llvm-project/lld/test/ELF/linkerscript/section-align2.test
Fangrui Song 0edc8b59ab
[ELF] Error if a section address is smaller than image base
When using `-no-pie` without a `SECTIONS` command, the linker uses the
target's default image base. If `-Ttext=` or `--section-start` specifies
an output section address below this base, the result is likely
unintended.

- With `--no-rosegment`, the PT_LOAD segment covering the ELF header cannot include `.text` if `.text`'s address is too low, causing an `error: output file too large`.
- With default `--rosegment`:
  - If a read-only section (e.g., `.rodata`) exists, a similar `error: output file too large` occurs.
  - Without read-only sections, the PT_LOAD segment covering the ELF header and program headers includes no sections, which is unusual and likely undesired. This also causes non-ascending PT_LOAD `p_vaddr` values related to the PT_LOAD that overlaps with PT_PHDR (#138584).

To prevent these issues, report an error if a section address is below
the image base and suggest `--image-base`. This check also applies when
`--image-base` is explicitly set but is skipped when a `SECTIONS`
command is used.

Pull Request: https://github.com/llvm/llvm-project/pull/140187
2025-05-21 09:19:47 -07:00

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# REQUIRES: aarch64
## Test ALIGN and its interaction with explicit output section addresses.
# RUN: echo '.globl _start; _start: ret; .section .data.rel.ro,"aw"; .balign 8; .byte 0; .data; .byte 0; \
# RUN: .section .data2,"aw"; .balign 8; .byte 0; \
# RUN: .section .data3,"aw"; .balign 32; .byte 0; \
# RUN: .bss; .balign 32; .byte 0' | \
# RUN: llvm-mc -filetype=obj -triple=aarch64 - -o %t.o
# RUN: ld.lld -T %s %t.o -o %t 2>&1 | FileCheck --check-prefix=WARN %s --implicit-check-not=warning:
# RUN: llvm-readelf -S %t | FileCheck %s
## Check we don't warn in the absence of SECTIONS.
# RUN: ld.lld --fatal-warnings -Ttext=0x10000 --image-base=0x10000 %t.o -o /dev/null
# WARN: warning: address (0x10004) of section .data.rel.ro is not a multiple of alignment (16)
# WARN: warning: address (0x20001) of section .data2 is not a multiple of alignment (8)
# WARN: warning: address (0x20021) of section .bss is not a multiple of alignment (32)
# CHECK: Name Type Address Off Size ES Flg Lk Inf Al
# CHECK-NEXT: NULL 0000000000000000 000000 000000 00 0 0 0
# CHECK-NEXT: .text PROGBITS 0000000000010000 010000 000004 00 AX 0 0 4
# CHECK-NEXT: .data.rel.ro PROGBITS 0000000000010004 010004 000005 00 WA 0 0 16
# CHECK-NEXT: .data PROGBITS 0000000000020000 020000 000001 00 WA 0 0 1
# CHECK-NEXT: .data2 PROGBITS 0000000000020001 020001 000008 00 WA 0 0 8
# CHECK-NEXT: .data3 PROGBITS 0000000000020020 020020 000001 00 WA 0 0 32
# CHECK-NEXT: .bss NOBITS 0000000000020021 020021 000020 00 WA 0 0 32
SECTIONS {
.text 0x10000 : { *(.text) }
## sh_addr is aligned to 16.
.data.rel.ro . : ALIGN(16) { *(.data.rel.ro) }
.data 0x20000 : { *(.data) }
## The output section address is set without ALIGN. sh_addr is set to Dot, ignoring alignment.
## sh_addralign is the maximum of input section alignments, 8.
.data2 . : { *(.data2) }
## sh_addr is aligned to 32.
## The input section has a larger alignment and is thus preceded by a gap.
.data3 : ALIGN(16) { *(.data3) }
## sh_addr is aligned to 16.
## The input section has a larger alignment and is thus preceded by a gap.
.bss . : ALIGN(16) { *(.bss) }
}