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ARC: MMU Exception Handling
* MMU I-TLB / D-TLB Miss Exceptions - Fast Path TLB Refill Handler - slowpath TLB creation via do_page_fault() -> update_mmu_cache() * Duplicate PD Exception Handler Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta
parent
f1f3347da9
commit
cc562d2eae
@ -13,6 +13,7 @@
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/* Build Configuration Registers */
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#define ARC_REG_VECBASE_BCR 0x68
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#define ARC_REG_MMU_BCR 0x6f
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/* status32 Bits Positions */
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#define STATUS_H_BIT 0 /* CPU Halted */
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@ -36,6 +37,35 @@
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#define STATUS_U_MASK (1<<STATUS_U_BIT)
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#define STATUS_L_MASK (1<<STATUS_L_BIT)
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/*
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* ECR: Exception Cause Reg bits-n-pieces
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* [23:16] = Exception Vector
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* [15: 8] = Exception Cause Code
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* [ 7: 0] = Exception Parameters (for certain types only)
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*/
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#define ECR_VEC_MASK 0xff0000
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#define ECR_CODE_MASK 0x00ff00
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#define ECR_PARAM_MASK 0x0000ff
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/* Exception Cause Vector Values */
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#define ECR_V_INSN_ERR 0x02
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#define ECR_V_MACH_CHK 0x20
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#define ECR_V_ITLB_MISS 0x21
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#define ECR_V_DTLB_MISS 0x22
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#define ECR_V_PROTV 0x23
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/* Protection Violation Exception Cause Code Values */
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#define ECR_C_PROTV_INST_FETCH 0x00
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#define ECR_C_PROTV_LOAD 0x01
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#define ECR_C_PROTV_STORE 0x02
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#define ECR_C_PROTV_XCHG 0x03
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#define ECR_C_PROTV_MISALIG_DATA 0x04
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/* DTLB Miss Exception Cause Code Values */
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#define ECR_C_BIT_DTLB_LD_MISS 8
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#define ECR_C_BIT_DTLB_ST_MISS 9
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/* Auxiliary registers */
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#define AUX_IDENTITY 4
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#define AUX_INTR_VEC_BASE 0x25
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@ -58,6 +88,44 @@
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#define TIMER_CTRL_IE (1 << 0) /* Interupt when Count reachs limit */
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#define TIMER_CTRL_NH (1 << 1) /* Count only when CPU NOT halted */
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#if defined(CONFIG_ARC_MMU_V1)
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#define CONFIG_ARC_MMU_VER 1
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#elif defined(CONFIG_ARC_MMU_V2)
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#define CONFIG_ARC_MMU_VER 2
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#elif defined(CONFIG_ARC_MMU_V3)
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#define CONFIG_ARC_MMU_VER 3
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#else
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#error "Error: MMU ver"
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#endif
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/* MMU Management regs */
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#define ARC_REG_TLBPD0 0x405
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#define ARC_REG_TLBPD1 0x406
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#define ARC_REG_TLBINDEX 0x407
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#define ARC_REG_TLBCOMMAND 0x408
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#define ARC_REG_PID 0x409
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#define ARC_REG_SCRATCH_DATA0 0x418
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/* Bits in MMU PID register */
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#define MMU_ENABLE (1 << 31) /* Enable MMU for process */
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/* Error code if probe fails */
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#define TLB_LKUP_ERR 0x80000000
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/* TLB Commands */
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#define TLBWrite 0x1
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#define TLBRead 0x2
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#define TLBGetIndex 0x3
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#define TLBProbe 0x4
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#if (CONFIG_ARC_MMU_VER >= 2)
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#define TLBWriteNI 0x5 /* write JTLB without inv uTLBs */
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#define TLBIVUTLB 0x6 /* explicitly inv uTLBs */
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#else
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#undef TLBWriteNI /* These cmds don't exist on older MMU */
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#undef TLBIVUTLB
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#endif
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/* Instruction cache related Auxiliary registers */
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#define ARC_REG_IC_BCR 0x77 /* Build Config reg */
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#define ARC_REG_IC_IVIC 0x10
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@ -205,6 +273,24 @@ struct arc_fpu {
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* Build Configuration Registers, with encoded hardware config
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*/
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struct bcr_mmu_1_2 {
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#ifdef CONFIG_CPU_BIG_ENDIAN
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unsigned int ver:8, ways:4, sets:4, u_itlb:8, u_dtlb:8;
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#else
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unsigned int u_dtlb:8, u_itlb:8, sets:4, ways:4, ver:8;
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#endif
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};
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struct bcr_mmu_3 {
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#ifdef CONFIG_CPU_BIG_ENDIAN
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unsigned int ver:8, ways:4, sets:4, osm:1, reserv:3, pg_sz:4,
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u_itlb:4, u_dtlb:4;
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#else
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unsigned int u_dtlb:4, u_itlb:4, pg_sz:4, reserv:3, osm:1, sets:4,
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ways:4, ver:8;
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#endif
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};
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struct bcr_cache {
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#ifdef CONFIG_CPU_BIG_ENDIAN
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unsigned int pad:12, line_len:4, sz:4, config:4, ver:8;
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@ -218,12 +304,17 @@ struct bcr_cache {
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* Generic structures to hold build configuration used at runtime
