Register”, and AMD Architecture Programmer’s Manual, Volume
- // 2: System Programming (24593-3.24), 3.1.6 “RFLAGS Register”.
- #if defined(ARCH_CPU_X86)
- EXPECT_EQ(context.uts.ts32.__cs & ~0xffff, 0u);
- EXPECT_EQ(context.uts.ts32.__ds & ~0xffff, 0u);
- EXPECT_EQ(context.uts.ts32.__es & ~0xffff, 0u);
- EXPECT_EQ(context.uts.ts32.__fs & ~0xffff, 0u);
- EXPECT_EQ(context.uts.ts32.__gs & ~0xffff, 0u);
- EXPECT_EQ(context.uts.ts32.__ss & ~0xffff, 0u);
- EXPECT_EQ(context.uts.ts32.__eflags & 0xffc0802a, 2u);
- #elif defined(ARCH_CPU_X86_64)
- EXPECT_EQ(context.uts.ts64.__cs & ~UINT64_C(0xffff), 0u);
- EXPECT_EQ(context.uts.ts64.__fs & ~UINT64_C(0xffff), 0u);
- EXPECT_EQ(context.uts.ts64.__gs & ~UINT64_C(0xffff), 0u);
- EXPECT_EQ(context.uts.ts64.__rflags & UINT64_C(0xffffffffffc0802a), 2u);
- #endif
- #endif
- }
- // A CPU-independent function to return the program counter.
- uintptr_t ProgramCounterFromContext(const NativeCPUContext& context) {
- #if defined(ARCH_CPU_X86)
- return context.uts.ts32.__eip;
- #elif defined(ARCH_CPU_X86_64)
- return context.uts.ts64.__rip;
- #endif
- }
- // A CPU-independent function to return the stack pointer.
- uintptr_t StackPointerFromContext(const NativeCPUContext& context) {
- #if defined(ARCH_CPU_X86)
- return context.uts.ts32.__esp;
- #elif defined(ARCH_CPU_X86_64)
- return context.uts.ts64.__rsp;
- #endif
- }
- void TestCaptureContext() {
- NativeCPUContext 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);
- #if !defined(ADDRESS_SANITIZER)
- // AddressSanitizer can cause enough code bloat that the “nearby” check would
- // likely fail.
- const uintptr_t kReferencePC =
- reinterpret_cast<uintptr_t>(TestCaptureContext);
- EXPECT_LT(pc - kReferencePC, 64u);
- #endif // !defined(ADDRESS_SANITIZER)
- // 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;
- NativeCPUContext 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<uintptr_t>(&context_1),
- reinterpret_cast<uintptr_t>(&context_2)),
- std::min(reinterpret_cast<uintptr_t>(&pc),
- reinterpret_cast<uintptr_t>(&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(StackPointerFromContext(context_2), sp);
- EXPECT_GT(ProgramCounterFromContext(context_2), pc);
- }
- TEST(CaptureContextMac, CaptureContext) {
- ASSERT_NO_FATAL_FAILURE(TestCaptureContext());
- }
- } // namespace
- } // namespace test
- } // namespace crashpad
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