[PATCH v2] bfd: Add minimal support to handle note that describes xsave layout
Jan Beulich
jbeulich@suse.com
Mon Dec 8 07:24:21 GMT 2025
On 08.12.2025 06:21, Balasubrmanian, Vignesh wrote:
> [AMD Official Use Only - AMD Internal Distribution Only]
>
> I'm sorry for the oversight on this, juggling between paternity and other priorities.
>
> Addressed your review comments from V1 in this.
> Would you like me to resend this patch with above update on the commit message ?
"Addressed review comments" isn't a useful piece of information for review
purposes. I don't suppose you expect everyone to recall what comments were
given? Such a summary can be pretty brief, but it's pretty helpful to be
there.
As to re-sending: That's up to you; I'd be fine (for this instance) if you
simply replied by clarifying what was changed.
Jan
> -----Original Message-----
> From: Jan Beulich <jbeulich@suse.com>
> Sent: Friday, October 10, 2025 12:13 PM
> To: Balasubrmanian, Vignesh <Vignesh.Balasubrmanian@amd.com>
> Cc: binutils@sourceware.org; George, Jini Susan <JiniSusan.George@amd.com>; christina.schimpe@intel.com; Sharma, Alok Kumar <AlokKumar.Sharma@amd.com>; jhb@FreeBSD.org; simark@simark.ca
> Subject: Re: [PATCH v2] bfd: Add minimal support to handle note that describes xsave layout
>
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
>
>
> On 29.09.2025 04:10, Vignesh Balasubramanian wrote:
>> This note section is already supported by Linux kernel.
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/com
>> mit/arch/x86/kernel/fpu/xstate.c?id=ba386777a30b38dabcc7fb8a89ec2869a0
>> 9915f7
>>
>> Co-Authored-By: Jini Susan George <jinisusan.george@amd.com>
>> ---
>> bfd/elf-bfd.h | 2 ++
>> bfd/elf.c | 24 +++++++++++++++++++++++-
>> binutils/readelf.c | 2 ++
>> include/elf/common.h | 2 ++
>> 4 files changed, 29 insertions(+), 1 deletion(-)
>
> While this looks all plausible, can you please clarify what was changed in v2?
>
> Jan
>
>> diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h index
>> 9ce81ebd314..2877d82b907 100644
>> --- a/bfd/elf-bfd.h
>> +++ b/bfd/elf-bfd.h
>> @@ -2926,6 +2926,8 @@ extern char *elfcore_write_prxfpreg
>> (bfd *, char *, int *, const void *, int); extern char
>> *elfcore_write_xstatereg
>> (bfd *, char *, int *, const void *, int);
>> +extern char *elfcore_write_xsave_layout
>> + (bfd *, char *, int *, const void *, int);
>> extern char *elfcore_write_x86_segbases
>> (bfd *, char *, int *, const void *, int); extern char
>> *elfcore_write_i386_tls diff --git a/bfd/elf.c b/bfd/elf.c index
>> bde7414ee21..07e672f07a5 100644
>> --- a/bfd/elf.c
>> +++ b/bfd/elf.c
>> @@ -114,6 +114,7 @@ SECTION
>> #define NOTE_PSEUDO_SECTION_X86_SEGBASES ".reg-x86-segbases"
>> #define NOTE_PSEUDO_SECTION_XFP ".reg-xfp"
>> #define NOTE_PSEUDO_SECTION_XSTATE ".reg-xstate"
>> +#define NOTE_PSEUDO_SECTION_XSAVE_LAYOUT ".reg-xsave-layout"
>>
>> static int elf_sort_sections (const void *, const void *); static
>> bool assign_file_positions_except_relocs (bfd *, struct bfd_link_info
>> *); @@ -10492,6 +10493,14 @@ elfcore_grok_sspreg (bfd *abfd, Elf_Internal_Note *note)
