4 files changed, 25 insertions, 6 deletions

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 694abc628e9b..99f10c585cbe 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -29,7 +29,7 @@
 #include "builtin.h"
 #include "check.h"
 
-bool no_fp, no_unreachable, retpoline, module;
+bool no_fp, no_unreachable, retpoline, module, backtrace;
 
 static const char * const check_usage[] = {
         "objtool check [<options>] file.o",
@@ -41,6 +41,7 @@ const struct option check_options[] = {
         OPT_BOOLEAN('u', "no-unreachable", &no_unreachable, "Skip 'unreachable instruction' warnings"),
         OPT_BOOLEAN('r', "retpoline", &retpoline, "Validate retpoline assumptions"),
         OPT_BOOLEAN('m', "module", &module, "Indicates the object will be part of a kernel module"),
+        OPT_BOOLEAN('b', "backtrace", &backtrace, "unwind on error"),
         OPT_END(),
 };
 
diff --git a/tools/objtool/builtin.h b/tools/objtool/builtin.h
index 28ff40e19a14..65fd3cc3c98b 100644
--- a/tools/objtool/builtin.h
+++ b/tools/objtool/builtin.h
@@ -20,7 +20,7 @@
 #include <subcmd/parse-options.h>
 
 extern const struct option check_options[];
-extern bool no_fp, no_unreachable, retpoline, module;
+extern bool no_fp, no_unreachable, retpoline, module, backtrace;
 
 extern int cmd_check(int argc, const char **argv);
 extern int cmd_orc(int argc, const char **argv);
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 8d8191f25381..ccc66af5907f 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1885,8 +1885,11 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
                 if (!insn->ignore_alts) {
                         list_for_each_entry(alt, &insn->alts, list) {
                                 ret = validate_branch(file, alt->insn, state);
-                                if (ret)
-                                        return 1;
+                                if (ret) {
+                                        if (backtrace)
+                                                BT_FUNC("(alt)", insn);
+                                        return ret;
+                                }
                         }
                 }
 
@@ -1933,8 +1936,11 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
                              insn->jump_dest->func->pfunc == func)) {
                                 ret = validate_branch(file, insn->jump_dest,
                                                       state);
-                                if (ret)
-                                        return 1;
+                                if (ret) {
+                                        if (backtrace)
+                                                BT_FUNC("(branch)", insn);
+                                        return ret;
+                                }
 
                         } else if (func && has_modified_stack_frame(&state)) {
                                 WARN_FUNC("sibling call from callable instruction with modified stack frame",
@@ -2005,6 +2011,8 @@ static int validate_unwind_hints(struct objtool_file *file)
         for_each_insn(file, insn) {
                 if (insn->hint && !insn->visited) {
                         ret = validate_branch(file, insn, state);
+                        if (ret && backtrace)
+                                BT_FUNC("<=== (hint)", insn);
                         warnings += ret;
                 }
         }
@@ -2133,6 +2141,8 @@ static int validate_functions(struct objtool_file *file)
                                 continue;
 
                         ret = validate_branch(file, insn, state);
+                        if (ret && backtrace)
+                                BT_FUNC("<=== (func)", insn);
                         warnings += ret;
                 }
         }
diff --git a/tools/objtool/warn.h b/tools/objtool/warn.h
index afd9f7a05f6d..f4fbb972b611 100644
--- a/tools/objtool/warn.h
+++ b/tools/objtool/warn.h
@@ -64,6 +64,14 @@ static inline char *offstr(struct section *sec, unsigned long offset)
         free(_str);                                     \
 })
 
+#define BT_FUNC(format, insn, ...)                      \
+({                                                      \
+        struct instruction *_insn = (insn);             \
+        char *_str = offstr(_insn->sec, _insn->offset); \
+        WARN("  %s: " format, _str, ##__VA_ARGS__);     \
+        free(_str);                                     \
+})
+
 #define WARN_ELF(format, ...)                           \
         WARN(format ": %s", ##__VA_ARGS__, elf_errmsg(-1))