From patchwork Mon May 4 01:09:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ira Weiny X-Patchwork-Id: 11524919 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B551F913 for ; Mon, 4 May 2020 01:10:39 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 715122071C for ; Mon, 4 May 2020 01:10:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="KVE5XcLB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 715122071C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=wthwM2o19iwlJKBWRDJjBAnMJpzsXCIs5AahbCOUYlM=; b=KVE5XcLBwYnzqd 8cCQChysZe9j9n+gA0BMZEBZ9bdN69FyHkktv+pcD2rbtY1mhdKzncyvCDCY8TDVPKaQOKmLrANLs YI5np1rOQxlL9mXwTi0svXD3F4Wha7Gjur0JXbc4iAgTd0kQqkGB5E75H/CInApJTIiLP7JQ267F4 ro60yOvytr5+hrZU+0L/GyRyTGmnXbdfa2QnuXy69+ZhlH38paQ2BGtWpGDEBUPl1V0IMbdfveGlc vkB1i1QqKokt8glw7rXFoDmXle1DA4I/AWD/VJ996NVceDSeUdsthIVNE1Zldwrc4QHTalJHRTGKF YV7BlzzrV60UtVES2V1A==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jVPcx-0005AH-09; Mon, 04 May 2020 01:10:35 +0000 Received: from mga17.intel.com ([192.55.52.151]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jVPbp-00042J-Um; Mon, 04 May 2020 01:09:28 +0000 IronPort-SDR: 0lN/jp8apDQmbCU/3JbhRakM4Nz7XiD0p4XLaqCNOuwh0hxGPZk+XLabtru2Pti2zyF2G2YToW lwmwMc9fGqoA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 May 2020 18:09:25 -0700 IronPort-SDR: 78HfdS5E/sUZTr6rW4qdMrVg2KBSjTymtvnOmDPQ2pQ911uxvpCqRBWfQH/i1qx69xDtF31hj/ 5LV/nPWyE3zQ== X-IronPort-AV: E=Sophos;i="5.73,350,1583222400"; d="scan'208";a="368958229" Received: from iweiny-desk2.sc.intel.com (HELO localhost) ([10.3.52.147]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 May 2020 18:09:25 -0700 From: ira.weiny@intel.com To: linux-kernel@vger.kernel.org, Andrew Morton , Christian Koenig , Huang Rui Subject: [PATCH V2 06/11] arch/kmap_atomic: Consolidate duplicate code Date: Sun, 3 May 2020 18:09:07 -0700 Message-Id: <20200504010912.982044-7-ira.weiny@intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200504010912.982044-1-ira.weiny@intel.com> References: <20200504010912.982044-1-ira.weiny@intel.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200503_180926_049840_54976C53 X-CRM114-Status: GOOD ( 16.87 ) X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [192.55.52.151 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Zijlstra , Benjamin Herrenschmidt , Dave Hansen , dri-devel@lists.freedesktop.org, "James E.J. Bottomley" , Max Filippov , Paul Mackerras , "H. Peter Anvin" , sparclinux@vger.kernel.org, Ira Weiny , Thomas Gleixner , Helge Deller , x86@kernel.org, linux-csky@vger.kernel.org, Ingo Molnar , linux-snps-arc@lists.infradead.org, linux-xtensa@linux-xtensa.org, Borislav Petkov , Andy Lutomirski , Dan Williams , linux-arm-kernel@lists.infradead.org, Chris Zankel , Thomas Bogendoerfer , linux-parisc@vger.kernel.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, "David S. Miller" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org From: Ira Weiny Every arch has the same code to ensure atomic operations and a check for !HIGHMEM page. Remove the duplicate code by defining a core kmap_atomic() which only calls the arch specific kmap_atomic_high() when the page is high memory. Signed-off-by: Ira Weiny Reviewed-by: Christoph Hellwig --- Changes from V1: Adjust to preserve bisect-ability Remove unneeded kmap_atomic_high declarations --- arch/arc/include/asm/highmem.h | 1 - arch/arc/mm/highmem.c | 9 ++------- arch/arm/include/asm/highmem.h | 1 - arch/arm/mm/highmem.c | 9 ++------- arch/csky/include/asm/highmem.h | 1 - arch/csky/mm/highmem.c | 9 ++------- arch/microblaze/include/asm/highmem.h | 4 ++-- arch/mips/include/asm/highmem.h | 1 - arch/mips/mm/cache.c | 2 +- arch/mips/mm/highmem.c | 18 ++---------------- arch/nds32/include/asm/highmem.h | 1 - arch/nds32/mm/highmem.c | 9 ++------- arch/powerpc/include/asm/highmem.h | 4 ++-- arch/powerpc/mm/highmem.c | 6 ------ arch/sparc/include/asm/highmem.h | 1 - arch/sparc/mm/highmem.c | 9 ++------- arch/x86/include/asm/highmem.h | 5 ++++- arch/x86/mm/highmem_32.c | 14 -------------- arch/xtensa/include/asm/highmem.h | 1 - arch/xtensa/mm/highmem.c | 9 ++------- include/linux/highmem.h | 23 +++++++++++++++++++++++ 21 files changed, 46 insertions(+), 91 deletions(-) diff --git a/arch/arc/include/asm/highmem.h b/arch/arc/include/asm/highmem.h index 8387a5596a91..db425cd38545 100644 --- a/arch/arc/include/asm/highmem.h +++ b/arch/arc/include/asm/highmem.h @@ -30,7 +30,6 @@ #include -extern void *kmap_atomic(struct page *page); extern void __kunmap_atomic(void *kvaddr); extern void kmap_init(void); diff --git a/arch/arc/mm/highmem.c b/arch/arc/mm/highmem.c index 4db13a6b9f3b..0964b011c29f 100644 --- a/arch/arc/mm/highmem.c +++ b/arch/arc/mm/highmem.c @@ -49,16 +49,11 @@ extern pte_t * pkmap_page_table; static pte_t * fixmap_page_table; -void *kmap_atomic(struct page *page) +void *kmap_atomic_high(struct page *page) { int idx, cpu_idx; unsigned long vaddr; - preempt_disable(); - pagefault_disable(); - if (!PageHighMem(page)) - return page_address(page); - cpu_idx = kmap_atomic_idx_push(); idx = cpu_idx + KM_TYPE_NR * smp_processor_id(); vaddr = FIXMAP_ADDR(idx); @@ -68,7 +63,7 @@ void *kmap_atomic(struct page *page) return (void *)vaddr; } -EXPORT_SYMBOL(kmap_atomic); +EXPORT_SYMBOL(kmap_atomic_high); void __kunmap_atomic(void *kv) { diff --git a/arch/arm/include/asm/highmem.h b/arch/arm/include/asm/highmem.h index 736f65283e7b..8c80bfe18a34 100644 --- a/arch/arm/include/asm/highmem.h +++ b/arch/arm/include/asm/highmem.h @@ -60,7 +60,6 @@ static inline void *kmap_high_get(struct page *page) * when CONFIG_HIGHMEM is not set. */ #ifdef CONFIG_HIGHMEM -extern void *kmap_atomic(struct page *page); extern void __kunmap_atomic(void *kvaddr); extern void *kmap_atomic_pfn(unsigned long pfn); #endif diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c index c700b32350ee..075fdc235091 100644 --- a/arch/arm/mm/highmem.c +++ b/arch/arm/mm/highmem.c @@ -31,18 +31,13 @@ static inline pte_t get_fixmap_pte(unsigned long vaddr) return *ptep; } -void *kmap_atomic(struct page *page) +void *kmap_atomic_high(struct page *page) { unsigned int idx; unsigned long vaddr; void *kmap; int type; - preempt_disable(); - pagefault_disable(); - if (!PageHighMem(page)) - return page_address(page); - #ifdef CONFIG_DEBUG_HIGHMEM /* * There is no cache coherency issue when non VIVT, so force the @@ -76,7 +71,7 @@ void *kmap_atomic(struct page *page) return (void *)vaddr; } -EXPORT_SYMBOL(kmap_atomic); +EXPORT_SYMBOL(kmap_atomic_high); void __kunmap_atomic(void *kvaddr) { diff --git a/arch/csky/include/asm/highmem.h b/arch/csky/include/asm/highmem.h index be11c5b67122..8ceee12f9bc1 100644 --- a/arch/csky/include/asm/highmem.h +++ b/arch/csky/include/asm/highmem.h @@ -32,7 +32,6 @@ extern pte_t *pkmap_page_table; #define ARCH_HAS_KMAP_FLUSH_TLB extern void kmap_flush_tlb(unsigned long addr); -extern void *kmap_atomic(struct page *page); extern void __kunmap_atomic(void *kvaddr); extern void *kmap_atomic_pfn(unsigned long pfn); extern struct page *kmap_atomic_to_page(void *ptr); diff --git a/arch/csky/mm/highmem.c b/arch/csky/mm/highmem.c index e9952211264b..63d74b47eee6 