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[ELF] writeTrapInstr: Don't decrease p_memsz #139207

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Merged
merged 1 commit into from
May 10, 2025
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[ELF] writeTrapInstr: Don't decrease p_memsz #139207

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9 changes: 6 additions & 3 deletions lld/ELF/Writer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2960,9 +2960,12 @@ template <class ELFT> void Writer<ELFT>::writeTrapInstr() {
if (p->p_type == PT_LOAD)
last = p.get();

if (last && (last->p_flags & PF_X))
last->p_memsz = last->p_filesz =
alignToPowerOf2(last->p_filesz, ctx.arg.maxPageSize);
if (last && (last->p_flags & PF_X)) {
last->p_filesz = alignToPowerOf2(last->p_filesz, ctx.arg.maxPageSize);
// p_memsz might be larger than the aligned p_filesz due to trailing BSS
// sections. Don't decrease it.
last->p_memsz = std::max(last->p_memsz, last->p_filesz);
}
}
}

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53 changes: 40 additions & 13 deletions lld/test/ELF/fill-trap.s
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@@ -1,26 +1,28 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
# RUN: rm -rf %t && split-file %s %t && cd %t
# RUN: llvm-mc -filetype=obj -triple=x86_64 a.s -o a.o
# RUN: llvm-mc -filetype=obj -triple=x86_64 bss.s -o bss.o

## -z noseparate-code is the default: text segment is not tail padded.
# RUN: ld.lld %t.o -o %t
# RUN: llvm-readobj -l %t | FileCheck %s --check-prefixes=CHECK,NOPAD
# RUN: ld.lld %t.o -z noseparate-code -z common-page-size=512 -o %t
# RUN: llvm-readobj -l %t | FileCheck %s --check-prefixes=CHECK,NOPAD
# RUN: ld.lld a.o -o out
# RUN: llvm-readobj -l out | FileCheck %s --check-prefixes=CHECK,NOPAD
# RUN: ld.lld a.o -z noseparate-code -z common-page-size=512 -o out
# RUN: llvm-readobj -l out | FileCheck %s --check-prefixes=CHECK,NOPAD

## -z separate-code pads the tail of text segment with traps.
## Make common-page-size smaller than max-page-size.
## Check that we use max-page-size instead of common-page-size for padding.
# RUN: ld.lld %t.o -z separate-code -z common-page-size=512 -o %t
# RUN: llvm-readobj -l %t | FileCheck %s --check-prefixes=CHECK,PAD
# RUN: od -Ax -x -N16 -j0x1ff0 %t | FileCheck %s --check-prefix=FILL
# RUN: ld.lld a.o -z separate-code -z common-page-size=512 -o out
# RUN: llvm-readobj -l out | FileCheck %s --check-prefixes=CHECK,PAD
# RUN: od -Ax -x -N16 -j0x1ff0 out | FileCheck %s --check-prefix=FILL

## -z separate-loadable-segments pads all segments, including the text segment.
# RUN: ld.lld %t.o -z separate-loadable-segments -z common-page-size=512 -o %t
# RUN: llvm-readobj -l %t | FileCheck %s --check-prefixes=CHECK,PAD
# RUN: od -Ax -x -N16 -j0x1ff0 %t | FileCheck %s --check-prefix=FILL
# RUN: ld.lld a.o -z separate-loadable-segments -z common-page-size=512 -o out
# RUN: llvm-readobj -l out | FileCheck %s --check-prefixes=CHECK,PAD
# RUN: od -Ax -x -N16 -j0x1ff0 out | FileCheck %s --check-prefix=FILL

# RUN: ld.lld %t.o -z separate-code -z noseparate-code -z common-page-size=512 -o %t
# RUN: llvm-readobj -l %t | FileCheck %s --check-prefixes=CHECK,NOPAD
# RUN: ld.lld a.o -z separate-code -z noseparate-code -z common-page-size=512 -o out
# RUN: llvm-readobj -l out | FileCheck %s --check-prefixes=CHECK,NOPAD

# CHECK: ProgramHeader {
# CHECK: Type: PT_LOAD
Expand All @@ -39,6 +41,31 @@
## Check that executable page is filled with traps at its end.
# FILL: 001ff0 cccc cccc cccc cccc cccc cccc cccc cccc

## There is a single RWX segment. Test that p_memsz is not truncated to p_filesz.
# RUN: ld.lld a.o bss.o -z separate-loadable-segments -T rwx.lds -z max-page-size=64 -o rwx
# RUN: llvm-readelf -l rwx | FileCheck %s --check-prefix=RWX

# RWX: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
# RWX-NEXT: LOAD 0x000080 0x0000000000000000 0x0000000000000000 0x000040 0x000404 RWE 0x40

# RUN: ld.lld a.o bss.o -z separate-loadable-segments --omagic -o omagic
# RUN: llvm-readelf -l omagic | FileCheck %s --check-prefix=OMAGIC

# OMAGIC: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
# OMAGIC-NEXT:LOAD 0x0000b0 0x00000000002000b0 0x00000000002000b0 0x000004 0x000404 RWE 0x4

#--- a.s
.globl _start
_start:
nop

#--- bss.s
.bss
.space 1024

#--- rwx.lds
PHDRS { all PT_LOAD; }
SECTIONS {
.text : {*(.text*)} :all
.bss : {*(.bss*)} :all
}
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