From: Ram Pai Date: Mon, 6 Nov 2017 08:50:49 +0000 (-0800) Subject: powerpc: shifted-by-one hidx value X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=7b84947cadf18f9a7763f281509db1f24073b4af;p=openwrt%2Fstaging%2Fblogic.git powerpc: shifted-by-one hidx value 0xf is considered invalid hidx value. It indicates absence of a backing HPTE. A PTE is initialized to 0xf either a) when it is new it is newly allocated to hold 4k-backing-HPTE or b) Any time it gets demoted to a 4k-backing-HPTE This patch shifts the representation by one-modulo-0xf; i.e hidx 0 is represented as 1, 1 as 2,... , and 0xf as 0. This convention lets us initialize the secondary-part of the PTE to all zeroes. PTEs are anyway zero'd when allocated. We do not have to zero them again; thus saving on the initialization. Signed-off-by: Ram Pai Signed-off-by: Michael Ellerman --- diff --git a/arch/powerpc/include/asm/book3s/64/hash-64k.h b/arch/powerpc/include/asm/book3s/64/hash-64k.h index 73ed988e6da5..b78d94e5249b 100644 --- a/arch/powerpc/include/asm/book3s/64/hash-64k.h +++ b/arch/powerpc/include/asm/book3s/64/hash-64k.h @@ -63,13 +63,21 @@ static inline real_pte_t __real_pte(pte_t pte, pte_t *ptep) return rpte; } +/* + * shift the hidx representation by one-modulo-0xf; i.e hidx 0 is respresented + * as 1, 1 as 2,... , and 0xf as 0. This convention lets us represent a + * invalid hidx 0xf with a 0x0 bit value. PTEs are anyway zero'd when + * allocated. We dont have to zero them gain; thus save on the initialization. + */ +#define HIDX_UNSHIFT_BY_ONE(x) ((x + 0xfUL) & 0xfUL) /* shift backward by one */ +#define HIDX_SHIFT_BY_ONE(x) ((x + 0x1UL) & 0xfUL) /* shift forward by one */ #define HIDX_BITS(x, index) (x << (index << 2)) #define BITS_TO_HIDX(x, index) ((x >> (index << 2)) & 0xfUL) -#define INVALID_RPTE_HIDX ~(0x0UL) +#define INVALID_RPTE_HIDX 0x0UL static inline unsigned long __rpte_to_hidx(real_pte_t rpte, unsigned long index) { - return BITS_TO_HIDX(rpte.hidx, index); + return HIDX_UNSHIFT_BY_ONE(BITS_TO_HIDX(rpte.hidx, index)); } /* @@ -82,7 +90,7 @@ static inline unsigned long pte_set_hidx(pte_t *ptep, real_pte_t rpte, unsigned long *hidxp = (unsigned long *)(ptep + PTRS_PER_PTE); rpte.hidx &= ~HIDX_BITS(0xfUL, subpg_index); - *hidxp = rpte.hidx | HIDX_BITS(hidx, subpg_index); + *hidxp = rpte.hidx | HIDX_BITS(HIDX_SHIFT_BY_ONE(hidx), subpg_index); /* * Anyone reading PTE must ensure hidx bits are read after reading the