5a58e98c20
Close #57618: currently we align the end of PT_GNU_RELRO to a common-page-size boundary, but do not align the end of the associated PT_LOAD. This is benign when runtime_page_size >= common-page-size. However, when runtime_page_size < common-page-size, it is possible that `alignUp(end(PT_LOAD), page_size) < alignDown(end(PT_GNU_RELRO), page_size)`. In this case, rtld's mprotect call for PT_GNU_RELRO will apply to unmapped regions and lead to an error, e.g. ``` error while loading shared libraries: cannot apply additional memory protection after relocation: Cannot allocate memory ``` To fix the issue, add a padding section .relro_padding like mold, which is contained in the PT_GNU_RELRO segment and the associated PT_LOAD segment. The section also prevents strip from corrupting PT_LOAD program headers. .relro_padding has the largest `sortRank` among RELRO sections. Therefore, it is naturally placed at the end of `PT_GNU_RELRO` segment in the absence of `PHDRS`/`SECTIONS` commands. In the presence of `SECTIONS` commands, we place .relro_padding immediately before a symbol assignment using DATA_SEGMENT_RELRO_END (see also https://reviews.llvm.org/D124656), if present. DATA_SEGMENT_RELRO_END is changed to align to max-page-size instead of common-page-size. Some edge cases worth mentioning: * ppc64-toc-addis-nop.s: when PHDRS is present, do not append .relro_padding * avoid-empty-program-headers.s: when the only RELRO section is .tbss, it is not part of PT_LOAD segment, therefore we do not append .relro_padding. --- Close #65002: GNU ld from 2.39 onwards aligns the end of PT_GNU_RELRO to a max-page-size boundary (https://sourceware.org/PR28824) so that the last page is protected even if runtime_page_size > common-page-size. In my opinion, losing protection for the last page when the runtime page size is larger than common-page-size is not really an issue. Double mapping a page of up to max-common-page for the protection could cause undesired VM waste. Internally we had users complaining about 2MiB max-page-size applying to shared objects. Therefore, the end of .relro_padding is padded to a common-page-size boundary. Users who are really anxious can set common-page-size to match their runtime page size. --- 17 tests need updating as there are lots of change detectors.
65 lines
1.7 KiB
ArmAsm
65 lines
1.7 KiB
ArmAsm
// Test that notes (both from object files and synthetic) are duplicated into
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// each partition.
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// REQUIRES: x86
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// RUN: llvm-mc %s -o %t.o -filetype=obj --triple=x86_64-unknown-linux
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// RUN: ld.lld %t.o -o %t --shared --gc-sections --build-id=sha1
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// RUN: llvm-objcopy --extract-main-partition %t %t0
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// RUN: llvm-objcopy --extract-partition=part1 %t %t1
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// RUN: llvm-readobj --all %t0 | FileCheck %s
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// RUN: llvm-readobj --all %t1 | FileCheck %s
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// CHECK: Type: PT_NOTE
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// CHECK-NEXT: Offset: 0x{{0*}}[[NOTE_OFFSET:[^ ]*]]
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// CHECK: Notes [
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// CHECK-NEXT: NoteSection {
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// CHECK-NEXT: Name: .note.obj
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// CHECK-NEXT: Offset: 0x{{0*}}[[NOTE_OFFSET]]
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// CHECK-NEXT: Size:
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// CHECK-NEXT: Note {
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// CHECK-NEXT: Owner: foo
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// CHECK-NEXT: Data size: 0x4
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// CHECK-NEXT: Type: NT_VERSION (version)
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// CHECK-NEXT: Description data (
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// CHECK-NEXT: 0000: 62617200 |bar.|
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// CHECK-NEXT: )
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// CHECK-NEXT: }
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// CHECK-NEXT: }
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// CHECK-NEXT: NoteSection {
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// CHECK-NEXT: Name: .note.gnu.build-id
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// CHECK-NEXT: Offset:
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// CHECK-NEXT: Size:
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// CHECK-NEXT: Note {
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// CHECK-NEXT: Owner: GNU
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// CHECK-NEXT: Data size:
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// CHECK-NEXT: Type: NT_GNU_BUILD_ID (unique build ID bitstring)
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// CHECK-NEXT: Build ID: d5101cb9d03b7e836ba9b64f5768a0b31980920f{{$}}
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// CHECK-NEXT: }
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// CHECK-NEXT: }
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// CHECK-NEXT: ]
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.section .llvm_sympart,"",@llvm_sympart
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.asciz "part1"
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.quad p1
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.section .data.p0,"aw",@progbits
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.globl p0
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p0:
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.section .data.p1,"aw",@progbits
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.globl p1
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p1:
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.section .note.obj,"a",@note
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.align 4
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.long 2f-1f
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.long 3f-2f
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.long 1
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1: .asciz "foo"
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2: .asciz "bar"
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3:
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