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From: Ilya Leoshkevich <iii@linux.ibm.com>
To: Alexander Gordeev <agordeev@linux.ibm.com>,
        Alexander Potapenko <glider@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christoph Lameter <cl@linux.com>, David Rientjes <rientjes@google.com>,
        Heiko Carstens <hca@linux.ibm.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>, Marco Elver <elver@google.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Pekka Enberg <penberg@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Vasily Gorbik <gor@linux.ibm.com>, Vlastimil Babka <vbabka@suse.cz>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Hyeonggon Yoo <42.hyeyoo@gmail.com>, kasan-dev@googlegroups.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        linux-s390@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
        Mark Rutland <mark.rutland@arm.com>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Sven Schnelle <svens@linux.ibm.com>,
        Ilya Leoshkevich <iii@linux.ibm.com>
Subject: [PATCH v4 26/35] s390/diag: Unpoison diag224() output buffer
Date: Thu, 13 Jun 2024 17:34:28 +0200
Message-ID: <20240613153924.961511-27-iii@linux.ibm.com>
In-Reply-To: <20240613153924.961511-1-iii@linux.ibm.com>
References: <20240613153924.961511-1-iii@linux.ibm.com>
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Diagnose 224 stores 4k bytes, which currently cannot be deduced from
the inline assembly constraints. This leads to KMSAN false positives.

Fix the constraints by using a 4k-sized struct instead of a raw
pointer. While at it, prettify them too.

Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 arch/s390/kernel/diag.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/s390/kernel/diag.c b/arch/s390/kernel/diag.c
index 8dee9aa0ec95..8a7009618ba7 100644
--- a/arch/s390/kernel/diag.c
+++ b/arch/s390/kernel/diag.c
@@ -278,12 +278,14 @@ int diag224(void *ptr)
 	int rc = -EOPNOTSUPP;
 
 	diag_stat_inc(DIAG_STAT_X224);
-	asm volatile(
-		"	diag	%1,%2,0x224\n"
-		"0:	lhi	%0,0x0\n"
+	asm volatile("\n"
+		"	diag	%[type],%[addr],0x224\n"
+		"0:	lhi	%[rc],0\n"
 		"1:\n"
 		EX_TABLE(0b,1b)
-		: "+d" (rc) :"d" (0), "d" (addr) : "memory");
+		: [rc] "+d" (rc)
+		, "=m" (*(struct { char buf[PAGE_SIZE]; } *)ptr)
+		: [type] "d" (0), [addr] "d" (addr));
 	return rc;
 }
 EXPORT_SYMBOL(diag224);
-- 
2.45.1