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*/
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struct cpuinfo_arc_mmu {
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unsigned int ver, pg_sz, sets, ways, u_dtlb, u_itlb, num_tlb;
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};
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struct cpuinfo_arc_cache {
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unsigned int has_aliasing, sz, line_len, assoc, ver;
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};
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struct cpuinfo_arc {
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struct cpuinfo_arc_cache icache, dcache;
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struct cpuinfo_arc_mmu mmu;
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};
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extern struct cpuinfo_arc cpuinfo_arc700[];
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104
arch/arc/include/asm/tlb-mmu1.h
Normal file
104
arch/arc/include/asm/tlb-mmu1.h
Normal file
@ -0,0 +1,104 @@
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/*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef __ASM_TLB_MMU_V1_H__
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#define __ASM_TLB_MMU_V1_H__
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#if defined(__ASSEMBLY__) && defined(CONFIG_ARC_MMU_VER == 1)
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#include <asm/tlb.h>
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.macro TLB_WRITE_HEURISTICS
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#define JH_HACK1
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#undef JH_HACK2
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#undef JH_HACK3
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#ifdef JH_HACK3
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; Calculate set index for 2-way MMU
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; -avoiding use of GetIndex from MMU
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; and its unpleasant LFSR pseudo-random sequence
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;
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; r1 = TLBPD0 from TLB_RELOAD above
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;
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; -- jh_ex_way_set not cleared on startup
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; didn't want to change setup.c
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; hence extra instruction to clean
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;
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; -- should be in cache since in same line
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; as r0/r1 saves above
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;
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ld r0,[jh_ex_way_sel] ; victim pointer
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and r0,r0,1 ; clean
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xor.f r0,r0,1 ; flip
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st r0,[jh_ex_way_sel] ; store back
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asr r0,r1,12 ; get set # <<1, note bit 12=R=0
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or.nz r0,r0,1 ; set way bit
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and r0,r0,0xff ; clean
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sr r0,[ARC_REG_TLBINDEX]
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#endif
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#ifdef JH_HACK2
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; JH hack #2
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; Faster than hack #1 in non-thrash case, but hard-coded for 2-way MMU
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; Slower in thrash case (where it matters) because more code is executed
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; Inefficient due to two-register paradigm of this miss handler
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;
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/* r1 = data TLBPD0 at this point */
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lr r0,[eret] /* instruction address */
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xor r0,r0,r1 /* compare set # */
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and.f r0,r0,0x000fe000 /* 2-way MMU mask */
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bne 88f /* not in same set - no need to probe */
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lr r0,[eret] /* instruction address */
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and r0,r0,PAGE_MASK /* VPN of instruction address */
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; lr r1,[ARC_REG_TLBPD0] /* Data VPN+ASID - already in r1 from TLB_RELOAD*/
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and r1,r1,0xff /* Data ASID */
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or r0,r0,r1 /* Instruction address + Data ASID */
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lr r1,[ARC_REG_TLBPD0] /* save TLBPD0 containing data TLB*/
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sr r0,[ARC_REG_TLBPD0] /* write instruction address to TLBPD0 */
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sr TLBProbe, [ARC_REG_TLBCOMMAND] /* Look for instruction */
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lr r0,[ARC_REG_TLBINDEX] /* r0 = index where instruction is, if at all */
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sr r1,[ARC_REG_TLBPD0] /* restore TLBPD0 */
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xor r0,r0,1 /* flip bottom bit of data index */
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b.d 89f
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sr r0,[ARC_REG_TLBINDEX] /* and put it back */
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88:
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sr TLBGetIndex, [ARC_REG_TLBCOMMAND]
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89:
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#endif
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#ifdef JH_HACK1
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;
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; Always checks whether instruction will be kicked out by dtlb miss
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;
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mov_s r3, r1 ; save PD0 prepared by TLB_RELOAD in r3
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lr r0,[eret] /* instruction address */
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and r0,r0,PAGE_MASK /* VPN of instruction address */
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bmsk r1,r3,7 /* Data ASID, bits 7-0 */
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or_s r0,r0,r1 /* Instruction address + Data ASID */
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sr r0,[ARC_REG_TLBPD0] /* write instruction address to TLBPD0 */
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sr TLBProbe, [ARC_REG_TLBCOMMAND] /* Look for instruction */
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lr r0,[ARC_REG_TLBINDEX] /* r0 = index where instruction is, if at all */
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sr r3,[ARC_REG_TLBPD0] /* restore TLBPD0 */
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sr TLBGetIndex, [ARC_REG_TLBCOMMAND]
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lr r1,[ARC_REG_TLBINDEX] /* r1 = index where MMU wants to put data */
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cmp r0,r1 /* if no match on indices, go around */
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xor.eq r1,r1,1 /* flip bottom bit of data index */
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sr r1,[ARC_REG_TLBINDEX] /* and put it back */
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#endif
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.endm
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#endif
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#endif
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41
arch/arc/include/asm/tlb.h
Normal file
41
arch/arc/include/asm/tlb.h
Normal file
@ -0,0 +1,41 @@
