From e4df5f5ab50939d4a36aa6c8076c7aa571fb56df Mon Sep 17 00:00:00 2001
From: Christopher Ferris <cferris@google.com>
Date: Mon, 12 Feb 2018 13:24:18 -0800
Subject: [PATCH] Fix computation of pc.

Fix the case where a non-zero load bias or a non-zero elf offset causes
the pc to be set incorrectly.

Add unit tests for these cases.

Bug: 73172903

Test: Ran unit tests.
Test: Ran the unit tests from the simpleperf CL that detected the failure.
Change-Id: Id8802c00b34c66875edd4926a20c5fccd2bb7d72
---
 libunwindstack/Unwinder.cpp           |  2 +-
 libunwindstack/tests/UnwinderTest.cpp | 72 +++++++++++++++++++++++++++
 2 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/libunwindstack/Unwinder.cpp b/libunwindstack/Unwinder.cpp
index dfd7b185c..5e3293325 100644
--- a/libunwindstack/Unwinder.cpp
+++ b/libunwindstack/Unwinder.cpp
@@ -91,7 +91,7 @@ void Unwinder::FillInFrame(MapInfo* map_info, Elf* elf, uint64_t adjusted_rel_pc
     return;
   }
 
-  frame->pc = map_info->start + adjusted_rel_pc;
+  frame->pc = map_info->start + adjusted_rel_pc - elf->GetLoadBias() - map_info->elf_offset;
   frame->map_name = map_info->name;
   frame->map_offset = map_info->offset;
   frame->map_start = map_info->start;
diff --git a/libunwindstack/tests/UnwinderTest.cpp b/libunwindstack/tests/UnwinderTest.cpp
index 7358ae607..7fbae4cf8 100644
--- a/libunwindstack/tests/UnwinderTest.cpp
+++ b/libunwindstack/tests/UnwinderTest.cpp
@@ -102,6 +102,22 @@ class UnwinderTest : public ::testing::Test {
     info->load_bias = 0;
     maps_.FakeAddMapInfo(info);
 
+    info = new MapInfo(0xa5000, 0xa6000, 0, PROT_READ | PROT_WRITE | PROT_EXEC,
+                       "/fake/fake_load_bias.so");
+    elf = new ElfFake(new MemoryFake);
+    info->elf.reset(elf);
+    elf->FakeSetInterface(new ElfInterfaceFake(nullptr));
+    elf->FakeSetLoadBias(0x5000);
+    maps_.FakeAddMapInfo(info);
+
+    info = new MapInfo(0xa7000, 0xa8000, 0, PROT_READ | PROT_WRITE | PROT_EXEC,
+                       "/fake/fake_offset.oat");
+    elf = new ElfFake(new MemoryFake);
+    info->elf.reset(elf);
+    elf->FakeSetInterface(new ElfInterfaceFake(nullptr));
+    info->elf_offset = 0x8000;
+    maps_.FakeAddMapInfo(info);
+
     process_memory_.reset(new MemoryFake);
   }
 
@@ -180,6 +196,62 @@ TEST_F(UnwinderTest, multiple_frames) {
   EXPECT_EQ(PROT_READ | PROT_WRITE, frame->map_flags);
 }
 
+TEST_F(UnwinderTest, non_zero_load_bias) {
+  ElfInterfaceFake::FakePushFunctionData(FunctionData("Frame0", 0));
+
+  regs_.FakeSetPc(0xa5500);
+  regs_.FakeSetSp(0x10000);
+  ElfInterfaceFake::FakePushStepData(StepData(0, 0, true));
+
+  Unwinder unwinder(64, &maps_, &regs_, process_memory_);
+  unwinder.Unwind();
+  EXPECT_EQ(ERROR_NONE, unwinder.LastErrorCode());
+
+  ASSERT_EQ(1U, unwinder.NumFrames());
+
+  auto* frame = &unwinder.frames()[0];
+  EXPECT_EQ(0U, frame->num);
+  EXPECT_EQ(0x5500U, frame->rel_pc);
+  EXPECT_EQ(0xa5500U, frame->pc);
+  EXPECT_EQ(0x10000U, frame->sp);
+  EXPECT_EQ("Frame0", frame->function_name);
+  EXPECT_EQ(0U, frame->function_offset);
+  EXPECT_EQ("/fake/fake_load_bias.so", frame->map_name);
+  EXPECT_EQ(0U, frame->map_offset);
+  EXPECT_EQ(0xa5000U, frame->map_start);
+  EXPECT_EQ(0xa6000U, frame->map_end);
+  EXPECT_EQ(0x5000U, frame->map_load_bias);
+  EXPECT_EQ(PROT_READ | PROT_WRITE | PROT_EXEC, frame->map_flags);
+}
+
+TEST_F(UnwinderTest, non_zero_elf_offset) {
+  ElfInterfaceFake::FakePushFunctionData(FunctionData("Frame0", 0));
+
+  regs_.FakeSetPc(0xa7500);
+  regs_.FakeSetSp(0x10000);
+  ElfInterfaceFake::FakePushStepData(StepData(0, 0, true));
+
+  Unwinder unwinder(64, &maps_, &regs_, process_memory_);
+  unwinder.Unwind();
+  EXPECT_EQ(ERROR_NONE, unwinder.LastErrorCode());
+
+  ASSERT_EQ(1U, unwinder.NumFrames());
+
+  auto* frame = &unwinder.frames()[0];
+  EXPECT_EQ(0U, frame->num);
+  EXPECT_EQ(0x8500U, frame->rel_pc);
+  EXPECT_EQ(0xa7500U, frame->pc);
+  EXPECT_EQ(0x10000U, frame->sp);
+  EXPECT_EQ("Frame0", frame->function_name);
+  EXPECT_EQ(0U, frame->function_offset);
+  EXPECT_EQ("/fake/fake_offset.oat", frame->map_name);
+  EXPECT_EQ(0U, frame->map_offset);
+  EXPECT_EQ(0xa7000U, frame->map_start);
+  EXPECT_EQ(0xa8000U, frame->map_end);
+  EXPECT_EQ(0U, frame->map_load_bias);
+  EXPECT_EQ(PROT_READ | PROT_WRITE | PROT_EXEC, frame->map_flags);
+}
+
 TEST_F(UnwinderTest, non_zero_map_offset) {
   ElfInterfaceFake::FakePushFunctionData(FunctionData("Frame0", 0));