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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>
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parent
746a9e6ba2
commit
0578a97098
1 changed files with 15 additions and 16 deletions
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@ -1389,10 +1389,11 @@ bool uprobe_deny_signal(void)
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*/
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*/
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static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs)
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static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs)
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{
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{
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if (arch_uprobe_skip_sstep(&uprobe->arch, regs))
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if (uprobe->flags & UPROBE_SKIP_SSTEP) {
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return true;
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if (arch_uprobe_skip_sstep(&uprobe->arch, regs))
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return true;
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uprobe->flags &= ~UPROBE_SKIP_SSTEP;
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uprobe->flags &= ~UPROBE_SKIP_SSTEP;
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}
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return false;
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return false;
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}
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}
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@ -1494,12 +1495,12 @@ static void handle_swbp(struct pt_regs *regs)
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utask = add_utask();
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utask = add_utask();
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/* Cannot allocate; re-execute the instruction. */
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/* Cannot allocate; re-execute the instruction. */
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if (!utask)
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if (!utask)
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goto cleanup_ret;
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goto restart;
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}
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}
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handler_chain(uprobe, regs);
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handler_chain(uprobe, regs);
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if (uprobe->flags & UPROBE_SKIP_SSTEP && can_skip_sstep(uprobe, regs))
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if (can_skip_sstep(uprobe, regs))
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goto cleanup_ret;
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goto out;
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if (!pre_ssout(uprobe, regs, bp_vaddr)) {
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if (!pre_ssout(uprobe, regs, bp_vaddr)) {
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arch_uprobe_enable_step(&uprobe->arch);
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arch_uprobe_enable_step(&uprobe->arch);
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@ -1508,15 +1509,13 @@ static void handle_swbp(struct pt_regs *regs)
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return;
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return;
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}
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}
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cleanup_ret:
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restart:
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if (!(uprobe->flags & UPROBE_SKIP_SSTEP))
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/*
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* cannot singlestep; cannot skip instruction;
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/*
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* re-execute the instruction.
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* cannot singlestep; cannot skip instruction;
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*/
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* re-execute the instruction.
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instruction_pointer_set(regs, bp_vaddr);
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*/
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out:
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instruction_pointer_set(regs, bp_vaddr);
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put_uprobe(uprobe);
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put_uprobe(uprobe);
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}
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}
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