From 6cef9adffcf9af3c632e58e0d7d4d6e1d0525980 Mon Sep 17 00:00:00 2001
From: Yichao Yu <yyc1992@gmail.com>
Date: Thu, 29 Sep 2016 22:41:57 -0400
Subject: [PATCH] Fix PREL31 relocation on ARM
This is a 31bits relative relocation instead of a 32bits absolute relocation.
---
lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp | 4 ++++
.../RuntimeDyld/ARM/ELF_ARM_EXIDX_relocations.s | 23 ++++++++++++++++++++++
2 files changed, 27 insertions(+)
create mode 100644 test/ExecutionEngine/RuntimeDyld/ARM/ELF_ARM_EXIDX_relocations.s
diff --git a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
index 6929732..2e0d168 100644
--- a/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
+++ b/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
@@ -463,7 +463,11 @@ void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section,
case ELF::R_ARM_NONE:
break;
+ // Write a 31bit signed offset
case ELF::R_ARM_PREL31:
+ *TargetPtr &= 0x80000000;
+ *TargetPtr |= (Value - FinalAddress) & ~0x80000000;
+ break;
case ELF::R_ARM_TARGET1:
case ELF::R_ARM_ABS32:
*TargetPtr = Value;
diff --git a/test/ExecutionEngine/RuntimeDyld/ARM/ELF_ARM_EXIDX_relocations.s b/test/ExecutionEngine/RuntimeDyld/ARM/ELF_ARM_EXIDX_relocations.s
new file mode 100644
index 0000000..eb07b00
--- /dev/null
+++ b/test/ExecutionEngine/RuntimeDyld/ARM/ELF_ARM_EXIDX_relocations.s
@@ -0,0 +1,23 @@
+# RUN: llvm-mc -triple=arm-linux-gnueabihf -filetype=obj -o %T/reloc.o %s
+# RUN: llvm-rtdyld -triple=arm-linux-gnueabihf -verify -map-section reloc.o,.ARM.exidx=0x6000 -map-section reloc.o,.text=0x4000 -dummy-extern __aeabi_unwind_cpp_pr0=0x1234 -check=%s %T/reloc.o
+
+ .text
+ .syntax unified
+ .eabi_attribute 67, "2.09" @ Tag_conformance
+ .cpu cortex-a8
+ .fpu neon
+ .file "reloc.c"
+ .globl g
+ .align 2
+ .type g,%function
+g:
+ .fnstart
+ movw r0, #1
+ bx lr
+ .Lfunc_end0:
+ .size g, .Lfunc_end0-g
+ .fnend
+
+# rtdyld-check: *{4}(section_addr(reloc.o, .ARM.exidx)) = (g - (section_addr(reloc.o, .ARM.exidx))) & 0x7fffffff
+# Compat unwind info: finish(0xb0), finish(0xb0), finish(0xb0)
+# rtdyld-check: *{4}(section_addr(reloc.o, .ARM.exidx) + 0x4) = 0x80b0b0b0
--
2.10.0