objtool: Remove instruction::list
authorPeter Zijlstra <peterz@infradead.org>
Wed, 8 Feb 2023 17:18:05 +0000 (18:18 +0100)
committerIngo Molnar <mingo@kernel.org>
Thu, 23 Feb 2023 08:21:44 +0000 (09:21 +0100)
commit1c34496e5856886d565665fb64029ecdeb080ffb
treeb16d5206ee8cb8094790a588145c748d35ade447
parent6ea17e848a8ba5138b30e936c4b71877bc972c13
objtool: Remove instruction::list

Replace the instruction::list by allocating instructions in arrays of
256 entries and stringing them together by (amortized) find_insn().
This shrinks instruction by 16 bytes and brings it down to 128.

 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) --- */
- long unsigned int          immediate;            /*    64     8 */
- unsigned int               len;                  /*    72     4 */
- u8                         type;                 /*    76     1 */
-
- /* Bitfield combined with previous fields */
+ struct hlist_node          hash;                 /*     0    16 */
+ struct list_head           call_node;            /*    16    16 */
+ struct section *           sec;                  /*    32     8 */
+ long unsigned int          offset;               /*    40     8 */
+ long unsigned int          immediate;            /*    48     8 */
+ u8                         len;                  /*    56     1 */
+ u8                         prev_len;             /*    57     1 */
+ u8                         type;                 /*    58     1 */
+ s8                         instr;                /*    59     1 */
+ u32                        idx:8;                /*    60: 0  4 */
+ u32                        dead_end:1;           /*    60: 8  4 */
+ u32                        ignore:1;             /*    60: 9  4 */
+ u32                        ignore_alts:1;        /*    60:10  4 */
+ u32                        hint:1;               /*    60:11  4 */
+ u32                        save:1;               /*    60:12  4 */
+ u32                        restore:1;            /*    60:13  4 */
+ u32                        retpoline_safe:1;     /*    60:14  4 */
+ u32                        noendbr:1;            /*    60:15  4 */
+ u32                        entry:1;              /*    60:16  4 */
+ u32                        visited:4;            /*    60:17  4 */
+ u32                        no_reloc:1;           /*    60:21  4 */

- u16                        dead_end:1;           /*    76: 8  2 */
- u16                        ignore:1;             /*    76: 9  2 */
- u16                        ignore_alts:1;        /*    76:10  2 */
- u16                        hint:1;               /*    76:11  2 */
- u16                        save:1;               /*    76:12  2 */
- u16                        restore:1;            /*    76:13  2 */
- u16                        retpoline_safe:1;     /*    76:14  2 */
- u16                        noendbr:1;            /*    76:15  2 */
- u16                        entry:1;              /*    78: 0  2 */
- u16                        visited:4;            /*    78: 1  2 */
- u16                        no_reloc:1;           /*    78: 5  2 */
+ /* XXX 10 bits hole, try to pack */

- /* XXX 2 bits hole, try to pack */
- /* Bitfield combined with next fields */
-
- s8                         instr;                /*    79     1 */
- struct alt_group *         alt_group;            /*    80     8 */
- struct instruction *       jump_dest;            /*    88     8 */
- struct instruction *       first_jump_src;       /*    96     8 */
+ /* --- cacheline 1 boundary (64 bytes) --- */
+ struct alt_group *         alt_group;            /*    64     8 */
+ struct instruction *       jump_dest;            /*    72     8 */
+ struct instruction *       first_jump_src;       /*    80     8 */
  union {
- struct symbol *    _call_dest;           /*   104     8 */
- struct reloc *     _jump_table;          /*   104     8 */
- };                                               /*   104     8 */
- struct alternative *       alts;                 /*   112     8 */
- struct symbol *            sym;                  /*   120     8 */
- /* --- cacheline 2 boundary (128 bytes) --- */
- struct stack_op *          stack_ops;            /*   128     8 */
- struct cfi_state *         cfi;                  /*   136     8 */
+ struct symbol *    _call_dest;           /*    88     8 */
+ struct reloc *     _jump_table;          /*    88     8 */
+ };                                               /*    88     8 */
+ struct alternative *       alts;                 /*    96     8 */
+ struct symbol *            sym;                  /*   104     8 */
+ struct stack_op *          stack_ops;            /*   112     8 */
+ struct cfi_state *         cfi;                  /*   120     8 */

- /* size: 144, cachelines: 3, members: 28 */
- /* sum members: 142 */
- /* sum bitfield members: 14 bits, bit holes: 1, sum bit holes: 2 bits */
- /* last cacheline: 16 bytes */
+ /* size: 128, cachelines: 2, members: 29 */
+ /* sum members: 124 */
+ /* sum bitfield members: 22 bits, bit holes: 1, sum bit holes: 10 bits */
 };

pre: 5:38.18 real,   213.25 user,    124.90 sys,     23449040 mem
post: 5:03.34 real,   210.75 user,    88.80 sys,      20241232 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/20230208172245.851307606@infradead.org
tools/objtool/check.c
tools/objtool/include/objtool/check.h
tools/objtool/include/objtool/objtool.h
tools/objtool/objtool.c