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    Subject[PATCH 5.11 381/775] objtool: Fix retpoline detection in asm code
    Date
    From: Josh Poimboeuf <jpoimboe@redhat.com>

    [ Upstream commit 1f9a1b74942485a0a29e7c4a9a9f2fe8aea17766 ]

    The JMP_NOSPEC macro branches to __x86_retpoline_*() rather than the
    __x86_indirect_thunk_*() wrappers used by C code. Detect jumps to
    __x86_retpoline_*() as retpoline dynamic jumps.

    Presumably this doesn't trigger a user-visible bug. I only found it
    when testing vmlinux.o validation.

    Fixes: 39b735332cb8 ("objtool: Detect jumps to retpoline thunks")
    Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
    Link: https://lore.kernel.org/r/31f5833e2e4f01e3d755889ac77e3661e906c09f.1611263461.git.jpoimboe@redhat.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    tools/objtool/arch/x86/special.c | 2 +-
    tools/objtool/check.c | 3 ++-
    tools/objtool/check.h | 11 +++++++++++
    3 files changed, 14 insertions(+), 2 deletions(-)

    diff --git a/tools/objtool/arch/x86/special.c b/tools/objtool/arch/x86/special.c
    index fd4af88c0ea52..151b13d0a2676 100644
    --- a/tools/objtool/arch/x86/special.c
    +++ b/tools/objtool/arch/x86/special.c
    @@ -48,7 +48,7 @@ bool arch_support_alt_relocation(struct special_alt *special_alt,
    * replacement group.
    */
    return insn->offset == special_alt->new_off &&
    - (insn->type == INSN_CALL || is_static_jump(insn));
    + (insn->type == INSN_CALL || is_jump(insn));
    }

    /*
    diff --git a/tools/objtool/check.c b/tools/objtool/check.c
    index 2e154f00ccec2..48e22e3c6f186 100644
    --- a/tools/objtool/check.c
    +++ b/tools/objtool/check.c
    @@ -789,7 +789,8 @@ static int add_jump_destinations(struct objtool_file *file)
    dest_sec = reloc->sym->sec;
    dest_off = reloc->sym->sym.st_value +
    arch_dest_reloc_offset(reloc->addend);
    - } else if (strstr(reloc->sym->name, "_indirect_thunk_")) {
    + } else if (!strncmp(reloc->sym->name, "__x86_indirect_thunk_", 21) ||
    + !strncmp(reloc->sym->name, "__x86_retpoline_", 16)) {
    /*
    * Retpoline jumps are really dynamic jumps in
    * disguise, so convert them accordingly.
    diff --git a/tools/objtool/check.h b/tools/objtool/check.h
    index 5ec00a4b891b6..2804848e628e3 100644
    --- a/tools/objtool/check.h
    +++ b/tools/objtool/check.h
    @@ -54,6 +54,17 @@ static inline bool is_static_jump(struct instruction *insn)
    insn->type == INSN_JUMP_UNCONDITIONAL;
    }

    +static inline bool is_dynamic_jump(struct instruction *insn)
    +{
    + return insn->type == INSN_JUMP_DYNAMIC ||
    + insn->type == INSN_JUMP_DYNAMIC_CONDITIONAL;
    +}
    +
    +static inline bool is_jump(struct instruction *insn)
    +{
    + return is_static_jump(insn) || is_dynamic_jump(insn);
    +}
    +
    struct instruction *find_insn(struct objtool_file *file,
    struct section *sec, unsigned long offset);

    --
    2.27.0


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