From c6b11bb4ce2b550f15fc33488a2b353793f41f91 Mon Sep 17 00:00:00 2001 From: Simon Wallis Date: Wed, 13 May 2020 10:40:14 +0100 Subject: [PATCH] Clang crash targeting ARM or Thumb when assembling a prel31 relocation variant 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 --- .../ARM/MCTargetDesc/ARMELFObjectWriter.cpp | 30 ++++++++++++++----- test/MC/ARM/error-location.s | 18 +++++++++++ 2 files changed, 40 insertions(+), 8 deletions(-) diff --git a/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp b/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp index 6bd6addcb6d..4eaa8102101 100644 --- a/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp +++ b/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp @@ -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: diff --git a/test/MC/ARM/error-location.s b/test/MC/ARM/error-location.s index 29bb5fe1b62..3f9fa0c2370 100644 --- a/test/MC/ARM/error-location.s +++ b/test/MC/ARM/error-location.s @@ -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