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llvm-project/lld/test/ELF/linkerscript/lma-align.test

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[ELF] Respect output section alignment for AT> (non-null lmaRegion) When lmaRegion is non-null, respect `sec->alignment` This rule is analogous to `switchTo(sec)` which advances sh_addr (VMA). This fixes the p_paddr misalignment issue as reported by https://android-review.googlesource.com/c/trusty/external/trusted-firmware-a/+/1230058 Note, `sec->alignment` is the maximum of ALIGN and input section alignments. We may overalign LMA than GNU ld. linkerscript/align-lma.s has a FIXME that demonstrates another bug: `.bss ... >RAM` should be placed in a different PT_LOAD (GNU ld behavior) because its lmaRegion (nullptr) is different from the previous section's lmaRegion (ROM). Reviewed By: psmith Differential Revision: https://reviews.llvm.org/D74286
2020-02-09 03:07:03 +08:00
# REQUIRES: x86
# RUN: echo 'ret; .data.rel.ro; .balign 16; .byte 0; .data; .byte 0; .bss; .byte 0' | \
# RUN: llvm-mc -filetype=obj -triple=x86_64 - -o %t.o
# RUN: ld.lld -T %s %t.o -o %t
# RUN: llvm-readelf -S -l %t | FileCheck %s
# 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 0000000000001000 001000 000001 00 AX 0 0 4
# CHECK-NEXT: .data.rel.ro PROGBITS 0000000000011000 002000 000001 00 WA 0 0 16
# CHECK-NEXT: .data PROGBITS 0000000000011010 002010 000001 00 WA 0 0 16
[ELF] Start a new PT_LOAD if LMA region is different GNU ld has a counterintuitive lang_propagate_lma_regions rule. ``` // .foo's LMA region is propagated to .bar because their VMA region is the same, // and .bar does not have an explicit output section address (addr_tree). .foo : { *(.foo) } >RAM AT> FLASH .bar : { *(.bar) } >RAM // An explicit output section address disables propagation. .foo : { *(.foo) } >RAM AT> FLASH .bar . : { *(.bar) } >RAM ``` In both cases, lld thinks .foo's LMA region is propagated and places .bar in the same PT_LOAD, so lld diverges from GNU ld w.r.t. the second case (lma-align.test). This patch changes Writer<ELFT>::createPhdrs to disable propagation (start a new PT_LOAD). A user of the first case can make linker scripts portable by explicitly specifying `AT>`. By contrast, there was no workaround for the old behavior. This change uncovers another LMA related bug in assignOffsets() where `ctx->lmaOffset = 0;` was omitted. It caused a spurious "load address range overlaps" error for at2.test The new PT_LOAD rule is complex. For convenience, I listed the origins of some subexpressions: * rL323449: `sec->memRegion == load->firstSec->memRegion`; linkerscript/at3.test * D43284: `load->lastSec == Out::programHeaders` (don't start a new PT_LOAD after program headers); linkerscript/at4.test * D58892: `sec != relroEnd` (start a new PT_LOAD after PT_GNU_RELRO) Reviewed By: psmith Differential Revision: https://reviews.llvm.org/D74297
2020-02-09 14:04:06 +08:00
# CHECK-NEXT: .bss NOBITS 0000000000011040 002040 000001 00 WA 0 0 64
[ELF] Respect output section alignment for AT> (non-null lmaRegion) When lmaRegion is non-null, respect `sec->alignment` This rule is analogous to `switchTo(sec)` which advances sh_addr (VMA). This fixes the p_paddr misalignment issue as reported by https://android-review.googlesource.com/c/trusty/external/trusted-firmware-a/+/1230058 Note, `sec->alignment` is the maximum of ALIGN and input section alignments. We may overalign LMA than GNU ld. linkerscript/align-lma.s has a FIXME that demonstrates another bug: `.bss ... >RAM` should be placed in a different PT_LOAD (GNU ld behavior) because its lmaRegion (nullptr) is different from the previous section's lmaRegion (ROM). Reviewed By: psmith Differential Revision: https://reviews.llvm.org/D74286
2020-02-09 03:07:03 +08:00
# CHECK: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
# CHECK-NEXT: LOAD 0x001000 0x0000000000001000 0x0000000000001000 0x000001 0x000001 R E 0x1000
# CHECK-NEXT: LOAD 0x002000 0x0000000000011000 0x0000000000001010 0x000001 0x000001 RW 0x1000
[ELF] Start a new PT_LOAD if LMA region is different GNU ld has a counterintuitive lang_propagate_lma_regions rule. ``` // .foo's LMA region is propagated to .bar because their VMA region is the same, // and .bar does not have an explicit output section address (addr_tree). .foo : { *(.foo) } >RAM AT> FLASH .bar : { *(.bar) } >RAM // An explicit output section address disables propagation. .foo : { *(.foo) } >RAM AT> FLASH .bar . : { *(.bar) } >RAM ``` In both cases, lld thinks .foo's LMA region is propagated and places .bar in the same PT_LOAD, so lld diverges from GNU ld w.r.t. the