[patch RFC 04/15] arc/mm/highmem: Use generic kmap atomic implementation

Thomas Gleixner
2020-09-19T09:50:14Z

Adopt the map ordering to match the other architectures and the generic
code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: linux-snps-arc@lists.infradead.org
---
Note: Completely untested
---
arch/arc/Kconfig | 1
arch/arc/include/asm/highmem.h | 8 ++++++-
arch/arc/mm/highmem.c | 44 -----------------------------------------
3 files changed, 9 insertions(+), 44 deletions(-)

--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -508,6 +508,7 @@ config LINUX_RAM_BASE
config HIGHMEM
bool "High Memory Support"
select ARCH_DISCONTIGMEM_ENABLE
+ select KMAP_ATOMIC_GENERIC
help
With ARC 2G:2G address split, only upper 2G is directly addressable by
kernel. Enable this to potentially allow access to rest of 2G and PAE
--- a/arch/arc/include/asm/highmem.h
+++ b/arch/arc/include/asm/highmem.h
@@ -15,7 +15,10 @@
#define FIXMAP_BASE (PAGE_OFFSET - FIXMAP_SIZE - PKMAP_SIZE)
#define FIXMAP_SIZE PGDIR_SIZE /* only 1 PGD worth */
#define KM_TYPE_NR ((FIXMAP_SIZE >> PAGE_SHIFT)/NR_CPUS)
-#define FIXMAP_ADDR(nr) (FIXMAP_BASE + ((nr) << PAGE_SHIFT))
+
+#define FIX_KMAP_BEGIN (0)
+#define FIX_KMAP_END ((FIXMAP_SIZE >> PAGE_SHIFT) - 1)
+#define FIXADDR_TOP (FIXMAP_BASE + FIXMAP_SIZE - PAGE_SIZE)

/* start after fixmap area */
#define PKMAP_BASE (FIXMAP_BASE + FIXMAP_SIZE)
@@ -29,6 +32,9 @@

extern void kmap_init(void);

+#define arch_kmap_temp_post_unmap(vaddr) \
+ local_flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE)
+
static inline void flush_cache_kmaps(void)
{
flush_cache_all();
--- a/arch/arc/mm/highmem.c
+++ b/arch/arc/mm/highmem.c
@@ -47,48 +47,6 @@
*/

extern pte_t * pkmap_page_table;
-static pte_t * fixmap_page_table;
-
-void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
-{
- int idx, cpu_idx;
- unsigned long vaddr;
-
- cpu_idx = kmap_atomic_idx_push();
- idx = cpu_idx + KM_TYPE_NR * smp_processor_id();
- vaddr = FIXMAP_ADDR(idx);
-
- set_pte_at(&init_mm, vaddr, fixmap_page_table + idx,
- mk_pte(page, prot));
-
- return (void *)vaddr;
-}
-EXPORT_SYMBOL(kmap_atomic_high_prot);
-
-void kunmap_atomic_high(void *kv)
-{
- unsigned long kvaddr = (unsigned long)kv;
-
- if (kvaddr >= FIXMAP_BASE && kvaddr < (FIXMAP_BASE + FIXMAP_SIZE)) {
-
- /*
- * Because preemption is disabled, this vaddr can be associated
- * with the current allocated index.
- * But in case of multiple live kmap_atomic(), it still relies on
- * callers to unmap in right order.
- */
- int cpu_idx = kmap_atomic_idx();
- int idx = cpu_idx + KM_TYPE_NR * smp_processor_id();
-
- WARN_ON(kvaddr != FIXMAP_ADDR(idx));
-
- pte_clear(&init_mm, kvaddr, fixmap_page_table + idx);
- local_flush_tlb_kernel_range(kvaddr, kvaddr + PAGE_SIZE);
-
- kmap_atomic_idx_pop();
- }
-}
-EXPORT_SYMBOL(kunmap_atomic_high);

static noinline pte_t * __init alloc_kmap_pgtable(unsigned long kvaddr)
{
@@ -113,5 +71,5 @@ void __init kmap_init(void)
pkmap_page_table = alloc_kmap_pgtable(PKMAP_BASE);

BUILD_BUG_ON(LAST_PKMAP > PTRS_PER_PTE);
- fixmap_page_table = alloc_kmap_pgtable(FIXMAP_BASE);
+ alloc_kmap_pgtable(FIXMAP_BASE);
}