1 files changed, 0 insertions, 96 deletions
diff --git a/debian/patches/thumb-function-bounds.diff b/debian/patches/thumb-function-bounds.diff
deleted file mode 100644
index 1fd8c729..00000000
--- a/debian/patches/thumb-function-bounds.diff
+++ /dev/null
@@ -1,96 +0,0 @@
-From: Benjamin Barenblat <bbaren@google.com>
-Subject: Correct Thumb function bound computation in the symbolizer
-Forwarded: yes
-Applied-Upstream: https://github.com/abseil/abseil-cpp/commit/1ae9b71c474628d60eb251a3f62967fe64151bb2
-
-On 32-bit ARM, all functions are aligned to multiples of two bytes, and
-the lowest-order bit in a function’s address is ignored by the CPU when
-computing branch targets. That bit is still present in instructions and
-ELF symbol tables, though; it’s repurposed to indicate whether the
-function contains ARM or Thumb code. If the symbolizer doesn’t ignore
-that bit, it will believe Thumb functions have boundaries that are off
-by one byte, so instruct the symbolizer to null out the lowest-order bit
-after retrieving it from the symbol table.
-
-The author works at Google. Upstream applied this patch as Piper
-revision 369254082 and exported it to GitHub; the Applied-Upstream URL
-above points to the exported commit.
-
---- a/absl/debugging/symbolize_elf.inc
-+++ b/absl/debugging/symbolize_elf.inc
-@@ -701,6 +701,16 @@
-       const char *start_address =
-           ComputeOffset(original_start_address, relocation);
- 
-+#ifdef __arm__
-+      // ARM functions are always aligned to multiples of two bytes; the
-+      // lowest-order bit in start_address is ignored by the CPU and indicates
-+      // whether the function contains ARM (0) or Thumb (1) code. We don't care
-+      // about what encoding is being used; we just want the real start address
-+      // of the function.
-+      start_address = reinterpret_cast<const char *>(
-+          reinterpret_cast<uintptr_t>(start_address) & ~1);
-+#endif
-+
-       if (deref_function_descriptor_pointer &&
-           InSection(original_start_address, opd)) {
-         // The opd section is mapped into memory.  Just dereference
---- a/absl/debugging/symbolize_test.cc
-+++ b/absl/debugging/symbolize_test.cc
-@@ -477,6 +477,46 @@
- #endif
- }
- 
-+#if defined(__arm__) && ABSL_HAVE_ATTRIBUTE(target)
-+// Test that we correctly identify bounds of Thumb functions on ARM.
-+//
-+// Thumb functions have the lowest-order bit set in their addresses in the ELF
-+// symbol table. This requires some extra logic to properly compute function
-+// bounds. To test this logic, nudge a Thumb function right up against an ARM
-+// function and try to symbolize the ARM function.
-+//
-+// A naive implementation will simply use the Thumb function's entry point as
-+// written in the symbol table and will therefore treat the Thumb function as
-+// extending one byte further in the instruction stream than it actually does.
-+// When asked to symbolize the start of the ARM function, it will identify an
-+// overlap between the Thumb and ARM functions, and it will return the name of
-+// the Thumb function.
-+//
-+// A correct implementation, on the other hand, will null out the lowest-order
-+// bit in the Thumb function's entry point. It will correctly compute the end of
-+// the Thumb function, it will find no overlap between the Thumb and ARM
-+// functions, and it will return the name of the ARM function.
-+
-+__attribute__((target("thumb"))) int ArmThumbOverlapThumb(int x) {
-+  return x * x * x;
-+}
-+
-+__attribute__((target("arm"))) int ArmThumbOverlapArm(int x) {
-+  return x * x * x;
-+}
-+
-+void ABSL_ATTRIBUTE_NOINLINE TestArmThumbOverlap() {
-+#if defined(ABSL_HAVE_ATTRIBUTE_NOINLINE)
-+  const char *symbol = TrySymbolize((void *)&ArmThumbOverlapArm);
-+  ABSL_RAW_CHECK(symbol != nullptr, "TestArmThumbOverlap failed");
-+  ABSL_RAW_CHECK(strcmp("ArmThumbOverlapArm()", symbol) == 0,
-+                 "TestArmThumbOverlap failed");
-+  std::cout << "TestArmThumbOverlap passed" << std::endl;
-+#endif
-+}
-+
-+#endif  // defined(__arm__) && ABSL_HAVE_ATTRIBUTE(target)
-+
- #elif defined(_WIN32)
- #if !defined(ABSL_CONSUME_DLL)
- 
-@@ -551,6 +591,9 @@
-   TestWithPCInsideInlineFunction();
-   TestWithPCInsideNonInlineFunction();
-   TestWithReturnAddress();
-+#if defined(__arm__) && ABSL_HAVE_ATTRIBUTE(target)
-+  TestArmThumbOverlap();
-+#endif
- #endif
- 
-   return RUN_ALL_TESTS();