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.
35 lines
969 B
ArmAsm
35 lines
969 B
ArmAsm
# REQUIRES: ppc
|
|
## Test PPC64 specific section layout. See also section-layout.s.
|
|
|
|
# RUN: llvm-mc -filetype=obj -triple=powerpc64le %s -o %t.o
|
|
# RUN: llvm-mc -filetype=obj -triple=powerpc64le %p/Inputs/shared.s -o %t1.o
|
|
# RUN: ld.lld -shared -soname=t1.so %t1.o -o %t1.so
|
|
# RUN: ld.lld %t.o %t1.so -o %t
|
|
# RUN: llvm-readelf -S %t | FileCheck %s
|
|
|
|
# CHECK: .text
|
|
# CHECK-NEXT: .tdata
|
|
# CHECK-NEXT: .tbss
|
|
# CHECK-NEXT: .dynamic
|
|
# CHECK-NEXT: .got
|
|
# CHECK-NEXT: .toc
|
|
## The end of .relro_padding is aligned to a common-page-size boundary.
|
|
# CHECK-NEXT: .relro_padding NOBITS 0000000010020400 000400 000c00 00 WA 0 0 1
|
|
# CHECK-NEXT: .data
|
|
# CHECK-NEXT: .branch_lt
|
|
|
|
.globl _start
|
|
_start:
|
|
addis 3, 2, bar2@got@ha
|
|
ld 3, bar2@got@l(3)
|
|
addis 5, 2, .Lbar@toc@ha
|
|
ld 5, .Lbar@toc@l(5)
|
|
|
|
.section .toc,"aw",@progbits
|
|
.Lbar:
|
|
.tc bar[TC], bar
|
|
|
|
.section .tdata,"awT",@progbits; .space 1
|
|
.section .tbss,"awT",@nobits; .space 1
|
|
.section .data,"aw",@progbits; .space 1
|