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    Subject[tip:perf/core] uprobes: Copy_insn() shouldn't depend on mm/vma/ vaddr
    Commit-ID:  d436615e60c386095dac4a9bf72b08868d2a7564
    Gitweb: http://git.kernel.org/tip/d436615e60c386095dac4a9bf72b08868d2a7564
    Author: Oleg Nesterov <oleg@redhat.com>
    AuthorDate: Fri, 15 Jun 2012 17:43:42 +0200
    Committer: Ingo Molnar <mingo@kernel.org>
    CommitDate: Sat, 16 Jun 2012 09:10:45 +0200

    uprobes: Copy_insn() shouldn't depend on mm/vma/vaddr

    1. copy_insn() doesn't need "addr", it can use uprobe->offset.
    Remove this argument.

    2. Change copy_insn/__copy_insn to accept "struct file*" instead
    of vma.

    copy_insn() is called only once and mm/vma/vaddr are random, it
    shouldn't depend on them.

    Signed-off-by: Oleg Nesterov <oleg@redhat.com>
    Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
    Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
    Cc: Anton Arapov <anton@redhat.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Link: http://lkml.kernel.org/r/20120615154342.GA9598@redhat.com
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    ---
    kernel/events/uprobes.c | 15 ++++++---------
    1 files changed, 6 insertions(+), 9 deletions(-)

    diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
    index 2671d9a..08ef566 100644
    --- a/kernel/events/uprobes.c
    +++ b/kernel/events/uprobes.c
    @@ -591,10 +591,9 @@ static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc)
    }

    static int
    -__copy_insn(struct address_space *mapping, struct vm_area_struct *vma, char *insn,
    +__copy_insn(struct address_space *mapping, struct file *filp, char *insn,
    unsigned long nbytes, unsigned long offset)
    {
    - struct file *filp = vma->vm_file;
    struct page *page;
    void *vaddr;
    unsigned long off1;
    @@ -625,15 +624,13 @@ __copy_insn(struct address_space *mapping, struct vm_area_struct *vma, char *ins
    return 0;
    }

    -static int
    -copy_insn(struct uprobe *uprobe, struct vm_area_struct *vma, unsigned long addr)
    +static int copy_insn(struct uprobe *uprobe, struct file *filp)
    {
    struct address_space *mapping;
    unsigned long nbytes;
    int bytes;

    - addr &= ~PAGE_MASK;
    - nbytes = PAGE_SIZE - addr;
    + nbytes = PAGE_SIZE - (uprobe->offset & ~PAGE_MASK);
    mapping = uprobe->inode->i_mapping;

    /* Instruction at end of binary; copy only available bytes */
    @@ -644,13 +641,13 @@ copy_insn(struct uprobe *uprobe, struct vm_area_struct *vma, unsigned long addr)

    /* Instruction at the page-boundary; copy bytes in second page */
    if (nbytes < bytes) {
    - if (__copy_insn(mapping, vma, uprobe->arch.insn + nbytes,
    + if (__copy_insn(mapping, filp, uprobe->arch.insn + nbytes,
    bytes - nbytes, uprobe->offset + nbytes))
    return -ENOMEM;

    bytes = nbytes;
    }
    - return __copy_insn(mapping, vma, uprobe->arch.insn, bytes, uprobe->offset);
    + return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset);
    }

    /*
    @@ -696,7 +693,7 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
    addr = (unsigned long)vaddr;

    if (!(uprobe->flags & UPROBE_COPY_INSN)) {
    - ret = copy_insn(uprobe, vma, addr);
    + ret = copy_insn(uprobe, vma->vm_file);
    if (ret)
    return ret;


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