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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: linux-arch@vger.kernel.org,
	Linus Torvalds <torvalds@linuxfoundation.org>,
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Subject: [patch RFC 09/15] nds32/mm/highmem: Switch to generic kmap atomic
Date: Sat, 19 Sep 2020 11:18:00 +0200
Message-ID: <20200919092616.736510871@linutronix.de> (raw)
In-Reply-To: <20200919091751.011116649@linutronix.de>

The mapping code is odd and looks broken. See FIXME in the comment.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Nick Hu <nickhu@andestech.com>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Vincent Chen <deanbo422@gmail.com>
---
Note: Completely untested
---
 arch/nds32/Kconfig.cpu           |    1 
 arch/nds32/include/asm/highmem.h |   21 +++++++++++++----
 arch/nds32/mm/Makefile           |    1 
 arch/nds32/mm/highmem.c          |   48 ---------------------------------------
 4 files changed, 17 insertions(+), 54 deletions(-)

--- a/arch/nds32/Kconfig.cpu
+++ b/arch/nds32/Kconfig.cpu
@@ -157,6 +157,7 @@ config HW_SUPPORT_UNALIGNMENT_ACCESS
 config HIGHMEM
 	bool "High Memory Support"
 	depends on MMU && !CPU_CACHE_ALIASING
+        select KMAP_ATOMIC_GENERIC
 	help
 	  The address space of Andes processors is only 4 Gigabytes large
 	  and it has to accommodate user address space, kernel address
--- a/arch/nds32/include/asm/highmem.h
+++ b/arch/nds32/include/asm/highmem.h
@@ -45,11 +45,22 @@ extern pte_t *pkmap_page_table;
 extern void kmap_init(void);
 
 /*
- * The following functions are already defined by <linux/highmem.h>
- * when CONFIG_HIGHMEM is not set.
+ * FIXME: The below looks broken vs. a kmap_atomic() in task context which
+ * is interupted and another kmap_atomic() happens in interrupt context.
+ * But what do I know about nds32. -- tglx
  */
-#ifdef CONFIG_HIGHMEM
-extern void *kmap_atomic_pfn(unsigned long pfn);
-#endif
+#define arch_kmap_temp_post_map(vaddr, pteval)			\
+	do {							\
+		__nds32__tlbop_inv(vaddr);			\
+		__nds32__mtsr_dsb(vaddr, NDS32_SR_TLB_VPN);	\
+		__nds32__tlbop_rwr(pteval);			\
+		__nds32__isb();					\
+	} while (0)
+
+#define arch_kmap_temp_pre_unmap(vaddr, pte)			\
+	do {							\
+		__nds32__tlbop_inv(vaddr);			\
+		__nds32__isb();					\
+	} while (0)
 
 #endif
--- a/arch/nds32/mm/Makefile
+++ b/arch/nds32/mm/Makefile
@@ -3,7 +3,6 @@ obj-y				:= extable.o tlb.o fault.o init
                                    mm-nds32.o cacheflush.o proc.o
 
 obj-$(CONFIG_ALIGNMENT_TRAP)	+= alignment.o
-obj-$(CONFIG_HIGHMEM)           += highmem.o
 
 ifdef CONFIG_FUNCTION_TRACER
 CFLAGS_REMOVE_proc.o     = $(CC_FLAGS_FTRACE)
--- a/arch/nds32/mm/highmem.c
+++ /dev/null
@@ -1,48 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-// Copyright (C) 2005-2017 Andes Technology Corporation
-
-#include <linux/export.h>
-#include <linux/highmem.h>
-#include <linux/sched.h>
-#include <linux/smp.h>
-#include <linux/interrupt.h>
-#include <linux/memblock.h>
-#include <asm/fixmap.h>
-#include <asm/tlbflush.h>
-
-void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
-{
-	unsigned int idx;
-	unsigned long vaddr, pte;
-	int type;
-	pte_t *ptep;
-
-	type = kmap_atomic_idx_push();
-
-	idx = type + KM_TYPE_NR * smp_processor_id();
-	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
-	pte = (page_to_pfn(page) << PAGE_SHIFT) | prot;
-	ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
-	set_pte(ptep, pte);
-
-	__nds32__tlbop_inv(vaddr);
-	__nds32__mtsr_dsb(vaddr, NDS32_SR_TLB_VPN);
-	__nds32__tlbop_rwr(pte);
-	__nds32__isb();
-	return (void *)vaddr;
-}
-EXPORT_SYMBOL(kmap_atomic_high_prot);
-
-void kunmap_atomic_high(void *kvaddr)
-{
-	if (kvaddr >= (void *)FIXADDR_START) {
-		unsigned long vaddr = (unsigned long)kvaddr;
-		pte_t *ptep;
-		kmap_atomic_idx_pop();
-		__nds32__tlbop_inv(vaddr);
-		__nds32__isb();
-		ptep = pte_offset_kernel(pmd_off_k(vaddr), vaddr);
-		set_pte(ptep, 0);
-	}
-}
-EXPORT_SYMBOL(kunmap_atomic_high);


