[PATCH AUTOSEL 5.10 061/116] x86/mce: Allow instrumentation during task work queueing

From: Sasha Levin
Date: Mon Jan 17 2022 - 22:13:09 EST


From: Borislav Petkov <bp@xxxxxxx>

[ Upstream commit 4fbce464db81a42f9a57ee242d6150ec7f996415 ]

Fixes

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

Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lore.kernel.org/r/20211208111343.8130-6-bp@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/x86/kernel/cpu/mce/core.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 14b34963eb1f7..34fffffaf8730 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1443,6 +1443,14 @@ noinstr void do_machine_check(struct pt_regs *regs)
if (worst != MCE_AR_SEVERITY && !kill_it)
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. */
@@ -1468,6 +1476,9 @@ noinstr void do_machine_check(struct pt_regs *regs)
if (m.kflags & MCE_IN_KERNEL_COPYIN)
queue_task_work(&m, msg, kill_it);
}
+
+ instrumentation_end();
+
out:
mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
}
--
2.34.1