From 50c95a739c91ae70cf8481936611aa1f5397a384 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Wed, 26 May 2021 12:13:13 -0700 Subject: x86: Propery check PC16 reloc overflow in 16-bit mode instructions commit a7664973b24a242cd9ea17deb5eaf503065fc0bd Author: Jan Beulich Date: Mon Apr 26 10:41:35 2021 +0200 x86: correct overflow checking for 16-bit PC-relative relocs caused linker failure when building 16-bit program in a 32-bit ELF container. Update GNU_PROPERTY_X86_FEATURE_2_USED with #define GNU_PROPERTY_X86_FEATURE_2_CODE16 (1U << 12) to indicate that 16-bit mode instructions are used in the input object: https://groups.google.com/g/x86-64-abi/c/UvvXWeHIGMA to indicate that 16-bit mode instructions are used in the object to allow linker to properly perform relocation overflow check for 16-bit PC-relative relocations in 16-bit mode instructions. 1. Update x86 assembler to always generate the GNU property note with GNU_PROPERTY_X86_FEATURE_2_CODE16 for .code16 in ELF object. 2. Update i386 and x86-64 linkers to use 16-bit PC16 relocations if input object is marked with GNU_PROPERTY_X86_FEATURE_2_CODE16. bfd/ PR ld/27905 * elf32-i386.c: Include "libiberty.h". (elf_howto_table): Add 16-bit R_386_PC16 entry. (elf_i386_rtype_to_howto): Add a BFD argument. Use 16-bit R_386_PC16 if input has 16-bit mode instructions. (elf_i386_info_to_howto_rel): Update elf_i386_rtype_to_howto call. (elf_i386_tls_transition): Likewise. (elf_i386_relocate_section): Likewise. * elf64-x86-64.c (x86_64_elf_howto_table): Add 16-bit R_X86_64_PC16 entry. (elf_x86_64_rtype_to_howto): Use 16-bit R_X86_64_PC16 if input has 16-bit mode instructions. * elfxx-x86.c (_bfd_x86_elf_parse_gnu_properties): Set elf_x86_has_code16 if relocatable input is marked with GNU_PROPERTY_X86_FEATURE_2_CODE16. * elfxx-x86.h (elf_x86_obj_tdata): Add has_code16. (elf_x86_has_code16): New. binutils/ PR ld/27905 * readelf.c (decode_x86_feature_2): Support GNU_PROPERTY_X86_FEATURE_2_CODE16. gas/ PR ld/27905 * config/tc-i386.c (set_code_flag): Update x86_feature_2_used with GNU_PROPERTY_X86_FEATURE_2_CODE16 for .code16 in ELF object. (set_16bit_gcc_code_flag): Likewise. (x86_cleanup): Always generate the GNU property note if x86_feature_2_used isn't 0. * testsuite/gas/i386/code16-2.d: New file. * testsuite/gas/i386/code16-2.s: Likewise. * testsuite/gas/i386/x86-64-code16-2.d: Likewise. * testsuite/gas/i386/i386.exp: Run code16-2 and x86-64-code16-2. include/ PR ld/27905 * elf/common.h (GNU_PROPERTY_X86_FEATURE_2_CODE16): New. ld/ PR ld/27905 * testsuite/ld-i386/code16.d: New file. * testsuite/ld-i386/code16.t: Likewise. * testsuite/ld-x86-64/code16.d: Likewise. * testsuite/ld-x86-64/code16.t: Likewise. * testsuite/ld-i386/i386.exp: Run code16. * testsuite/ld-x86-64/x86-64.exp: Likewise. --- bfd/elfxx-x86.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'bfd/elfxx-x86.c') diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c index 62d516a..29dc7f0 100644 --- a/bfd/elfxx-x86.c +++ b/bfd/elfxx-x86.c @@ -2353,6 +2353,7 @@ _bfd_x86_elf_parse_gnu_properties (bfd *abfd, unsigned int type, || (type >= GNU_PROPERTY_X86_UINT32_OR_AND_LO && type <= GNU_PROPERTY_X86_UINT32_OR_AND_HI)) { + unsigned int number; if (datasz != 4) { _bfd_error_handler @@ -2361,7 +2362,13 @@ _bfd_x86_elf_parse_gnu_properties (bfd *abfd, unsigned int type, return property_corrupt; } prop = _bfd_elf_get_property (abfd, type, datasz); - prop->u.number |= bfd_h_get_32 (abfd, ptr); + number = bfd_h_get_32 (abfd, ptr); + if ((abfd->flags + & (DYNAMIC | BFD_LINKER_CREATED | BFD_PLUGIN)) == 0 + && type == GNU_PROPERTY_X86_FEATURE_2_USED + && (number & GNU_PROPERTY_X86_FEATURE_2_CODE16) != 0) + elf_x86_has_code16 (abfd) = 1; + prop->u.number |= number; prop->pr_kind = property_number; return property_number; } -- cgit v1.1