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[ELF][AArch64] Add R_AARCH64_PLT32 relocation type. 

The R_AARCH64_PLT32 relocation type will be documented in the next release
of ELF for the 64-bit Arm Architecture. It is being added in draft state
for the benefit of the position independent vtable feature.

R_AARCH64_PLT32 is very similar to R_AARCH64_PREL32. The intention is to
provide a signed 32-bit integer representing an offset from the place
to a function.
- It relocates 32-bit data
- The expression is S + A - P
- The overflow check for the expression is -2^31 <= X < 2^31
- The relocation generates Thunks/Veneers/Stubs and PLT entries as per
  R_AArch64_CALL26
- If the symbol S is an undefined weak the ABI does not define its value.

The ABI defines a code for ilp32 for completeness, I have added the code
but have only added to the existing reloc-types-elf-aarch64.text as there
is no ilp32 equivalent.

Differential Revision: https://reviews.llvm.org/D77647
This commit is contained in:
Peter Smith 2020-04-06 22:21:39 +01:00
parent 916044d819
commit 02cd80e68e
2 changed files with 4 additions and 0 deletions
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2
llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def
View File

@ -132,6 +132,7 @@ ELF_RELOC(R_AARCH64_TLS_DTPREL64, 0x405)
ELF_RELOC(R_AARCH64_TLS_TPREL64, 0x406)
ELF_RELOC(R_AARCH64_TLSDESC, 0x407)
ELF_RELOC(R_AARCH64_IRELATIVE, 0x408)
ELF_RELOC(R_AARCH64_PLT32, 0x409)
// ELF_RELOC(R_AARCH64_P32_NONE, 0)
ELF_RELOC(R_AARCH64_P32_ABS32, 0x001)
@ -219,3 +220,4 @@ ELF_RELOC(R_AARCH64_P32_TLS_DTPMOD, 0x0b9)
ELF_RELOC(R_AARCH64_P32_TLS_TPREL, 0x0ba)
ELF_RELOC(R_AARCH64_P32_TLSDESC, 0x0bb)
ELF_RELOC(R_AARCH64_P32_IRELATIVE, 0x0bc)
ELF_RELOC(R_AARCH64_P32_PLT32, 0x0bd)

2
llvm/test/tools/llvm-readobj/ELF/reloc-types-elf-aarch64.test
View File

@ -127,6 +127,7 @@
# CHECK: Type: R_AARCH64_TLS_TPREL64 (1030)
# CHECK: Type: R_AARCH64_TLSDESC (1031)
# CHECK: Type: R_AARCH64_IRELATIVE (1032)
# CHECK: Type: R_AARCH64_PLT32 (1033)
--- !ELF
FileHeader:
@ -267,3 +268,4 @@ Sections:
- Type: R_AARCH64_TLS_TPREL64
- Type: R_AARCH64_TLSDESC
- Type: R_AARCH64_IRELATIVE
- Type: R_AARCH64_PLT32