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/*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef _ASM_ARC_TLB_H
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#define _ASM_ARC_TLB_H
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#ifdef __KERNEL__
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#include <asm/pgtable.h>
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/* Masks for actual TLB "PD"s */
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#define PTE_BITS_IN_PD0 (_PAGE_GLOBAL | _PAGE_PRESENT)
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#define PTE_BITS_IN_PD1 (PAGE_MASK | _PAGE_CACHEABLE | \
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_PAGE_EXECUTE | _PAGE_WRITE | _PAGE_READ | \
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_PAGE_K_EXECUTE | _PAGE_K_WRITE | _PAGE_K_READ)
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#ifndef __ASSEMBLY__
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#include <linux/pagemap.h>
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#include <asm-generic/tlb.h>
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#ifdef CONFIG_ARC_DBG_TLB_PARANOIA
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void tlb_paranoid_check(unsigned int pid_sw, unsigned long address);
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#else
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#define tlb_paranoid_check(a, b)
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#endif
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void arc_mmu_init(void);
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extern char *arc_mmu_mumbojumbo(int cpu_id, char *buf, int len);
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void __init read_decode_mmu_bcr(void);
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#endif /* __ASSEMBLY__ */
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#endif /* __KERNEL__ */
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#endif /* _ASM_ARC_TLB_H */
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@ -21,3 +21,270 @@ int asid_cache = FIRST_ASID;
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* see get_new_mmu_context (asm-arc/mmu_context.h)
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*/
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struct mm_struct *asid_mm_map[NUM_ASID + 1];
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/*
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* Routine to create a TLB entry
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*/
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void create_tlb(struct vm_area_struct *vma, unsigned long address, pte_t *ptep)
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{
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unsigned long flags;
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unsigned int idx, asid_or_sasid;
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unsigned long pd0_flags;
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/*
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* create_tlb() assumes that current->mm == vma->mm, since
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* -it ASID for TLB entry is fetched from MMU ASID reg (valid for curr)
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* -completes the lazy write to SASID reg (again valid for curr tsk)
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*
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* Removing the assumption involves
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* -Using vma->mm->context{ASID,SASID}, as opposed to MMU reg.
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* -Fix the TLB paranoid debug code to not trigger false negatives.
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* -More importantly it makes this handler inconsistent with fast-path
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* TLB Refill handler which always deals with "current"
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*
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* Lets see the use cases when current->mm != vma->mm and we land here
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* 1. execve->copy_strings()->__get_user_pages->handle_mm_fault
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* Here VM wants to pre-install a TLB entry for user stack while
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* current->mm still points to pre-execve mm (hence the condition).
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* However the stack vaddr is soon relocated (randomization) and
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* move_page_tables() tries to undo that TLB entry.
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* Thus not creating TLB entry is not any worse.
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*
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* 2. ptrace(POKETEXT) causes a CoW - debugger(current) inserting a
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* breakpoint in debugged task. Not creating a TLB now is not
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* performance critical.
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*
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* Both the cases above are not good enough for code churn.
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*/
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if (current->active_mm != vma->vm_mm)
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return;
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local_irq_save(flags);
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tlb_paranoid_check(vma->vm_mm->context.asid, address);
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address &= PAGE_MASK;
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/* update this PTE credentials */
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pte_val(*ptep) |= (_PAGE_PRESENT | _PAGE_ACCESSED);
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/* Create HW TLB entry Flags (in PD0) from PTE Flags */
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#if (CONFIG_ARC_MMU_VER <= 2)
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pd0_flags = ((pte_val(*ptep) & PTE_BITS_IN_PD0) >> 1);
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#else
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pd0_flags = ((pte_val(*ptep) & PTE_BITS_IN_PD0));
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#endif
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/* ASID for this task */
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asid_or_sasid = read_aux_reg(ARC_REG_PID) & 0xff;
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write_aux_reg(ARC_REG_TLBPD0, address | pd0_flags | asid_or_sasid);
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/* Load remaining info in PD1 (Page Frame Addr and Kx/Kw/Kr Flags) */
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write_aux_reg(ARC_REG_TLBPD1, (pte_val(*ptep) & PTE_BITS_IN_PD1));
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/* First verify if entry for this vaddr+ASID already exists */
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write_aux_reg(ARC_REG_TLBCOMMAND, TLBProbe);
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idx = read_aux_reg(ARC_REG_TLBINDEX);
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/*
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* If Not already present get a free slot from MMU.
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* Otherwise, Probe would have located the entry and set INDEX Reg
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* with existing location. This will cause Write CMD to over-write
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* existing entry with new PD0 and PD1
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*/
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if (likely(idx & TLB_LKUP_ERR))
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write_aux_reg(ARC_REG_TLBCOMMAND, TLBGetIndex);
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/*
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* Commit the Entry to MMU
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* It doesnt sound safe to use the TLBWriteNI cmd here
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* which doesn't flush uTLBs. I'd rather be safe than sorry.
