uprobes/x86: Reimplement arch_uretprobe_is_alive()
Add the x86 specific version of arch_uretprobe_is_alive() helper. It returns true if the stack frame mangled by prepare_uretprobe() is still on stack. So if it returns false, we know that the probed function has already returned. We add the new return_instance->stack member and change the generic code to initialize it in prepare_uretprobe, but it should be equally useful for other architectures. TODO: this assumes that the probed application can't use multiple stacks (say sigaltstack). We will try to improve this logic later. Tested-by: Pratyush Anand <panand@redhat.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Anton Arapov <arapov@gmail.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20150721134018.GA4766@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -985,3 +985,8 @@ arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs
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return -1;
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return -1;
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}
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}
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bool arch_uretprobe_is_alive(struct return_instance *ret, struct pt_regs *regs)
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{
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return regs->sp <= ret->stack;
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}
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@ -95,6 +95,7 @@ struct uprobe_task {
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struct return_instance {
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struct return_instance {
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struct uprobe *uprobe;
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struct uprobe *uprobe;
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unsigned long func;
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unsigned long func;
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unsigned long stack; /* stack pointer */
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unsigned long orig_ret_vaddr; /* original return address */
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unsigned long orig_ret_vaddr; /* original return address */
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bool chained; /* true, if instance is nested */
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bool chained; /* true, if instance is nested */
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@ -1562,6 +1562,7 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
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ri->uprobe = get_uprobe(uprobe);
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ri->uprobe = get_uprobe(uprobe);
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ri->func = instruction_pointer(regs);
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ri->func = instruction_pointer(regs);
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ri->stack = user_stack_pointer(regs);
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ri->orig_ret_vaddr = orig_ret_vaddr;
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ri->orig_ret_vaddr = orig_ret_vaddr;
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ri->chained = chained;
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ri->chained = chained;
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