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    Subject[PATCH 05/10] objtool: Remove instruction::reloc
    Instead of caching the reloc for each instruction, only keep a
    negative cache of not having a reloc (by far the most common case).

    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 */

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

    - /* size: 160, cachelines: 3, members: 29 */
    - /* sum members: 158 */
    - /* sum bitfield members: 13 bits, bit holes: 1, sum bit holes: 3 bits */
    - /* last cacheline: 32 bytes */
    + /* size: 152, cachelines: 3, members: 29 */
    + /* sum members: 150 */
    + /* sum bitfield members: 14 bits, bit holes: 1, sum bit holes: 2 bits */
    + /* last cacheline: 24 bytes */
    };

    pre: 5:48.89 real, 220.96 user, 127.55 sys, 24834672 mem
    post: 5:39.35 real, 215.58 user, 123.69 sys, 23448736 mem

    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    ---
    tools/objtool/check.c | 26 ++++++++++++--------------
    tools/objtool/include/objtool/check.h | 6 +++---
    2 files changed, 15 insertions(+), 17 deletions(-)

    --- a/tools/objtool/check.c
    +++ b/tools/objtool/check.c
    @@ -1307,26 +1307,24 @@ __weak bool arch_is_rethunk(struct symbo
    return false;
    }

    -#define NEGATIVE_RELOC ((void *)-1L)
    -
    static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
    {
    - if (insn->reloc == NEGATIVE_RELOC)
    + struct reloc *reloc;
    +
    + if (insn->no_reloc)
    return NULL;

    - if (!insn->reloc) {
    - if (!file)
    - return NULL;
    -
    - insn->reloc = find_reloc_by_dest_range(file->elf, insn->sec,
    - insn->offset, insn->len);
    - if (!insn->reloc) {
    - insn->reloc = NEGATIVE_RELOC;
    - return NULL;
    - }
    + if (!file)
    + return NULL;
    +
    + reloc = find_reloc_by_dest_range(file->elf, insn->sec,
    + insn->offset, insn->len);
    + if (!reloc) {
    + insn->no_reloc = 1;
    + return NULL;
    }

    - return insn->reloc;
    + return reloc;
    }

    static void remove_insn_ops(struct instruction *insn)
    --- a/tools/objtool/include/objtool/check.h
    +++ b/tools/objtool/include/objtool/check.h
    @@ -55,8 +55,9 @@ struct instruction {
    retpoline_safe : 1,
    noendbr : 1,
    entry : 1,
    - visited : 4;
    - /* 3 bit hole */
    + visited : 4,
    + no_reloc : 1;
    + /* 2 bit hole */

    s8 instr;

    @@ -65,7 +66,6 @@ struct instruction {
    struct instruction *jump_dest;
    struct instruction *first_jump_src;
    struct reloc *jump_table;
    - struct reloc *reloc;
    struct alternative *alts;
    struct symbol *sym;
    struct stack_op *stack_ops;

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