sh: Fix up and optimize the kmap_coherent() interface.

This fixes up the kmap_coherent/kunmap_coherent() interface for recent
changes both in the page fault path and the shared cache flushers, as
well as adding in some optimizations.

One of the key things to note here is that the TLB flush itself is
deferred until the unmap, and the call in to update_mmu_cache() itself
goes away, relying on the regular page fault path to handle the lazy
dcache writeback if necessary.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 17 insertions, 19 deletions

diff --git a/arch/sh/mm/kmap.c b/arch/sh/mm/kmap.c
index 3eecf0d..c52cd8c 100644
--- a/arch/sh/mm/kmap.c
+++ b/arch/sh/mm/kmap.c
@@ -24,9 +24,6 @@ void __init kmap_coherent_init(void)
 {
 	unsigned long vaddr;
 
-	if (!boot_cpu_data.dcache.n_aliases)
-		return;
-
 	/* cache the first coherent kmap pte */
 	vaddr = __fix_to_virt(FIX_CMAP_BEGIN);
 	kmap_coherent_pte = kmap_get_fixmap_pte(vaddr);
@@ -35,30 +32,31 @@ void __init kmap_coherent_init(void)
 void *kmap_coherent(struct page *page, unsigned long addr)
 {
 	enum fixed_addresses idx;
-	unsigned long vaddr, flags;
-	pte_t pte;
+	unsigned long vaddr;
 
 	BUG_ON(test_bit(PG_dcache_dirty, &page->flags));
 
-	inc_preempt_count();
-
-	idx = (addr & current_cpu_data.dcache.alias_mask) >> PAGE_SHIFT;
-	vaddr = __fix_to_virt(FIX_CMAP_END - idx);
-	pte = mk_pte(page, PAGE_KERNEL);
+	pagefault_disable();
 
-	local_irq_save(flags);
-	flush_tlb_one(get_asid(), vaddr);
-	local_irq_restore(flags);
+	idx = FIX_CMAP_END -
+		((addr & current_cpu_data.dcache.alias_mask) >> PAGE_SHIFT);
+	vaddr = __fix_to_virt(idx);
 
-	update_mmu_cache(NULL, vaddr, pte);
-
-	set_pte(kmap_coherent_pte - (FIX_CMAP_END - idx), pte);
+	BUG_ON(!pte_none(*(kmap_coherent_pte - idx)));
+	set_pte(kmap_coherent_pte - idx, mk_pte(page, PAGE_KERNEL));
 
 	return (void *)vaddr;
 }
 
-void kunmap_coherent(void)
+void kunmap_coherent(void *kvaddr)
 {
-	dec_preempt_count();
-	preempt_check_resched();
+	if (kvaddr >= (void *)FIXADDR_START) {
+		unsigned long vaddr = (unsigned long)kvaddr & PAGE_MASK;
+		enum fixed_addresses idx = __virt_to_fix(vaddr);
+
+		pte_clear(&init_mm, vaddr, kmap_coherent_pte - idx);
+		local_flush_tlb_one(get_asid(), vaddr);
+	}
+
+	pagefault_enable();
 }