Linkers group input note sections with the same name into one output note section with the same name. One output note section is placed in one PT_NOTE segment. Since new linkers merge input .note.gnu.property sections into one output .note.gnu.property section, there is only one NT_GNU_PROPERTY_TYPE_0 note in one PT_NOTE segment with new linkers. Since older linkers treat input .note.gnu.property section as a generic note section and just concatenate all input .note.gnu.property sections into one output .note.gnu.property section without merging them, we may see invalid NT_GNU_PROPERTY_TYPE_0 note in PT_NOTE segment: [hjl@gnu-4 tmp]$ cat x.S #ifdef __LP64__ # define ALIGN 3 #else # define ALIGN 2 #endif .section ".note", "a" .p2align ALIGN .long 1f - 0f /* name length. */ .long 3f - 1f /* data length. */ /* NT_GNU_PROPERTY_TYPE_0 */ .long 5 /* note type. */ 0: .asciz "GNU" /* vendor name. */ 1: .p2align ALIGN /* GNU_PROPERTY_X86_ISA_1_USED */ .long 0xc0010000 /* pr_type. */ .long 5f - 4f /* pr_datasz. */ 4: .long 0x80000002 5: .p2align ALIGN /* GNU_PROPERTY_X86_FEATURE_2_USED */ .long 0xc0010001 /* pr_type. */ .long 5f - 4f /* pr_datasz. */ 4: .long 0x9 5: .p2align ALIGN 3: .text .globl _start _start: ret [hjl@gnu-4 tmp]$ gcc -c x.S -Wa,-mx86-used-note=no [hjl@gnu-4 tmp]$ ld -o x x.o [hjl@gnu-4 tmp]$ cat y.s .text .globl _start _start: movaps %xmm0, %xmm1 [hjl@gnu-4 tmp]$ gcc -c y.s -Wa,-mx86-used-note=yes [hjl@gnu-4 tmp]$ ld -o y y.o [hjl@gnu-4 tmp]$ readelf -n x Displaying notes found in: .note Owner Data size Description GNU 0x00000020 NT_GNU_PROPERTY_TYPE_0 Properties: x86 ISA used: SSE Invalid x86 feature used: x86, XMM [hjl@gnu-4 tmp]$ readelf -n y Displaying notes found in: .note.gnu.property Owner Data size Description GNU 0x00000020 NT_GNU_PROPERTY_TYPE_0 Properties: x86 ISA used: SSE x86 feature used: x86, XMM [hjl@gnu-4 tmp]$ 'x' has invalid NT_GNU_PROPERTY_TYPE_0 note. But GNU_PROPERTY_X86_ISA_1_USED has the GNU_PROPERTY_X86_UINT32_VALID bit set, which can also be set by -mx86-used-note=yes. We need a way to mark NT_GNU_PROPERTY_TYPE_0 note in PT_NOTE segment is valid.
The master branch has been updated by H.J. Lu <hjl@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=0a59decbb81676ac30deede1bb6b6e241cd75502 commit 0a59decbb81676ac30deede1bb6b6e241cd75502 Author: H.J. Lu <hjl.tools@gmail.com> Date: Fri Dec 14 04:55:08 2018 -0800 elf: Add PT_GNU_PROPERTY segment type Linkers group input note sections with the same name into one output note section with the same name. One output note section is placed in one PT_NOTE segment. New linkers merge all input .note.gnu.property sections into one output .note.gnu.property section with a single NT_GNU_PROPERTY_TYPE_0 note in a single PT_NOTE segment. Since older linkers treat input .note.gnu.property section as a generic note section and just concatenate all input .note.gnu.property sections into one output .note.gnu.property section without merging them, we may see one or more NT_GNU_PROPERTY_TYPE_0 notes in PT_NOTE segment, which are invalid. GNU_PROPERTY_X86_UINT32_VALID was defined to address this issue such that linker sets the bit for non-relocatable outputs. But it isn't sufficient: 1. It doesn't cover generic properties. 