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*/
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write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
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local_irq_restore(flags);
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}
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/* arch hook called by core VM at the end of handle_mm_fault( ),
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* when a new PTE is entered in Page Tables or an existing one
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* is modified. We aggresively pre-install a TLB entry
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*/
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void update_mmu_cache(struct vm_area_struct *vma, unsigned long vaddress,
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pte_t *ptep)
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{
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create_tlb(vma, vaddress, ptep);
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}
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/* Read the Cache Build Confuration Registers, Decode them and save into
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* the cpuinfo structure for later use.
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* No Validation is done here, simply read/convert the BCRs
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*/
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void __init read_decode_mmu_bcr(void)
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{
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unsigned int tmp;
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struct bcr_mmu_1_2 *mmu2; /* encoded MMU2 attr */
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struct bcr_mmu_3 *mmu3; /* encoded MMU3 attr */
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struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu;
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tmp = read_aux_reg(ARC_REG_MMU_BCR);
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mmu->ver = (tmp >> 24);
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if (mmu->ver <= 2) {
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mmu2 = (struct bcr_mmu_1_2 *)&tmp;
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mmu->pg_sz = PAGE_SIZE;
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mmu->sets = 1 << mmu2->sets;
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mmu->ways = 1 << mmu2->ways;
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mmu->u_dtlb = mmu2->u_dtlb;
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mmu->u_itlb = mmu2->u_itlb;
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} else {
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mmu3 = (struct bcr_mmu_3 *)&tmp;
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mmu->pg_sz = 512 << mmu3->pg_sz;
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mmu->sets = 1 << mmu3->sets;
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mmu->ways = 1 << mmu3->ways;
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mmu->u_dtlb = mmu3->u_dtlb;
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mmu->u_itlb = mmu3->u_itlb;
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}
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mmu->num_tlb = mmu->sets * mmu->ways;
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}
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void __init arc_mmu_init(void)
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{
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/*
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* ASID mgmt data structures are compile time init
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* asid_cache = FIRST_ASID and asid_mm_map[] all zeroes
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*/
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local_flush_tlb_all();
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/* Enable the MMU */
|
||||
write_aux_reg(ARC_REG_PID, MMU_ENABLE);
|
||||
}
|
||||
|
||||
/*
|
||||
* TLB Programmer's Model uses Linear Indexes: 0 to {255, 511} for 128 x {2,4}
|
||||
* The mapping is Column-first.
|
||||
* --------------------- -----------
|
||||
* |way0|way1|way2|way3| |way0|way1|
|
||||
* --------------------- -----------
|
||||
* [set0] | 0 | 1 | 2 | 3 | | 0 | 1 |
|
||||
* [set1] | 4 | 5 | 6 | 7 | | 2 | 3 |
|
||||
* ~ ~ ~ ~
|
||||
* [set127] | 508| 509| 510| 511| | 254| 255|
|
||||
* --------------------- -----------
|
||||
* For normal operations we don't(must not) care how above works since
|
||||
* MMU cmd getIndex(vaddr) abstracts that out.
|
||||