100644 --- a/arch/csky/mm/highmem.c +++ b/arch/csky/mm/highmem.c @@ -21,16 +21,11 @@ EXPORT_SYMBOL(kmap_flush_tlb); EXPORT_SYMBOL(kmap); -void *kmap_atomic(struct page *page) +void *kmap_atomic_high(struct page *page) { unsigned long vaddr; int idx, type; - preempt_disable(); - pagefault_disable(); - if (!PageHighMem(page)) - return page_address(page); - type = kmap_atomic_idx_push(); idx = type + KM_TYPE_NR*smp_processor_id(); vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); @@ -42,7 +37,7 @@ void *kmap_atomic(struct page *page) return (void *)vaddr; } -EXPORT_SYMBOL(kmap_atomic); +EXPORT_SYMBOL(kmap_atomic_high); void __kunmap_atomic(void *kvaddr) { diff --git a/arch/microblaze/include/asm/highmem.h b/arch/microblaze/include/asm/highmem.h index ec9954b091e1..00c75a423ac4 100644 --- a/arch/microblaze/include/asm/highmem.h +++ b/arch/microblaze/include/asm/highmem.h @@ -63,9 +63,9 @@ void *kmap_atomic_prot(struct page *page, pgprot_t prot) } extern void __kunmap_atomic(void *kvaddr); -static inline void *kmap_atomic(struct page *page) +static inline void *kmap_atomic_high(struct page *page) { - return kmap_atomic_prot(page, kmap_prot); + return kmap_atomic_high_prot(page, kmap_prot); } #define flush_cache_kmaps() { flush_icache(); flush_dcache(); } diff --git a/arch/mips/include/asm/highmem.h b/arch/mips/include/asm/highmem.h index 24e7e7e5cc7b..8bdbbfc322ad 100644 --- a/arch/mips/include/asm/highmem.h +++ b/arch/mips/include/asm/highmem.h @@ -48,7 +48,6 @@ extern pte_t *pkmap_page_table; #define ARCH_HAS_KMAP_FLUSH_TLB extern void kmap_flush_tlb(unsigned long addr); -extern void *kmap_atomic(struct page *page); extern void __kunmap_atomic(void *kvaddr); extern void *kmap_atomic_pfn(unsigned long pfn); diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c index 33b409391ddb..f015bb51fab0 100644 --- a/arch/mips/mm/cache.c +++ b/arch/mips/mm/cache.c @@ -14,9 +14,9 @@ #include #include #include +#include #include -#include #include #include #include diff --git a/arch/mips/mm/highmem.c b/arch/mips/mm/highmem.c index eb8ec8493f2f..2bda56372995 100644 --- a/arch/mips/mm/highmem.c +++ b/arch/mips/mm/highmem.c @@ -18,25 +18,11 @@ void kmap_flush_tlb(unsigned long addr) } EXPORT_SYMBOL(kmap_flush_tlb); -/* - * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because - * no global lock is needed and because the kmap code must perform a global TLB - * invalidation when the kmap pool wraps. - * - * However when holding an atomic kmap is is not legal to sleep, so atomic - * kmaps are appropriate for short, tight code paths only. - */ - -void *kmap_atomic(struct page *page) +void *kmap_atomic_high(struct page *page) { unsigned long vaddr; int idx, type; - preempt_disable(); - pagefault_disable(); - if (!PageHighMem(page)) - return page_address(page); - type = kmap_atomic_idx_push(); idx = type + KM_TYPE_NR*smp_processor_id(); vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); @@ -48,7 +34,7 @@ void *kmap_atomic(struct page *page) return (void*) vaddr; } -EXPORT_SYMBOL(kmap_atomic); +EXPORT_SYMBOL(kmap_atomic_high); void __kunmap_atomic(void *kvaddr) { diff --git a/arch/nds32/include/asm/highmem.h b/arch/nds32/include/asm/highmem.h index c93c7368bb3f..a3970e566ede 100644 --- a/arch/nds32/include/asm/highmem.h +++ b/arch/nds32/include/asm/highmem.h @@ -51,7 +51,6 @@ extern void kmap_init(void); * when CONFIG_HIGHMEM is not set. */ #ifdef CONFIG_HIGHMEM -extern void *kmap_atomic(struct page *page); extern void __kunmap_atomic(void *kvaddr); extern void *kmap_atomic_pfn(unsigned long pfn); extern