2. When -mx86-used-note=yes is passed to x86 assembler, the GNU_PROPERTY_X86_UINT32_VALID bit is set in GNU_PROPERTY_X86_ISA_1_USED property in object file and older linkers generate invalid NT_GNU_PROPERTY_TYPE_0 notes with the GNU_PROPERTY_X86_UINT32_VALID bit set. I am proposing the following changes: 1. Add PT_GNU_PROPERTY segment type: # define PT_GNU_PROPERTY (PT_LOOS + 0x474e553) which covers .note.gnu.property section. 2. Remove GNU_PROPERTY_X86_UINT32_VALID. bfd/ PR ld/23900 * elf.c (get_program_header_size): Add a PT_GNU_PROPERTY segment for NOTE_GNU_PROPERTY_SECTION_NAME. (_bfd_elf_map_sections_to_segments): Create a PT_GNU_PROPERTY segment for NOTE_GNU_PROPERTY_SECTION_NAME. * elfxx-x86.c (_bfd_elf_link_setup_gnu_properties): Don't set GNU_PROPERTY_X86_UINT32_VALID. binutils/ PR ld/23900 * readelf.c (get_segment_type): Support PT_GNU_PROPERTY. (decode_x86_isa): Don't check GNU_PROPERTY_X86_UINT32_VALID. (decode_x86_feature_1): Likewise. (decode_x86_feature_2): Likewise. (print_gnu_property_note): Remove GNU_PROPERTY_X86_UINT32_VALID check. * testsuite/binutils-all/i386/empty.d: Updated. * testsuite/binutils-all/x86-64/empty-x32.d: Likewise. * testsuite/binutils-all/x86-64/empty.d: Likewise. * testsuite/binutils-all/i386/pr21231b.s: Change GNU_PROPERTY_X86_ISA_1_USED bits to 0x7fffffff. * testsuite/binutils-all/x86-64/pr21231b.s: Likewise. gas/ PR ld/23900 * config/tc-i386.c (x86_cleanup): Don't set GNU_PROPERTY_X86_UINT32_VALID. * testsuite/gas/i386/property-1.s: Change GNU_PROPERTY_X86_ISA_1_USED bits to 0. include/ PR ld/23900 * elf/common.h (PT_GNU_PROPERTY): New. (GNU_PROPERTY_X86_UINT32_VALID): Removed. ld/ PR ld/23900 * testsuite/ld-elf/elf.exp: Run PR ld/23900 test. * testsuite/ld-elf/pr23900-1-32.rd: New file. * testsuite/ld-elf/pr23900-1-64.rd: Likewise. * testsuite/ld-elf/pr23900-1.d: Likewise. * testsuite/ld-elf/pr23900-1.s: Likewise. * testsuite/ld-elf/pr23900-2.s: Likewise. * testsuite/ld-elf/pr23900-2a.d: Likewise. * testsuite/ld-elf/pr23900-2b.d: Likewise. * testsuite/ld-i386/ibt-plt-1.d: Adjusted. * testsuite/ld-i386/ibt-plt-2c.d: Likewise. * testsuite/ld-i386/ibt-plt-2d.d: Likewise. * testsuite/ld-i386/ibt-plt-3d.d: Likewise. * testsuite/ld-x86-64/ibt-plt-1-x32.d: Likewise. * testsuite/ld-x86-64/ibt-plt-1.d: Likewise. * testsuite/ld-x86-64/ibt-plt-2c-x32.d: Likewise. * testsuite/ld-x86-64/ibt-plt-2c.d: Likewise. * testsuite/ld-x86-64/ibt-plt-2d-x32.d: Likewise. * testsuite/ld-x86-64/ibt-plt-2c.d: Likewise. * testsuite/ld-x86-64/ibt-plt-3c-x32.d: Likewise. * testsuite/ld-x86-64/ibt-plt-3c.d: Likewise. * testsuite/ld-x86-64/ibt-plt-3d-x32.d: Likewise. * testsuite/ld-x86-64/ibt-plt-3d.d: Likewise. * testsuite/ld-i386/pr23372c.d: Expect <None> for GNU_PROPERTY_X86_ISA_1_USED. * testsuite/ld-x86-64/pr23372c-x32.d: Likewise. * testsuite/ld-x86-64/pr23372c.d: Likewise. * testsuite/ld-x86-64/pr23372d-x32.d: Likewise. * testsuite/ld-x86-64/pr23372d.d: Likewise. * testsuite/ld-x86-64/property-x86-5a.s: Change GNU_PROPERTY_X86_ISA_1_USED bits to 0. * testsuite/ld-x86-64/property-x86-5b.s: Likewise.
The master branch has been updated by H.J. Lu <hjl@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b4654b109bd023d0a22f445db7d4e27f769593f4 commit b4654b109bd023d0a22f445db7d4e27f769593f4 Author: H.J. Lu <hjl.tools@gmail.com> Date: Tue Jan 21 05:43:59 2020 -0800 pr23900-1.d: Also check PT_GNU_PROPERTY program header Also pass -l to readelf to check PT_GNU_PROPERTY program header. PR ld/23900 * testsuite/ld-elf/pr23900-1.d: Also pass -l to readelf.
Fixed.