* However for walking WAYS of a SET, we need to know this
|
||||
*/
|
||||
#define SET_WAY_TO_IDX(mmu, set, way) ((set) * mmu->ways + (way))
|
||||
|
||||
/* Handling of Duplicate PD (TLB entry) in MMU.
|
||||
* -Could be due to buggy customer tapeouts or obscure kernel bugs
|
||||
* -MMU complaints not at the time of duplicate PD installation, but at the
|
||||
* time of lookup matching multiple ways.
|
||||
* -Ideally these should never happen - but if they do - workaround by deleting
|
||||
* the duplicate one.
|
||||
* -Knob to be verbose abt it.(TODO: hook them up to debugfs)
|
||||
*/
|
||||
volatile int dup_pd_verbose = 1;/* Be slient abt it or complain (default) */
|
||||
|
||||
void do_tlb_overlap_fault(unsigned long cause, unsigned long address,
|
||||
struct pt_regs *regs)
|
||||
{
|
||||
int set, way, n;
|
||||
unsigned int pd0[4], pd1[4]; /* assume max 4 ways */
|
||||
unsigned long flags, is_valid;
|
||||
struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu;
|
||||
|
||||
local_irq_save(flags);
|
||||
|
||||
/* re-enable the MMU */
|
||||
write_aux_reg(ARC_REG_PID, MMU_ENABLE | read_aux_reg(ARC_REG_PID));
|
||||
|
||||
/* loop thru all sets of TLB */
|
||||
for (set = 0; set < mmu->sets; set++) {
|
||||
|
||||
/* read out all the ways of current set */
|
||||
for (way = 0, is_valid = 0; way < mmu->ways; way++) {
|
||||
write_aux_reg(ARC_REG_TLBINDEX,
|
||||
SET_WAY_TO_IDX(mmu, set, way));
|
||||
write_aux_reg(ARC_REG_TLBCOMMAND, TLBRead);
|
||||
pd0[way] = read_aux_reg(ARC_REG_TLBPD0);
|
||||
pd1[way] = read_aux_reg(ARC_REG_TLBPD1);
|
||||
is_valid |= pd0[way] & _PAGE_PRESENT;
|
||||
}
|
||||
|
||||
/* If all the WAYS in SET are empty, skip to next SET */
|
||||
if (!is_valid)
|
||||
continue;
|
||||
|
||||
/* Scan the set for duplicate ways: needs a nested loop */
|
||||
for (way = 0; way < mmu->ways; way++) {
|
||||
if (!pd0[way])
|
||||
continue;
|
||||
|
||||
for (n = way + 1; n < mmu->ways; n++) {
|
||||
if ((pd0[way] & PAGE_MASK) ==
|
||||
(pd0[n] & PAGE_MASK)) {
|
||||
|
||||
if (dup_pd_verbose) {
|
||||
pr_info("Duplicate PD's @"
|
||||
"[%d:%d]/[%d:%d]\n",
|
||||
set, way, set, n);
|
||||
pr_info("TLBPD0[%u]: %08x\n",
|
||||
way, pd0[way]);
|
||||
}
|
||||
|
||||
/*
|
||||
* clear entry @way and not @n. This is
|
||||
* critical to our optimised loop
|
||||
*/
|
||||
pd0[way] = pd1[way] = 0;
|
||||
write_aux_reg(ARC_REG_TLBINDEX,
|
||||
SET_WAY_TO_IDX(mmu, set, way));
|
||||
__tlb_entry_erase();
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
local_irq_restore(flags);
|
||||
}
|
||||
|
||||
/***********************************************************************
|
||||
* Diagnostic Routines
|
||||
* -Called from Low Level TLB Hanlders if things don;t look good
|
||||
**********************************************************************/
|
||||
|
||||
#ifdef CONFIG_ARC_DBG_TLB_PARANOIA
|
||||
|
||||
/*
|
||||
* Low Level ASM TLB handler calls this if it finds that HW and SW ASIDS
|
||||
* don't match
|
||||
*/
|
||||
void print_asid_mismatch(int is_fast_path)
|
||||
{
|
||||
int pid_sw, pid_hw;
|
||||
pid_sw = current->active_mm->context.asid;
|
||||
pid_hw = read_aux_reg(ARC_REG_PID) & 0xff;
|
||||
|
||||
pr_emerg("ASID Mismatch in %s Path Handler: sw-pid=0x%x hw-pid=0x%x\n",
|
||||
is_fast_path ? "Fast" : "Slow", pid_sw, pid_hw);
|
||||
|
||||
__asm__ __volatile__("flag 1");
|
||||
}
|
||||
|
||||
void tlb_paranoid_check(unsigned int pid_sw, unsigned long addr)
|
||||
{
|
||||
unsigned int pid_hw;
|
||||
|
||||
pid_hw = read_aux_reg(ARC_REG_PID) & 0xff;
|
||||
|
||||
if (addr < 0x70000000 && ((pid_hw != pid_sw) || (pid_sw == NO_ASID)))
|
||||
print_asid_mismatch(0);
|
||||
}
|
||||
#endif
|
||||
|
||||
351
arch/arc/mm/tlbex.S
Normal file
351
arch/arc/mm/tlbex.S
Normal file
@ -0,0 +1,351 @@
|
||||
/*
|
||||
* TLB Exception Handling for ARC
|
||||
*
|
||||
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
|
||||
*
|
||||
* This program is free software; you can redistribute it and/or modify
|
||||
* it under the terms of the GNU General Public License version 2 as
|
||||
* published by the Free Software Foundation.
|
||||
*
|
||||
* Vineetg: April 2011 :
|
||||
* -MMU v1: moved out legacy code into a seperate file
|
||||
* -MMU v3: PD{0,1} bits layout changed: They don't overlap anymore,
|
||||
* helps avoid a shift when preparing PD0 from PTE
|
||||
*
|
||||
* Vineetg: July 2009
|
||||
* -For MMU V2, we need not do heuristics at the time of commiting a D-TLB
|
||||
* entry, so that it doesn't knock out it's I-TLB entry
|
||||
* -Some more fine tuning:
|
||||
* bmsk instead of add, asl.cc instead of branch, delay slot utilise etc
|
||||
*
|
||||
* Vineetg: July 2009
|
||||
* -Practically rewrote the I/D TLB Miss handlers
|
||||
* Now 40 and 135 instructions a peice as compared to 131 and 449 resp.
