linux-kernel - [PATCH v5 07/17] objtool: Remove SAVE/RESTORE hints

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Date:   Thu, 16 Apr 2020 13:47:13 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     tglx@...utronix.de, jpoimboe@...hat.com
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org, peterz@...radead.org,
        mhiramat@...nel.org, mbenes@...e.cz, jthierry@...hat.com,
        alexandre.chartre@...cle.com
Subject: [PATCH v5 07/17] objtool: Remove SAVE/RESTORE hints

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

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/include/asm/orc_types.h       |    4 ---
 arch/x86/include/asm/unwind_hints.h    |   13 ----------
 tools/arch/x86/include/asm/orc_types.h |    4 ---
 tools/objtool/check.c                  |   42 ++-------------------------------
 tools/objtool/check.h                  |    2 -
 5 files changed, 7 insertions(+), 58 deletions(-)

--- a/arch/x86/include/asm/orc_types.h
+++ b/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__
 /*
--- a/arch/x86/include/asm/unwind_hints.h
+++ b/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
@@ -118,9 +109,7 @@
 	".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)
+#define UNWIND_HINT_RET_OFFSET(offset) UNWIND_HINT(0, (offset), UNWIND_HINT_TYPE_RET_OFFSET, 0)
 
 #endif /* __ASSEMBLY__ */
 
--- a/tools/arch/x86/include/asm/orc_types.h
+++ b/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__
 /*
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1246,15 +1246,7 @@ static int read_unwind_hints(struct objt
 
 		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;
 		}
@@ -2070,37 +2062,9 @@ static int validate_branch(struct objtoo
 				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;
--- a/tools/objtool/check.h
+++ b/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;