objtool: Fix retpoline detection in asm code

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

diff --git a/tools/objtool/arch/x86/special.c b/tools/objtool/arch/x86/special.c
index b4bd3505fc9466e1749fd93cb26d7fd880081517..e707d9bcd1616480be236c6ba2e3ab8e70f8d13b 100644 (file)
--- 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 3bdd946c2027ef415fb57f4154faa924e1ac27d5..081572170f6b34ca3e6d47927962fdc55c127396 100644 (file)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -785,7 +785,8 @@ 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/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index f4e041fbdab26ef8bcd48ff5b339a2b1105eaf87..b408636c020189913a38a70a9ad7c90ffdebd8fb 100644 (file)
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -68,6 +68,17 @@ 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);