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Commit 48b0e548 authored by David S. Miller's avatar David S. Miller
Browse files

[SPARC64]: Fix ugly dependency on NR_CPUS being a power-of-2. 



The page->flags D-cache dirty state tracking depended upon
NR_CPUS being a power-of-2 via it's "NR_CPUS - 1" masking.

Fix that to use a fixed (256 - 1) mask as that is the limit
imposed by thread_info->cpu which is a "u8".

Finally, add a compile time check that NR_CPUS is not greater
than 256.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 40a085c4

arch/sparc64/mm/init.c

+17 −6
Original line number Diff line number Diff line
@@ -121,15 +121,24 @@ __inline__ void flush_dcache_page_impl(struct page *page) 
}



#define PG_dcache_dirty		PG_arch_1

#define PG_dcache_cpu_shift	24

#define PG_dcache_cpu_mask	(256 - 1)



#if NR_CPUS > 256

#error D-cache dirty tracking and thread_info->cpu need fixing for > 256 cpus

#endif



#define dcache_dirty_cpu(page) \

	(((page)->flags >> 24) & (NR_CPUS - 1UL))

	(((page)->flags >> PG_dcache_cpu_shift) & PG_dcache_cpu_mask)



static __inline__ void set_dcache_dirty(struct page *page, int this_cpu)

{

	unsigned long mask = this_cpu;

	unsigned long non_cpu_bits = ~((NR_CPUS - 1UL) << 24UL);

	mask = (mask << 24) | (1UL << PG_dcache_dirty);

	unsigned long non_cpu_bits;



	non_cpu_bits = ~(PG_dcache_cpu_mask << PG_dcache_cpu_shift);

	mask = (mask << PG_dcache_cpu_shift) | (1UL << PG_dcache_dirty);



	__asm__ __volatile__("1:\n\t"

			     "ldx	[%2], %%g7\n\t"

			     "and	%%g7, %1, %%g1\n\t"
@@ -151,7 +160,7 @@ static __inline__ void clear_dcache_dirty_cpu(struct page *page, unsigned long c 
	__asm__ __volatile__("! test_and_clear_dcache_dirty\n"

			     "1:\n\t"

			     "ldx	[%2], %%g7\n\t"

			     "srlx	%%g7, 24, %%g1\n\t"

			     "srlx	%%g7, %4, %%g1\n\t"

			     "and	%%g1, %3, %%g1\n\t"

			     "cmp	%%g1, %0\n\t"

			     "bne,pn	%%icc, 2f\n\t"
@@ -164,7 +173,8 @@ static __inline__ void clear_dcache_dirty_cpu(struct page *page, unsigned long c 
			     "2:"

			     : /* no outputs */

			     : "r" (cpu), "r" (mask), "r" (&page->flags),

			       "i" (NR_CPUS - 1UL)

			       "i" (PG_dcache_cpu_mask),

			       "i" (PG_dcache_cpu_shift)

			     : "g1", "g7");

}
@@ -180,7 +190,8 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t p 
	if (pfn_valid(pfn) &&

	    (page = pfn_to_page(pfn), page_mapping(page)) &&

	    ((pg_flags = page->flags) & (1UL << PG_dcache_dirty))) {

		int cpu = ((pg_flags >> 24) & (NR_CPUS - 1UL));

		int cpu = ((pg_flags >> PG_dcache_cpu_shift) &

			   PG_dcache_cpu_mask);

		int this_cpu = get_cpu();



		/* This is just to optimize away some function calls