Support a map that represents gdb jit elf data.

Changes:
- Add a new flag to the libbacktrace and libunwindstack map data.
- Modify the unwinder to handle this map to use the raw pc when stepping.
- Add new unit tests for this case.

Bug: http://b/73127105
Test: Run simpleperf to unwind through jit symfiles.
Test: Run new unit tests.
Test: Run 137-cfi test on host.
Change-Id: I10bc0410680accc6d35fe51e9f1098911f667e01

libbacktrace/include/backtrace/BacktraceMap.h

@@ -40,6 +40,10 @@ struct backtrace_stackinfo_t;
 // Special flag to indicate a map is in /dev/. However, a map in
 // /dev/ashmem/... does not set this flag.
 static constexpr int PROT_DEVICE_MAP = 0x8000;
+// Special flag to indicate that this map represents an elf file
+// created by ART for use with the gdb jit debug interface.
+// This should only ever appear in offline maps data.
+static constexpr int PROT_JIT_SYMFILE_MAP = 0x4000;
 
 struct backtrace_map_t {
   uint64_t start = 0;

libunwindstack/Android.bp

@@ -194,6 +194,7 @@ cc_test {
         "tests/files/offline/eh_frame_hdr_begin_x86_64/*",
         "tests/files/offline/jit_debug_arm/*",
         "tests/files/offline/jit_debug_x86/*",
+        "tests/files/offline/jit_map_arm/*",
         "tests/files/offline/gnu_debugdata_arm/*",
         "tests/files/offline/straddle_arm/*",
         "tests/files/offline/straddle_arm64/*",

libunwindstack/Maps.cpp

@@ -25,6 +25,7 @@
 
 #include <android-base/unique_fd.h>
 
+#include <algorithm>
 #include <cctype>
 #include <memory>
 #include <string>
@@ -209,6 +210,11 @@ void Maps::Add(uint64_t start, uint64_t end, uint64_t offset, uint64_t flags,
   maps_.push_back(map_info);
 }
 
+void Maps::Sort() {
+  std::sort(maps_.begin(), maps_.end(),
+            [](const MapInfo* a, const MapInfo* b) { return a->start < b->start; });
+}
+
 Maps::~Maps() {
   for (auto& map : maps_) {
     delete map;

libunwindstack/Unwinder.cpp

@@ -29,6 +29,7 @@
 #include <unwindstack/Elf.h>
 #include <unwindstack/JitDebug.h>
 #include <unwindstack/MapInfo.h>
+#include <unwindstack/Maps.h>
 #include <unwindstack/Unwinder.h>
 
 #if !defined(NO_LIBDEXFILE_SUPPORT)
@@ -142,26 +143,31 @@ void Unwinder::Unwind(const std::vector<std::string>* initial_map_names_to_skip,
     uint64_t cur_sp = regs_->sp();
 
     MapInfo* map_info = maps_->Find(regs_->pc());
-    uint64_t rel_pc;
     uint64_t pc_adjustment = 0;
     uint64_t step_pc;
+    uint64_t rel_pc;
     Elf* elf;
     if (map_info == nullptr) {
-      rel_pc = regs_->pc();
-      step_pc = rel_pc;
+      step_pc = regs_->pc();
+      rel_pc = step_pc;
       last_error_.code = ERROR_INVALID_MAP;
     } else {
       if (ShouldStop(map_suffixes_to_ignore, map_info->name)) {
         break;
       }
       elf = map_info->GetElf(process_memory_, true);
-      rel_pc = elf->GetRelPc(regs_->pc(), map_info);
+      step_pc = regs_->pc();
+      rel_pc = elf->GetRelPc(step_pc, map_info);
+      // Everyone except elf data in gdb jit debug maps uses the relative pc.
+      if (!(map_info->flags & MAPS_FLAGS_JIT_SYMFILE_MAP)) {
+        step_pc = rel_pc;
+      }
       if (adjust_pc) {
         pc_adjustment = regs_->GetPcAdjustment(rel_pc, elf);
       } else {
         pc_adjustment = 0;
       }
-      step_pc = rel_pc - pc_adjustment;
+      step_pc -= pc_adjustment;
 
       // If the pc is in an invalid elf file, try and get an Elf object
       // using the jit debug information.

