From 6656920b0b50beacb6cb64cf55273cbb686e436e Mon Sep 17 00:00:00 2001 From: Chris Zankel Date: Wed, 22 Aug 2007 10:14:51 -0700 Subject: [XTENSA] Add support for cache-aliasing Add support for processors that have cache-aliasing issues, such as the Stretch S5000 processor. Cache-aliasing means that the size of the cache (for one way) is larger than the page size, thus, a page can end up in several places in cache depending on the virtual to physical translation. The method used here is to map a user page temporarily through the auto-refill way 0 and of of the DTLB. We probably will want to revisit this issue and use a better approach with kmap/kunmap. Signed-off-by: Chris Zankel --- arch/xtensa/kernel/asm-offsets.c | 13 ++++--- arch/xtensa/kernel/entry.S | 75 +++++++++++++++++++++++++++++++++++++--- 2 files changed, 77 insertions(+), 11 deletions(-) (limited to 'arch/xtensa/kernel') diff --git a/arch/xtensa/kernel/asm-offsets.c b/arch/xtensa/kernel/asm-offsets.c index d0323cd6a2e..d5ffe7b6443 100644 --- a/arch/xtensa/kernel/asm-offsets.c +++ b/arch/xtensa/kernel/asm-offsets.c @@ -18,12 +18,13 @@ #include #include #include +#include + #include #include #include #define DEFINE(sym, val) asm volatile("\n->" #sym " %0 " #val : : "i" (val)) -#define BLANK() asm volatile("\n->" : : ) int main(void) { @@ -63,7 +64,6 @@ int main(void) DEFINE(PT_SIZE, sizeof(struct pt_regs)); DEFINE(PT_AREG_END, offsetof (struct pt_regs, areg[XCHAL_NUM_AREGS])); DEFINE(PT_USER_SIZE, offsetof(struct pt_regs, areg[XCHAL_NUM_AREGS])); - BLANK(); /* struct task_struct */ DEFINE(TASK_PTRACE, offsetof (struct task_struct, ptrace)); @@ -73,27 +73,26 @@ int main(void) DEFINE(TASK_THREAD, offsetof (struct task_struct, thread)); DEFINE(TASK_THREAD_INFO, offsetof (struct task_struct, stack)); DEFINE(TASK_STRUCT_SIZE, sizeof (struct task_struct)); - BLANK(); /* struct thread_info (offset from start_struct) */ DEFINE(THREAD_RA, offsetof (struct task_struct, thread.ra)); DEFINE(THREAD_SP, offsetof (struct task_struct, thread.sp)); DEFINE(THREAD_CP_SAVE, offsetof (struct task_struct, thread.cp_save)); DEFINE(THREAD_CURRENT_DS, offsetof (struct task_struct, thread.current_ds)); - BLANK(); /* struct mm_struct */ DEFINE(MM_USERS, offsetof(struct mm_struct, mm_users)); DEFINE(MM_PGD, offsetof (struct mm_struct, pgd)); DEFINE(MM_CONTEXT, offsetof (struct mm_struct, context)); - BLANK(); - DEFINE(PT_SINGLESTEP_BIT, PT_SINGLESTEP_BIT); + + /* struct page */ + DEFINE(PAGE_FLAGS, offsetof(struct page, flags)); /* constants */ DEFINE(_CLONE_VM, CLONE_VM); DEFINE(_CLONE_UNTRACED, CLONE_UNTRACED); + DEFINE(PG_ARCH_1, PG_arch_1); return 0; } - diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S index 65741e3368e..91a689eca43 100644 --- a/arch/xtensa/kernel/entry.S +++ b/arch/xtensa/kernel/entry.S @@ -7,7 +7,7 @@ * License. See the file "COPYING" in the main directory of this archive * for more details. * - * Copyright (C) 2004-2005 by Tensilica Inc. + * Copyright (C) 2004-2007 by Tensilica Inc. * * Chris Zankel * @@ -169,7 +169,7 @@ _user_exception: * We have to save all registers up to the first '1' from * the right, except the current frame (bit 0). * Assume a2 is: 001001000110001 - * All regiser frames starting from the top fiel to the marked '1' + * All register frames starting from the top field to the marked '1' * must be saved. */ @@ -1590,7 +1590,7 @@ ENTRY(fast_second_level_miss) * The messy computation for 'pteval' above really simplifies * into the following: * - * pteval = ((pmdval - PAGE_OFFSET) & PAGE_MASK) | PAGE_KERNEL + * pteval = ((pmdval - PAGE_OFFSET) & PAGE_MASK) | PAGE_DIRECTORY */ movi a1, -PAGE_OFFSET @@ -1602,7 +1602,7 @@ ENTRY(fast_second_level_miss) or a0, a0, a1 # ... | PAGE_DIRECTORY /* - * We utilize all three wired-ways (7-9( to hold pmd translations. + * We utilize all three wired-ways (7-9) to hold pmd translations. * Memory regions are mapped to the DTLBs according to bits 28 and 29. * This allows to map the three most common regions to three different * DTLBs: @@ -1652,6 +1652,73 @@ ENTRY(fast_second_level_miss) 9: l32i a0, a1, TASK_ACTIVE_MM # unlikely case mm == 0 j 8b +#if (DCACHE_WAY_SIZE > PAGE_SIZE) + +2: /* Special case for cache aliasing. + * We (should) only get here if a clear_user_page, copy_user_page + * or the aliased cache flush functions got preemptively interrupted + * by another task. Re-establish temporary mapping to the + * TLBTEMP_BASE areas. + */ + + /* We shouldn't be in a double exception */ + + l32i a0, a2, PT_DEPC + bgeui a0, VALID_DOUBLE_EXCEPTION_ADDRESS, 2f + + /* Make sure the exception originated in the special functions */ + + movi a0, __tlbtemp_mapping_start + rsr a3, EPC_1 + bltu a3, a0, 2f + movi a0, __tlbtemp_mapping_end + bgeu a3, a0, 2f + + /* Check if excvaddr was in one of the TLBTEMP_BASE areas. */ + + movi a3, TLBTEMP_BASE_1 + rsr a0, EXCVADDR + bltu a0, a3, 2f + + addi a1, a0, -(2 << (DCACHE_ALIAS_ORDER + PAGE_SHIFT)) + bgeu a1, a3, 2f + + /* Check if we have to restore an ITLB mapping. */ + + movi a1, __tlbtemp_mapping_itlb + rsr a3, EPC_1 + sub a3, a3, a1 + + /* Calculate VPN */ + + movi a1, PAGE_MASK + and a1, a1, a0 + + /* Jump for ITLB entry */ + + bgez a3, 1f + + /* We can use up to two TLBTEMP areas, one for src and one for dst. */ + + extui a3, a0, PAGE_SHIFT + DCACHE_ALIAS_ORDER, 1 + add a1, a3, a1 + + /* PPN is in a6 for the first TLBTEMP area and in a7 for the second. */ + + mov a0, a6 + movnez a0, a7, a3 + j 3b + + /* ITLB entry. We only use dst in a6. */ + +1: witlb a6, a1 + isync + j 4b + + +#endif // DCACHE_WAY_SIZE > PAGE_SIZE + + 2: /* Invalid PGD, default exception handling */ movi a3, exc_table -- cgit v1.2.3