|
||||
* Hence Leaner by 1.5 K
|
||||
* Used Conditional arithmetic to replace excessive branching
|
||||
* Also used short instructions wherever possible
|
||||
*
|
||||
* Vineetg: Aug 13th 2008
|
||||
* -Passing ECR (Exception Cause REG) to do_page_fault( ) for printing
|
||||
* more information in case of a Fatality
|
||||
*
|
||||
* Vineetg: March 25th Bug #92690
|
||||
* -Added Debug Code to check if sw-ASID == hw-ASID
|
||||
|
||||
* Rahul Trivedi, Amit Bhor: Codito Technologies 2004
|
||||
*/
|
||||
|
||||
.cpu A7
|
||||
|
||||
#include <linux/linkage.h>
|
||||
#include <asm/entry.h>
|
||||
#include <asm/tlb.h>
|
||||
#include <asm/pgtable.h>
|
||||
#include <asm/arcregs.h>
|
||||
#include <asm/cache.h>
|
||||
#include <asm/processor.h>
|
||||
#if (CONFIG_ARC_MMU_VER == 1)
|
||||
#include <asm/tlb-mmu1.h>
|
||||
#endif
|
||||
|
||||
;--------------------------------------------------------------------------
|
||||
; scratch memory to save the registers (r0-r3) used to code TLB refill Handler
|
||||
; For details refer to comments before TLBMISS_FREEUP_REGS below
|
||||
;--------------------------------------------------------------------------
|
||||
|
||||
.section .data
|
||||
.global ex_saved_reg1
|
||||
.align 1 << L1_CACHE_SHIFT ; IMP: Must be Cache Line aligned
|
||||
.type ex_saved_reg1, @object
|
||||
.size ex_saved_reg1, 16
|
||||
ex_saved_reg1:
|
||||
.zero 16
|
||||
|
||||
;============================================================================
|
||||
; Troubleshooting Stuff
|
||||
;============================================================================
|
||||
|
||||
; Linux keeps ASID (Address Space ID) in task->active_mm->context.asid
|
||||
; When Creating TLB Entries, instead of doing 3 dependent loads from memory,
|
||||
; we use the MMU PID Reg to get current ASID.
|
||||
; In bizzare scenrios SW and HW ASID can get out-of-sync which is trouble.
|
||||
; So we try to detect this in TLB Mis shandler
|
||||
|
||||
|
||||
.macro DBG_ASID_MISMATCH
|
||||
|
||||
#ifdef CONFIG_ARC_DBG_TLB_PARANOIA
|
||||
|
||||
; make sure h/w ASID is same as s/w ASID
|
||||
|
||||
GET_CURR_TASK_ON_CPU r3
|
||||
ld r0, [r3, TASK_ACT_MM]
|
||||
ld r0, [r0, MM_CTXT+MM_CTXT_ASID]
|
||||
|
||||
lr r1, [ARC_REG_PID]
|
||||
and r1, r1, 0xFF
|
||||
breq r1, r0, 5f
|
||||
|
||||
; Error if H/w and S/w ASID don't match, but NOT if in kernel mode
|
||||
lr r0, [erstatus]
|
||||
bbit0 r0, STATUS_U_BIT, 5f
|
||||
|
||||
; We sure are in troubled waters, Flag the error, but to do so
|
||||
; need to switch to kernel mode stack to call error routine
|
||||
GET_TSK_STACK_BASE r3, sp
|
||||
|
||||
; Call printk to shoutout aloud
|
||||
mov r0, 1
|
||||
j print_asid_mismatch
|
||||
|
||||
5: ; ASIDs match so proceed normally
|
||||
nop
|
||||
|
||||
#endif
|
||||
|
||||
.endm
|
||||
|
||||
;============================================================================
|
||||
;TLB Miss handling Code
|
||||
;============================================================================
|
||||
|
||||
;-----------------------------------------------------------------------------
|
||||
; This macro does the page-table lookup for the faulting address.
|
||||
; OUT: r0 = PTE faulted on, r1 = ptr to PTE, r2 = Faulting V-address
|
||||
.macro LOAD_FAULT_PTE
|
||||
|
||||
lr r2, [efa]
|
||||
|
||||
lr r1, [ARC_REG_SCRATCH_DATA0] ; current pgd
|
||||
|
||||
lsr r0, r2, PGDIR_SHIFT ; Bits for indexing into PGD
|
||||
ld.as r1, [r1, r0] ; PGD entry corresp to faulting addr
|
||||
and.f r1, r1, PAGE_MASK ; Ignoring protection and other flags
|
||||
; contains Ptr to Page Table
|
||||
bz.d do_slow_path_pf ; if no Page Table, do page fault
|
||||
|
||||
; Get the PTE entry: The idea is
|
||||
; (1) x = addr >> PAGE_SHIFT -> masks page-off bits from @fault-addr
|
||||
; (2) y = x & (PTRS_PER_PTE - 1) -> to get index
|
||||
; (3) z = pgtbl[y]
|
||||
; To avoid the multiply by in end, we do the -2, <<2 below
|
||||
|
||||
lsr r0, r2, (PAGE_SHIFT - 2)
|
||||
and r0, r0, ( (PTRS_PER_PTE - 1) << 2)
|
||||
ld.aw r0, [r1, r0] ; get PTE and PTE ptr for fault addr
|
||||
|
||||
.endm
|
||||
|
||||
;-----------------------------------------------------------------
|
||||
; Convert Linux PTE entry into TLB entry
|
||||
; A one-word PTE entry is programmed as two-word TLB Entry [PD0:PD1] in mmu
|
||||
; IN: r0 = PTE, r1 = ptr to PTE
|
||||
|
||||
.macro CONV_PTE_TO_TLB
|
||||
and r3, r0, PTE_BITS_IN_PD1 ; Extract permission flags+PFN from PTE
|
||||
sr r3, [ARC_REG_TLBPD1] ; these go in PD1
|
||||
|
||||
and r2, r0, PTE_BITS_IN_PD0 ; Extract other PTE flags: (V)alid, (G)lb
|
||||
#if (CONFIG_ARC_MMU_VER <= 2) /* Neednot be done with v3 onwards */
|
||||
lsr r2, r2 ; shift PTE flags to match layout in PD0
