uprobes: Don't recheck vma/f_mapping in write_opcode()

write_opcode() rechecks valid_vma() and ->f_mapping, this is
pointless. The caller, register_for_each_vma() or uprobe_mmap(),
has already done these checks under mmap_sem.

To clarify, uprobe_mmap() checks valid_vma() only, but we can
rely on build_probe_list(vm_file->f_mapping->host).

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar.vnet.ibm.com>
Cc: Anton Arapov <anton@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20120729182212.GA20304@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index f935327..a2b32a5 100644 (file)
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -206,33 +206,16 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
                        unsigned long vaddr, uprobe_opcode_t opcode)
 {
        struct page *old_page, *new_page;
-       struct address_space *mapping;
        void *vaddr_old, *vaddr_new;
        struct vm_area_struct *vma;
-       struct uprobe *uprobe;
        int ret;
+
 retry:
        /* Read the page with vaddr into memory */
        ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma);
        if (ret <= 0)
                return ret;
 
-       ret = -EINVAL;
-
-       /*
-        * We are interested in text pages only. Our pages of interest
-        * should be mapped for read and execute only. We desist from
-        * adding probes in write mapped pages since the breakpoints
-        * might end up in the file copy.
-        */
-       if (!valid_vma(vma, is_swbp_insn(&opcode)))
-               goto put_out;
-
-       uprobe = container_of(auprobe, struct uprobe, arch);
-       mapping = uprobe->inode->i_mapping;
-       if (mapping != vma->vm_file->f_mapping)
-               goto put_out;
-
        ret = -ENOMEM;
        new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
        if (!new_page)