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.
76 lines
2.6 KiB
ArmAsm
76 lines
2.6 KiB
ArmAsm
# REQUIRES: x86
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# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
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# RUN: ld.lld %t.o -o %t.out
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# RUN: llvm-readelf -x .text %t.out | FileCheck %s
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# CHECK: Hex dump of section '.text':
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# CHECK-NEXT: 01020304
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## --shuffle-sections= shuffles input sections.
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# RUN: ld.lld --shuffle-sections='*=1' %t.o -o %t1.out
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# RUN: llvm-readelf -x .text %t1.out | FileCheck %s --check-prefix=SHUFFLE1
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# SHUFFLE1: Hex dump of section '.text':
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# SHUFFLE1-NEXT: 030402cc 01
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## Test that --shuffle-sections= can be used with --symbol-ordering-file
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# RUN: echo "foo" > %t_order.txt
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# RUN: echo "_start " >> %t_order.txt
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# RUN: ld.lld --symbol-ordering-file %t_order.txt --shuffle-sections='*=2' %t.o -o %t2.out
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# RUN: llvm-readelf -x .text %t2.out | FileCheck %s --check-prefix=SHUFFLE2
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# SHUFFLE2: Hex dump of section '.text':
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# SHUFFLE2-NEXT: 02cccccc 010304
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# RUN: ld.lld -z norelro --symbol-ordering-file %t_order.txt --shuffle-sections='*=3' %t.o -o %t3.out
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# RUN: llvm-readelf -x .text %t3.out | FileCheck %s --check-prefix=SHUFFLE3
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# SHUFFLE3: Hex dump of section '.text':
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# SHUFFLE3-NEXT: 02cccccc 010403
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## As a special case, -1 reverses sections as a stable transform.
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# RUN: ld.lld --shuffle-sections '*=-1' %t.o -o %t-1.out
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# RUN: llvm-readelf -x .text %t-1.out | FileCheck %s --check-prefix=SHUFFLE-1
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# SHUFFLE-1: Hex dump of section '.text':
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# SHUFFLE-1-NEXT: 040302cc 01
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## .text does not change its order while .text.{foo,bar,zed} are reversed.
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# RUN: ld.lld --shuffle-sections '.text.*=-1' %t.o -o %t4.out
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# RUN: llvm-readelf -x .text %t4.out | FileCheck %s --check-prefix=SHUFFLE4
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# SHUFFLE4: Hex dump of section '.text':
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# SHUFFLE4-NEXT: 01040302
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## Reversing twice restores the original order.
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# RUN: ld.lld --shuffle-sections '.text.*=-1' --shuffle-sections '.text.*=-1' %t.o -o %t.out
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# RUN: llvm-readelf -x .text %t.out | FileCheck %s
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## Test all possible invalid cases.
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# RUN: not ld.lld --shuffle-sections= 2>&1 | FileCheck %s --check-prefix=USAGE -DV=
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# RUN: not ld.lld --shuffle-sections=a= 2>&1 | FileCheck %s --check-prefix=USAGE -DV=a=
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# RUN: not ld.lld --shuffle-sections==0 2>&1 | FileCheck %s --check-prefix=USAGE -DV==0
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# RUN: not ld.lld --shuffle-sections=a 2>&1 | FileCheck %s --check-prefix=USAGE -DV=a
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# USAGE: error: --shuffle-sections=: expected <section_glob>=<seed>, but got '[[V]]'
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# RUN: not ld.lld --shuffle-sections='['=0 2>&1 | FileCheck %s --check-prefix=INVALID
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# INVALID: error: --shuffle-sections=: invalid glob pattern, unmatched '[': [
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## .text has an alignment of 4.
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.global _start
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_start:
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.byte 1
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.section .text.foo,"ax"
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.global foo
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foo:
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.byte 2
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.section .text.bar,"ax"
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.global bar
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bar:
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.byte 3
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.section .text.zed,"ax"
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.global zed
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zed:
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.byte 4
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