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    Subject[PATCH 2/3] uprobes/core: remove uprobe_opcode_sz
    From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

    uprobe_opcode_sz refers to the smallest instruction size for that
    architecture. UPROBES_BKPT_INSN_SIZE refers to the size of the breakpoint
    instruction for that architecture.

    For now we are assuming that both uprobe_opcode_sz and
    UPROBES_BKPT_INSN_SIZE are the same for all archs and hence removing
    uprobe_opcode_sz in favour of UPROBES_BKPT_INSN_SIZE.

    However if we have to support architectures where the smallest instruction
    size is different from the size of breakpoint instruction, we may have to
    re-introduce uprobe_opcode_sz.

    Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
    ---
    include/linux/uprobes.h | 2 --
    kernel/uprobes.c | 6 +++---
    2 files changed, 3 insertions(+), 5 deletions(-)

    diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
    index 64e45f1..fd45b70 100644
    --- a/include/linux/uprobes.h
    +++ b/include/linux/uprobes.h
    @@ -37,8 +37,6 @@ struct uprobe_arch_info {};
    #define MAX_UINSN_BYTES 4
    #endif

    -#define uprobe_opcode_sz sizeof(uprobe_opcode_t)
    -
    /* flags that denote/change uprobes behaviour */

    /* Have a copy of original instruction */
    diff --git a/kernel/uprobes.c b/kernel/uprobes.c
    index 884817f..ee496ad 100644
    --- a/kernel/uprobes.c
    +++ b/kernel/uprobes.c
    @@ -244,8 +244,8 @@ static int write_opcode(struct mm_struct *mm, struct uprobe *uprobe,

    /* poke the new insn in, ASSUMES we don't cross page boundary */
    vaddr &= ~PAGE_MASK;
    - BUG_ON(vaddr + uprobe_opcode_sz > PAGE_SIZE);
    - memcpy(vaddr_new + vaddr, &opcode, uprobe_opcode_sz);
    + BUG_ON(vaddr + UPROBES_BKPT_INSN_SIZE > PAGE_SIZE);
    + memcpy(vaddr_new + vaddr, &opcode, UPROBES_BKPT_INSN_SIZE);

    kunmap_atomic(vaddr_new);
    kunmap_atomic(vaddr_old);
    @@ -293,7 +293,7 @@ static int read_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_
    lock_page(page);
    vaddr_new = kmap_atomic(page);
    vaddr &= ~PAGE_MASK;
    - memcpy(opcode, vaddr_new + vaddr, uprobe_opcode_sz);
    + memcpy(opcode, vaddr_new + vaddr, UPROBES_BKPT_INSN_SIZE);
    kunmap_atomic(vaddr_new);
    unlock_page(page);




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