The patch titled
Subject: s390/irqflags: ddo not instrument arch_local_irq_*() with KMSAN
has been added to the -mm mm-unstable branch. Its filename is
s390-irqflags-do-not-instrument-arch_local_irq_-with-kmsan.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/s390-irqflags-do-not-instrument-arch_local_irq_-with-kmsan.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Subject: s390/irqflags: ddo not instrument arch_local_irq_*() with KMSAN
Date: Thu, 14 Dec 2023 00:24:47 +0100
KMSAN generates the following false positives 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/20231213233605.661251-28-iii@xxxxxxxxxxxxx
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Cc: Sven Schnelle <svens@xxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/s390/include/asm/irqflags.h | 18 +++++++++++++++---
drivers/s390/char/sclp.c | 2 +-
2 files changed, 16 insertions(+), 4 deletions(-)
--- a/arch/s390/include/asm/irqflags.h~s390-irqflags-do-not-instrument-arch_local_irq_-with-kmsan
+++ a/arch/s390/include/asm/irqflags.h
@@ -37,12 +37,19 @@ static __always_inline void __arch_local
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 +59,12 @@ static __always_inline void arch_local_i
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);
}
--- a/drivers/s390/char/sclp.c~s390-irqflags-do-not-instrument-arch_local_irq_-with-kmsan
+++ a/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 */
_
Patches currently in -mm which might be from iii@xxxxxxxxxxxxx are
ftrace-unpoison-ftrace_regs-in-ftrace_ops_list_func.patch
kmsan-make-the-tests-compatible-with-kmsanpanic=1.patch
kmsan-disable-kmsan-when-deferred_struct_page_init-is-enabled.patch
kmsan-increase-the-maximum-store-size-to-4096.patch
kmsan-fix-is_bad_asm_addr-on-arches-with-overlapping-address-spaces.patch
kmsan-fix-kmsan_copy_to_user-on-arches-with-overlapping-address-spaces.patch
kmsan-remove-a-useless-assignment-from-kmsan_vmap_pages_range_noflush.patch
kmsan-remove-an-x86-specific-include-from-kmsanh.patch
kmsan-expose-kmsan_get_metadata.patch
kmsan-export-panic_on_kmsan.patch
kmsan-allow-disabling-kmsan-checks-for-the-current-task.patch
kmsan-support-slab_poison.patch
kmsan-use-align_down-in-kmsan_get_metadata.patch
mm-slub-let-kmsan-access-metadata.patch
mm-slub-unpoison-the-memchr_inv-return-value.patch
mm-kfence-disable-kmsan-when-checking-the-canary.patch
lib-zlib-unpoison-dfltcc-output-buffers.patch
kmsan-accept-ranges-starting-with-0-on-s390.patch
s390-turn-off-kmsan-for-boot-vdso-and-purgatory.patch
s390-use-a-larger-stack-for-kmsan.patch
s390-boot-add-the-kmsan-runtime-stub.patch
s390-checksum-add-a-kmsan-check.patch
s390-cpacf-unpoison-the-results-of-cpacf_trng.patch
s390-cpumf-unpoison-stcctm-output-buffer.patch
s390-diag-unpoison-diag224-output-buffer.patch
s390-ftrace-unpoison-ftrace_regs-in-kprobe_ftrace_handler.patch
s390-irqflags-do-not-instrument-arch_local_irq_-with-kmsan.patch
s390-mm-define-kmsan-metadata-for-vmalloc-and-modules.patch
s390-string-add-kmsan-support.patch
s390-traps-unpoison-the-kernel_stack_overflows-pt_regs.patch
s390-uaccess-add-kmsan-support-to-put_user-and-get_user.patch
s390-unwind-disable-kmsan-checks.patch
s390-implement-the-architecture-specific-kmsan-functions.patch
kmsan-enable-on-s390.patch
