Merge tag 'core-mm-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull kmap updates from Thomas Gleixner:
 "The new preemtible kmap_local() implementation:

   - Consolidate all kmap_atomic() internals into a generic
     implementation which builds the base for the kmap_local() API and
     make the kmap_atomic() interface wrappers which handle the
     disabling/enabling of preemption and pagefaults.

   - Switch the storage from per-CPU to per task and provide scheduler
     support for clearing mapping when scheduling out and restoring them
     when scheduling back in.

   - Merge the migrate_disable/enable() code, which is also part of the
     scheduler pull request. This was required to make the kmap_local()
     interface available which does not disable preemption when a
     mapping is established. It has to disable migration instead to
     guarantee that the virtual address of the mapped slot is the same
     across preemption.

   - Provide better debug facilities: guard pages and enforced
     utilization of the mapping mechanics on 64bit systems when the
     architecture allows it.

   - Provide the new kmap_local() API which can now be used to cleanup
     the kmap_atomic() usage sites all over the place. Most of the usage
     sites do not require the implicit disabling of preemption and
     pagefaults so the penalty on 64bit and 32bit non-highmem systems is
     removed and quite some of the code can be simplified. A wholesale
     conversion is not possible because some usage depends on the
     implicit side effects and some need to be cleaned up because they
     work around these side effects.

     The migrate disable side effect is only effective on highmem
     systems and when enforced debugging is enabled. On 64bit and 32bit
     non-highmem systems the overhead is completely avoided"

* tag 'core-mm-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
  ARM: highmem: Fix cache_is_vivt() reference
  x86/crashdump/32: Simplify copy_oldmem_page()
  io-mapping: Provide iomap_local variant
  mm/highmem: Provide kmap_local*
  sched: highmem: Store local kmaps in task struct
  x86: Support kmap_local() forced debugging
  mm/highmem: Provide CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP
  mm/highmem: Provide and use CONFIG_DEBUG_KMAP_LOCAL
  microblaze/mm/highmem: Add dropped #ifdef back
  xtensa/mm/highmem: Make generic kmap_atomic() work correctly
  mm/highmem: Take kmap_high_get() properly into account
  highmem: High implementation details and document API
  Documentation/io-mapping: Remove outdated blurb
  io-mapping: Cleanup atomic iomap
  mm/highmem: Remove the old kmap_atomic cruft
  highmem: Get rid of kmap_types.h
  xtensa/mm/highmem: Switch to generic kmap atomic
  sparc/mm/highmem: Switch to generic kmap atomic
  powerpc/mm/highmem: Switch to generic kmap atomic
  nds32/mm/highmem: Switch to generic kmap atomic
  ...

6 files changed, 42 insertions, 102 deletions

diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index d0dfa50bd0bb..dc22ef3cf4be 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -666,6 +666,7 @@ endchoice
 config HIGHMEM
 	bool "High Memory Support"
 	depends on MMU
+	select KMAP_LOCAL
 	help
 	  Linux can use the full amount of RAM in the system by
 	  default. However, the default MMUv2 setup only maps the
diff --git a/arch/xtensa/include/asm/fixmap.h b/arch/xtensa/include/asm/fixmap.h
index a06ffb0c61c7..1c65dc1d3397 100644
--- a/arch/xtensa/include/asm/fixmap.h
+++ b/arch/xtensa/include/asm/fixmap.h
@@ -16,64 +16,23 @@
 #ifdef CONFIG_HIGHMEM
 #include <linux/threads.h>
 #include <linux/pgtable.h>
-#include <asm/kmap_types.h>
-#endif
+#include <asm/kmap_size.h>
 
-/*
- * Here we define all the compile-time 'special' virtual
- * addresses. The point is to have a constant address at
- * compile time, but to set the physical address only
- * in the boot process. We allocate these special addresses
- * from the start of the consistent memory region upwards.
- * Also this lets us do fail-safe vmalloc(), we
- * can guarantee that these special addresses and
- * vmalloc()-ed addresses never overlap.
- *
- * these 'compile-time allocated' memory buffers are
- * fixed-size 4k pages. (or larger if used with an increment
- * higher than 1) use fixmap_set(idx,phys) to associate
- * physical memory with fixmap indices.
- */
+/* The map slots for temporary mappings via kmap_atomic/local(). */
 enum fixed_addresses {
-#ifdef CONFIG_HIGHMEM
-	/* reserved pte's for temporary kernel mappings */
 	FIX_KMAP_BEGIN,
 	FIX_KMAP_END = FIX_KMAP_BEGIN +
-		(KM_TYPE_NR * NR_CPUS * DCACHE_N_COLORS) - 1,
-#endif
+		(KM_MAX_IDX * NR_CPUS * DCACHE_N_COLORS) - 1,
 	__end_of_fixed_addresses
 };
 
