objtool: Remove SAVE/RESTORE hints

The SAVE/RESTORE hints are now unused; remove them.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.926738768@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Author: Peter Zijlstra

arch/x86/include/asm/orc_types.h

@@ -58,9 +58,7 @@
 #define ORC_TYPE_CALL			0
 #define ORC_TYPE_REGS			1
 #define ORC_TYPE_REGS_IRET		2
-#define UNWIND_HINT_TYPE_SAVE		3
-#define UNWIND_HINT_TYPE_RESTORE	4
-#define UNWIND_HINT_TYPE_RET_OFFSET	5
+#define UNWIND_HINT_TYPE_RET_OFFSET	3
 
 #ifndef __ASSEMBLY__
 /*

arch/x86/include/asm/unwind_hints.h

@@ -86,15 +86,6 @@
 	UNWIND_HINT sp_offset=\sp_offset
 .endm
 
-.macro UNWIND_HINT_SAVE
-	UNWIND_HINT type=UNWIND_HINT_TYPE_SAVE
-.endm
-
-.macro UNWIND_HINT_RESTORE
-	UNWIND_HINT type=UNWIND_HINT_TYPE_RESTORE
-.endm
-
-
 /*
  * RET_OFFSET: Used on instructions that terminate a function; mostly RETURN
  * and sibling calls. On these, sp_offset denotes the expected offset from
@@ -104,24 +95,6 @@
 	UNWIND_HINT type=UNWIND_HINT_TYPE_RET_OFFSET sp_offset=\sp_offset
 .endm
 
-#else /* !__ASSEMBLY__ */
-
-#define UNWIND_HINT(sp_reg, sp_offset, type, end)		\
-	"987: \n\t"						\
-	".pushsection .discard.unwind_hints\n\t"		\
-	/* struct unwind_hint */				\
-	".long 987b - .\n\t"					\
-	".short " __stringify(sp_offset) "\n\t"			\
-	".byte " __stringify(sp_reg) "\n\t"			\
-	".byte " __stringify(type) "\n\t"			\
-	".byte " __stringify(end) "\n\t"			\
-	".balign 4 \n\t"					\
-	".popsection\n\t"
-
-#define UNWIND_HINT_SAVE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_SAVE, 0)
-
-#define UNWIND_HINT_RESTORE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_RESTORE, 0)
-
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_X86_UNWIND_HINTS_H */

tools/arch/x86/include/asm/orc_types.h

@@ -58,9 +58,7 @@
 #define ORC_TYPE_CALL			0
 #define ORC_TYPE_REGS			1
 #define ORC_TYPE_REGS_IRET		2
-#define UNWIND_HINT_TYPE_SAVE		3
-#define UNWIND_HINT_TYPE_RESTORE	4
-#define UNWIND_HINT_TYPE_RET_OFFSET	5
+#define UNWIND_HINT_TYPE_RET_OFFSET	3
 
 #ifndef __ASSEMBLY__
 /*

tools/objtool/check.c

@@ -1254,15 +1254,7 @@ static int read_unwind_hints(struct objtool_file *file)
 
 		cfa = &insn->state.cfa;
 
-		if (hint->type == UNWIND_HINT_TYPE_SAVE) {
-			insn->save = true;
-			continue;
-
-		} else if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
-			insn->restore = true;
-			insn->hint = true;
-
-		} else if (hint->type == UNWIND_HINT_TYPE_RET_OFFSET) {
+		if (hint->type == UNWIND_HINT_TYPE_RET_OFFSET) {
 			insn->ret_offset = hint->sp_offset;
 			continue;
 		}
@@ -2113,37 +2105,9 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 				return 0;
 		}
 
-		if (insn->hint) {
-			if (insn->restore) {
-				struct instruction *save_insn, *i;
-
-				i = insn;
-				save_insn = NULL;
-				sym_for_each_insn_continue_reverse(file, func, i) {
-					if (i->save) {
-						save_insn = i;
-						break;
-					}
-				}
-
-				if (!save_insn) {
-					WARN_FUNC("no corresponding CFI save for CFI restore",
-						  sec, insn->offset);
-					return 1;
-				}
-
-				if (!save_insn->visited) {
-					WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
-						  sec, insn->offset);
-					return 1;
-				}
-
-				insn->state = save_insn->state;
-			}
-
+		if (insn->hint)
 			state = insn->state;
-
-		} else
+		else
 			insn->state = state;
 
 		insn->visited |= visited;

tools/objtool/check.h

@@ -34,7 +34,7 @@ struct instruction {
 	enum insn_type type;
 	unsigned long immediate;
 	bool alt_group, dead_end, ignore, ignore_alts;
-	bool hint, save, restore;
+	bool hint;
 	bool retpoline_safe;
 	u8 visited;
 	u8 ret_offset;