Commit 220ef8dc authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

uprobes/x86: Move UPROBE_FIX_SETF logic from arch_uprobe_post_xol() to default_post_xol_op() 



UPROBE_FIX_SETF is only needed to handle "popf" correctly but it is
processed by the generic arch_uprobe_post_xol() code. This doesn't
allows us to make ->fixups private for default_xol_ops.

1 Change default_post_xol_op(UPROBE_FIX_SETF) to set ->saved_tf = T.

   "popf" always reads the flags from stack, it doesn't matter if TF
   was set or not before single-step. Ignoring the naming, this is
   even more logical, "saved_tf" means "owned by application" and we
   do not own this flag after "popf".

2. Change arch_uprobe_post_xol() to save ->saved_tf into the local
   "bool send_sigtrap" before ->post_xol().

3. Change arch_uprobe_post_xol() to ignore UPROBE_FIX_SETF and just
   check ->saved_tf after ->post_xol().

With this patch ->fixups and ->rip_rela_target_address are only used
by default_xol_ops hooks, we are ready to remove them from the common
part of arch_uprobe.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Reviewed-by: default avatarJim Keniston <jkenisto@us.ibm.com>
parent 6ded5f38

arch/x86/kernel/uprobes.c

+12 −8
Original line number Diff line number Diff line
@@ -441,6 +441,9 @@ static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs 
			return -ERESTART;

		}

	}

	/* popf; tell the caller to not touch TF */

	if (auprobe->fixups & UPROBE_FIX_SETF)

		utask->autask.saved_tf = true;



	return 0;

}
@@ -757,15 +760,15 @@ bool arch_uprobe_xol_was_trapped(struct task_struct *t) 
int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)

{

	struct uprobe_task *utask = current->utask;

	bool send_sigtrap = utask->autask.saved_tf;

	int err = 0;



	WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);

	current->thread.trap_nr = utask->autask.saved_trap_nr;



	if (auprobe->ops->post_xol) {

		int err = auprobe->ops->post_xol(auprobe, regs);

		err = auprobe->ops->post_xol(auprobe, regs);

		if (err) {

			if (!utask->autask.saved_tf)

				regs->flags &= ~X86_EFLAGS_TF;

			/*

			 * Restore ->ip for restart or post mortem analysis.

			 * ->post_xol() must not return -ERESTART unless this
@@ -773,8 +776,8 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) 
			 */

			regs->ip = utask->vaddr;

			if (err == -ERESTART)

				return 0;

			return err;

				err = 0;

			send_sigtrap = false;

		}

	}

	/*
@@ -782,12 +785,13 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) 
	 * so we can get an extra SIGTRAP if we do not clear TF. We need

	 * to examine the opcode to make it right.

	 */

	if (utask->autask.saved_tf)

	if (send_sigtrap)

		send_sig(SIGTRAP, current, 0);

	else if (!(auprobe->fixups & UPROBE_FIX_SETF))



	if (!utask->autask.saved_tf)

		regs->flags &= ~X86_EFLAGS_TF;



	return 0;

	return err;

}



/* callback routine for handling exceptions. */

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