-#define FIXADDR_TOP     (XCHAL_KSEG_CACHED_VADDR - PAGE_SIZE)
+#define FIXADDR_END     (XCHAL_KSEG_CACHED_VADDR - PAGE_SIZE)
 #define FIXADDR_SIZE	(__end_of_fixed_addresses << PAGE_SHIFT)
-#define FIXADDR_START	((FIXADDR_TOP - FIXADDR_SIZE) & PMD_MASK)
+/* Enforce that FIXADDR_START is PMD aligned to handle cache aliasing */
+#define FIXADDR_START	((FIXADDR_END - FIXADDR_SIZE) & PMD_MASK)
+#define FIXADDR_TOP	(FIXADDR_START + FIXADDR_SIZE - PAGE_SIZE)
 
-#define __fix_to_virt(x)	(FIXADDR_START + ((x) << PAGE_SHIFT))
-#define __virt_to_fix(x)	(((x) - FIXADDR_START) >> PAGE_SHIFT)
-
-#ifndef __ASSEMBLY__
-/*
- * 'index to address' translation. If anyone tries to use the idx
- * directly without translation, we catch the bug with a NULL-deference
- * kernel oops. Illegal ranges of incoming indices are caught too.
- */
-static __always_inline unsigned long fix_to_virt(const unsigned int idx)
-{
-	/* Check if this memory layout is broken because fixmap overlaps page
-	 * table.
-	 */
-	BUILD_BUG_ON(FIXADDR_START <
-		     TLBTEMP_BASE_1 + TLBTEMP_SIZE);
-	BUILD_BUG_ON(idx >= __end_of_fixed_addresses);
-	return __fix_to_virt(idx);
-}
-
-static inline unsigned long virt_to_fix(const unsigned long vaddr)
-{
-	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
-	return __virt_to_fix(vaddr);
-}
-
-#endif
+#include <asm-generic/fixmap.h>
 
+#endif /* CONFIG_HIGHMEM */
 #endif
diff --git a/arch/xtensa/include/asm/highmem.h b/arch/xtensa/include/asm/highmem.h
index eac503215f17..34b8b620e7f1 100644
--- a/arch/xtensa/include/asm/highmem.h
+++ b/arch/xtensa/include/asm/highmem.h
@@ -12,13 +12,13 @@
 #ifndef _XTENSA_HIGHMEM_H
 #define _XTENSA_HIGHMEM_H
 
+#ifdef CONFIG_HIGHMEM
 #include <linux/wait.h>
 #include <linux/pgtable.h>
 #include <asm/cacheflush.h>
 #include <asm/fixmap.h>
-#include <asm/kmap_types.h>
 
-#define PKMAP_BASE		((FIXADDR_START - \
+#define PKMAP_BASE		((FIXADDR_START -			\
 				  (LAST_PKMAP + 1) * PAGE_SIZE) & PMD_MASK)
 #define LAST_PKMAP		(PTRS_PER_PTE * DCACHE_N_COLORS)
 #define LAST_PKMAP_MASK		(LAST_PKMAP - 1)
@@ -59,6 +59,13 @@ static inline wait_queue_head_t *get_pkmap_wait_queue_head(unsigned int color)
 {
 	return pkmap_map_wait_arr + color;
 }
+
+enum fixed_addresses kmap_local_map_idx(int type, unsigned long pfn);
+#define arch_kmap_local_map_idx		kmap_local_map_idx
+
+enum fixed_addresses kmap_local_unmap_idx(int type, unsigned long addr);
+#define arch_kmap_local_unmap_idx	kmap_local_unmap_idx
+
 #endif
 
 extern pte_t *pkmap_page_table;
@@ -68,6 +75,10 @@ static inline void flush_cache_kmaps(void)
 	flush_cache_all();
 }
 
+#define arch_kmap_local_post_unmap(vaddr)	\
+	local_flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE)
+
 void kmap_init(void);
 
+#endif /* CONFIG_HIGHMEM */
 #endif
diff --git a/arch/xtensa/mm/highmem.c b/arch/xtensa/mm/highmem.c
index 673196fe862e..35c4f7d4a333 100644
--- a/arch/xtensa/mm/highmem.c
+++ b/arch/xtensa/mm/highmem.c
@@ -12,8 +12,6 @@
 #include <linux/highmem.h>
 #include <asm/tlbflush.h>
 
