From: H.J. Lu Date: Thu, 22 May 2025 03:29:49 +0000 (+0800) Subject: x86: Check MODRM for call and jmp in binutils older than 2.45 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=refs%2Fheads%2Fbinutils-2_39-branch;p=thirdparty%2Fbinutils-gdb.git x86: Check MODRM for call and jmp in binutils older than 2.45 When i386 glibc was assembled with commit: commit 11c2852449825a5f486f63bc40aabed56b7c04c1 (HEAD) Author: Jan Beulich Date: Fri Feb 21 10:24:50 2025 +0100 x86: widen @got{,pcrel} support to PUSH and APX IMUL With us doing the transformation to an immediate operand for MOV and various ALU insns, there's little reason to then not support the same conversion for the other two insns which have respective immediate operand forms. Unfortunately for IMUL (due to the 0F opcode prefix) there's no suitable relocation, so the pre-APX forms cannot be marked for relaxation in the assembler. "pushl main@GOT(%ebx)" in sysdeps/i386/start.S was assembled to 1c: ff b3 00 00 00 00 push 0x0(%ebx) 1e: R_386_GOT32X main Linkers in binutils versions older than 2.45 treated it as jmp and relaxed it to 22c: e9 cf ff ff ff jmp 200
231: 90 nop Update elf_i386_convert_load_reloc in binutils versions older than 2.45 to check MODRM for call and jmp to work with i386 glibc assembled with binutils 2.45 or newer. Do the same in elf_x86_64_convert_load_reloc. PR ld/32991 * elf32-i386.c (elf_i386_convert_load_reloc): Check MODRM for call and jmp. * elf64-x86-64.c (elf_x86_64_convert_load_reloc): Likewise. Signed-off-by: H.J. Lu (cherry picked from commit 452f5511154ca02095a271cf085e17f536587207) --- diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c index 52b1db44546..22d90504d26 100644 --- a/bfd/elf32-i386.c +++ b/bfd/elf32-i386.c @@ -1315,6 +1315,15 @@ elf_i386_convert_load_reloc (bfd *abfd, Elf_Internal_Shdr *symtab_hdr, if (opcode == 0xff) { + switch (modrm & 0x38) + { + case 0x10: /* CALL */ + case 0x20: /* JMP */ + break; + default: + return true; + } + /* We have "call/jmp *foo@GOT[(%reg)]". */ if ((h->root.type == bfd_link_hash_defined || h->root.type == bfd_link_hash_defweak) diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c index 62a9a22317a..174b9c7806a 100644 --- a/bfd/elf64-x86-64.c +++ b/bfd/elf64-x86-64.c @@ -1659,6 +1659,15 @@ elf_x86_64_convert_load_reloc (bfd *abfd, /* Convert R_X86_64_GOTPCRELX and R_X86_64_REX_GOTPCRELX to R_X86_64_PC32. */ modrm = bfd_get_8 (abfd, contents + roff - 1); + switch (modrm & 0x38) + { + case 0x10: /* CALL */ + case 0x20: /* JMP */ + break; + default: + return true; + } + if (modrm == 0x25) { /* Convert to "jmp foo nop". */