second case (lma-align.test). This patch changes Writer<ELFT>::createPhdrs to disable propagation (start a new PT_LOAD). A user of the first case can make linker scripts portable by explicitly specifying `AT>`. By contrast, there was no workaround for the old behavior. This change uncovers another LMA related bug in assignOffsets() where `ctx->lmaOffset = 0;` was omitted. It caused a spurious "load address range overlaps" error for at2.test The new PT_LOAD rule is complex. For convenience, I listed the origins of some subexpressions: * rL323449: `sec->memRegion == load->firstSec->memRegion`; linkerscript/at3.test * D43284: `load->lastSec == Out::programHeaders` (don't start a new PT_LOAD after program headers); linkerscript/at4.test * D58892: `sec != relroEnd` (start a new PT_LOAD after PT_GNU_RELRO) Reviewed By: psmith Differential Revision: https://reviews.llvm.org/D74297
2020-02-09 14:04:06 +08:00
# CHECK-NEXT: LOAD 0x002010 0x0000000000011010 0x0000000000001020 0x000001 0x000001 RW 0x1000
# CHECK-NEXT: LOAD 0x002040 0x0000000000011040 0x0000000000011040 0x000000 0x000001 RW 0x1000
[ELF] Respect output section alignment for AT> (non-null lmaRegion) When lmaRegion is non-null, respect `sec->alignment` This rule is analogous to `switchTo(sec)` which advances sh_addr (VMA). This fixes the p_paddr misalignment issue as reported by https://android-review.googlesource.com/c/trusty/external/trusted-firmware-a/+/1230058 Note, `sec->alignment` is the maximum of ALIGN and input section alignments. We may overalign LMA than GNU ld. linkerscript/align-lma.s has a FIXME that demonstrates another bug: `.bss ... >RAM` should be placed in a different PT_LOAD (GNU ld behavior) because its lmaRegion (nullptr) is different from the previous section's lmaRegion (ROM). Reviewed By: psmith Differential Revision: https://reviews.llvm.org/D74286
2020-02-09 03:07:03 +08:00
MEMORY {
ROM : ORIGIN = 0x1000, LENGTH = 1K
RAM : ORIGIN = 0x11000, LENGTH = 1K
}
SECTIONS {
.text 0x1000 : { *(.text*) } >ROM
## Input section alignment decides output section alignment.
.data.rel.ro 0x11000 : { *(.data.rel.ro) } >RAM AT>ROM
## ALIGN decides output section alignment.
.data . : ALIGN(16) { *(.data*) } >RAM AT>ROM
[ELF] Start a new PT_LOAD if LMA region is different GNU ld has a counterintuitive lang_propagate_lma_regions rule. ``` // .foo's LMA region is propagated to .bar because their VMA region is the same, // and .bar does not have an explicit output section address (addr_tree). .foo : { *(.foo) } >RAM AT> FLASH .bar : { *(.bar) } >RAM // An explicit output section address disables propagation. .foo : { *(.foo) } >RAM AT> FLASH .bar . : { *(.bar) } >RAM ``` In both cases, lld thinks .foo's LMA region is propagated and places .bar in the same PT_LOAD, so lld diverges from GNU ld w.r.t. the second case (lma-align.test). This patch changes Writer<ELFT>::createPhdrs to disable propagation (start a new PT_LOAD). A user of the first case can make linker scripts portable by explicitly specifying `AT>`. By contrast, there was no workaround for the old behavior. This change uncovers another LMA related bug in assignOffsets() where `ctx->lmaOffset = 0;` was omitted. It caused a spurious "load address range overlaps" error for at2.test The new PT_LOAD rule is complex. For convenience, I listed the origins of some subexpressions: * rL323449: `sec->memRegion == load->firstSec->memRegion`; linkerscript/at3.test * D43284: `load->lastSec == Out::programHeaders` (don't start a new PT_LOAD after program headers); linkerscript/at4.test * D58892: `sec != relroEnd` (start a new PT_LOAD after PT_GNU_RELRO) Reviewed By: psmith Differential Revision: https://reviews.llvm.org/D74297
2020-02-09 14:04:06 +08:00
## Start a new PT_LOAD because the LMA region is different from the previous one.
[ELF] Respect output section alignment for AT> (non-null lmaRegion) When lmaRegion is non-null, respect `sec->alignment` This rule is analogous to `switchTo(sec)` which advances sh_addr (VMA). This fixes the p_paddr misalignment issue as reported by https://android-review.googlesource.com/c/trusty/external/trusted-firmware-a/+/1230058 Note, `sec->alignment` is the maximum of ALIGN and input section alignments. We may overalign LMA than GNU ld. linkerscript/align-lma.s has a FIXME that demonstrates another bug: `.bss ... >RAM` should be placed in a different PT_LOAD (GNU ld behavior) because its lmaRegion (nullptr) is different from the previous section's lmaRegion (ROM). Reviewed By: psmith Differential Revision: https://reviews.llvm.org/D74286
2020-02-09 03:07:03 +08:00
.bss . : ALIGN(64) { *(.bss*) } >RAM
}