-static pte_t *kmap_pte;
-
 #if DCACHE_WAY_SIZE > PAGE_SIZE
 unsigned int last_pkmap_nr_arr[DCACHE_N_COLORS];
 wait_queue_head_t pkmap_map_wait_arr[DCACHE_N_COLORS];
@@ -25,67 +23,37 @@ static void __init kmap_waitqueues_init(void)
 	for (i = 0; i < ARRAY_SIZE(pkmap_map_wait_arr); ++i)
 		init_waitqueue_head(pkmap_map_wait_arr + i);
 }
-#else
-static inline void kmap_waitqueues_init(void)
-{
-}
-#endif
 
 static inline enum fixed_addresses kmap_idx(int type, unsigned long color)
 {
-	return (type + KM_TYPE_NR * smp_processor_id()) * DCACHE_N_COLORS +
-		color;
+	int idx = (type + KM_MAX_IDX * smp_processor_id()) * DCACHE_N_COLORS;
+
+	/*
+	 * The fixmap operates top down, so the color offset needs to be
+	 * reverse as well.
+	 */
+	return idx + DCACHE_N_COLORS - 1 - color;
 }
 
-void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
+enum fixed_addresses kmap_local_map_idx(int type, unsigned long pfn)
 {
-	enum fixed_addresses idx;
-	unsigned long vaddr;
-
-	idx = kmap_idx(kmap_atomic_idx_push(),
-		       DCACHE_ALIAS(page_to_phys(page)));
-	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
-#ifdef CONFIG_DEBUG_HIGHMEM
-	BUG_ON(!pte_none(*(kmap_pte + idx)));
-#endif
-	set_pte(kmap_pte + idx, mk_pte(page, prot));
-
-	return (void *)vaddr;
+	return kmap_idx(type, DCACHE_ALIAS(pfn << PAGE_SHIFT));
 }
-EXPORT_SYMBOL(kmap_atomic_high_prot);
 
-void kunmap_atomic_high(void *kvaddr)
+enum fixed_addresses kmap_local_unmap_idx(int type, unsigned long addr)
 {
-	if (kvaddr >= (void *)FIXADDR_START &&
-	    kvaddr < (void *)FIXADDR_TOP) {
-		int idx = kmap_idx(kmap_atomic_idx(),
-				   DCACHE_ALIAS((unsigned long)kvaddr));
-
-		/*
-		 * Force other mappings to Oops if they'll try to access this
-		 * pte without first remap it.  Keeping stale mappings around
-		 * is a bad idea also, in case the page changes cacheability
-		 * attributes or becomes a protected page in a hypervisor.
-		 */
-		pte_clear(&init_mm, kvaddr, kmap_pte + idx);
-		local_flush_tlb_kernel_range((unsigned long)kvaddr,
-					     (unsigned long)kvaddr + PAGE_SIZE);
-
-		kmap_atomic_idx_pop();
-	}
+	return kmap_idx(type, DCACHE_ALIAS(addr));
 }
-EXPORT_SYMBOL(kunmap_atomic_high);
+
+#else
+static inline void kmap_waitqueues_init(void) { }
+#endif
 
 void __init kmap_init(void)
 {
-	unsigned long kmap_vstart;
-
 	/* Check if this memory layout is broken because PKMAP overlaps
 	 * page table.
 	 */
 	BUILD_BUG_ON(PKMAP_BASE < TLBTEMP_BASE_1 + TLBTEMP_SIZE);
-	/* cache the first kmap pte */
-	kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
-	kmap_pte = virt_to_kpte(kmap_vstart);
 	kmap_waitqueues_init();
 }
diff --git a/arch/xtensa/mm/init.c b/arch/xtensa/mm/init.c
index 8731b7ad9308..2daeba9e454e 100644
--- a/arch/xtensa/mm/init.c
+++ b/arch/xtensa/mm/init.c
@@ -147,8 +147,8 @@ void __init mem_init(void)
 #ifdef CONFIG_HIGHMEM
 		PKMAP_BASE, PKMAP_BASE + LAST_PKMAP * PAGE_SIZE,
 		(LAST_PKMAP*PAGE_SIZE) >> 10,
-		FIXADDR_START, FIXADDR_TOP,
-		(FIXADDR_TOP - FIXADDR_START) >> 10,
+		FIXADDR_START, FIXADDR_END,
+		(FIXADDR_END - FIXADDR_START) >> 10,
 #endif
 		PAGE_OFFSET, PAGE_OFFSET +
 		(max_low_pfn - min_low_pfn) * PAGE_SIZE,
diff --git a/arch/xtensa/mm/mmu.c b/arch/xtensa/mm/mmu.c
index fd2193df8a14..7e4d97dc8bd8 100644
--- a/arch/xtensa/mm/mmu.c
+++ b/arch/xtensa/mm/mmu.c
@@ -52,7 +52,8 @@ static void * __init init_pmd(unsigned long vaddr, unsigned long n_pages)
 
 static void __init fixedrange_init(void)
 {
-	init_pmd(__fix_to_virt(0), __end_of_fixed_addresses);
+	BUILD_BUG_ON(FIXADDR_START < TLBTEMP_BASE_1 + TLBTEMP_SIZE);
+	init_pmd(FIXADDR_START, __end_of_fixed_addresses);
 }
 #endif