  parent reply index

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-19  9:17 [patch RFC 00/15] mm/highmem: Provide a preemptible variant of kmap_atomic & friends Thomas Gleixner
2020-09-19  9:17 ` [patch RFC 01/15] mm/highmem: Un-EXPORT __kmap_atomic_idx() Thomas Gleixner
2020-09-21  6:23   ` Christoph Hellwig
2020-09-19  9:17 ` [patch RFC 02/15] highmem: Provide generic variant of kmap_atomic* Thomas Gleixner
2020-09-21  6:28   ` Christoph Hellwig
2020-09-19  9:17 ` [patch RFC 03/15] x86/mm/highmem: Use generic kmap atomic implementation Thomas Gleixner
2020-09-19  9:17 ` [patch RFC 04/15] arc/mm/highmem: " Thomas Gleixner
2020-09-19  9:17 ` [patch RFC 05/15] ARM: highmem: Switch to generic kmap atomic Thomas Gleixner
2020-09-19  9:17 ` [patch RFC 06/15] csky/mm/highmem: " Thomas Gleixner
2020-09-23  0:05   ` Guo Ren
2020-09-19  9:17 ` [patch RFC 07/15] microblaze/mm/highmem: " Thomas Gleixner
2020-09-19  9:17 ` [patch RFC 08/15] mips/mm/highmem: " Thomas Gleixner
2020-09-19  9:18 ` Thomas Gleixner [this message]
2020-09-19  9:18 ` [patch RFC 10/15] powerpc/mm/highmem: " Thomas Gleixner
2020-09-19  9:18 ` [patch RFC 11/15] sparc/mm/highmem: " Thomas Gleixner
2020-09-19  9:18 ` [patch RFC 12/15] xtensa/mm/highmem: " Thomas Gleixner
2020-09-19  9:18 ` [patch RFC 13/15] mm/highmem: Remove the old kmap_atomic cruft Thomas Gleixner
2020-09-19  9:18 ` [patch RFC 14/15] sched: highmem: Store temporary kmaps in task struct Thomas Gleixner
2020-09-19  9:18 ` [patch RFC 15/15] mm/highmem: Provide kmap_temporary* Thomas Gleixner
2020-09-19 10:35 ` [patch RFC 00/15] mm/highmem: Provide a preemptible variant of kmap_atomic & friends Daniel Vetter
2020-09-19 10:37   ` Daniel Vetter
2020-09-20  6:23     ` Thomas Gleixner
2020-09-20  8:23       ` Daniel Vetter
2020-09-20 17:24         ` Thomas Gleixner
2020-09-19 17:18 ` Linus Torvalds
2020-09-19 17:39   ` Matthew Wilcox
2020-09-19 19:13     ` Linus Torvalds
2020-09-21 19:58     ` Ira Weiny
2020-09-20  6:41   ` Thomas Gleixner
2020-09-20  8:49     ` Thomas Gleixner
2020-09-20 16:57       ` Linus Torvalds
2020-09-20 17:40         ` Thomas Gleixner
2020-09-20 17:42           ` Linus Torvalds
2020-09-20 17:58             ` Linus Torvalds
2020-09-21  7:39             ` Thomas Gleixner
2020-09-21 16:24               ` Linus Torvalds
2020-09-21 19:27                 ` Thomas Gleixner
2020-09-23  8:40                   ` peterz
2020-09-23 13:35                     ` Thomas Gleixner
2020-09-23 15:52                     ` Steven Rostedt
2020-09-23 20:55                       ` Thomas Gleixner
2020-09-23 21:12                         ` Steven Rostedt
2020-09-24  6:57                           ` Thomas Gleixner
2020-09-24 12:32                             ` Steven Rostedt
2020-09-24 12:42                               ` Peter Zijlstra
2020-09-24 13:51                                 ` Steven Rostedt
2020-09-24 13:58                                   ` Peter Zijlstra
2020-09-24 17:55                               ` Thomas Gleixner
2020-09-24 18:58                                 ` Steven Rostedt
2020-09-24  8:27                       ` peterz
2020-09-24 19:36                         ` Daniel Bristot de Oliveira
2020-09-23 10:19                   ` peterz
2020-09-23 12:33                     ` Thomas Gleixner
2020-09-23 14:33                   ` Thomas Gleixner

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