The kmap_atomic* interfaces in all architectures are pretty much the same
except for post map operations (flush) and pre- and post unmap operations.

Provide a generic variant for that.

Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: linux...@kvack.org
---
V3: Do not reuse the kmap_atomic_idx pile and use kmap_size.h right away
V2: Address review comments from Christoph (style and EXPORT variant)
---
 include/linux/highmem.h |   82 ++++++++++++++++++++++-----
 mm/Kconfig              |    3 +
 mm/highmem.c            |  144 +++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 211 insertions(+), 18 deletions(-)

--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -31,9 +31,16 @@ static inline void invalidate_kernel_vma
 
 #include <asm/kmap_types.h>
 
+/*
+ * Outside of CONFIG_HIGHMEM to support X86 32bit iomap_atomic() cruft.
+ */
+#ifdef CONFIG_KMAP_LOCAL
+void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot);
+void *__kmap_local_page_prot(struct page *page, pgprot_t prot);
+void kunmap_local_indexed(void *vaddr);
+#endif
+
 #ifdef CONFIG_HIGHMEM
-extern void *kmap_atomic_high_prot(struct page *page, pgprot_t prot);
-extern void kunmap_atomic_high(void *kvaddr);
 #include <asm/highmem.h>
 
 #ifndef ARCH_HAS_KMAP_FLUSH_TLB
@@ -81,6 +88,11 @@ static inline void kunmap(struct page *p
  * be used in IRQ contexts, so in some (very limited) cases we need
  * it.
  */
+
+#ifndef CONFIG_KMAP_LOCAL
+void *kmap_atomic_high_prot(struct page *page, pgprot_t prot);
+void kunmap_atomic_high(void *kvaddr);
+
 static inline void *kmap_atomic_prot(struct page *page, pgprot_t prot)
 {
        preempt_disable();
@@ -89,7 +101,38 @@ static inline void *kmap_atomic_prot(str
                return page_address(page);
        return kmap_atomic_high_prot(page, prot);
 }
-#define kmap_atomic(page)      kmap_atomic_prot(page, kmap_prot)
+
+static inline void __kunmap_atomic(void *vaddr)
+{
+       kunmap_atomic_high(vaddr);
+}
+#else /* !CONFIG_KMAP_LOCAL */
+
+static inline void *kmap_atomic_prot(struct page *page, pgprot_t prot)
+{
+       preempt_disable();
+       pagefault_disable();
+       return __kmap_local_page_prot(page, prot);
+}
+
+static inline void *kmap_atomic_pfn(unsigned long pfn)
+{
+       preempt_disable();
+       pagefault_disable();
+       return __kmap_local_pfn_prot(pfn, kmap_prot);
+}
+
+static inline void __kunmap_atomic(void *addr)
+{
+       kunmap_local_indexed(addr);
+}
+
+#endif /* CONFIG_KMAP_LOCAL */
+
+static inline void *kmap_atomic(struct page *page)
+{
+       return kmap_atomic_prot(page, kmap_prot);
+}
 
 /* declarations for linux/mm/highmem.c */
 unsigned int nr_free_highpages(void);
@@ -147,25 +190,33 @@ static inline void *kmap_atomic(struct p
        pagefault_disable();
        return page_address(page);
 }
-#define kmap_atomic_prot(page, prot)   kmap_atomic(page)
 
-static inline void kunmap_atomic_high(void *addr)
+static inline void *kmap_atomic_prot(struct page *page, pgprot_t prot)
+{
+       return kmap_atomic(page);
+}
+
+static inline void *kmap_atomic_pfn(unsigned long pfn)
+{
+       return kmap_atomic(pfn_to_page(pfn));
+}
+
+static inline void __kunmap_atomic(void *addr)
 {
        /*
         * Mostly nothing to do in the CONFIG_HIGHMEM=n case as kunmap_atomic()
-        * handles re-enabling faults + preemption
+        * handles re-enabling faults and preemption
         */
 #ifdef ARCH_HAS_FLUSH_ON_KUNMAP
        kunmap_flush_on_unmap(addr);
 #endif
 }
 
-#define kmap_atomic_pfn(pfn)   kmap_atomic(pfn_to_page(pfn))
-
 #define kmap_flush_unused()    do {} while(0)
 
 #endif /* CONFIG_HIGHMEM */
 
+#if !defined(CONFIG_KMAP_LOCAL)
 #if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)
 
 DECLARE_PER_CPU(int, __kmap_atomic_idx);
@@ -196,22 +247,21 @@ static inline void kmap_atomic_idx_pop(v
        __this_cpu_dec(__kmap_atomic_idx);
 #endif
 }
-
+#endif
 #endif
 
 /*
  * Prevent people trying to call kunmap_atomic() as if it were kunmap()
  * kunmap_atomic() should get the return value of kmap_atomic, not the page.
  */
-#define kunmap_atomic(addr)                                     \
-do {                                                            \
-       BUILD_BUG_ON(__same_type((addr), struct page *));       \
-       kunmap_atomic_high(addr);                                  \
-       pagefault_enable();                                     \
-       preempt_enable();                                       \
+#define kunmap_atomic(__addr)                                  \
+do {                                                           \
+       BUILD_BUG_ON(__same_type((__addr), struct page *));     \
+       __kunmap_atomic(__addr);                                \
+       pagefault_enable();                                     \
+       preempt_enable();                                       \
 } while (0)
 
-
 /* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
 #ifndef clear_user_highpage
 static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -872,4 +872,7 @@ config ARCH_HAS_HUGEPD
 config MAPPING_DIRTY_HELPERS
         bool
 
