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>

1 files changed, 1 insertions, 18 deletions

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index f93532748bca..a2b32a51d0a2 100644
--- 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)