struct page *kmap_atomic_to_page(void *ptr); diff --git a/arch/nds32/mm/highmem.c b/arch/nds32/mm/highmem.c index f9348bec0ecb..f5f3a21460c4 100644 --- a/arch/nds32/mm/highmem.c +++ b/arch/nds32/mm/highmem.c @@ -10,18 +10,13 @@ #include #include -void *kmap_atomic(struct page *page) +void *kmap_atomic_high(struct page *page) { unsigned int idx; unsigned long vaddr, pte; int type; pte_t *ptep; - preempt_disable(); - pagefault_disable(); - if (!PageHighMem(page)) - return page_address(page); - type = kmap_atomic_idx_push(); idx = type + KM_TYPE_NR * smp_processor_id(); @@ -37,7 +32,7 @@ void *kmap_atomic(struct page *page) return (void *)vaddr; } -EXPORT_SYMBOL(kmap_atomic); +EXPORT_SYMBOL(kmap_atomic_high); void __kunmap_atomic(void *kvaddr) { diff --git a/arch/powerpc/include/asm/highmem.h b/arch/powerpc/include/asm/highmem.h index d049806a8354..74fa2c726fde 100644 --- a/arch/powerpc/include/asm/highmem.h +++ b/arch/powerpc/include/asm/highmem.h @@ -71,9 +71,9 @@ static inline void *kmap_atomic_prot(struct page *page, pgprot_t prot) } extern void __kunmap_atomic(void *kvaddr); -static inline void *kmap_atomic(struct page *page) +static inline void *kmap_atomic_high(struct page *page) { - return kmap_atomic_prot(page, kmap_prot); + return kmap_atomic_high_prot(page, kmap_prot); } diff --git a/arch/powerpc/mm/highmem.c b/arch/powerpc/mm/highmem.c index f075cef6d663..67aaa5217f7f 100644 --- a/arch/powerpc/mm/highmem.c +++ b/arch/powerpc/mm/highmem.c @@ -24,12 +24,6 @@ #include #include -/* - * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap - * gives a more generic (and caching) interface. But kmap_atomic can - * be used in IRQ contexts, so in some (very limited) cases we need - * it. - */ void *kmap_atomic_high_prot(struct page *page, pgprot_t prot) { unsigned long vaddr; diff --git a/arch/sparc/include/asm/highmem.h b/arch/sparc/include/asm/highmem.h index 4bdb79fed02c..458210c5bc38 100644 --- a/arch/sparc/include/asm/highmem.h +++ b/arch/sparc/include/asm/highmem.h @@ -50,7 +50,6 @@ void kmap_init(void) __init; #define PKMAP_END (PKMAP_ADDR(LAST_PKMAP)) -void *kmap_atomic(struct page *page); void __kunmap_atomic(void *kvaddr); #define flush_cache_kmaps() flush_cache_all() diff --git a/arch/sparc/mm/highmem.c b/arch/sparc/mm/highmem.c index d4a80adea7e5..b53070ab6a31 100644 --- a/arch/sparc/mm/highmem.c +++ b/arch/sparc/mm/highmem.c @@ -53,16 +53,11 @@ void __init kmap_init(void) kmap_prot = __pgprot(SRMMU_ET_PTE | SRMMU_PRIV | SRMMU_CACHE); } -void *kmap_atomic(struct page *page) +void *kmap_atomic_high(struct page *page) { unsigned long vaddr; long idx, type; - preempt_disable(); - pagefault_disable(); - if (!PageHighMem(page)) - return page_address(page); - type = kmap_atomic_idx_push(); idx = type + KM_TYPE_NR*smp_processor_id(); vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); @@ -87,7 +82,7 @@ void *kmap_atomic(struct page *page) return (void*) vaddr; } -EXPORT_SYMBOL(kmap_atomic); +EXPORT_SYMBOL(kmap_atomic_high); void __kunmap_atomic(void *kvaddr) { diff --git a/arch/x86/include/asm/highmem.h b/arch/x86/include/asm/highmem.h index 61f47fef40e5..9393d55a2adb 100644 --- a/arch/x86/include/asm/highmem.h +++ b/arch/x86/include/asm/highmem.h @@ -68,7 +68,10 @@ static inline void *kmap_atomic_prot(struct page *page, pgprot_t prot) return kmap_atomic_high_prot(page, prot); } -void *kmap_atomic(struct page *page); +static inline void *kmap_atomic_high(struct page *page) +{ + return kmap_atomic_high_prot(page, kmap_prot); +} void __kunmap_atomic(void *kvaddr); void *kmap_atomic_pfn(unsigned