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authorOleg Nesterov <oleg@redhat.com>2012-06-15 17:43:50 +0200
committerIngo Molnar <mingo@kernel.org>2012-06-16 09:10:47 +0200
commitd9c4a30e82614d43b55893a73f31e7284007ce82 (patch)
treeb877ed2338d27237e40b2587cdf9e6cd56fefe57 /kernel/events/uprobes.c
parenteb2bf57bee42c7565032f93adaa211e2c9fcc52c (diff)
downloadlinux-d9c4a30e82614d43b55893a73f31e7284007ce82.tar.bz2
uprobes: Move BUG_ON(UPROBE_SWBP_INSN_SIZE) from write_opcode() to install_breakpoint()
write_opcode() ensures that UPROBE_SWBP_INSN doesn't cross the page boundary. This looks a bit confusing, the check does not depend on vaddr and it is enough to do it only once right after install_breakpoint()->arch_uprobe_analyze_insn(). 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/20120615154350.GA9611@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events/uprobes.c')
-rw-r--r--kernel/events/uprobes.c11
1 files changed, 5 insertions, 6 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 14c71a2aadad..b9c61bda9029 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -210,7 +210,6 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
void *vaddr_old, *vaddr_new;
struct vm_area_struct *vma;
struct uprobe *uprobe;
- unsigned long pgoff;
int ret;
retry:
/* Read the page with vaddr into memory */
@@ -251,11 +250,7 @@ retry:
vaddr_new = kmap_atomic(new_page);
memcpy(vaddr_new, vaddr_old, PAGE_SIZE);
-
- /* poke the new insn in, ASSUMES we don't cross page boundary */
- pgoff = (vaddr & ~PAGE_MASK);
- BUG_ON(pgoff + UPROBE_SWBP_INSN_SIZE > PAGE_SIZE);
- memcpy(vaddr_new + pgoff, &opcode, UPROBE_SWBP_INSN_SIZE);
+ memcpy(vaddr_new + (vaddr & ~PAGE_MASK), &opcode, UPROBE_SWBP_INSN_SIZE);
kunmap_atomic(vaddr_new);
kunmap_atomic(vaddr_old);
@@ -699,6 +694,10 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
if (ret)
return ret;
+ /* write_opcode() assumes we don't cross page boundary */
+ BUG_ON((uprobe->offset & ~PAGE_MASK) +
+ UPROBE_SWBP_INSN_SIZE > PAGE_SIZE);
+
uprobe->flags |= UPROBE_COPY_INSN;
}