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Re: [PATCH v2] Add support for the x86 XSAVE extended state on FreeBSD/x86.
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: John Baldwin <jhb at freebsd dot org>
- Cc: GDB <gdb-patches at sourceware dot org>, Binutils <binutils at sourceware dot org>, Mark Kettenis <mark dot kettenis at xs4all dot nl>, Pedro Alves <palves at redhat dot com>
- Date: Mon, 13 Apr 2015 10:47:35 -0700
- Subject: Re: [PATCH v2] Add support for the x86 XSAVE extended state on FreeBSD/x86.
- Authentication-results: sourceware.org; auth=none
- References: <55149C11 dot 8000709 at FreeBSD dot org>
On Thu, Mar 26, 2015 at 4:53 PM, John Baldwin <jhb@freebsd.org> wrote:
> Recognize NT_X86_XSTATE notes in FreeBSD process cores. Recent
> FreeBSD versions include a note containing the XSAVE state for each
> thread in the process when XSAVE is in use. The note stores a copy of
> the current XSAVE mask in a reserved section of the machine-defined
> XSAVE state at the same offset as Linux's NT_X86_XSTATE note.
>
> For native processes, use the PT_GETXSTATE_INFO ptrace request to
> determine if XSAVE is enabled, and if so the active XSAVE state mask
> (that is, the value of %xcr0 for the target process) as well as the
> size of XSAVE state area. Use the PT_GETXSTATE and PT_SETXSTATE requests
> to fetch and store the XSAVE state, respectively, in the BSD x86
> native targets.
>
> In addition, the FreeBSD amd64 and i386 native targets now include
> "read_description" target methods to determine the correct x86 target
> description for the current XSAVE mask. On FreeBSD amd64 this also
> properly returns an i386 target description for 32-bit binaries which
> allows the 64-bit GDB to run 32-bit binaries.
>
> Note that the ptrace changes are in the BSD native targets, not the
> FreeBSD-specific native targets since that is where the other ptrace
> register accesses occur. Of the other BSDs, NetBSD and DragonFly use
> XSAVE in the kernel but do not currently export the extended state via
> ptrace(2). OpenBSD does not currently support XSAVE.
>
> bfd/ChangeLog:
>
> * elf.c (elfcore_grok_note): Recognize NT_X86_XSTATE on
> FreeBSD.
> (elfcore_write_xstatereg): Use correct note name on FreeBSD.
>
...
> ---
> diff --git a/bfd/elf.c b/bfd/elf.c
> index 13d4272..7cd3533 100644
> --- a/bfd/elf.c
> +++ b/bfd/elf.c
> @@ -8670,6 +8670,9 @@ elfcore_grok_note (bfd *abfd, Elf_Internal_Note *note)
> if (note->namesz == 6
> && strcmp (note->namedata, "LINUX") == 0)
> return elfcore_grok_xstatereg (abfd, note);
> + else if (note->namesz == 8
> + && strcmp (note->namedata, "FreeBSD") == 0)
> + return elfcore_grok_xstatereg (abfd, note);
> else
> return TRUE;
OK.
> @@ -9490,6 +9493,8 @@ elfcore_write_xstatereg (bfd *abfd, char *buf, int *bufsiz,
> const void *xfpregs, int size)
> {
> char *note_name = "LINUX";
> + if (get_elf_backend_data (abfd)->elf_osabi == ELFOSABI_FREEBSD)
> + note_name = "FreeBSD";
Please use
else
note_name = "LINUX";
bfd change is OK with this change. Thanks.
> return elfcore_write_note (abfd, buf, bufsiz,
> note_name, NT_X86_XSTATE, xfpregs, size);
> }
>
H.J.