+config KMAP_LOCAL
+       bool
+
 endmenu
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -31,9 +31,11 @@
 #include <asm/tlbflush.h>
 #include <linux/vmalloc.h>
 
+#ifndef CONFIG_KMAP_LOCAL
 #if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)
 DEFINE_PER_CPU(int, __kmap_atomic_idx);
 #endif
+#endif
 
 /*
  * Virtual_count is not a pure "count".
@@ -365,9 +367,147 @@ void kunmap_high(struct page *page)
        if (need_wakeup)
                wake_up(pkmap_map_wait);
 }
-
 EXPORT_SYMBOL(kunmap_high);
-#endif /* CONFIG_HIGHMEM */
+#endif /* CONFIG_HIGHMEM */
+
+#ifdef CONFIG_KMAP_LOCAL
+
+#include <asm/kmap_size.h>
+
+static DEFINE_PER_CPU(int, __kmap_local_idx);
+
+static inline int kmap_local_idx_push(void)
+{
+       int idx = __this_cpu_inc_return(__kmap_local_idx) - 1;
+
+       WARN_ON_ONCE(in_irq() && !irqs_disabled());
+       BUG_ON(idx >= KM_MAX_IDX);
+       return idx;
+}
+
+static inline int kmap_local_idx(void)
+{
+       return __this_cpu_read(__kmap_local_idx) - 1;
+}
+
+static inline void kmap_local_idx_pop(void)
+{
+       int idx = __this_cpu_dec_return(__kmap_local_idx);
+
+       BUG_ON(idx < 0);
+}
+
+#ifndef arch_kmap_local_post_map
+# define arch_kmap_local_post_map(vaddr, pteval)       do { } while (0)
+#endif
+#ifndef arch_kmap_local_pre_unmap
+# define arch_kmap_local_pre_unmap(vaddr)              do { } while (0)
+#endif
+
+#ifndef arch_kmap_local_post_unmap
+# define arch_kmap_local_post_unmap(vaddr)             do { } while (0)
+#endif
+
+#ifndef arch_kmap_local_map_idx
+#define arch_kmap_local_map_idx(idx, pfn)      kmap_local_calc_idx(idx)
+#endif
+
+#ifndef arch_kmap_local_unmap_idx
+#define arch_kmap_local_unmap_idx(idx, vaddr)  kmap_local_calc_idx(idx)
+#endif
+
+#ifndef arch_kmap_local_high_get
+static inline void *arch_kmap_local_high_get(struct page *page)
+{
+       return NULL;
+}
+#endif
+
+/* Unmap a local mapping which was obtained by kmap_high_get() */
+static inline void kmap_high_unmap_local(unsigned long vaddr)
+{
+#ifdef ARCH_NEEDS_KMAP_HIGH_GET
+       if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP))
+               kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
+#endif
+}
+
+static inline int kmap_local_calc_idx(int idx)
+{
+       return idx + KM_MAX_IDX * smp_processor_id();
+}
+
+static pte_t *__kmap_pte;
+
+static pte_t *kmap_get_pte(void)
+{
+       if (!__kmap_pte)
+               __kmap_pte = virt_to_kpte(__fix_to_virt(FIX_KMAP_BEGIN));
+       return __kmap_pte;
+}
+
+void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot)
+{
+       pte_t pteval, *kmap_pte = kmap_get_pte();
+       unsigned long vaddr;
+       int idx;
+
+       preempt_disable();
+       idx = arch_kmap_local_map_idx(kmap_local_idx_push(), pfn);
+       vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+       BUG_ON(!pte_none(*(kmap_pte - idx)));
+       pteval = pfn_pte(pfn, prot);
+       set_pte_at(&init_mm, vaddr, kmap_pte - idx, pteval);
+       arch_kmap_local_post_map(vaddr, pteval);
+       preempt_enable();
+
+       return (void *)vaddr;
+}
+EXPORT_SYMBOL_GPL(__kmap_local_pfn_prot);
+
+void *__kmap_local_page_prot(struct page *page, pgprot_t prot)
+{
+       void *kmap;
+
+       if (!PageHighMem(page))
+               return page_address(page);
+
+       /* Try kmap_high_get() if architecture has it enabled */
+       kmap = arch_kmap_local_high_get(page);
+       if (kmap)
+               return kmap;
+
+       return __kmap_local_pfn_prot(page_to_pfn(page), prot);
+}
+EXPORT_SYMBOL(__kmap_local_page_prot);
+
+void kunmap_local_indexed(void *vaddr)
+{
+       unsigned long addr = (unsigned long) vaddr & PAGE_MASK;
+       pte_t *kmap_pte = kmap_get_pte();
+       int idx;
+
+       if (addr < __fix_to_virt(FIX_KMAP_END) ||
+           addr > __fix_to_virt(FIX_KMAP_BEGIN)) {
+               WARN_ON_ONCE(addr < PAGE_OFFSET);
+
+               /* Handle mappings which were obtained by kmap_high_get() */
+               kmap_high_unmap_local(addr);
+               return;
+       }
+
+       preempt_disable();
+       idx = arch_kmap_local_unmap_idx(kmap_local_idx(), addr);
+       WARN_ON_ONCE(addr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
+
+       arch_kmap_local_pre_unmap(addr);
+       pte_clear(&init_mm, addr, kmap_pte - idx);
+       arch_kmap_local_post_unmap(addr);
+       kmap_local_idx_pop();
+       preempt_enable();
+}
+EXPORT_SYMBOL(kunmap_local_indexed);
+#endif
 
 #if defined(HASHED_PAGE_VIRTUAL)
 

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