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    Subject[tip:x86/asm] x86/vdso: Replace hex int80 CFI annotations with GAS directives
    Commit-ID:  29c0ce9508458ed31a9db2ed425f64c0d6d3ddfb
    Gitweb: http://git.kernel.org/tip/29c0ce9508458ed31a9db2ed425f64c0d6d3ddfb
    Author: Andy Lutomirski <luto@kernel.org>
    AuthorDate: Mon, 5 Oct 2015 17:47:59 -0700
    Committer: Ingo Molnar <mingo@kernel.org>
    CommitDate: Fri, 9 Oct 2015 09:41:06 +0200

    x86/vdso: Replace hex int80 CFI annotations with GAS directives

    Maintaining the current CFI annotations written in R'lyehian is
    difficult for most of us. Translate them to something a little
    closer to English.

    This will remove the CFI data for kernels built with extremely
    old versions of binutils. I think this is a fair tradeoff for
    the ability for mortals to edit the asm.

    Signed-off-by: Andy Lutomirski <luto@kernel.org>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: linux-kernel@vger.kernel.org
    Link: http://lkml.kernel.org/r/ae3ff4ff5278b4bfc1e1dab368823469866d4b71.1444091584.git.luto@kernel.org
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    ---
    arch/x86/entry/vdso/vdso32/system_call.S | 48 ++++++--------------------------
    1 file changed, 8 insertions(+), 40 deletions(-)

    diff --git a/arch/x86/entry/vdso/vdso32/system_call.S b/arch/x86/entry/vdso/vdso32/system_call.S
    index b15b7c0..b52cbfb 100644
    --- a/arch/x86/entry/vdso/vdso32/system_call.S
    +++ b/arch/x86/entry/vdso/vdso32/system_call.S
    @@ -1,6 +1,10 @@
    /*
    * Code for the vDSO. This version uses the old int $0x80 method.
    - *
    +*/
    +
    +#include <asm/dwarf2.h>
    +
    +/*
    * First get the common code for the sigreturn entry points.
    * This must come first.
    */
    @@ -11,46 +15,10 @@
    .type __kernel_vsyscall,@function
    ALIGN
    __kernel_vsyscall:
    -.LSTART_vsyscall:
    + CFI_STARTPROC
    int $0x80
    ret
    -.LEND_vsyscall:
    - .size __kernel_vsyscall,.-.LSTART_vsyscall
    - .previous
    -
    - .section .eh_frame,"a",@progbits
    -.LSTARTFRAMEDLSI:
    - .long .LENDCIEDLSI-.LSTARTCIEDLSI
    -.LSTARTCIEDLSI:
    - .long 0 /* CIE ID */
    - .byte 1 /* Version number */
    - .string "zR" /* NUL-terminated augmentation string */
    - .uleb128 1 /* Code alignment factor */
    - .sleb128 -4 /* Data alignment factor */
    - .byte 8 /* Return address register column */
    - .uleb128 1 /* Augmentation value length */
    - .byte 0x1b /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
    - .byte 0x0c /* DW_CFA_def_cfa */
    - .uleb128 4
    - .uleb128 4
    - .byte 0x88 /* DW_CFA_offset, column 0x8 */
    - .uleb128 1
    - .align 4
    -.LENDCIEDLSI:
    - .long .LENDFDEDLSI-.LSTARTFDEDLSI /* Length FDE */
    -.LSTARTFDEDLSI:
    - .long .LSTARTFDEDLSI-.LSTARTFRAMEDLSI /* CIE pointer */
    - .long .LSTART_vsyscall-. /* PC-relative start address */
    - .long .LEND_vsyscall-.LSTART_vsyscall
    - .uleb128 0
    - .align 4
    -.LENDFDEDLSI:
    - .previous
    + CFI_ENDPROC

    - /*
    - * Pad out the segment to match the size of the sysenter.S version.
    - */
    -VDSO32_vsyscall_eh_frame_size = 0x40
    - .section .data,"aw",@progbits
    - .space VDSO32_vsyscall_eh_frame_size-(.LENDFDEDLSI-.LSTARTFRAMEDLSI), 0
    + .size __kernel_vsyscall,.-__kernel_vsyscall
    .previous

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