diff options
Diffstat (limited to 'arch/arc/mm/cache.c')
| -rw-r--r-- | arch/arc/mm/cache.c | 118 |
1 files changed, 18 insertions, 100 deletions
diff --git a/arch/arc/mm/cache.c b/arch/arc/mm/cache.c index a2fbea3ee07c..55c6de138eae 100644 --- a/arch/arc/mm/cache.c +++ b/arch/arc/mm/cache.c @@ -205,93 +205,24 @@ slc_chk: #define OP_INV_IC 0x4 /* - * I-Cache Aliasing in ARC700 VIPT caches (MMU v1-v3) + * Cache Flush programming model * - * ARC VIPT I-cache uses vaddr to index into cache and paddr to match the tag. - * The orig Cache Management Module "CDU" only required paddr to invalidate a - * certain line since it sufficed as index in Non-Aliasing VIPT cache-geometry. - * Infact for distinct V1,V2,P: all of {V1-P},{V2-P},{P-P} would end up fetching - * the exact same line. + * ARC700 MMUv3 I$ and D$ are both VIPT and can potentially alias. + * Programming model requires both paddr and vaddr irrespecive of aliasing + * considerations: + * - vaddr in {I,D}C_IV?L + * - paddr in {I,D}C_PTAG * - * However for larger Caches (way-size > page-size) - i.e. in Aliasing config, - * paddr alone could not be used to correctly index the cache. + * In HS38x (MMUv4), D$ is PIPT, I$ is VIPT and can still alias. + * Programming model is different for aliasing vs. non-aliasing I$ + * - D$ / Non-aliasing I$: only paddr in {I,D}C_IV?L + * - Aliasing I$: same as ARC700 above (so MMUv3 routine used for MMUv4 I$) * - * ------------------ - * MMU v1/v2 (Fixed Page Size 8k) - * ------------------ - * The solution was to provide CDU with these additonal vaddr bits. These - * would be bits [x:13], x would depend on cache-geometry, 13 comes from - * standard page size of 8k. - * H/w folks chose [17:13] to be a future safe range, and moreso these 5 bits - * of vaddr could easily be "stuffed" in the paddr as bits [4:0] since the - * orig 5 bits of paddr were anyways ignored by CDU line ops, as they - * represent the offset within cache-line. The adv of using this "clumsy" - * interface for additional info was no new reg was needed in CDU programming - * model. - * - * 17:13 represented the max num of bits passable, actual bits needed were - * fewer, based on the num-of-aliases possible. - * -for 2 alias possibility, only bit 13 needed (32K cache) - * -for 4 alias possibility, bits 14:13 needed (64K cache) - * - * ------------------ - * MMU v3 - * ------------------ - * This ver of MMU supports variable page sizes (1k-16k): although Linux will - * only support 8k (default), 16k and 4k. - * However from hardware perspective, smaller page sizes aggravate aliasing - * meaning more vaddr bits needed to disambiguate the cache-line-op ; - * the existing scheme of piggybacking won't work for certain configurations. - * Two new registers IC_PTAG and DC_PTAG inttoduced. - * "tag" bits are provided in PTAG, index bits in existing IVIL/IVDL/FLDL regs + * - If PAE40 is enabled, independent of aliasing considerations, the higher + * bits needs to be written into PTAG_HI */ static inline -void __cache_line_loop_v2(phys_addr_t paddr, unsigned long vaddr, - unsigned long sz, const int op, const int full_page) -{ - unsigned int aux_cmd; - int num_lines; - - if (op == OP_INV_IC) { - aux_cmd = ARC_REG_IC_IVIL; - } else { - /* d$ cmd: INV (discard or wback-n-discard) OR FLUSH (wback) */ - aux_cmd = op & OP_INV ? ARC_REG_DC_IVDL : ARC_REG_DC_FLDL; - } - - /* Ensure we properly floor/ceil the non-line aligned/sized requests - * and have @paddr - aligned to cache line and integral @num_lines. - * This however can be avoided for page sized since: - * -@paddr will be cache-line aligned already (being page aligned) - * -@sz will be