Fix a interaction/regression between uprobes based shared library tracing & GDB.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'perf-urgent-2020-07-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into master

Pull uprobe fix from Ingo Molnar:
 "Fix an interaction/regression between uprobes based shared library
  tracing & GDB"

* tag 'perf-urgent-2020-07-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  uprobes: Change handle_swbp() to send SIGTRAP with si_code=SI_KERNEL, to fix GDB regression

kernel/events/uprobes.c

@@ -2199,7 +2199,7 @@ static void handle_swbp(struct pt_regs *regs)
 	if (!uprobe) {
 		if (is_swbp > 0) {
 			/* No matching uprobe; signal SIGTRAP. */
-			send_sig(SIGTRAP, current, 0);
+			force_sig(SIGTRAP);
 		} else {
 			/*
 			 * Either we raced with uprobe_unregister() or we can't