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    Subject[tip:x86/pti] x86/retpoline/checksum32: Convert assembler indirect jumps
    Commit-ID:  6a2b9eb3c189a848fbfc5b3a0b282bc03bc142af
    Gitweb: https://git.kernel.org/tip/6a2b9eb3c189a848fbfc5b3a0b282bc03bc142af
    Author: David Woodhouse <dwmw@amazon.co.uk>
    AuthorDate: Tue, 9 Jan 2018 14:43:15 +0000
    Committer: Thomas Gleixner <tglx@linutronix.de>
    CommitDate: Wed, 10 Jan 2018 18:28:24 +0100

    x86/retpoline/checksum32: Convert assembler indirect jumps

    Convert all indirect jumps in 32bit checksum assembler code to use
    non-speculative sequences when CONFIG_RETPOLINE is enabled.

    Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Acked-by: Arjan van de Ven <arjan@linux.intel.com>
    Acked-by: Ingo Molnar <mingo@kernel.org>
    Cc: gnomes@lxorguk.ukuu.org.uk
    Cc: Rik van Riel <riel@redhat.com>
    Cc: Andi Kleen <ak@linux.intel.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Jiri Kosina <jikos@kernel.org>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Dave Hansen <dave.hansen@intel.com>
    Cc: Kees Cook <keescook@google.com>
    Cc: Tim Chen <tim.c.chen@linux.intel.com>
    Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org>
    Cc: Paul Turner <pjt@google.com>
    Link: https://lkml.kernel.org/r/1515508997-6154-10-git-send-email-dwmw@amazon.co.uk


    ---
    arch/x86/lib/checksum_32.S | 7 ++++---
    1 file changed, 4 insertions(+), 3 deletions(-)

    diff --git a/arch/x86/lib/checksum_32.S b/arch/x86/lib/checksum_32.S
    index 4d34bb5..46e71a7 100644
    --- a/arch/x86/lib/checksum_32.S
    +++ b/arch/x86/lib/checksum_32.S
    @@ -29,7 +29,8 @@
    #include <asm/errno.h>
    #include <asm/asm.h>
    #include <asm/export.h>
    -
    +#include <asm/nospec-branch.h>
    +
    /*
    * computes a partial checksum, e.g. for TCP/UDP fragments
    */
    @@ -156,7 +157,7 @@ ENTRY(csum_partial)
    negl %ebx
    lea 45f(%ebx,%ebx,2), %ebx
    testl %esi, %esi
    - jmp *%ebx
    + JMP_NOSPEC %ebx

    # Handle 2-byte-aligned regions
    20: addw (%esi), %ax
    @@ -439,7 +440,7 @@ ENTRY(csum_partial_copy_generic)
    andl $-32,%edx
    lea 3f(%ebx,%ebx), %ebx
    testl %esi, %esi
    - jmp *%ebx
    + JMP_NOSPEC %ebx
    1: addl $64,%esi
    addl $64,%edi
    SRC(movb -32(%edx),%bl) ; SRC(movb (%edx),%bl)
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