This is a note to let you know that I've just added the patch titled
x86/mce: Mark mce_panic() noinstr
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-mce-mark-mce_panic-noinstr.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 26fd4c4293fdaa19bc0936c7dbef365b175d0fba
Author: Borislav Petkov <bp@xxxxxxx>
Date: Mon Nov 1 13:39:35 2021 +0100
x86/mce: Mark mce_panic() noinstr
[ Upstream commit 3c7ce80a818fa7950be123cac80cd078e5ac1013 ]
And allow instrumentation inside it because it does calls to other
facilities which will not be tagged noinstr.
Fixes
vmlinux.o: warning: objtool: do_machine_check()+0xc73: call to mce_panic() leaves .noinstr.text section
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lore.kernel.org/r/20211208111343.8130-8-bp@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 34fffffaf8730..64d8a96a2bf1e 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -295,11 +295,17 @@ static void wait_for_panic(void)
panic("Panicing machine check CPU died");
}
-static void mce_panic(const char *msg, struct mce *final, char *exp)
+static noinstr void mce_panic(const char *msg, struct mce *final, char *exp)
{
- int apei_err = 0;
struct llist_node *pending;
struct mce_evt_llist *l;
+ int apei_err = 0;
+
+ /*
+ * Allow instrumentation around external facilities usage. Not that it
+ * matters a whole lot since the machine is going to panic anyway.
+ */
+ instrumentation_begin();
if (!fake_panic) {
/*
@@ -314,7 +320,7 @@ static void mce_panic(const char *msg, struct mce *final, char *exp)
} else {
/* Don't log too much for fake panic */
if (atomic_inc_return(&mce_fake_panicked) > 1)
- return;
+ goto out;
}
pending = mce_gen_pool_prepare_records();
/* First print corrected ones that are still unlogged */
@@ -352,6 +358,9 @@ static void mce_panic(const char *msg, struct mce *final, char *exp)
panic(msg);
} else
pr_emerg(HW_ERR "Fake kernel panic: %s\n", msg);
+
+out:
+ instrumentation_end();
}
/* Support code for software error injection */
