From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Cornelia Huck <cohuck@redhat.com>,
David Hildenbrand <david@redhat.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jon Masters <jcm@redhat.com>, Marcus Meissner <meissner@suse.de>,
Jiri Kosina <jkosina@suse.cz>,
Dominik Brodowski <linux@dominikbrodowski.net>,
Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
Pavel Machek <pavel@ucw.cz>,
David Woodhouse <dwmw2@infradead.org>
Subject: [PATCH 2/6] s390: add optimized array_index_mask_nospec
Date: Wed, 7 Feb 2018 08:00:07 +0100 [thread overview]
Message-ID: <1517986811-27819-3-git-send-email-schwidefsky@de.ibm.com> (raw)
In-Reply-To: <1517986811-27819-1-git-send-email-schwidefsky@de.ibm.com>
Add an optimized version of the array_index_mask_nospec function for
s390 based on a compare and a subtract with borrow.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
arch/s390/include/asm/barrier.h | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/arch/s390/include/asm/barrier.h b/arch/s390/include/asm/barrier.h
index 1043260..f9eddbc 100644
--- a/arch/s390/include/asm/barrier.h
+++ b/arch/s390/include/asm/barrier.h
@@ -49,6 +49,30 @@ do { \
#define __smp_mb__before_atomic() barrier()
#define __smp_mb__after_atomic() barrier()
+/**
+ * array_index_mask_nospec - generate a mask for array_idx() that is
+ * ~0UL when the bounds check succeeds and 0 otherwise
+ * @index: array element index
+ * @size: number of elements in array
+ */
+#define array_index_mask_nospec array_index_mask_nospec
+static inline unsigned long array_index_mask_nospec(unsigned long index,
+ unsigned long size)
+{
+ unsigned long mask;
+
+ if (__builtin_constant_p(size) && size > 0) {
+ asm(" clgr %2,%1\n"
+ " slbgr %0,%0\n"
+ :"=d" (mask) : "d" (size-1), "d" (index) :"cc");
+ return mask;
+ }
+ asm(" clgr %1,%2\n"
+ " slbgr %0,%0\n"
+ :"=d" (mask) : "d" (size), "d" (index) :"cc");
+ return ~mask;
+}
+
#include <asm-generic/barrier.h>
#endif /* __ASM_BARRIER_H */
--
2.7.4
next prev parent reply other threads:[~2018-02-07 7:00 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-07 7:00 [PATCH 0/6] s390: improve speculative execution handling v3 Martin Schwidefsky
2018-02-07 7:00 ` [PATCH 1/6] s390: scrub registers on kernel entry and KVM exit Martin Schwidefsky
2018-02-07 7:00 ` Martin Schwidefsky [this message]
2018-02-07 7:00 ` [PATCH 3/6] s390/alternative: use a copy of the facility bit mask Martin Schwidefsky
2018-02-07 7:00 ` [PATCH 4/6] s390: add options to change branch prediction behaviour for the kernel Martin Schwidefsky
2018-02-07 10:02 ` Pavel Machek
2018-02-07 11:49 ` Martin Schwidefsky
2018-02-07 7:00 ` [PATCH 5/6] s390: run user space and KVM guests with modified branch prediction Martin Schwidefsky
2018-02-07 7:00 ` [PATCH 6/6] s390: introduce execute-trampolines for branches Martin Schwidefsky
2018-02-07 10:07 ` Pavel Machek
2018-02-07 11:51 ` Martin Schwidefsky
2018-02-07 12:07 ` David Woodhouse
2018-02-07 12:17 ` Martin Schwidefsky
2018-02-07 12:20 ` David Woodhouse
2018-02-07 17:55 ` Linus Torvalds
2018-02-07 23:44 ` Masahiro Yamada
2018-02-08 0:05 ` Linus Torvalds
2018-02-08 0:57 ` Kees Cook
2018-02-08 17:11 ` Masahiro Yamada
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