diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arc/mm/cache_arc700.c | 201 |
1 files changed, 17 insertions, 184 deletions
diff --git a/arch/arc/mm/cache_arc700.c b/arch/arc/mm/cache_arc700.c index 5aaa955a3aac..da9de401681d 100644 --- a/arch/arc/mm/cache_arc700.c +++ b/arch/arc/mm/cache_arc700.c @@ -72,16 +72,6 @@ #include <asm/cachectl.h> #include <asm/setup.h> - -#ifdef CONFIG_ARC_HAS_ICACHE -static void __ic_line_inv_no_alias(unsigned long, int); -static void __ic_line_inv_2_alias(unsigned long, int); -static void __ic_line_inv_4_alias(unsigned long, int); - -/* Holds the ptr to flush routine, dependign on size due to aliasing issues */ -static void (*___flush_icache_rtn) (unsigned long, int); -#endif - char *arc_cache_mumbojumbo(int cpu_id, char *buf, int len) { int n = 0; @@ -171,30 +161,6 @@ void __cpuinit arc_cache_init(void) } #endif - - /* - * if Cache way size is <= page size then no aliasing exhibited - * otherwise ratio determines num of aliases. - * e.g. 32K I$, 2 way set assoc, 8k pg size - * way-sz = 32k/2 = 16k - * way-pg-ratio = 16k/8k = 2, so 2 aliases possible - * (meaning 1 line could be in 2 possible locations). - */ - way_pg_ratio = ic->sz / ARC_ICACHE_WAYS / PAGE_SIZE; - switch (way_pg_ratio) { - case 0: - case 1: - ___flush_icache_rtn = __ic_line_inv_no_alias; - break; - case 2: - ___flush_icache_rtn = __ic_line_inv_2_alias; - break; - case 4: - ___flush_icache_rtn = __ic_line_inv_4_alias; - break; - default: - panic("Unsupported I-Cache Sz\n"); - } #endif /* Enable/disable I-Cache */ @@ -391,75 +357,38 @@ static inline void __dc_line_op(unsigned long start, unsigned long sz, /* * I-Cache Aliasing in ARC700 VIPT caches * - * For fetching code from I$, ARC700 uses vaddr (embedded in program code) - * to "index" into SET of cache-line and paddr from MMU to match the TAG - * in the WAYS of SET. - * - * However the CDU iterface (to flush/inv) lines from software, only takes - * paddr (to have simpler hardware interface). For simpler cases, using paddr - * alone suffices. - * e.g. 2-way-set-assoc, 16K I$ (8k MMU pg sz, 32b cache line size): - * way_sz = cache_sz / num_ways = 16k/2 = 8k - * num_sets = way_sz / line_sz = 8k/32 = 256 => 8 bits - * Ignoring the bottom 5 bits corresp to the off within a 32b cacheline, - * bits req for calc set-index = bits 12:5 (0 based). Since this range fits - * inside the bottom 13 bits of paddr, which are same for vaddr and paddr - * (with 8k pg sz), paddr alone can be safely used by CDU to unambigously - * locate a cache-line. + * 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. * - * However for a difft sized cache, say 32k I$, above math yields need - * for 14 bits of vaddr to locate a cache line, which can't be provided by - * paddr, since the bit 13 (0 based) might differ between the two. - * - * This lack of extra bits needed for correct line addressing, defines the - * classical problem of Cache aliasing with VIPT architectures - * num_aliases = 1 << extra_bits - * e.g. 2-way-set-assoc, 32K I$ with 8k MMU pg sz => 2 aliases - * 2-way-set-assoc, 64K I$ with 8k MMU pg sz => 4 aliases - * 2-way-set-assoc, 16K I$ with 8k MMU pg sz => NO aliases + * However for larger Caches (way-size > page-size) - i.e. in Aliasing config, + * paddr alone could not be used to correctly index the cache. * * ------------------ * 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-geom. + * 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. + * 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) * - * Since vaddr was not available for all instances of I$ flush req by core - * kernel, the only safe way (non-optimal though) was to kill all possible - * lines which could represent an alias (even if they didnt represent one - * in execution). - * e.g. for 64K I$, 4 aliases possible, so we did - * flush start - * flush start | 0x01 - * flush start | 0x2 - * flush start | 0x3 - * - * The penalty was invoking the operation itself, since tag match is anyways - * paddr based, a line which didn't represent an alias would not match the - * paddr, hence wont be killed - * - * Note that aliasing concerns are independent of line-sz for a given cache - * geometry (size + set_assoc) because the extra bits required by line-sz are - * reduced from the set calc. - * e.g. 2-way-set-assoc, 32K I$ with 8k MMU pg sz and using math above - * 32b line-sz: 9 bits set-index-calc, 5 bits offset-in-line => 1 