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    Subject[PATCH 4.14 126/140] x86/speculation, objtool: Annotate indirect calls/jumps for objtool
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Peter Zijlstra <peterz@infradead.org>

    commit 9e0e3c5130e949c389caabc8033e9799b129e429 upstream.

    Annotate the indirect calls/jumps in the CALL_NOSPEC/JUMP_NOSPEC
    alternatives.

    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
    Acked-by: Thomas Gleixner <tglx@linutronix.de>
    Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Arjan van de Ven <arjan@linux.intel.com>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: Dave Hansen <dave.hansen@linux.intel.com>
    Cc: David Woodhouse <dwmw2@infradead.org>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/x86/include/asm/nospec-branch.h | 27 +++++++++++++++++++++++----
    1 file changed, 23 insertions(+), 4 deletions(-)

    --- a/arch/x86/include/asm/nospec-branch.h
    +++ b/arch/x86/include/asm/nospec-branch.h
    @@ -68,6 +68,18 @@
    .endm

    /*
    + * This should be used immediately before an indirect jump/call. It tells
    + * objtool the subsequent indirect jump/call is vouched safe for retpoline
    + * builds.
    + */
    +.macro ANNOTATE_RETPOLINE_SAFE
    + .Lannotate_\@:
    + .pushsection .discard.retpoline_safe
    + _ASM_PTR .Lannotate_\@
    + .popsection
    +.endm
    +
    +/*
    * These are the bare retpoline primitives for indirect jmp and call.
    * Do not use these directly; they only exist to make the ALTERNATIVE
    * invocation below less ugly.
    @@ -103,9 +115,9 @@
    .macro JMP_NOSPEC reg:req
    #ifdef CONFIG_RETPOLINE
    ANNOTATE_NOSPEC_ALTERNATIVE
    - ALTERNATIVE_2 __stringify(jmp *\reg), \
    + ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; jmp *\reg), \
    __stringify(RETPOLINE_JMP \reg), X86_FEATURE_RETPOLINE, \
    - __stringify(lfence; jmp *\reg), X86_FEATURE_RETPOLINE_AMD
    + __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *\reg), X86_FEATURE_RETPOLINE_AMD
    #else
    jmp *\reg
    #endif
    @@ -114,9 +126,9 @@
    .macro CALL_NOSPEC reg:req
    #ifdef CONFIG_RETPOLINE
    ANNOTATE_NOSPEC_ALTERNATIVE
    - ALTERNATIVE_2 __stringify(call *\reg), \
    + ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; call *\reg), \
    __stringify(RETPOLINE_CALL \reg), X86_FEATURE_RETPOLINE,\
    - __stringify(lfence; call *\reg), X86_FEATURE_RETPOLINE_AMD
    + __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; call *\reg), X86_FEATURE_RETPOLINE_AMD
    #else
    call *\reg
    #endif
    @@ -144,6 +156,12 @@
    ".long 999b - .\n\t" \
    ".popsection\n\t"

    +#define ANNOTATE_RETPOLINE_SAFE \
    + "999:\n\t" \
    + ".pushsection .discard.retpoline_safe\n\t" \
    + _ASM_PTR " 999b\n\t" \
    + ".popsection\n\t"
    +
    #if defined(CONFIG_X86_64) && defined(RETPOLINE)

    /*
    @@ -153,6 +171,7 @@
    # define CALL_NOSPEC \
    ANNOTATE_NOSPEC_ALTERNATIVE \
    ALTERNATIVE( \
    + ANNOTATE_RETPOLINE_SAFE \
    "call *%[thunk_target]\n", \
    "call __x86_indirect_thunk_%V[thunk_target]\n", \
    X86_FEATURE_RETPOLINE)

    \
     
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