s390/irqflags: do not instrument arch_local_irq_*() with KMSAN

Lockdep generates the following false positives with KMSAN on s390x:

[    6.063666] DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled())
[         ...]
[    6.577050] Call Trace:
[    6.619637]  [<000000000690d2de>] check_flags+0x1fe/0x210
[    6.665411] ([<000000000690d2da>] check_flags+0x1fa/0x210)
[    6.707478]  [<00000000006cec1a>] lock_acquire+0x2ca/0xce0
[    6.749959]  [<00000000069820ea>] _raw_spin_lock_irqsave+0xea/0x190
[    6.794912]  [<00000000041fc988>] __stack_depot_save+0x218/0x5b0
[    6.838420]  [<000000000197affe>] __msan_poison_alloca+0xfe/0x1a0
[    6.882985]  [<0000000007c5827c>] start_kernel+0x70c/0xd50
[    6.927454]  [<0000000000100036>] startup_continue+0x36/0x40

Between trace_hardirqs_on() and `stosm __mask, 3` lockdep thinks that
interrupts are on, but on the CPU they are still off.  KMSAN
instrumentation takes spinlocks, giving lockdep a chance to see and
complain about this discrepancy.

KMSAN instrumentation is inserted in order to poison the __mask variable.
Disable instrumentation in the respective functions.  They are very small
and it's easy to see that no important metadata updates are lost because
of this.

Link: https://lkml.kernel.org/r/20240621113706.315500-31-iii@linux.ibm.com
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <kasan-dev@googlegroups.com>
Cc: Marco Elver <elver@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/s390/include/asm/irqflags.h b/arch/s390/include/asm/irqflags.h
index 02427b205c11e619213f9a6555ae99487e495ff9..bcab456dfb803c77939fcb22f1205f989155013f 100644 (file)
--- a/arch/s390/include/asm/irqflags.h
+++ b/arch/s390/include/asm/irqflags.h
@@ -37,12 +37,18 @@ static __always_inline void __arch_local_irq_ssm(unsigned long flags)
        asm volatile("ssm   %0" : : "Q" (flags) : "memory");
 }
 
-static __always_inline unsigned long arch_local_save_flags(void)
+#ifdef CONFIG_KMSAN
+#define arch_local_irq_attributes noinline notrace __no_sanitize_memory __maybe_unused
+#else
+#define arch_local_irq_attributes __always_inline
+#endif
+
+static arch_local_irq_attributes unsigned long arch_local_save_flags(void)
 {
        return __arch_local_irq_stnsm(0xff);
 }
 
-static __always_inline unsigned long arch_local_irq_save(void)
+static arch_local_irq_attributes unsigned long arch_local_irq_save(void)
 {
        return __arch_local_irq_stnsm(0xfc);
 }
@@ -52,7 +58,12 @@ static __always_inline void arch_local_irq_disable(void)
        arch_local_irq_save();
 }
 
-static __always_inline void arch_local_irq_enable(void)
+static arch_local_irq_attributes void arch_local_irq_enable_external(void)
+{
+       __arch_local_irq_stosm(0x01);
+}
+
+static arch_local_irq_attributes void arch_local_irq_enable(void)
 {
        __arch_local_irq_stosm(0x03);
 }

diff --git a/drivers/s390/char/sclp.c b/drivers/s390/char/sclp.c
index fbe29cabcbb83b9c7d303d131a27802c8be89dda..f3621adbd5debc59d2b71fc1be2790e0cbd31f76 100644 (file)
--- a/drivers/s390/char/sclp.c
+++ b/drivers/s390/char/sclp.c
@@ -736,7 +736,7 @@ sclp_sync_wait(void)
        cr0_sync.val = cr0.val & ~CR0_IRQ_SUBCLASS_MASK;
        cr0_sync.val |= 1UL << (63 - 54);
        local_ctl_load(0, &cr0_sync);
-       __arch_local_irq_stosm(0x01);
+       arch_local_irq_enable_external();
        /* Loop until driver state indicates finished request */
        while (sclp_running_state != sclp_running_state_idle) {
                /* Check for expired request timer */