[llvm] [JITLink][AArch32] Fix Unaligned Data Symbol Address Resolution (PR #97030)
Eymen Ünay via llvm-commits
llvm-commits at lists.llvm.org
Fri Jun 28 06:45:21 PDT 2024
https://github.com/eymay updated https://github.com/llvm/llvm-project/pull/97030
>From 5244f5f64e60dc596313577d5584df64ef210581 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Eymen=20=C3=9Cnay?= <eymenunay at outlook.com>
Date: Fri, 28 Jun 2024 12:34:26 +0300
Subject: [PATCH 1/2] [JITLink][AArch32] Fix Unaligned Data Symbol Address
Resolution
The ARM architecture uses the LSB bit for ARM/Thumb mode switch
flagging. This is true for alignments of 2 and 4 but in data
relocations the alignment is 1 allowing the LSB bit to be set.
ELF::STT_OBJECT typed symbols are made to bypass the TargetFlag
mechanism assuming they are the only symbols affected by data
relocations.
The test is a minimal example of the issue mentioned below.
Fixes the issue "Orc global constructor order test fails on 32
bit ARM #95911".
---
.../ExecutionEngine/JITLink/ELF_aarch32.cpp | 8 +++
.../JITLink/AArch32/data-alignment.s | 50 +++++++++++++++++++
.../ExecutionEngine/Orc/global-ctor-order.ll | 4 --
3 files changed, 58 insertions(+), 4 deletions(-)
create mode 100644 llvm/test/ExecutionEngine/JITLink/AArch32/data-alignment.s
diff --git a/llvm/lib/ExecutionEngine/JITLink/ELF_aarch32.cpp b/llvm/lib/ExecutionEngine/JITLink/ELF_aarch32.cpp
index 908b88fef1b31..3d8af86afa76b 100644
--- a/llvm/lib/ExecutionEngine/JITLink/ELF_aarch32.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/ELF_aarch32.cpp
@@ -200,6 +200,9 @@ class ELFLinkGraphBuilder_aarch32
protected:
TargetFlagsType makeTargetFlags(const typename ELFT::Sym &Sym) override {
+ // Data symbols do not have Arm or Thumb flags.
+ if (Sym.getType() == ELF::STT_OBJECT)
+ return TargetFlagsType{};
if (Sym.getValue() & 0x01)
return aarch32::ThumbSymbol;
return TargetFlagsType{};
@@ -208,6 +211,11 @@ class ELFLinkGraphBuilder_aarch32
orc::ExecutorAddrDiff getRawOffset(const typename ELFT::Sym &Sym,
TargetFlagsType Flags) override {
assert((makeTargetFlags(Sym) & Flags) == Flags);
+ // Data relocations can be aligned to 1 making some symbol addresses have
+ // their LSB set. To access the real addresses of these symbols their LSB
+ // should be protected.
+ if (Sym.getType() == ELF::STT_OBJECT)
+ return Sym.getValue();
static constexpr uint64_t ThumbBit = 0x01;
return Sym.getValue() & ~ThumbBit;
}
diff --git a/llvm/test/ExecutionEngine/JITLink/AArch32/data-alignment.s b/llvm/test/ExecutionEngine/JITLink/AArch32/data-alignment.s
new file mode 100644
index 0000000000000..bda6872a7be0c
--- /dev/null
+++ b/llvm/test/ExecutionEngine/JITLink/AArch32/data-alignment.s
@@ -0,0 +1,50 @@
+# RUN: llvm-mc -triple=armv7-linux-gnueabi -arm-add-build-attributes -filetype=obj -o %t_armv7.o %s
+# RUN: llvm-objdump -s --section=.rodata %t_armv7.o | FileCheck --check-prefix=CHECK-DATA %s
+# RUN: llvm-jitlink -noexec -slab-address 0x76ff0000 -slab-allocate 10Kb \
+# RUN: -slab-page-size 4096 -check %s %t_armv7.o
+
+# RUN: llvm-mc -triple=thumbv7-linux-gnueabi -arm-add-build-attributes -filetype=obj -o %t_thumbv7.o %s
+# RUN: llvm-objdump -s --section=.rodata %t_thumbv7.o | FileCheck --check-prefix=CHECK-DATA %s
+# RUN: llvm-jitlink -noexec -slab-address 0x76ff0000 -slab-allocate 10Kb \
+# RUN: -slab-page-size 4096 -check %s %t_armv7.o
+
+# The strings of "H1\00", "H2\00" and "H3\00" are encoded as
+# 0x483100, 0x483200 and 0x483300 .rodata section.
+# CHECK-DATA: Contents of section .rodata:
+# CHECK-DATA: 0000 48310048 32004833 00
+
+# FIXME: The expression we want is either *{3}(Lstr.H1) = ...
+# or *{4}(Lstr.H1) & 0x00ffffff = ...
+# The first is not supported and the latter segfaults.
+# Also, whitespaces are not recognized and not consumed by the checker.