extra bit - * 64b line-sz: 8 bits set-index-calc, 6 bits offset-in-line => 1 extra bit - * * ------------------ * MMU v3 * ------------------ - * This ver of MMU supports var page sizes (1k-16k) - Linux will support - * 8k (default), 16k and 4k. + * 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 aggrevate aliasing * meaning more vaddr bits needed to disambiguate the cache-line-op ; * the existing scheme of piggybacking won't work for certain configurations. @@ -468,105 +397,10 @@ static inline void __dc_line_op(unsigned long start, unsigned long sz, */ /*********************************************************** - * Machine specific helpers for per line I-Cache invalidate. - * 3 routines to accpunt for 1, 2, 4 aliases possible - */ - -static void __ic_line_inv_no_alias(unsigned long start, int num_lines) -{ - while (num_lines-- > 0) { -#if (CONFIG_ARC_MMU_VER > 2) - write_aux_reg(ARC_REG_IC_PTAG, start); -#endif - write_aux_reg(ARC_REG_IC_IVIL, start); - start += ARC_ICACHE_LINE_LEN; - } -} - -static void __ic_line_inv_2_alias(unsigned long start, int num_lines) -{ - while (num_lines-- > 0) { - -#if (CONFIG_ARC_MMU_VER > 2) - /* - * MMU v3, CDU prog model (for line ops) now uses a new IC_PTAG - * reg to pass the "tag" bits and existing IVIL reg only looks - * at bits relevant for "index" (details above) - * Programming Notes: - * -when writing tag to PTAG reg, bit chopping can be avoided, - * CDU ignores non-tag bits. - * -Ideally "index" must be computed from vaddr, but it is not - * avail in these rtns. So to be safe, we kill the lines in all - * possible indexes corresp to num of aliases possible for - * given cache config. - */ - write_aux_reg(ARC_REG_IC_PTAG, start); - write_aux_reg(ARC_REG_IC_IVIL, - start & ~(0x1 << PAGE_SHIFT)); - write_aux_reg(ARC_REG_IC_IVIL, start | (0x1 << PAGE_SHIFT)); -#else - write_aux_reg(ARC_REG_IC_IVIL, start); - write_aux_reg(ARC_REG_IC_IVIL, start | 0x01); -#endif - start += ARC_ICACHE_LINE_LEN; - } -} - -static void __ic_line_inv_4_alias(unsigned long start, int num_lines) -{ - while (num_lines-- > 0) { - -#if (CONFIG_ARC_MMU_VER > 2) - write_aux_reg(ARC_REG_IC_PTAG, start); - - write_aux_reg(ARC_REG_IC_IVIL, - start & ~(0x3 << PAGE_SHIFT)); - write_aux_reg(ARC_REG_IC_IVIL, - start & ~(0x2 << PAGE_SHIFT)); - write_aux_reg(ARC_REG_IC_IVIL, - start & ~(0x1 << PAGE_SHIFT)); - write_aux_reg(ARC_REG_IC_IVIL, start | (0x3 << PAGE_SHIFT)); -#else - write_aux_reg(ARC_REG_IC_IVIL, start); - write_aux_reg(ARC_REG_IC_IVIL, start | 0x01); - write_aux_reg(ARC_REG_IC_IVIL, start | 0x02); - write_aux_reg(ARC_REG_IC_IVIL, start | 0x03); -#endif - start += ARC_ICACHE_LINE_LEN; - } -} - -static void __ic_line_inv(unsigned long start, unsigned long sz) -{ - unsigned long flags; - int num_lines, slack; - - /* - * Ensure we properly floor/ceil the non-line aligned/sized requests - * and have @start - aligned to cache line, and integral @num_lines - * However page sized flushes can be compile time optimised. - * -@start will be cache-line aligned already (being page aligned) - * -@sz will be integral multiple of line size (being page sized). - */ - if (!(__builtin_constant_p(sz) && sz == PAGE_SIZE)) { - slack = start & ~ICACHE_LINE_MASK; - sz += slack; - start -= slack; - } - - num_lines = DIV_ROUND_UP(sz, ARC_ICACHE_LINE_LEN); - - local_irq_save(flags); - (*___flush_icache_rtn) (start, num_lines); - local_irq_restore(flags); -} - -/* Unlike routines above, having vaddr for flush op (along with paddr), - * prevents the need to speculatively kill the lines in multiple sets - * based on ratio of way_sz : pg_sz + * Machine specific helper for per line I-Cache invalidate. */ -static void __ic_line_inv_vaddr(unsigned long phy_start, - unsigned long vaddr, unsigned long sz) +static void __ic_line_inv_vaddr(unsigned long phy_start, unsigned long vaddr, + unsigned long sz) { unsigned long flags; int num_lines, slack; @@ -595,7 +429,7 @@ static void __ic_line_inv_vaddr(unsigned long phy_start, write_aux_reg(ARC_REG_IC_IVIL, vaddr); vaddr += ARC_ICACHE_LINE_LEN; #else - /* this paddr contains vaddrs bits as needed */ + /* paddr contains stuffed vaddrs bits */ write_aux_reg(ARC_REG_IC_IVIL, addr); #endif addr += ARC_ICACHE_LINE_LEN; @@ -605,7 +439,6 @@ static void __ic_line_inv_vaddr(unsigned long phy_start, #else -#define __ic_line_inv(start, sz) #define __ic_line_inv_vaddr(pstart, vstart, sz) #endif /* CONFIG_ARC_HAS_ICACHE */ |