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[ELF][PPC32] Make R_PPC32_PLTREL retain .got

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PLT usage needs the first 12 bytes of the .got section. We need to keep .got and
DT_GOT_PPC even if .got/_GLOBAL_OFFSET_TABLE_ are not referenced (large PIC code
may only reference .got2), which is the case in OpenBSD's ld.so, leading
to a misleading error, "unsupported insecure BSS PLT object".

Fix this by adding R_PPC32_PLTREL to the list of hasGotOffRel.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D114982

(cherry picked from commit 885fb9a257)
This commit is contained in:
George Koehler 2021-12-16 18:06:49 -08:00 committed by Fangrui Song
parent 87ca22cba2
commit e68f640dee
3 changed files with 40 additions and 5 deletions
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4
lld/ELF/Relocations.cpp
View File

@ -1409,8 +1409,8 @@ static void scanReloc(InputSectionBase &sec, OffsetGetter &getOffset, RelTy *&i,
// The 4 types that relative GOTPLT are all x86 and x86-64 specific.
if (oneof<R_GOTPLTONLY_PC, R_GOTPLTREL, R_GOTPLT, R_TLSGD_GOTPLT>(expr)) {
in.gotPlt->hasGotPltOffRel = true;
} else if (oneof<R_GOTONLY_PC, R_GOTREL, R_PPC64_TOCBASE, R_PPC64_RELAX_TOC>(
expr)) {
} else if (oneof<R_GOTONLY_PC, R_GOTREL, R_PPC32_PLTREL, R_PPC64_TOCBASE,
R_PPC64_RELAX_TOC>( expr)) {
in.got->hasGotOffRel = true;
}

6
lld/test/ELF/ppc32-ifunc-nonpreemptible-pic.s
View File

@ -7,12 +7,12 @@
# RUN: llvm-objdump -d --no-show-raw-insn %t | FileCheck %s
# RELOC: .rela.dyn {
# RELOC-NEXT: 0x30248 R_PPC_RELATIVE - 0x101A8
# RELOC-NEXT: 0x3024C R_PPC_IRELATIVE - 0x10188
# RELOC-NEXT: 0x30254 R_PPC_RELATIVE - 0x101A8
# RELOC-NEXT: 0x30258 R_PPC_IRELATIVE - 0x10188
# RELOC-NEXT: }
# SYM: 000101a8 0 FUNC GLOBAL DEFAULT {{.*}} func
# HEX: 0x00030248 00000000
# HEX: 0x00030254 00000000
.section .got2,"aw"
.long func

35
lld/test/ELF/ppc32-reloc-pltrel.s Normal file
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@ -0,0 +1,35 @@
# REQUIRES: ppc
## Ensure R_PPC_PLTREL retains .got even in the absence of
## .got/_GLOBAL_OFFSET_TABLE_ references.
# RUN: llvm-mc -filetype=obj -triple=powerpc %s -o %t.o
# RUN: ld.lld -shared %t.o -o %t.so
# RUN: llvm-readobj -Sdr %t.so | FileCheck %s
.section .got2,"aw",@progbits
.set .LTOC, .+0x8000
.text
.L0:
addis 30,30,.LTOC-.L0@ha
addi 30,30,.LTOC-.L0@l
bl baz+0x8000@plt
## DT_PPC_GOT must point to .got, which must have the 12-byte header.
## The only relocation is an R_PPC_JMP_SLOT.
# CHECK: Sections [
# CHECK: Name: .got (
# CHECK: Address:
# CHECK-SAME: {{ }}[[#%x,GOT:]]
# CHECK: Size:
# CHECK-SAME: {{ 12$}}
# CHECK: DynamicSection [
# CHECK-NEXT: Tag Type Name/Value
# CHECK: 0x70000000 PPC_GOT [[#GOT]]
# CHECK: Relocations [
# CHECK-NEXT: Section ([[#]]) .rela.plt {
# CHECK-NEXT: 0x[[#%x,]] R_PPC_JMP_SLOT baz 0x0
# CHECK-NEXT: }
# CHECK-NEXT: ]