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

Greg Kroah-Hartman
2022-07-23T10:00:18Z

From: Peter Zijlstra <peterz@infradead.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@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.195441549@infradead.org
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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;