x86/mce: Allow instrumentation during task work queueing

[ Upstream commit 4fbce46 ]

Fixes

  vmlinux.o: warning: objtool: do_machine_check()+0xdb1: call to queue_task_work() leaves .noinstr.text section

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211208111343.8130-6-bp@alien8.de
Signed-off-by: Sasha Levin <sashal@kernel.org>

arch/x86/kernel/cpu/mce/core.c

@@ -1454,6 +1454,14 @@ noinstr void do_machine_check(struct pt_regs *regs)
 	if (worst != MCE_AR_SEVERITY && !kill_current_task)
 		goto out;
 
+	/*
+	 * Enable instrumentation around the external facilities like
+	 * task_work_add() (via queue_task_work()), fixup_exception() etc.
+	 * For now, that is. Fixing this properly would need a lot more involved
+	 * reorganization.
+	 */
+	instrumentation_begin();
+
 	/* Fault was in user mode and we need to take some action */
 	if ((m.cs & 3) == 3) {
 		/* If this triggers there is no way to recover. Die hard. */
@@ -1479,6 +1487,9 @@ noinstr void do_machine_check(struct pt_regs *regs)
 		if (m.kflags & MCE_IN_KERNEL_COPYIN)
 			queue_task_work(&m, msg, kill_current_task);
 	}
+
+	instrumentation_end();
+
 out:
 	mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
 }