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| author |   Oleg Nesterov <oleg@redhat.com> | 2012-09-14 18:31:23 +0200 |
|---|---|---|
| committer | Oleg Nesterov <oleg@redhat.com> | 2012-09-29 21:21:52 +0200 |
| commit | 0578a97098dab967ece4b025fe5eb4984c4c86c0 (patch) | |
| tree | cf48aeca0e414d1eb2cafdfd28e8e31282a58af1 /kernel/events | |
| parent | uprobes: Do not setup ->active_uprobe/state prematurely (diff) | |
| download | linux-dev-0578a97098dab967ece4b025fe5eb4984c4c86c0.tar.xz linux-dev-0578a97098dab967ece4b025fe5eb4984c4c86c0.zip | |
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>
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/uprobes.c | 31 |
1 files changed, 15 insertions, 16 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 41f048c91425..d2392968d4e6 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); } |