x86/mce: Allow instrumentation during task work queueing

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

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index c11fc8d..d788ccc 100644 (file)
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1459,6 +1459,14 @@ 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. */
@@ -1487,6 +1495,9 @@ noinstr void do_machine_check(struct pt_regs *regs)
                if (m.kflags & MCE_IN_KERNEL_COPYIN)
                        queue_task_work(&m, msg, kill_me_never);
        }
+
+       instrumentation_end();
+
 out:
        mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
 }