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>

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 2671d9ad49beaa11943be1eb0227239b106719df..08ef566da7638cb82534bddaeae477c09a4c0058 100644 (file)
--- 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;