libunwindstack/include/unwindstack/Maps.h

@@ -30,6 +30,10 @@ namespace unwindstack {
 // Special flag to indicate a map is in /dev/. However, a map in
 // /dev/ashmem/... does not set this flag.
 static constexpr int MAPS_FLAGS_DEVICE_MAP = 0x8000;
+// Special flag to indicate that this map represents an elf file
+// created by ART for use with the gdb jit debug interface.
+// This should only ever appear in offline maps data.
+static constexpr int MAPS_FLAGS_JIT_SYMFILE_MAP = 0x4000;
 
 class Maps {
  public:
@@ -45,6 +49,8 @@ class Maps {
   void Add(uint64_t start, uint64_t end, uint64_t offset, uint64_t flags, const std::string& name,
            uint64_t load_bias);
 
+  void Sort();
+
   typedef std::vector<MapInfo*>::iterator iterator;
   iterator begin() { return maps_.begin(); }
   iterator end() { return maps_.end(); }

libunwindstack/tests/UnwindOfflineTest.cpp

@@ -18,6 +18,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <sys/mman.h>
 #include <unistd.h>
 
 #include <gtest/gtest.h>
@@ -1070,4 +1071,44 @@ TEST_F(UnwindOfflineTest, art_quick_osr_stub_arm) {
   EXPECT_EQ(0xcd4ff960U, unwinder.frames()[24].sp);
 }
 
+TEST_F(UnwindOfflineTest, jit_map_arm) {
+  Init("jit_map_arm/", ARCH_ARM);
+
+  maps_->Add(0xd025c788, 0xd025c9f0, 0, PROT_READ | PROT_EXEC | MAPS_FLAGS_JIT_SYMFILE_MAP,
+             "jit_map0.so", 0);
+  maps_->Add(0xd025cd98, 0xd025cff4, 0, PROT_READ | PROT_EXEC | MAPS_FLAGS_JIT_SYMFILE_MAP,
+             "jit_map1.so", 0);
+  maps_->Sort();
+
+  Unwinder unwinder(128, maps_.get(), regs_.get(), process_memory_);
+  unwinder.Unwind();
+
+  std::string frame_info(DumpFrames(unwinder));
+  ASSERT_EQ(6U, unwinder.NumFrames()) << "Unwind:\n" << frame_info;
+  EXPECT_EQ(
+      "  #00 pc 00000000  jit_map0.so "
+      "(com.example.simpleperf.simpleperfexamplewithnative.MixActivity.access$000)\n"
+      "  #01 pc 0000003d  jit_map1.so "
+      "(com.example.simpleperf.simpleperfexamplewithnative.MixActivity$1.run+60)\n"
+      "  #02 pc 004135bb  libart.so (art_quick_osr_stub+42)\n"
+
+      "  #03 pc 003851dd  libart.so (_ZN3art6Thread14CreateCallbackEPv+868)\n"
+      "  #04 pc 00062925  libc.so (_ZL15__pthread_startPv+22)\n"
+      "  #05 pc 0001de39  libc.so (__start_thread+24)\n",
+      frame_info);
+
+  EXPECT_EQ(0xd025c788U, unwinder.frames()[0].pc);
+  EXPECT_EQ(0xcd4ff140U, unwinder.frames()[0].sp);
+  EXPECT_EQ(0xd025cdd5U, unwinder.frames()[1].pc);
+  EXPECT_EQ(0xcd4ff140U, unwinder.frames()[1].sp);
+  EXPECT_EQ(0xe4a755bbU, unwinder.frames()[2].pc);
+  EXPECT_EQ(0xcd4ff160U, unwinder.frames()[2].sp);
+  EXPECT_EQ(0xe49e71ddU, unwinder.frames()[3].pc);
+  EXPECT_EQ(0xcd4ff8e8U, unwinder.frames()[3].sp);
+  EXPECT_EQ(0xe7df3925U, unwinder.frames()[4].pc);
+  EXPECT_EQ(0xcd4ff958U, unwinder.frames()[4].sp);
+  EXPECT_EQ(0xe7daee39U, unwinder.frames()[5].pc);
+  EXPECT_EQ(0xcd4ff960U, unwinder.frames()[5].sp);
+}
+
 }  // namespace unwindstack

libunwindstack/tests/files/offline/jit_map_arm/maps.txt

@@ -0,0 +1,2 @@
+e466e000-e4ae8000 r-xp 0 00:00 0 libart.so
+e7d91000-e7e31000 r-xp 0 00:00 0 libc.so

libunwindstack/tests/files/offline/jit_map_arm/regs.txt

@@ -0,0 +1,16 @@
+r0: e814103c
+r1: 12dcf218
+r2: 1a90df75
+r3: ffffffbf
+r4: 0
+r5: 12dc0800
+r6: 12dcf218
+r7: 1a90df75
+r8: 0
+r9: dd23cc00
+r10: 1c
+r11: cd4ff16c
+ip: 0
+sp: cd4ff140
+lr: d025cdd7
+pc: d025c788