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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>
This commit is contained in:
Oleg Nesterov 2012-07-29 20:22:12 +02:00 committed by Ingo Molnar
parent 35d56ca9d4
commit f403072c61
1 changed files with 1 additions and 18 deletions
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19
kernel/events/uprobes.c
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@ -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)