[tip: objtool/core] objtool: Make instruction::alts a single-linked list

From: tip-bot2 for Peter Zijlstra
Date: Thu Feb 23 2023 - 03:32:40 EST


The following commit has been merged into the objtool/core branch of tip:

Commit-ID: d54066546121426ecd7ad01a53ae429c4e37a9d5
Gitweb: https://git.kernel.org/tip/d54066546121426ecd7ad01a53ae429c4e37a9d5
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 08 Feb 2023 18:17:59 +01:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Thu, 23 Feb 2023 09:21:06 +01:00

objtool: Make instruction::alts a single-linked list

struct instruction {
struct list_head list; /* 0 16 */
struct hlist_node hash; /* 16 16 */
struct list_head call_node; /* 32 16 */
struct section * sec; /* 48 8 */
long unsigned int offset; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
unsigned int len; /* 64 4 */
enum insn_type type; /* 68 4 */
long unsigned int immediate; /* 72 8 */
u16 dead_end:1; /* 80: 0 2 */
u16 ignore:1; /* 80: 1 2 */
u16 ignore_alts:1; /* 80: 2 2 */
u16 hint:1; /* 80: 3 2 */
u16 save:1; /* 80: 4 2 */
u16 restore:1; /* 80: 5 2 */
u16 retpoline_safe:1; /* 80: 6 2 */
u16 noendbr:1; /* 80: 7 2 */
u16 entry:1; /* 80: 8 2 */

/* XXX 7 bits hole, try to pack */

s8 instr; /* 82 1 */
u8 visited; /* 83 1 */

/* XXX 4 bytes hole, try to pack */

struct alt_group * alt_group; /* 88 8 */
struct symbol * call_dest; /* 96 8 */
struct instruction * jump_dest; /* 104 8 */
struct instruction * first_jump_src; /* 112 8 */
struct reloc * jump_table; /* 120 8 */
/* --- cacheline 2 boundary (128 bytes) --- */
struct reloc * reloc; /* 128 8 */
- struct list_head alts; /* 136 16 */
- struct symbol * sym; /* 152 8 */
- struct stack_op * stack_ops; /* 160 8 */
- struct cfi_state * cfi; /* 168 8 */
+ struct alternative * alts; /* 136 8 */
+ struct symbol * sym; /* 144 8 */
+ struct stack_op * stack_ops; /* 152 8 */
+ struct cfi_state * cfi; /* 160 8 */

- /* size: 176, cachelines: 3, members: 29 */
- /* sum members: 170, holes: 1, sum holes: 4 */
+ /* size: 168, cachelines: 3, members: 29 */
+ /* sum members: 162, holes: 1, sum holes: 4 */
/* sum bitfield members: 9 bits, bit holes: 1, sum bit holes: 7 bits */
- /* last cacheline: 48 bytes */
+ /* last cacheline: 40 bytes */
};

pre: 5:58.50 real, 229.64 user, 128.65 sys, 26221520 mem
post: 5:48.86 real, 220.30 user, 128.34 sys, 24834672 mem

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx> # build only
Tested-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx> # compile and run
Link: https://lore.kernel.org/r/20230208172245.430556498@xxxxxxxxxxxxx
---
tools/objtool/check.c | 18 +++++++++---------
tools/objtool/include/objtool/check.h | 2 +-
2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 8109d74..9f83e85 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -23,7 +23,7 @@
#include <linux/static_call_types.h>

struct alternative {
- struct list_head list;
+ struct alternative *next;
struct instruction *insn;
bool skip_orig;
};
@@ -397,7 +397,6 @@ static int decode_instructions(struct objtool_file *file)
return -1;
}
memset(insn, 0, sizeof(*insn));
- INIT_LIST_HEAD(&insn->alts);
INIT_LIST_HEAD(&insn->call_node);

insn->sec = sec;
@@ -1780,7 +1779,6 @@ static int handle_group_alt(struct objtool_file *file,
return -1;
}
memset(nop, 0, sizeof(*nop));
- INIT_LIST_HEAD(&nop->alts);

nop->sec = special_alt->new_sec;
nop->offset = special_alt->new_off + special_alt->new_len;
@@ -1978,7 +1976,8 @@ static int add_special_section_alts(struct objtool_file *file)
alt->insn = new_insn;
alt->skip_orig = special_alt->skip_orig;
orig_insn->ignore_alts |= special_alt->skip_alt;
- list_add_tail(&alt->list, &orig_insn->alts);
+ alt->next = orig_insn->alts;
+ orig_insn->alts = alt;

list_del(&special_alt->list);
free(special_alt);
@@ -2037,7 +2036,8 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
}

alt->insn = dest_insn;
- list_add_tail(&alt->list, &insn->alts);
+ alt->next = insn->alts;
+ insn->alts = alt;
prev_offset = reloc->offset;
}

@@ -3594,10 +3594,10 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
if (propagate_alt_cfi(file, insn))
return 1;

- if (!insn->ignore_alts && !list_empty(&insn->alts)) {
+ if (!insn->ignore_alts && insn->alts) {
bool skip_orig = false;

- list_for_each_entry(alt, &insn->alts, list) {
+ for (alt = insn->alts; alt; alt = alt->next) {
if (alt->skip_orig)
skip_orig = true;

@@ -3796,11 +3796,11 @@ static int validate_entry(struct objtool_file *file, struct instruction *insn)

insn->visited |= VISITED_ENTRY;

- if (!insn->ignore_alts && !list_empty(&insn->alts)) {
+ if (!insn->ignore_alts && insn->alts) {
struct alternative *alt;
bool skip_orig = false;

- list_for_each_entry(alt, &insn->alts, list) {
+ for (alt = insn->alts; alt; alt = alt->next) {
if (alt->skip_orig)
skip_orig = true;

diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index 23e9819..7966f60 100644
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -66,7 +66,7 @@ struct instruction {
struct instruction *first_jump_src;
struct reloc *jump_table;
struct reloc *reloc;
- struct list_head alts;
+ struct alternative *alts;
struct symbol *sym;
struct stack_op *stack_ops;
struct cfi_state *cfi;