/* * TLB exception handling code for MIPS32 CPUs. * * Copyright (C) 1994, 1995, 1996 by Ralf Baechle and Andreas Busse * * Multi-cpu abstraction and reworking: * Copyright (C) 1996 David S. Miller (dm@engr.sgi.com) * * Carsten Langgaard, carstenl@mips.com * Copyright (C) 2000 MIPS Technologies, Inc. All rights reserved. * * Pete Popov, ppopov@pacbell.net * Added 36 bit phys address support. * Copyright (C) 2002 MontaVista Software, Inc. */ #include #include #include #include #include #include #include #include #include #include #include #include #define TLB_OPTIMIZE /* If you are paranoid, disable this. */ #ifdef CONFIG_64BIT_PHYS_ADDR /* We really only support 36 bit physical addresses on MIPS32 */ #define PTE_L lw #define PTE_S sw #define PTE_SRL srl #define P_MTC0 mtc0 #define PTE_HALF 4 /* pte_high contains pre-shifted, ready to go entry */ #define PTE_SIZE 8 #define PTEP_INDX_MSK 0xff0 #define PTE_INDX_MSK 0xff8 #define PTE_INDX_SHIFT 9 #define CONVERT_PTE(pte) #define PTE_MAKEWRITE_HIGH(pte, ptr) \ lw pte, 4(ptr); \ ori pte, (_PAGE_VALID | _PAGE_DIRTY); \ sw pte, 4(ptr); \ lw pte, 0(ptr); #define PTE_MAKEVALID_HIGH(pte, ptr) \ lw pte, 4(ptr); \ ori pte, pte, _PAGE_VALID; \ sw pte, 4(ptr); \ lw pte, 0(ptr); #else #define PTE_L lw #define PTE_S sw #define PTE_SRL srl #define P_MTC0 mtc0 #define PTE_HALF 0 #define PTE_SIZE 4 #define PTEP_INDX_MSK 0xff8 #define PTE_INDX_MSK 0xffc #define PTE_INDX_SHIFT 10 #define CONVERT_PTE(pte) srl pte, pte, 6 #define PTE_MAKEWRITE_HIGH(pte, ptr) #define PTE_MAKEVALID_HIGH(pte, ptr) #endif /* CONFIG_64BIT_PHYS_ADDR */ __INIT #ifdef CONFIG_64BIT_PHYS_ADDR #define GET_PTE_OFF(reg) #else #define GET_PTE_OFF(reg) srl reg, reg, 1 #endif /* * These handlers much be written in a relocatable manner * because based upon the cpu type an arbitrary one of the * following pieces of code will be copied to the KSEG0 * vector location. */ /* TLB refill, EXL == 0, MIPS32 version */ .set noreorder .set noat LEAF(except_vec0_r4000) .set mips3 #ifdef CONFIG_SMP mfc0 k1, CP0_CONTEXT la k0, pgd_current srl k1, 23 sll k1, 2 # log2(sizeof(pgd_t) addu k1, k0, k1 lw k1, (k1) #else lw k1, pgd_current # get pgd pointer #endif nop mfc0 k0, CP0_BADVADDR # Get faulting address srl k0, k0, _PGDIR_SHIFT # get pgd only bits sll k0, k0, 2 addu k1, k1, k0 # add in pgd offset mfc0 k0, CP0_CONTEXT # get context reg lw k1, (k1) GET_PTE_OFF(k0) # get pte offset and k0, k0, PTEP_INDX_MSK addu k1, k1, k0 # add in offset PTE_L k0, PTE_HALF(k1) # get even pte CONVERT_PTE(k0) P_MTC0 k0, CP0_ENTRYLO0 # load it PTE_L k1, (PTE_HALF+PTE_SIZE)(k1) # get odd pte CONVERT_PTE(k1) P_MTC0 k1, CP0_ENTRYLO1 # load it b 1f tlbwr # write random tlb entry 1: nop eret # return from trap END(except_vec0_r4000) /* * These are here to avoid putting ifdefs in tlb-r4k.c */ .set noreorder .set noat LEAF(except_vec0_nevada) .set mips3 PANIC("Nevada Exception Vec 0 called") END(except_vec0_nevada) .set noreorder .set noat LEAF(except_vec0_r4600) .set mips3 PANIC("R4600 Exception Vec 0 called") END(except_vec0_r4600) __FINIT /* * ABUSE of CPP macros 101. * * After this macro runs, the pte faulted on is * in register PTE, a ptr into the table in which * the pte belongs is in PTR. */ #ifdef CONFIG_SMP #define GET_PGD(scratch, ptr) \ mfc0 ptr, CP0_CONTEXT; \ la scratch, pgd_current;\ srl ptr, 23; \ sll ptr, 2; \ addu ptr, scratch, ptr; \ lw ptr, (ptr); #else #define GET_PGD(scratch, ptr) \ lw ptr, pgd_current; #endif #define LOAD_PTE(pte, ptr) \ GET_PGD(pte, ptr) \ mfc0 pte, CP0_BADVADDR; \ srl pte, pte, _PGDIR_SHIFT; \ sll pte, pte, 2; \ addu ptr, ptr, pte; \ mfc0 pte, CP0_BADVADDR; \ lw ptr, (ptr); \ srl pte, pte, PTE_INDX_SHIFT; \ and pte, pte, PTE_INDX_MSK; \ addu ptr, ptr, pte; \ PTE_L pte, (ptr); /* This places the even/odd pte pair in the page * table at PTR into ENTRYLO0 and ENTRYLO1 using * TMP as a scratch register. */ #define PTE_RELOAD(ptr, tmp) \ ori ptr, ptr, PTE_SIZE; \ xori ptr, ptr, PTE_SIZE; \ PTE_L tmp, (PTE_HALF+PTE_SIZE)(ptr); \ CONVERT_PTE(tmp); \ P_MTC0 tmp, CP0_ENTRYLO1; \ PTE_L ptr, PTE_HALF(ptr); \ CONVERT_PTE(ptr); \ P_MTC0 ptr, CP0_ENTRYLO0; #define DO_FAULT(write) \ .set noat; \ SAVE_ALL; \ mfc0 a2, CP0_BADVADDR; \ STI; \ .set at; \ move a0, sp; \ jal do_page_fault; \ li a1, write; \ j ret_from_exception; \ nop; \ .set noat; /* Check is PTE is present, if not then jump to LABEL. * PTR points to the page table where this PTE is located, * when the macro is done executing PTE will be restored * with it's original value. */ #define PTE_PRESENT(pte, ptr, label) \ andi pte, pte, (_PAGE_PRESENT | _PAGE_READ); \ xori pte, pte, (_PAGE_PRESENT | _PAGE_READ); \ bnez pte, label; \ PTE_L pte, (ptr); /* Make PTE valid, store result in PTR. */ #define PTE_MAKEVALID(pte, ptr) \ ori pte, pte, (_PAGE_VALID | _PAGE_ACCESSED); \ PTE_S pte, (ptr); /* Check if PTE can be written to, if not branch to LABEL. * Regardless restore PTE with value from PTR when done. */ #define PTE_WRITABLE(pte, ptr, label) \ andi pte, pte, (_PAGE_PRESENT | _PAGE_WRITE); \ xori pte, pte, (_PAGE_PRESENT | _PAGE_WRITE); \ bnez pte, label; \ PTE_L pte, (ptr); /* Make PTE writable, update software status bits as well, * then store at PTR. */ #define PTE_MAKEWRITE(pte, ptr) \ ori pte, pte, (_PAGE_ACCESSED | _PAGE_MODIFIED | \ _PAGE_VALID | _PAGE_DIRTY); \ PTE_S pte, (ptr); .set noreorder #define R5K_HAZARD nop .align 5 NESTED(handle_tlbl, PT_SIZE, sp) .set noat invalid_tlbl: #ifdef TLB_OPTIMIZE /* Test present bit in entry. */ LOAD_PTE(k0, k1) R5K_HAZARD tlbp PTE_PRESENT(k0, k1, nopage_tlbl) PTE_MAKEVALID_HIGH(k0, k1) PTE_MAKEVALID(k0, k1) PTE_RELOAD(k1, k0) nop b 1f tlbwi 1: nop .set mips3 eret .set mips0 #endif nopage_tlbl: DO_FAULT(0) END(handle_tlbl) .align 5 NESTED(handle_tlbs, PT_SIZE, sp) .set noat #ifdef TLB_OPTIMIZE .set mips3 li k0,0 LOAD_PTE(k0, k1) R5K_HAZARD tlbp # find faulting entry PTE_WRITABLE(k0, k1, nopage_tlbs) PTE_MAKEWRITE(k0, k1) PTE_MAKEWRITE_HIGH(k0, k1) PTE_RELOAD(k1, k0) nop b 1f tlbwi 1: nop .set mips3 eret .set mips0 #endif nopage_tlbs: DO_FAULT(1) END(handle_tlbs) .align 5 NESTED(handle_mod, PT_SIZE, sp) .set noat #ifdef TLB_OPTIMIZE .set mips3 LOAD_PTE(k0, k1) R5K_HAZARD tlbp # find faulting entry andi k0, k0, _PAGE_WRITE beqz k0, nowrite_mod PTE_L k0, (k1) /* Present and writable bits set, set accessed and dirty bits. */ PTE_MAKEWRITE(k0, k1) PTE_MAKEWRITE_HIGH(k0, k1) /* Now reload the entry into the tlb. */ PTE_RELOAD(k1, k0) nop b 1f tlbwi 1: nop .set mips3 eret .set mips0 #endif nowrite_mod: DO_FAULT(1) END(handle_mod)