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Clang crash targeting ARM or Thumb when assembling a prel31 relocation variant

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Summary:
In the assembler or inline assembler,
attempting to use an invalid fixup type
gives a crash with a segmentation fault.

__attribute__((naked))
void foo(void) {
 __asm__("mov r9, :lower16:bar(prel31)");
}

This should give a proper error message when building for ARM or Thumb.
This brings it in line with AARCH64.

This fixes all 8 instances of llvm_unreachable("Unsupported Modifier");
in ARM/MCTargetDesc/ARMELFObjectWriter.cpp.
A test is provided for each instance.

Reviewers: llvm-commits, MarkMurrayARM

Reviewed By: MarkMurrayARM

Subscribers: kristof.beyls, hiraditya, danielkiss

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D79782

Change-Id: I6971ba37f129cc453568fe71514ccb2ac9d16831
This commit is contained in:
Simon Wallis 2020-05-13 10:40:14 +01:00
parent cc03ee5234
commit c6b11bb4ce
2 changed files with 40 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp
View File

@ -92,7 +92,9 @@ unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
case FK_Data_4:
switch (Modifier) {
default:
llvm_unreachable("Unsupported Modifier");
Ctx.reportError(Fixup.getLoc(),
"invalid fixup for 4-byte pc-relative data relocation");
return ELF::R_ARM_NONE;
case MCSymbolRefExpr::VK_None: {
if (const MCSymbolRefExpr *SymRef = Target.getSymA()) {
// For GNU AS compatibility expressions such as
@ -162,21 +164,27 @@ unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
case FK_Data_1:
switch (Modifier) {
default:
llvm_unreachable("unsupported Modifier");
Ctx.reportError(Fixup.getLoc(),
"invalid fixup for 1-byte data relocation");
return ELF::R_ARM_NONE;
case MCSymbolRefExpr::VK_None:
return ELF::R_ARM_ABS8;
}
case FK_Data_2:
switch (Modifier) {
default:
llvm_unreachable("unsupported modifier");
Ctx.reportError(Fixup.getLoc(),
"invalid fixup for 2-byte data relocation");
return ELF::R_ARM_NONE;
case MCSymbolRefExpr::VK_None:
return ELF::R_ARM_ABS16;
}
case FK_Data_4:
switch (Modifier) {
default:
llvm_unreachable("Unsupported Modifier");
Ctx.reportError(Fixup.getLoc(),
"invalid fixup for 4-byte data relocation");
return ELF::R_ARM_NONE;
case MCSymbolRefExpr::VK_ARM_NONE:
return ELF::R_ARM_NONE;
case MCSymbolRefExpr::VK_GOT:
@ -218,7 +226,8 @@ unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
case ARM::fixup_arm_movt_hi16:
switch (Modifier) {
default:
llvm_unreachable("Unsupported Modifier");
Ctx.reportError(Fixup.getLoc(), "invalid fixup for ARM MOVT instruction");
return ELF::R_ARM_NONE;
case MCSymbolRefExpr::VK_None:
return ELF::R_ARM_MOVT_ABS;
case MCSymbolRefExpr::VK_ARM_SBREL:
@ -227,7 +236,8 @@ unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
case ARM::fixup_arm_movw_lo16:
switch (Modifier) {
default:
llvm_unreachable("Unsupported Modifier");
Ctx.reportError(Fixup.getLoc(), "invalid fixup for ARM MOVW instruction");
return ELF::R_ARM_NONE;
case MCSymbolRefExpr::VK_None:
return ELF::R_ARM_MOVW_ABS_NC;
case MCSymbolRefExpr::VK_ARM_SBREL:
@ -236,7 +246,9 @@ unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
case ARM::fixup_t2_movt_hi16:
switch (Modifier) {
default:
llvm_unreachable("Unsupported Modifier");
Ctx.reportError(Fixup.getLoc(),
"invalid fixup for Thumb MOVT instruction");
return ELF::R_ARM_NONE;
case MCSymbolRefExpr::VK_None:
return ELF::R_ARM_THM_MOVT_ABS;
case MCSymbolRefExpr::VK_ARM_SBREL:
@ -245,7 +257,9 @@ unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
case ARM::fixup_t2_movw_lo16:
switch (Modifier) {
default:
llvm_unreachable("Unsupported Modifier");
Ctx.reportError(Fixup.getLoc(),
"invalid fixup for Thumb MOVW instruction");
return ELF::R_ARM_NONE;
case MCSymbolRefExpr::VK_None:
return ELF::R_ARM_THM_MOVW_ABS_NC;
case MCSymbolRefExpr::VK_ARM_SBREL:

18
test/MC/ARM/error-location.s
View File

@ -1,4 +1,5 @@
@ RUN: not llvm-mc -triple armv7a--none-eabi -filetype obj < %s -o /dev/null 2>&1 | FileCheck %s
@ RUN: not llvm-mc -triple thumbv7a--none-eabi -filetype obj < %s -o /dev/null 2>&1 | FileCheck %s
@ Note: These errors are not always emitted in the order in which the relevant
@ source appears, this file is carefully ordered so that that is the case.
@ -16,7 +17,24 @@
@ CHECK: :[[@LINE+1]]:{{[0-9]+}}: error: Cannot represent a difference across sections
.word x_a - y_a
@ CHECK: :[[@LINE+1]]:{{[0-9]+}}: error: invalid fixup for {{ARM|Thumb}} MOVT instruction
movt r9, :upper16: bar(PREL31)
@ CHECK: :[[@LINE+1]]:{{[0-9]+}}: error: invalid fixup for {{ARM|Thumb}} MOVW instruction
movw r9, :lower16: bar(PREL31)
@ CHECK: :[[@LINE+1]]:{{[0-9]+}}: error: invalid fixup for 1-byte data relocation
.byte f30(PLT)
@ CHECK: :[[@LINE+1]]:{{[0-9]+}}: error: invalid fixup for 2-byte data relocation
.hword f30(PLT)
@ CHECK: :[[@LINE+1]]:{{[0-9]+}}: error: invalid fixup for 4-byte data relocation
.word f30(PLT)
@ CHECK: :[[@LINE+1]]:{{[0-9]+}}: error: invalid fixup for 4-byte pc-relative data relocation
.word x_a(PLT) - label1
label1:
w:
.word 0