1 files changed, 96 insertions, 4 deletions

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index a8cb69a26576..472e64e95891 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;
 			}
 
@@ -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 +1945,38 @@ 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 +2108,12 @@ 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 +2137,13 @@ 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;