[patch RFC 12/15] xtensa/mm/highmem: Switch to generic kmap atomic

Thomas Gleixner
2020-09-19T09:50:32Z

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: linux-xtensa@linux-xtensa.org
---
Note: Completely untested
---
arch/xtensa/Kconfig | 1
arch/xtensa/include/asm/highmem.h | 9 +++++++
arch/xtensa/mm/highmem.c | 44 +++-----------------------------------
3 files changed, 14 insertions(+), 40 deletions(-)

--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -679,6 +679,7 @@ endchoice
config HIGHMEM
bool "High Memory Support"
depends on MMU
+ select KMAP_ATOMIC_GENERIC
help
Linux can use the full amount of RAM in the system by
default. However, the default MMUv2 setup only maps the
--- a/arch/xtensa/include/asm/highmem.h
+++ b/arch/xtensa/include/asm/highmem.h
@@ -68,6 +68,15 @@ static inline void flush_cache_kmaps(voi
flush_cache_all();
}

+enum fixed_addresses kmap_temp_map_idx(int type, unsigned long pfn);
+#define arch_kmap_temp_map_idx kmap_temp_map_idx
+
+enum fixed_addresses kmap_temp_unmap_idx(int type, unsigned long addr);
+#define arch_kmap_temp_unmap_idx kmap_temp_unmap_idx
+
+#define arch_kmap_temp_post_unmap(vaddr) \
+ local_flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE)
+
void kmap_init(void);

#endif
--- 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];
@@ -37,55 +35,21 @@ static inline enum fixed_addresses kmap_
color;
}

-void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
+enum fixed_addresses kmap_temp_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_temp_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);

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();
}