|
||||
#endif
|
||||
|
||||
lr r3,[ARC_REG_TLBPD0] ; MMU prepares PD0 with vaddr and asid
|
||||
|
||||
or r3, r3, r2 ; S | vaddr | {sasid|asid}
|
||||
sr r3,[ARC_REG_TLBPD0] ; rewrite PD0
|
||||
.endm
|
||||
|
||||
;-----------------------------------------------------------------
|
||||
; Commit the TLB entry into MMU
|
||||
|
||||
.macro COMMIT_ENTRY_TO_MMU
|
||||
|
||||
/* Get free TLB slot: Set = computed from vaddr, way = random */
|
||||
sr TLBGetIndex, [ARC_REG_TLBCOMMAND]
|
||||
|
||||
/* Commit the Write */
|
||||
#if (CONFIG_ARC_MMU_VER >= 2) /* introduced in v2 */
|
||||
sr TLBWriteNI, [ARC_REG_TLBCOMMAND]
|
||||
#else
|
||||
sr TLBWrite, [ARC_REG_TLBCOMMAND]
|
||||
#endif
|
||||
.endm
|
||||
|
||||
;-----------------------------------------------------------------
|
||||
; ARC700 Exception Handling doesn't auto-switch stack and it only provides
|
||||
; ONE scratch AUX reg "ARC_REG_SCRATCH_DATA0"
|
||||
;
|
||||
; For Non-SMP, the scratch AUX reg is repurposed to cache task PGD, so a
|
||||
; "global" is used to free-up FIRST core reg to be able to code the rest of
|
||||
; exception prologue (IRQ auto-disabled on Exceptions, so it's IRQ-safe).
|
||||
; Since the Fast Path TLB Miss handler is coded with 4 regs, the remaining 3
|
||||
; need to be saved as well by extending the "global" to be 4 words. Hence
|
||||
; ".size ex_saved_reg1, 16"
|
||||
; [All of this dance is to avoid stack switching for each TLB Miss, since we
|
||||
; only need to save only a handful of regs, as opposed to complete reg file]
|
||||
|
||||
; As simple as that....
|
||||
|
||||
.macro TLBMISS_FREEUP_REGS
|
||||
st r0, [@ex_saved_reg1]
|
||||
mov_s r0, @ex_saved_reg1
|
||||
st_s r1, [r0, 4]
|
||||
st_s r2, [r0, 8]
|
||||
st_s r3, [r0, 12]
|
||||
|
||||
; VERIFY if the ASID in MMU-PID Reg is same as
|
||||
; one in Linux data structures
|
||||
|
||||
DBG_ASID_MISMATCH
|
||||
.endm
|
||||
|
||||
;-----------------------------------------------------------------
|
||||
.macro TLBMISS_RESTORE_REGS
|
||||
mov_s r0, @ex_saved_reg1
|
||||
ld_s r3, [r0,12]
|
||||
ld_s r2, [r0, 8]
|
||||
ld_s r1, [r0, 4]
|
||||
ld_s r0, [r0]
|
||||
.endm
|
||||
|
||||
.section .text, "ax",@progbits ;Fast Path Code, candidate for ICCM
|
||||
|
||||
;-----------------------------------------------------------------------------
|
||||
; I-TLB Miss Exception Handler
|
||||
;-----------------------------------------------------------------------------
|
||||
|
||||
ARC_ENTRY EV_TLBMissI
|
||||
|
||||
TLBMISS_FREEUP_REGS
|
||||
|
||||
;----------------------------------------------------------------
|
||||
; Get the PTE corresponding to V-addr accessed
|
||||
LOAD_FAULT_PTE
|
||||
|
||||
;----------------------------------------------------------------
|
||||
; VERIFY_PTE: Check if PTE permissions approp for executing code
|
||||
cmp_s r2, VMALLOC_START
|
||||
mov.lo r2, (_PAGE_PRESENT | _PAGE_READ | _PAGE_EXECUTE)
|
||||
mov.hs r2, (_PAGE_PRESENT | _PAGE_K_READ | _PAGE_K_EXECUTE)
|
||||
|
||||
and r3, r0, r2 ; Mask out NON Flag bits from PTE
|
||||
xor.f r3, r3, r2 ; check ( ( pte & flags_test ) == flags_test )
|
||||
bnz do_slow_path_pf
|
||||
|
||||
; Let Linux VM know that the page was accessed
|
||||
or r0, r0, (_PAGE_PRESENT | _PAGE_ACCESSED) ; set Accessed Bit
|
||||
st_s r0, [r1] ; Write back PTE
|
||||
|
||||
CONV_PTE_TO_TLB
|
||||
COMMIT_ENTRY_TO_MMU
|
||||
TLBMISS_RESTORE_REGS
|
||||
rtie
|
||||
|
||||
ARC_EXIT EV_TLBMissI
|
||||
|
||||
;-----------------------------------------------------------------------------
|
||||
; D-TLB Miss Exception Handler
|
||||
;-----------------------------------------------------------------------------
|
||||
|
||||
ARC_ENTRY EV_TLBMissD
|
||||
|
||||
TLBMISS_FREEUP_REGS
|
||||
|
||||
;----------------------------------------------------------------
|
||||
; Get the PTE corresponding to V-addr accessed
|
||||
; If PTE exists, it will setup, r0 = PTE, r1 = Ptr to PTE
|
||||
LOAD_FAULT_PTE
|
||||
|
||||
;----------------------------------------------------------------
|
||||
; VERIFY_PTE: Chk if PTE permissions approp for data access (R/W/R+W)
|
||||
|
||||
mov_s r2, 0
|
||||
lr r3, [ecr]
|
||||
btst_s r3, ECR_C_BIT_DTLB_LD_MISS ; Read Access
|
||||
or.nz r2, r2, _PAGE_READ ; chk for Read flag in PTE
|
||||
btst_s r3, ECR_C_BIT_DTLB_ST_MISS ; Write Access
|
||||
or.nz r2, r2, _PAGE_WRITE ; chk for Write flag in PTE
|
||||
; Above laddering takes care of XCHG access
|
||||
; which is both Read and Write
|
||||
|
||||
; If kernel mode access, ; make _PAGE_xx flags as _PAGE_K_xx
|
||||
; For copy_(to|from)_user, despite exception taken in kernel mode,
|
||||
; this code is not hit, because EFA would still be the user mode
|
||||
; address (EFA < 0x6000_0000).
