linux-kernel - [patch V2 18/18] io-mapping: Provide iomap

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Date:   Thu, 29 Oct 2020 23:18:24 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     linux-arch@...r.kernel.org,
        Linus Torvalds <torvalds@...uxfoundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Paul McKenney <paulmck@...nel.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Ard Biesheuvel <ardb@...nel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Christoph Hellwig <hch@....de>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        x86@...nel.org, Vineet Gupta <vgupta@...opsys.com>,
        linux-snps-arc@...ts.infradead.org,
        Russell King <linux@...linux.org.uk>,
        Arnd Bergmann <arnd@...db.de>,
        linux-arm-kernel@...ts.infradead.org, Guo Ren <guoren@...nel.org>,
        linux-csky@...r.kernel.org, Michal Simek <monstr@...str.eu>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        linux-mips@...r.kernel.org, Nick Hu <nickhu@...estech.com>,
        Greentime Hu <green.hu@...il.com>,
        Vincent Chen <deanbo422@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        linuxppc-dev@...ts.ozlabs.org,
        "David S. Miller" <davem@...emloft.net>,
        sparclinux@...r.kernel.org, Chris Zankel <chris@...kel.net>,
        Max Filippov <jcmvbkbc@...il.com>,
        linux-xtensa@...ux-xtensa.org
Subject: [patch V2 18/18] io-mapping: Provide iomap_local variant

Similar to kmap local provide a iomap local variant which only disables
migration, but neither disables pagefaults nor preemption.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
V2: Split out from the large combo patch and add the !IOMAP_ATOMIC variants
---
 include/linux/io-mapping.h |   34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

--- a/include/linux/io-mapping.h
+++ b/include/linux/io-mapping.h
@@ -83,6 +83,23 @@ io_mapping_unmap_atomic(void __iomem *va
 }
 
 static inline void __iomem *
+io_mapping_map_local_wc(struct io_mapping *mapping, unsigned long offset)
+{
+	resource_size_t phys_addr;
+
+	BUG_ON(offset >= mapping->size);
+	phys_addr = mapping->base + offset;
+	migrate_disable();
+	return __iomap_local_pfn_prot(PHYS_PFN(phys_addr), mapping->prot);
+}
+
+static inline void io_mapping_unmap_local(void __iomem *vaddr)
+{
+	kunmap_local_indexed((void __force *)vaddr);
+	migrate_enable();
+}
+
+static inline void __iomem *
 io_mapping_map_wc(struct io_mapping *mapping,
 		  unsigned long offset,
 		  unsigned long size)
@@ -101,7 +118,7 @@ io_mapping_unmap(void __iomem *vaddr)
 	iounmap(vaddr);
 }
 
-#else
+#else  /* HAVE_ATOMIC_IOMAP */
 
 #include <linux/uaccess.h>
 
@@ -166,7 +183,20 @@ io_mapping_unmap_atomic(void __iomem *va
 	preempt_enable();
 }
 
-#endif /* HAVE_ATOMIC_IOMAP */
+static inline void __iomem *
+io_mapping_map_local_wc(struct io_mapping *mapping, unsigned long offset)
+{
+	migrate_disable();
+	return io_mapping_map_wc(mapping, offset, PAGE_SIZE);
+}
+
+static inline void io_mapping_unmap_local(void __iomem *vaddr)
+{
+	io_mapping_unmap(vaddr);
+	migrate_enable();
+}
+
+#endif /* !HAVE_ATOMIC_IOMAP */
 
 static inline struct io_mapping *
 io_mapping_create_wc(resource_size_t base,