long pfn); void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot); diff --git a/arch/x86/mm/highmem_32.c b/arch/x86/mm/highmem_32.c index 48b56b1af902..c3e272a759e0 100644 --- a/arch/x86/mm/highmem_32.c +++ b/arch/x86/mm/highmem_32.c @@ -4,14 +4,6 @@ #include /* for totalram_pages */ #include -/* - * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because - * no global lock is needed and because the kmap code must perform a global TLB - * invalidation when the kmap pool wraps. - * - * However when holding an atomic kmap it is not legal to sleep, so atomic - * kmaps are appropriate for short, tight code paths only. - */ void *kmap_atomic_high_prot(struct page *page, pgprot_t prot) { unsigned long vaddr; @@ -28,12 +20,6 @@ void *kmap_atomic_high_prot(struct page *page, pgprot_t prot) } EXPORT_SYMBOL(kmap_atomic_high_prot); -void *kmap_atomic(struct page *page) -{ - return kmap_atomic_prot(page, kmap_prot); -} -EXPORT_SYMBOL(kmap_atomic); - /* * This is the same as kmap_atomic() but can map memory that doesn't * have a struct page associated with it. diff --git a/arch/xtensa/include/asm/highmem.h b/arch/xtensa/include/asm/highmem.h index 5a481f7def0b..1e6aa15c4bdf 100644 --- a/arch/xtensa/include/asm/highmem.h +++ b/arch/xtensa/include/asm/highmem.h @@ -68,7 +68,6 @@ static inline void flush_cache_kmaps(void) flush_cache_all(); } -void *kmap_atomic(struct page *page); void __kunmap_atomic(void *kvaddr); void kmap_init(void); diff --git a/arch/xtensa/mm/highmem.c b/arch/xtensa/mm/highmem.c index da734a2ed641..90b85a897cb0 100644 --- a/arch/xtensa/mm/highmem.c +++ b/arch/xtensa/mm/highmem.c @@ -37,16 +37,11 @@ static inline enum fixed_addresses kmap_idx(int type, unsigned long color) color; } -void *kmap_atomic(struct page *page) +void *kmap_atomic_high(struct page *page) { enum fixed_addresses idx; unsigned long vaddr; - preempt_disable(); - pagefault_disable(); - if (!PageHighMem(page)) - return page_address(page); - idx = kmap_idx(kmap_atomic_idx_push(), DCACHE_ALIAS(page_to_phys(page))); vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); @@ -57,7 +52,7 @@ void *kmap_atomic(struct page *page) return (void *)vaddr; } -EXPORT_SYMBOL(kmap_atomic); +EXPORT_SYMBOL(kmap_atomic_high); void __kunmap_atomic(void *kvaddr) { diff --git a/include/linux/highmem.h b/include/linux/highmem.h index ae6e8cb81043..86b93dee758a 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -32,6 +32,7 @@ static inline void invalidate_kernel_vmap_range(void *vaddr, int size) #include #ifdef CONFIG_HIGHMEM +extern void *kmap_atomic_high(struct page *page); #include #ifndef ARCH_HAS_KMAP_FLUSH_TLB @@ -61,6 +62,28 @@ static inline void kunmap(struct page *page) kunmap_high(page); } +/* + * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because + * no global lock is needed and because the kmap code must perform a global TLB + * invalidation when the kmap pool wraps. + * + * However when holding an atomic kmap is is not legal to sleep, so atomic + * kmaps are appropriate for short, tight code paths only. + * + * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap + * gives a more generic (and caching) interface. But kmap_atomic can + * be used in IRQ contexts, so in some (very limited) cases we need + * it. + */ +static inline void *kmap_atomic(struct page *page) +{ + preempt_disable(); + pagefault_disable(); + if (!PageHighMem(page)) + return page_address(page); + return kmap_atomic_high(page); +} + /* declarations for linux/mm/highmem.c */ unsigned int nr_free_highpages(void); extern atomic_long_t _totalhigh_pages;