+
+# jitlink-check: 0x00ffffff&*{4}(Lstr.H1) = 0x003148
+ .globl Lstr.H1
+ .type Lstr.H1,%object
+ .section .rodata,"a",%progbits
+Lstr.H1:
+ .asciz "H1"
+ .size Lstr.H1, 3
+
+# Not 0x324800
+# jitlink-check: 0x00ffffff&*{4}(Lstr.H2) = 0x003248
+ .globl Lstr.H2
+ .type Lstr.H2,%object
+Lstr.H2:
+ .asciz "H2"
+ .size Lstr.H2, 3
+
+# jitlink-check: 0x00ffffff&*{4}(Lstr.H3) = 0x003348
+ .globl Lstr.H3
+ .type Lstr.H3,%object
+Lstr.H3:
+ .asciz "H3"
+ .size Lstr.H3, 3
+
+# Empty main function for jitlink to be happy
+ .globl main
+ .type main,%function
+ .p2align 2
+main:
+ bx lr
+ .size main,.-main
diff --git a/llvm/test/ExecutionEngine/Orc/global-ctor-order.ll b/llvm/test/ExecutionEngine/Orc/global-ctor-order.ll
index de9a35465f8cb..98cf67af8276d 100644
--- a/llvm/test/ExecutionEngine/Orc/global-ctor-order.ll
+++ b/llvm/test/ExecutionEngine/Orc/global-ctor-order.ll
@@ -1,9 +1,5 @@
; Test that global constructors are correctly ordered
;
-; Uncovers a pre-existing issue on Arm 32 bit, see
-; https://github.com/llvm/llvm-project/issues/95911.
-; UNSUPPORTED: target=arm{{.*}}
-;
; RUN: lli -jit-kind=orc %s | FileCheck %s
;
; CHECK: H1
>From 608326f98ed0717262d706ad269de901e33cc609 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Eymen=20=C3=9Cnay?= <eymenunay at outlook.com>
Date: Fri, 28 Jun 2024 16:44:40 +0300
Subject: [PATCH 2/2] Enhance the test with LinkGraph and additional checks
---
.../JITLink/AArch32/ELF_data_alignment.s | 72 +++++++++++++++++++
.../JITLink/AArch32/data-alignment.s | 50 -------------
2 files changed, 72 insertions(+), 50 deletions(-)
create mode 100644 llvm/test/ExecutionEngine/JITLink/AArch32/ELF_data_alignment.s
delete mode 100644 llvm/test/ExecutionEngine/JITLink/AArch32/data-alignment.s
diff --git a/llvm/test/ExecutionEngine/JITLink/AArch32/ELF_data_alignment.s b/llvm/test/ExecutionEngine/JITLink/AArch32/ELF_data_alignment.s
new file mode 100644
index 0000000000000..935ba28a75974
--- /dev/null
+++ b/llvm/test/ExecutionEngine/JITLink/AArch32/ELF_data_alignment.s
@@ -0,0 +1,72 @@
+# RUN: llvm-mc -triple=armv7-linux-gnueabi -arm-add-build-attributes -filetype=obj -o %t_armv7.o %s
+# RUN: llvm-objdump -s --section=.rodata %t_armv7.o | FileCheck --check-prefix=CHECK-OBJ %s
+# RUN: llvm-jitlink -noexec -slab-address 0x76ff0000 -slab-allocate 10Kb \
+# RUN: -slab-page-size 4096 %t_armv7.o -debug-only=jitlink 2>&1 \
+# RUN: | FileCheck --check-prefix=CHECK-LG %s
+# RUN: llvm-jitlink -noexec -slab-address 0x76ff0000 -slab-allocate 10Kb \
+# RUN: -slab-page-size 4096 %t_armv7.o -check %s
+
+# RUN: llvm-mc -triple=thumbv7-linux-gnueabi -arm-add-build-attributes -filetype=obj -o %t_thumbv7.o %s
+# RUN: llvm-objdump -s --section=.rodata %t_thumbv7.o | FileCheck --check-prefix=CHECK-OBJ %s
+# RUN: llvm-jitlink -noexec -slab-address 0x76ff0000 -slab-allocate 10Kb \
+# RUN: -slab-page-size 4096 %t_thumbv7.o -debug-only=jitlink 2>&1 \
+# RUN: | FileCheck --check-prefix=CHECK-LG %s
+# RUN: llvm-jitlink -noexec -slab-address 0x76ff0000 -slab-allocate 10Kb \
+# RUN: -slab-page-size 4096 %t_thumbv7.o -check %s
+
+# The strings of "H1\00", "H2\00" and "H3\00" are encoded as
+# 0x483100, 0x483200 and 0x483300 .rodata section.
+# CHECK-OBJ: Contents of section .rodata:
+# CHECK-OBJ: 0000 48310048 32004833 00 H1.H2.H3.
