objtool: Make instruction::stack_ops 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 list_head           stack_ops;            /*   160    16 */
-	struct cfi_state *         cfi;                  /*   176     8 */
+	struct stack_op *          stack_ops;            /*   160     8 */
+	struct cfi_state *         cfi;                  /*   168     8 */

-	/* size: 184, cachelines: 3, members: 29 */
-	/* sum members: 178, holes: 1, sum holes: 4 */
+	/* size: 176, cachelines: 3, members: 29 */
+	/* sum members: 170, holes: 1, sum holes: 4 */
 	/* sum bitfield members: 9 bits, bit holes: 1, sum bit holes: 7 bits */
-	/* last cacheline: 56 bytes */
+	/* last cacheline: 48 bytes */
 };

pre:	5:58.22 real,   226.69 user,    131.22 sys,     26221520 mem
post:	5:58.50 real,   229.64 user,    128.65 sys,     26221520 mem

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org> # build only
Tested-by: Thomas Weißschuh <linux@weissschuh.net> # compile and run
Link: https://lore.kernel.org/r/20230208172245.362196959@infradead.org

1 files changed, 2 insertions, 2 deletions

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index c5c49277cf1a..9ef024fd648c 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -105,7 +105,7 @@ bool arch_pc_relative_reloc(struct reloc *reloc)
 #define ADD_OP(op) \
 	if (!(op = calloc(1, sizeof(*op)))) \
 		return -1; \
-	else for (list_add_tail(&op->list, ops_list); op; op = NULL)
+	else for (*ops_list = op, ops_list = &op->next; op; op = NULL)
 
 /*
  * Helpers to decode ModRM/SIB:
@@ -148,7 +148,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
 			    unsigned long offset, unsigned int maxlen,
 			    struct instruction *insn)
 {
-	struct list_head *ops_list = &insn->stack_ops;
+	struct stack_op **ops_list = &insn->stack_ops;
 	const struct elf *elf = file->elf;
 	struct insn ins;
 	int x86_64, ret;