linux-kernel - [PATCH 5.10 032/148] objtool: Cache instruction relocs

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Message-Id: <20220723095233.354758252@linuxfoundation.org>
Date:   Sat, 23 Jul 2022 11:54:04 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Borislav Petkov <bp@...e.de>, Ingo Molnar <mingo@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Ben Hutchings <ben@...adent.org.uk>
Subject: [PATCH 5.10 032/148] objtool: Cache instruction relocs

From: Peter Zijlstra <peterz@...radead.org>

commit 7bd2a600f3e9d27286bbf23c83d599e9cc7cf245 upstream.

Track the reloc of instructions in the new instruction->reloc field
to avoid having to look them up again later.

( Technically x86 instructions can have two relocations, but not jumps
  and calls, for which we're using this. )

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Reviewed-by: Miroslav Benes <mbenes@...e.cz>
Link: https://lkml.kernel.org/r/20210326151300.195441549@infradead.org
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 tools/objtool/check.c |   28 ++++++++++++++++++++++------
 tools/objtool/check.h |    1 +
 2 files changed, 23 insertions(+), 6 deletions(-)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -754,6 +754,25 @@ __weak bool arch_is_retpoline(struct sym
 	return false;
 }
 
+#define NEGATIVE_RELOC	((void *)-1L)
+
+static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
+{
+	if (insn->reloc == NEGATIVE_RELOC)
+		return NULL;
+
+	if (!insn->reloc) {
+		insn->reloc = find_reloc_by_dest_range(file->elf, insn->sec,
+						       insn->offset, insn->len);
+		if (!insn->reloc) {
+			insn->reloc = NEGATIVE_RELOC;
+			return NULL;
+		}
+	}
+
+	return insn->reloc;
+}
+
 /*
  * Find the destination instructions for all jumps.
  */
@@ -768,8 +787,7 @@ static int add_jump_destinations(struct
 		if (!is_static_jump(insn))
 			continue;
 
-		reloc = find_reloc_by_dest_range(file->elf, insn->sec,
-						 insn->offset, insn->len);
+		reloc = insn_reloc(file, insn);
 		if (!reloc) {
 			dest_sec = insn->sec;
 			dest_off = arch_jump_destination(insn);
@@ -901,8 +919,7 @@ static int add_call_destinations(struct
 		if (insn->type != INSN_CALL)
 			continue;
 
-		reloc = find_reloc_by_dest_range(file->elf, insn->sec,
-					       insn->offset, insn->len);
+		reloc = insn_reloc(file, insn);
 		if (!reloc) {
 			dest_off = arch_jump_destination(insn);
 			insn->call_dest = find_call_destination(insn->sec, dest_off);
@@ -1085,8 +1102,7 @@ static int handle_group_alt(struct objto
 		 * alternatives code can adjust the relative offsets
 		 * accordingly.
 		 */
-		alt_reloc = find_reloc_by_dest_range(file->elf, insn->sec,
-						   insn->offset, insn->len);
+		alt_reloc = insn_reloc(file, insn);
 		if (alt_reloc &&
 		    !arch_support_alt_relocation(special_alt, insn, alt_reloc)) {
 
--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -55,6 +55,7 @@ struct instruction {
 	struct instruction *jump_dest;
 	struct instruction *first_jump_src;
 	struct reloc *jump_table;
+	struct reloc *reloc;
 	struct list_head alts;
 	struct symbol *func;
 	struct list_head stack_ops;