commit eb4a6dbf5c6697c953942d079744c05da0c09d51
author Christopher Ferris <cferris@google.com> Wed Jul 19 12:37:45 2017 -0700
committer Christopher Ferris <cferris@google.com> Wed Jul 19 21:35:46 2017 +0000
tree 7a30b551fe2c60c4eae9e614f0a2091b55fcbf21
parent 33913ebfb5ca699d09459227284b3d324343fa43

Speed up StepIfSignalHandler path.

The StepIfSignalHandler code reads from the process memory object, which
is currently the slowest way to read memory. Change the code to read from
the elf memory object which will almost always be a memory mapped file and
should be really fast.

Also, move the tests for StepIfSignalHandler to its own file.

Bug: 23762183

Test: Unit tests pass.
Change-Id: I1100b50554e5ef736a87babd484f3f34e9071caa

libunwindstack/Regs.cpp

diff --git a/libunwindstack/Regs.cpp b/libunwindstack/Regs.cpp
index 33319b1..dea7b87 100644
--- a/libunwindstack/Regs.cpp
+++ b/libunwindstack/Regs.cpp
@@ -350,9 +350,12 @@
   return regs;
 }
 
-bool RegsArm::StepIfSignalHandler(Memory* memory) {
+bool RegsArm::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
   uint32_t data;
-  if (!memory->Read(pc(), &data, sizeof(data))) {
+  Memory* elf_memory = elf->memory();
+  // Read from elf memory since it is usually more expensive to read from
+  // process memory.
+  if (!elf_memory->Read(rel_pc, &data, sizeof(data))) {
     return false;
   }
 
@@ -371,7 +374,7 @@
     // Form 3 (thumb):
     // 0x77 0x27              movs r7, #77
     // 0x00 0xdf              svc 0
-    if (!memory->Read(sp(), &data, sizeof(data))) {
+    if (!process_memory->Read(sp(), &data, sizeof(data))) {
       return false;
     }
     if (data == 0x5ac3c35a) {
@@ -395,7 +398,7 @@
     // Form 3 (thumb):
     // 0xad 0x27              movs r7, #ad
     // 0x00 0xdf              svc 0
-    if (!memory->Read(sp(), &data, sizeof(data))) {
+    if (!process_memory->Read(sp(), &data, sizeof(data))) {
       return false;
     }
     if (data == sp() + 8) {
@@ -410,16 +413,19 @@
     return false;
   }
 
-  if (!memory->Read(offset, regs_.data(), sizeof(uint32_t) * ARM_REG_LAST)) {
+  if (!process_memory->Read(offset, regs_.data(), sizeof(uint32_t) * ARM_REG_LAST)) {
     return false;
   }
   SetFromRaw();
   return true;
 }
 
-bool RegsArm64::StepIfSignalHandler(Memory* memory) {
+bool RegsArm64::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
   uint64_t data;
-  if (!memory->Read(pc(), &data, sizeof(data))) {
+  Memory* elf_memory = elf->memory();
+  // Read from elf memory since it is usually more expensive to read from
+  // process memory.
+  if (!elf_memory->Read(rel_pc, &data, sizeof(data))) {
     return false;
   }
 
@@ -432,7 +438,8 @@
   }
 
   // SP + sizeof(siginfo_t) + uc_mcontext offset + X0 offset.
-  if (!memory->Read(sp() + 0x80 + 0xb0 + 0x08, regs_.data(), sizeof(uint64_t) * ARM64_REG_LAST)) {
+  if (!process_memory->Read(sp() + 0x80 + 0xb0 + 0x08, regs_.data(),
+                            sizeof(uint64_t) * ARM64_REG_LAST)) {
     return false;
   }
 
@@ -440,9 +447,12 @@
   return true;
 }
 
-bool RegsX86::StepIfSignalHandler(Memory* memory) {
+bool RegsX86::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
   uint64_t data;
-  if (!memory->Read(pc(), &data, sizeof(data))) {
+  Memory* elf_memory = elf->memory();
+  // Read from elf memory since it is usually more expensive to read from
+  // process memory.
+  if (!elf_memory->Read(rel_pc, &data, sizeof(data))) {
     return false;
   }
 
@@ -458,7 +468,7 @@
     //   int signum
     //   struct sigcontext (same format as mcontext)
     struct x86_mcontext_t context;
-    if (!memory->Read(sp() + 4, &context, sizeof(context))) {
+    if (!process_memory->Read(sp() + 4, &context, sizeof(context))) {
       return false;
     }
     regs_[X86_REG_EBP] = context.ebp;
@@ -484,12 +494,12 @@
 
     // Get the location of the sigcontext data.
     uint32_t ptr;
-    if (!memory->Read(sp() + 8, &ptr, sizeof(ptr))) {
+    if (!process_memory->Read(sp() + 8, &ptr, sizeof(ptr))) {
       return false;
     }
     // Only read the portion of the data structure we care about.
     x86_ucontext_t x86_ucontext;
-    if (!memory->Read(ptr + 0x14, &x86_ucontext.uc_mcontext, sizeof(x86_mcontext_t))) {
+    if (!process_memory->Read(ptr + 0x14, &x86_ucontext.uc_mcontext, sizeof(x86_mcontext_t))) {
       return false;
     }
     SetFromUcontext(&x86_ucontext);
@@ -498,14 +508,17 @@
   return false;
 }
 
-bool RegsX86_64::StepIfSignalHandler(Memory* memory) {
+bool RegsX86_64::StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) {
   uint64_t data;
-  if (!memory->Read(pc(), &data, sizeof(data)) || data != 0x0f0000000fc0c748) {
+  Memory* elf_memory = elf->memory();
+  // Read from elf memory since it is usually more expensive to read from
+  // process memory.
+  if (!elf_memory->Read(rel_pc, &data, sizeof(data)) || data != 0x0f0000000fc0c748) {
     return false;
   }
 
   uint16_t data2;
-  if (!memory->Read(pc() + 8, &data2, sizeof(data2)) || data2 != 0x0f05) {
+  if (!elf_memory->Read(rel_pc + 8, &data2, sizeof(data2)) || data2 != 0x0f05) {
     return false;
   }
 
@@ -517,7 +530,7 @@
   // Read the mcontext data from the stack.
   // sp points to the ucontext data structure, read only the mcontext part.
   x86_64_ucontext_t x86_64_ucontext;
-  if (!memory->Read(sp() + 0x28, &x86_64_ucontext.uc_mcontext, sizeof(x86_64_mcontext_t))) {
+  if (!process_memory->Read(sp() + 0x28, &x86_64_ucontext.uc_mcontext, sizeof(x86_64_mcontext_t))) {
     return false;
   }
   SetFromUcontext(&x86_64_ucontext);