integral multiple of line size (being page sized). - */ - if (!full_page) { - sz += paddr & ~CACHE_LINE_MASK; - paddr &= CACHE_LINE_MASK; - vaddr &= CACHE_LINE_MASK; - } - - num_lines = DIV_ROUND_UP(sz, L1_CACHE_BYTES); - - /* MMUv2 and before: paddr contains stuffed vaddrs bits */ - paddr |= (vaddr >> PAGE_SHIFT) & 0x1F; - - while (num_lines-- > 0) { - write_aux_reg(aux_cmd, paddr); - paddr += L1_CACHE_BYTES; - } -} - -/* - * For ARC700 MMUv3 I-cache and D-cache flushes - * - ARC700 programming model requires paddr and vaddr be passed in seperate - * AUX registers (*_IV*L and *_PTAG respectively) irrespective of whether the - * caches actually alias or not. - * - For HS38, only the aliasing I-cache configuration uses the PTAG reg - * (non aliasing I-cache version doesn't; while D-cache can't possibly alias) - */ -static inline void __cache_line_loop_v3(phys_addr_t paddr, unsigned long vaddr, unsigned long sz, const int op, const int full_page) { @@ -350,17 +281,6 @@ void __cache_line_loop_v3(phys_addr_t paddr, unsigned long vaddr, #ifndef USE_RGN_FLSH /* - * In HS38x (MMU v4), I-cache is VIPT (can alias), D-cache is PIPT - * Here's how cache ops are implemented - * - * - D-cache: only paddr needed (in DC_IVDL/DC_FLDL) - * - I-cache Non Aliasing: Despite VIPT, only paddr needed (in IC_IVIL) - * - I-cache Aliasing: Both vaddr and paddr needed (in IC_IVIL, IC_PTAG - * respectively, similar to MMU v3 programming model, hence - * __cache_line_loop_v3() is used) - * - * If PAE40 is enabled, independent of aliasing considerations, the higher bits - * needs to be written into PTAG_HI */ static inline void __cache_line_loop_v4(phys_addr_t paddr, unsigned long vaddr, @@ -460,11 +380,9 @@ void __cache_line_loop_v4(phys_addr_t paddr, unsigned long vaddr, #endif -#if (CONFIG_ARC_MMU_VER < 3) -#define __cache_line_loop __cache_line_loop_v2 -#elif (CONFIG_ARC_MMU_VER == 3) +#ifdef CONFIG_ARC_MMU_V3 #define __cache_line_loop __cache_line_loop_v3 -#elif (CONFIG_ARC_MMU_VER > 3) +#else #define __cache_line_loop __cache_line_loop_v4 #endif @@ -483,7 +401,7 @@ static inline void __before_dc_op(const int op) { if (op == OP_FLUSH_N_INV) { /* Dcache provides 2 cmd: FLUSH or INV - * INV inturn has sub-modes: DISCARD or FLUSH-BEFORE + * INV in turn has sub-modes: DISCARD or FLUSH-BEFORE * flush-n-inv is achieved by INV cmd but with IM=1 * So toggle INV sub-mode depending on op request and default */ @@ -832,7 +750,7 @@ static inline void arc_slc_enable(void) * -In SMP, if hardware caches are coherent * * There's a corollary case, where kernel READs from a userspace mapped page. - * If the U-mapping is not congruent to to K-mapping, former needs flushing. + * If the U-mapping is not congruent to K-mapping, former needs flushing. */ void flush_dcache_page(struct page *page) { @@ -992,7 +910,7 @@ EXPORT_SYMBOL(flush_icache_range); * @vaddr is typically user vaddr (breakpoint) or kernel vaddr (vmalloc) * However in one instance, when called by kprobe (for a breakpt in * builtin kernel code) @vaddr will be paddr only, meaning CDU operation will - * use a paddr to index the cache (despite VIPT). This is fine since since a + * use a paddr to index the cache (despite VIPT). This is fine since a * builtin kernel page will not have any virtual mappings. * kprobe on loadable module will be kernel vaddr. */ @@ -1123,7 +1041,7 @@ void clear_user_page(void *to, unsigned long u_vaddr, struct page *page) clear_page(to); clear_bit(PG_dc_clean, &page->flags); } - +EXPORT_SYMBOL(clear_user_page); /********************************************************************** * Explicit Cache flush request from user space via syscall |