1 files changed, 85 insertions, 1 deletions

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index ab6f0de7f90d..5e5db7b4d77b 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -497,6 +497,7 @@ static int add_jump_destinations(struct objtool_file *file)
                          * disguise, so convert them accordingly.
                          */
                         insn->type = INSN_JUMP_DYNAMIC;
+                        insn->retpoline_safe = true;
                         continue;
                 } else {
                         /* sibling call */
@@ -548,7 +549,8 @@ static int add_call_destinations(struct objtool_file *file)
                         if (!insn->call_dest && !insn->ignore) {
                                 WARN_FUNC("unsupported intra-function call",
                                           insn->sec, insn->offset);
-                                WARN("If this is a retpoline, please patch it in with alternatives and annotate it with ANNOTATE_NOSPEC_ALTERNATIVE.");
+                                if (retpoline)
+                                        WARN("If this is a retpoline, please patch it in with alternatives and annotate it with ANNOTATE_NOSPEC_ALTERNATIVE.");
                                 return -1;
                         }
 
@@ -1108,6 +1110,54 @@ static int read_unwind_hints(struct objtool_file *file)
         return 0;
 }
 
+static int read_retpoline_hints(struct objtool_file *file)
+{
+        struct section *sec, *relasec;
+        struct instruction *insn;
+        struct rela *rela;
+        int i;
+
+        sec = find_section_by_name(file->elf, ".discard.retpoline_safe");
+        if (!sec)
+                return 0;
+
+        relasec = sec->rela;
+        if (!relasec) {
+                WARN("missing .rela.discard.retpoline_safe section");
+                return -1;
+        }
+
+        if (sec->len % sizeof(unsigned long)) {
+                WARN("retpoline_safe size mismatch: %d %ld", sec->len, sizeof(unsigned long));
+                return -1;
+        }
+
+        for (i = 0; i < sec->len / sizeof(unsigned long); i++) {
+                rela = find_rela_by_dest(sec, i * sizeof(unsigned long));
+                if (!rela) {
+                        WARN("can't find rela for retpoline_safe[%d]", i);
+                        return -1;
+                }
+
+                insn = find_insn(file, rela->sym->sec, rela->addend);
+                if (!insn) {
+                        WARN("can't find insn for retpoline_safe[%d]", i);
+                        return -1;
+                }
+
+                if (insn->type != INSN_JUMP_DYNAMIC &&
+                    insn->type != INSN_CALL_DYNAMIC) {
+                        WARN_FUNC("retpoline_safe hint not a indirect jump/call",
+                                  insn->sec, insn->offset);
+                        return -1;
+                }
+
+                insn->retpoline_safe = true;
+        }
+
+        return 0;
+}
+
 static int decode_sections(struct objtool_file *file)
 {
         int ret;
@@ -1146,6 +1196,10 @@ static int decode_sections(struct objtool_file *file)
         if (ret)
                 return ret;
 
+        ret = read_retpoline_hints(file);
+        if (ret)
+                return ret;
+
         return 0;
 }
 
@@ -1891,6 +1945,29 @@ static int validate_unwind_hints(struct objtool_file *file)
         return warnings;
 }
 
+static int validate_retpoline(struct objtool_file *file)
+{
+        struct instruction *insn;
+        int warnings = 0;
+
+        for_each_insn(file, insn) {
+                if (insn->type != INSN_JUMP_DYNAMIC &&
+                    insn->type != INSN_CALL_DYNAMIC)
+                        continue;
+
+                if (insn->retpoline_safe)
+                        continue;
+
+                WARN_FUNC("indirect %s found in RETPOLINE build",
+                          insn->sec, insn->offset,
+                          insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
+
+                warnings++;
+        }
+
+        return warnings;
+}
+
 static bool is_kasan_insn(struct instruction *insn)
 {
         return (insn->type == INSN_CALL &&
@@ -2051,6 +2128,13 @@ int check(const char *_objname, bool orc)
         if (list_empty(&file.insn_list))
                 goto out;
 
+        if (retpoline) {
+                ret = validate_retpoline(&file);
+                if (ret < 0)
+                        return ret;
+                warnings += ret;
+        }
+
         ret = validate_functions(&file);
         if (ret < 0)
                 goto out;