>> return elfcore_make_note_pseudosection (abfd,
>> NOTE_PSEUDO_SECTION_SSP, note); }
>>
>> +/* Linux dumps the XSAVE Layout description in a note named "LINUX"
>> + with a note type of NT_X86_XSAVE_LAYOUT. */ static bool
>> +elfcore_grok_xsave_layout_desc (bfd *abfd, Elf_Internal_Note *note) {
>> + return elfcore_make_note_pseudosection (abfd,
>> +NOTE_PSEUDO_SECTION_XSAVE_LAYOUT, note); }
>> +
>> static bool
>> elfcore_grok_ppc_vmx (bfd *abfd, Elf_Internal_Note *note) { @@
>> -11211,6 +11220,7 @@ elfcore_grok_note (bfd *abfd, Elf_Internal_Note *note)
>> case NT_S390_VXRS_LOW: return elfcore_grok_s390_vxrs_low (abfd, note);
>> case NT_X86_SHSTK: return elfcore_grok_sspreg (abfd, note);
>> case NT_X86_XSTATE: return elfcore_grok_xstatereg (abfd, note);
>> + case NT_X86_XSAVE_LAYOUT: return elfcore_grok_xsave_layout_desc
>> + (abfd, note);
>> default: break;
>> }
>> }
>> @@ -12390,6 +12400,17 @@ elfcore_write_xstatereg (bfd *abfd, char *buf, int *bufsiz,
>> note_name, NT_X86_XSTATE, xfpregs, size);
>> }
>>
>> +char *
>> +elfcore_write_xsave_layout (bfd *abfd, char *buf, int *bufsiz,
>> + const void *xsave_layout, int size) {
>> + return elfcore_write_note (abfd, buf, bufsiz,
>> + NOTE_NAME_LINUX,
>> + NT_X86_XSAVE_LAYOUT,
>> + xsave_layout,
>> + size);
>> +}
>> +
>> static char *
>> elfcore_write_sspreg (bfd *abfd, char *buf, int *bufsiz,
>> const void *ssp, int size) @@ -13035,7 +13056,8 @@
>> elfcore_write_register_note (bfd *abfd,
>> { NOTE_PSEUDO_SECTION_TDESC, elfcore_write_gdb_tdesc},
>> { NOTE_PSEUDO_SECTION_X86_SEGBASES, elfcore_write_x86_segbases},
>> { NOTE_PSEUDO_SECTION_XFP, elfcore_write_prxfpreg},
>> - { NOTE_PSEUDO_SECTION_XSTATE, elfcore_write_xstatereg} /* NB/ No comma. */
>> + { NOTE_PSEUDO_SECTION_XSTATE, elfcore_write_xstatereg},
>> + { NOTE_PSEUDO_SECTION_XSAVE_LAYOUT, elfcore_write_xsave_layout} /* NB/ No comma. */
>> };
>>
>> int i;
>> diff --git a/binutils/readelf.c b/binutils/readelf.c index
>> fd9722c8afc..16f50318da9 100644
>> --- a/binutils/readelf.c
>> +++ b/binutils/readelf.c
>> @@ -21375,6 +21375,8 @@ get_note_type (Filedata * filedata, unsigned e_type)
>> return _("NT_386_IOPERM (x86 I/O permissions)");
>> case NT_X86_XSTATE:
>> return _("NT_X86_XSTATE (x86 XSAVE extended state)");
>> + case NT_X86_XSAVE_LAYOUT:
>> + return _("NT_X86_XSAVE_LAYOUT (x86 XSAVE Layout description)");
>> case NT_X86_CET:
>> return _("NT_X86_CET (x86 CET state)");
>> case NT_X86_SHSTK:
>> diff --git a/include/elf/common.h b/include/elf/common.h index
>> 5d0f93ebf56..c0894870fc5 100644
>> --- a/include/elf/common.h
>> +++ b/include/elf/common.h
>> @@ -696,6 +696,8 @@
>> #define NT_X86_SHSTK 0x204 /* x86 SHSTK state. */
>> /* This replaces NT_X86_CET (0x203). */
>> /* note name must be "LINUX". */
>> +#define NT_X86_XSAVE_LAYOUT 0x205 /* XSAVE layout description */
>> + /* note name must be "LINUX". */
>> #define NT_S390_HIGH_GPRS 0x300 /* S/390 upper halves of GPRs */
>> /* note name must be "LINUX". */
>> #define NT_S390_TIMER 0x301 /* S390 timer */
>
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