upstream fix for crash on %{arm} when throwing cpp exception

[packages/mold.git] / arm-exception-crash.patch

From 71daaa22dfaa3a99599c08b0d6681cb05b18e4ae Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@bluewhale.systems>
Date: Sat, 20 Aug 2022 21:19:33 +0800
Subject: [PATCH] [ELF] Fix ARM32 exception handling

Fixes https://github.com/rui314/mold/issues/646
---
 elf/arch-arm32.cc    |  8 ++++----
 test/elf/issue646.sh | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 4 deletions(-)
 create mode 100755 test/elf/issue646.sh

diff --git a/elf/arch-arm32.cc b/elf/arch-arm32.cc
index a470136d..473f50e1 100644
--- a/elf/arch-arm32.cc
+++ b/elf/arch-arm32.cc
@@ -583,9 +583,9 @@ void sort_arm_exidx(Context<E> &ctx) {
 
   tbb::parallel_for((i64)0, num_entries, [&](i64 i) {
     i64 offset = sizeof(Entry) * i;
-    ent[i].addr = sign_extend(ent[i].addr, 30) - offset;
+    ent[i].addr = sign_extend(ent[i].addr, 30) + offset;
     if (is_relative(ent[i].val))
-      ent[i].val = 0x7fff'ffff & (sign_extend(ent[i].val, 30) - offset);
+      ent[i].val = 0x7fff'ffff & (sign_extend(ent[i].val, 30) + offset);
   });
 
   tbb::parallel_sort(ent, ent + num_entries, [](const Entry &a, const Entry &b) {
@@ -595,9 +595,9 @@ void sort_arm_exidx(Context<E> &ctx) {
   // Write back the sorted records while adjusting relative addresses
   tbb::parallel_for((i64)0, num_entries, [&](i64 i) {
     i64 offset = sizeof(Entry) * i;
-    ent[i].addr = 0x7fff'ffff & (ent[i].addr + offset);
+    ent[i].addr = 0x7fff'ffff & (ent[i].addr - offset);
     if (is_relative(ent[i].val))
-      ent[i].val = 0x7fff'ffff & (ent[i].val + offset);
+      ent[i].val = 0x7fff'ffff & (ent[i].val - offset);
   });
 }
 
diff --git a/test/elf/issue646.sh b/test/elf/issue646.sh
new file mode 100755
index 00000000..816fca9b
--- /dev/null
+++ b/test/elf/issue646.sh
@@ -0,0 +1,40 @@
+#!/bin/bash
+export LC_ALL=C
+set -e
+CC="${TEST_CC:-cc}"
+CXX="${TEST_CXX:-c++}"
+GCC="${TEST_GCC:-gcc}"
+GXX="${TEST_GXX:-g++}"
+OBJDUMP="${OBJDUMP:-objdump}"
+MACHINE="${MACHINE:-$(uname -m)}"
+testname=$(basename "$0" .sh)
+echo -n "Testing $testname ... "
+t=out/test/elf/$MACHINE/$testname
+mkdir -p $t
+
+cat <<EOF | $CXX -o $t/a.o -c -xc++ -
+#include <iostream>
+#include <stdexcept>
+
+class Foo : public std::runtime_error {
+public:
+  using std::runtime_error::runtime_error;
+};
+
+static void do_throw() {
+  throw Foo("exception");
+}
+
+int main() {
+  try {
+    do_throw();
+  } catch (const Foo &e) {
+    std::cout << "error: " << e.what() << std::endl;
+  }
+}
+EOF
+
+$CXX -B. -o $t/exe $t/a.o
+$QEMU $t/exe | grep -q 'error: exception'
+
+echo OK