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authorOleg Nesterov <oleg@redhat.com>2012-09-14 18:31:23 +0200
committerAnton Arapov <anton@redhat.com>2012-10-29 11:47:42 +0100
commit8ce921a910e460092691a01fec74561d5f1efdc2 (patch)
tree2fb6ab7d109b1fc9d7c4c376a55c694fc8d8b791
parent32c38aef54b9e447d165fd07d7336232233e7720 (diff)
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uprobes: Fix UPROBE_SKIP_SSTEP checks in handle_swbp()
If handle_swbp()->add_utask() fails but UPROBE_SKIP_SSTEP is set, cleanup_ret: path do not restart the insn, this is wrong. Remove this check and add the additional label for can_skip_sstep() = T case. Note also that UPROBE_SKIP_SSTEP can be false positive, we simply can not trust it unless arch_uprobe_skip_sstep() was already called. Also, move another UPROBE_SKIP_SSTEP check before can_skip_sstep() into this helper, this looks more clean and understandable. Note: probably we should rename "skip" to "emulate" and I think that "clear UPROBE_SKIP_SSTEP" should be moved to arch_can_skip. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
-rw-r--r--kernel/events/uprobes.c31
1 files changed, 15 insertions, 16 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 41f048c..d239296 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1389,10 +1389,11 @@ bool uprobe_deny_signal(void)
*/
static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs)
{
- if (arch_uprobe_skip_sstep(&uprobe->arch, regs))
- return true;
-
- uprobe->flags &= ~UPROBE_SKIP_SSTEP;
+ if (uprobe->flags & UPROBE_SKIP_SSTEP) {
+ if (arch_uprobe_skip_sstep(&uprobe->arch, regs))
+ return true;
+ uprobe->flags &= ~UPROBE_SKIP_SSTEP;
+ }
return false;
}
@@ -1494,12 +1495,12 @@ static void handle_swbp(struct pt_regs *regs)
utask = add_utask();
/* Cannot allocate; re-execute the instruction. */
if (!utask)
- goto cleanup_ret;
+ goto restart;
}
handler_chain(uprobe, regs);
- if (uprobe->flags & UPROBE_SKIP_SSTEP && can_skip_sstep(uprobe, regs))
- goto cleanup_ret;
+ if (can_skip_sstep(uprobe, regs))
+ goto out;
if (!pre_ssout(uprobe, regs, bp_vaddr)) {
arch_uprobe_enable_step(&uprobe->arch);
@@ -1508,15 +1509,13 @@ static void handle_swbp(struct pt_regs *regs)
return;
}
-cleanup_ret:
- if (!(uprobe->flags & UPROBE_SKIP_SSTEP))
-
- /*
- * cannot singlestep; cannot skip instruction;
- * re-execute the instruction.
- */
- instruction_pointer_set(regs, bp_vaddr);
-
+restart:
+ /*
+ * cannot singlestep; cannot skip instruction;
+ * re-execute the instruction.
+ */
+ instruction_pointer_set(regs, bp_vaddr);
+out:
put_uprobe(uprobe);
}