+
+# CHECK-LG: Starting link phase 1 for graph
+# CHECK-LG: section .rodata:
+
+# CHECK-LG: block 0x0 size = 0x00000009, align = 1, alignment-offset = 0
+# CHECK-LG: symbols:
+# CHECK-LG: 0x0 (block + 0x00000000): size: 0x00000003, linkage: strong, scope: default, live - Lstr.H1
+# CHECK-LG: 0x3 (block + 0x00000003): size: 0x00000003, linkage: strong, scope: default, live - Lstr.H2
+# CHECK-LG-NOT: 0x2 (block + 0x00000002): size: 0x00000003, linkage: strong, scope: default, live - Lstr.H2
+# CHECK-LG: 0x6 (block + 0x00000006): size: 0x00000003, linkage: strong, scope: default, live - Lstr.H3
+
+# FIXME: The expression we want is either *{3}(Lstr.H1) = ...
+# or *{4}(Lstr.H1) & 0x00ffffff = ...
+# The first is not supported and the latter segfaults.
+# Also, whitespaces are not recognized and not consumed by the checker.
+
+# jitlink-check: Lstr.H1 = 0x76ff0000
+# jitlink-check: 0x00ffffff&*{4}(Lstr.H1) = 0x003148
+ .globl Lstr.H1
+ .type Lstr.H1,%object
+ .section .rodata,"a",%progbits
+Lstr.H1:
+ .asciz "H1"
+ .size Lstr.H1, 3
+
+# H2 is unaligned as its beginning address is base address + 0x3
+# Make sure the string we get is 0x003248 and not 0x324800
+# jitlink-check: Lstr.H2 = 0x76ff0003
+# jitlink-check: 0x00ffffff&*{4}(Lstr.H2) = 0x003248
+ .globl Lstr.H2
+ .type Lstr.H2,%object
+Lstr.H2:
+ .asciz "H2"
+ .size Lstr.H2, 3
+
+# jitlink-check: Lstr.H3 = 0x76ff0006
+# jitlink-check: 0x00ffffff&*{4}(Lstr.H3) = 0x003348
+ .globl Lstr.H3
+ .type Lstr.H3,%object
+Lstr.H3:
+ .asciz "H3"
+ .size Lstr.H3, 3
+
+ .text
+ .syntax unified
+# Empty main function for jitlink to be happy
+ .globl main
+ .type main,%function
+ .p2align 2
+main:
+ bx lr
+ .size main,.-main
diff --git a/llvm/test/ExecutionEngine/JITLink/AArch32/data-alignment.s b/llvm/test/ExecutionEngine/JITLink/AArch32/data-alignment.s
deleted file mode 100644
index bda6872a7be0c..0000000000000
--- a/llvm/test/ExecutionEngine/JITLink/AArch32/data-alignment.s
+++ /dev/null
@@ -1,50 +0,0 @@
-# RUN: llvm-mc -triple=armv7-linux-gnueabi -arm-add-build-attributes -filetype=obj -o %t_armv7.o %s
-# RUN: llvm-objdump -s --section=.rodata %t_armv7.o | FileCheck --check-prefix=CHECK-DATA %s
-# RUN: llvm-jitlink -noexec -slab-address 0x76ff0000 -slab-allocate 10Kb \
-# RUN: -slab-page-size 4096 -check %s %t_armv7.o
-
-# RUN: llvm-mc -triple=thumbv7-linux-gnueabi -arm-add-build-attributes -filetype=obj -o %t_thumbv7.o %s
-# RUN: llvm-objdump -s --section=.rodata %t_thumbv7.o | FileCheck --check-prefix=CHECK-DATA %s
-# RUN: llvm-jitlink -noexec -slab-address 0x76ff0000 -slab-allocate 10Kb \
-# RUN: -slab-page-size 4096 -check %s %t_armv7.o
-
-# The strings of "H1\00", "H2\00" and "H3\00" are encoded as
-# 0x483100, 0x483200 and 0x483300 .rodata section.
-# CHECK-DATA: Contents of section .rodata:
-# CHECK-DATA: 0000 48310048 32004833 00
-
-# FIXME: The expression we want is either *{3}(Lstr.H1) = ...
-# or *{4}(Lstr.H1) & 0x00ffffff = ...
-# The first is not supported and the latter segfaults.
-# Also, whitespaces are not recognized and not consumed by the checker.
-
-# jitlink-check: 0x00ffffff&*{4}(Lstr.H1) = 0x003148
- .globl Lstr.H1
- .type Lstr.H1,%object
- .section .rodata,"a",%progbits
-Lstr.H1:
- .asciz "H1"
- .size Lstr.H1, 3
-
-# Not 0x324800
-# jitlink-check: 0x00ffffff&*{4}(Lstr.H2) = 0x003248
- .globl Lstr.H2
- .type Lstr.H2,%object
-Lstr.H2:
- .asciz "H2"
- .size Lstr.H2, 3
-
-# jitlink-check: 0x00ffffff&*{4}(Lstr.H3) = 0x003348
- .globl Lstr.H3
- .type Lstr.H3,%object
-Lstr.H3:
- .asciz "H3"
- .size Lstr.H3, 3
-
-# Empty main function for jitlink to be happy
- .globl main
- .type main,%function
- .p2align 2
-main:
- bx lr
- .size main,.-main
More information about the llvm-commits
mailing list