1 files changed, 88 insertions, 5 deletions

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index a8cb69a26576..92b6a2c21631 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -18,6 +18,7 @@
 #include <string.h>
 #include <stdlib.h>
 
+#include "builtin.h"
 #include "check.h"
 #include "elf.h"
 #include "special.h"
@@ -33,7 +34,6 @@ struct alternative {
 };
 
 const char *objname;
-static bool no_fp;
 struct cfi_state initial_func_cfi;
 
 struct instruction *find_insn(struct objtool_file *file,
@@ -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;
                         }
 
@@ -923,7 +925,11 @@ static struct rela *find_switch_table(struct objtool_file *file,
                 if (find_symbol_containing(file->rodata, text_rela->addend))
                         continue;
 
-                return find_rela_by_dest(file->rodata, text_rela->addend);
+                rodata_rela = find_rela_by_dest(file->rodata, text_rela->addend);
+                if (!rodata_rela)
+                        continue;
+
+                return rodata_rela;
         }
 
         return NULL;
@@ -1108,6 +1114,41 @@ static int read_unwind_hints(struct objtool_file *file)
         return 0;
 }
 
+static int read_retpoline_hints(struct objtool_file *file)
+{
+        struct section *sec;
+        struct instruction *insn;
+        struct rela *rela;
+
+        sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
+        if (!sec)
+                return 0;
+
+        list_for_each_entry(rela, &sec->rela_list, list) {
+                if (rela->sym->type != STT_SECTION) {
+                        WARN("unexpected relocation symbol type in %s", sec->name);
+                        return -1;
+                }
+
+                insn = find_insn(file, rela->sym->sec, rela->addend);
+                if (!insn) {
+                        WARN("bad .discard.retpoline_safe entry");
+                        return -1;
+                }
+
+                if (insn->type != INSN_JUMP_DYNAMIC &&
+                    insn->type != INSN_CALL_DYNAMIC) {
+                        WARN_FUNC("retpoline_safe hint not an 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 +1187,10 @@ 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 +1936,38 @@ 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;
+
+                /*
+                 * .init.text code is ran before userspace and thus doesn't
+                 * strictly need retpolines, except for modules which are
+                 * loaded late, they very much do need retpoline in their
+                 * .init.text
+                 */
+                if (!strcmp(insn->sec->name, ".init.text") && !module)
+                        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 &&
@@ -2022,13 +2099,12 @@ static void cleanup(struct objtool_file *file)
         elf_close(file->elf);
 }
 
-int check(const char *_objname, bool _no_fp, bool no_unreachable, bool orc)
+int check(const char *_objname, bool orc)
 {
         struct objtool_file file;
         int ret, warnings = 0;
 
         objname = _objname;
-        no_fp = _no_fp;
 
         file.elf = elf_open(objname, orc ? O_RDWR : O_RDONLY);
         if (!file.elf)
@@ -2052,6 +2128,13 @@ int check(const char *_objname, bool _no_fp, bool no_unreachable, 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;