From a8c397317d6fce12d0ea1cac5482dbdd8b75fa6d Mon Sep 17 00:00:00 2001
From: Christopher Ferris <cferris@google.com>
Date: Mon, 12 Feb 2018 08:46:19 -0800
Subject: [PATCH] Clear dex pc to avoid duplicate frames.

Bug: 73228466

Test: Passes new unit tests, fails without change.
Change-Id: I3660bfd16cbf2d5cf96490ca7714bc5f97914884
---
 libunwindstack/Unwinder.cpp           |  2 +
 libunwindstack/tests/UnwinderTest.cpp | 58 +++++++++++++++++++++++++++
 2 files changed, 60 insertions(+)

diff --git a/libunwindstack/Unwinder.cpp b/libunwindstack/Unwinder.cpp
index 644bfa8d2..dfd7b185c 100644
--- a/libunwindstack/Unwinder.cpp
+++ b/libunwindstack/Unwinder.cpp
@@ -175,6 +175,8 @@ void Unwinder::Unwind(const std::vector<std::string>* initial_map_names_to_skip,
       if (regs_->dex_pc() != 0) {
         // Add a frame to represent the dex file.
         FillInDexFrame();
+        // Clear the dex pc so that we don't repeat this frame later.
+        regs_->set_dex_pc(0);
       }
 
       FillInFrame(map_info, elf, adjusted_rel_pc, adjusted_pc);
diff --git a/libunwindstack/tests/UnwinderTest.cpp b/libunwindstack/tests/UnwinderTest.cpp
index 09c6e047d..7358ae607 100644
--- a/libunwindstack/tests/UnwinderTest.cpp
+++ b/libunwindstack/tests/UnwinderTest.cpp
@@ -752,6 +752,64 @@ TEST_F(UnwinderTest, dex_pc_not_in_map) {
   EXPECT_EQ(PROT_READ | PROT_WRITE, frame->map_flags);
 }
 
+TEST_F(UnwinderTest, dex_pc_multiple_frames) {
+  ElfInterfaceFake::FakePushFunctionData(FunctionData("Frame0", 0));
+  ElfInterfaceFake::FakePushFunctionData(FunctionData("Frame1", 1));
+  regs_.FakeSetPc(0x1000);
+  regs_.FakeSetSp(0x10000);
+  regs_.FakeSetDexPc(0xa3400);
+  ElfInterfaceFake::FakePushStepData(StepData(0x33402, 0x10010, false));
+  ElfInterfaceFake::FakePushStepData(StepData(0, 0, true));
+
+  Unwinder unwinder(64, &maps_, &regs_, process_memory_);
+  unwinder.Unwind();
+  EXPECT_EQ(ERROR_NONE, unwinder.LastErrorCode());
+
+  ASSERT_EQ(3U, unwinder.NumFrames());
+
+  auto* frame = &unwinder.frames()[0];
+  EXPECT_EQ(0U, frame->num);
+  EXPECT_EQ(0x400U, frame->rel_pc);
+  EXPECT_EQ(0xa3400U, frame->pc);
+  EXPECT_EQ(0x10000U, frame->sp);
+  EXPECT_EQ("", frame->function_name);
+  EXPECT_EQ(0U, frame->function_offset);
+  EXPECT_EQ("/fake/fake.vdex", frame->map_name);
+  EXPECT_EQ(0U, frame->map_offset);
+  EXPECT_EQ(0xa3000U, frame->map_start);
+  EXPECT_EQ(0xa4000U, frame->map_end);
+  EXPECT_EQ(0U, frame->map_load_bias);
+  EXPECT_EQ(PROT_READ | PROT_WRITE | PROT_EXEC, frame->map_flags);
+
+  frame = &unwinder.frames()[1];
+  EXPECT_EQ(1U, frame->num);
+  EXPECT_EQ(0U, frame->rel_pc);
+  EXPECT_EQ(0x1000U, frame->pc);
+  EXPECT_EQ(0x10000U, frame->sp);
+  EXPECT_EQ("Frame0", frame->function_name);
+  EXPECT_EQ(0U, frame->function_offset);
+  EXPECT_EQ("/system/fake/libc.so", frame->map_name);
+  EXPECT_EQ(0U, frame->map_offset);
+  EXPECT_EQ(0x1000U, frame->map_start);
+  EXPECT_EQ(0x8000U, frame->map_end);
+  EXPECT_EQ(0U, frame->map_load_bias);
+  EXPECT_EQ(PROT_READ | PROT_WRITE, frame->map_flags);
+
+  frame = &unwinder.frames()[2];
+  EXPECT_EQ(2U, frame->num);
+  EXPECT_EQ(0x400U, frame->rel_pc);
+  EXPECT_EQ(0x33400U, frame->pc);
+  EXPECT_EQ(0x10010U, frame->sp);
+  EXPECT_EQ("Frame1", frame->function_name);
+  EXPECT_EQ(1U, frame->function_offset);
+  EXPECT_EQ("/fake/compressed.so", frame->map_name);
+  EXPECT_EQ(0U, frame->map_offset);
+  EXPECT_EQ(0x33000U, frame->map_start);
+  EXPECT_EQ(0x34000U, frame->map_end);
+  EXPECT_EQ(0U, frame->map_load_bias);
+  EXPECT_EQ(PROT_READ | PROT_WRITE, frame->map_flags);
+}
+
 // Verify format frame code.
 TEST_F(UnwinderTest, format_frame_static) {
   FrameData frame;