|
||||
; This code is for legit kernel mode faults, vmalloc specifically
|
||||
; (EFA: 0x7000_0000 to 0x7FFF_FFFF)
|
||||
|
||||
lr r3, [efa]
|
||||
cmp r3, VMALLOC_START - 1 ; If kernel mode access
|
||||
asl.hi r2, r2, 3 ; make _PAGE_xx flags as _PAGE_K_xx
|
||||
or r2, r2, _PAGE_PRESENT ; Common flag for K/U mode
|
||||
|
||||
; By now, r2 setup with all the Flags we need to check in PTE
|
||||
and r3, r0, r2 ; Mask out NON Flag bits from PTE
|
||||
brne.d r3, r2, do_slow_path_pf ; is ((pte & flags_test) == flags_test)
|
||||
|
||||
;----------------------------------------------------------------
|
||||
; UPDATE_PTE: Let Linux VM know that page was accessed/dirty
|
||||
lr r3, [ecr]
|
||||
or r0, r0, (_PAGE_PRESENT | _PAGE_ACCESSED) ; Accessed bit always
|
||||
btst_s r3, ECR_C_BIT_DTLB_ST_MISS ; See if it was a Write Access ?
|
||||
or.nz r0, r0, _PAGE_MODIFIED ; if Write, set Dirty bit as well
|
||||
st_s r0, [r1] ; Write back PTE
|
||||
|
||||
CONV_PTE_TO_TLB
|
||||
|
||||
#if (CONFIG_ARC_MMU_VER == 1)
|
||||
; MMU with 2 way set assoc J-TLB, needs some help in pathetic case of
|
||||
; memcpy where 3 parties contend for 2 ways, ensuing a livelock.
|
||||
; But only for old MMU or one with Metal Fix
|
||||
TLB_WRITE_HEURISTICS
|
||||
#endif
|
||||
|
||||
COMMIT_ENTRY_TO_MMU
|
||||
TLBMISS_RESTORE_REGS
|
||||
rtie
|
||||
|
||||
;-------- Common routine to call Linux Page Fault Handler -----------
|
||||
do_slow_path_pf:
|
||||
|
||||
; Restore the 4-scratch regs saved by fast path miss handler
|
||||
TLBMISS_RESTORE_REGS
|
||||
|
||||
; Slow path TLB Miss handled as a regular ARC Exception
|
||||
; (stack switching / save the complete reg-file).
|
||||
; That requires freeing up r9
|
||||
EXCPN_PROLOG_FREEUP_REG r9
|
||||
|
||||
lr r9, [erstatus]
|
||||
|
||||
SWITCH_TO_KERNEL_STK
|
||||
SAVE_ALL_SYS
|
||||
|
||||
; ------- setup args for Linux Page fault Hanlder ---------
|
||||
mov_s r0, sp
|
||||
lr r2, [efa]
|
||||
lr r3, [ecr]
|
||||
|
||||
; Both st and ex imply WRITE access of some sort, hence do_page_fault( )
|
||||
; invoked with write=1 for DTLB-st/ex Miss and write=0 for ITLB miss or
|
||||
; DTLB-ld Miss
|
||||
; DTLB Miss Cause code is ld = 0x01 , st = 0x02, ex = 0x03
|
||||
; Following code uses that fact that st/ex have one bit in common
|
||||
|
||||
btst_s r3, ECR_C_BIT_DTLB_ST_MISS
|
||||
mov.z r1, 0
|
||||
mov.nz r1, 1
|
||||
|
||||
; We don't want exceptions to be disabled while the fault is handled.
|
||||
; Now that we have saved the context we return from exception hence
|
||||
; exceptions get re-enable
|
||||
|
||||
FAKE_RET_FROM_EXCPN r9
|
||||
|
||||
bl do_page_fault
|
||||
b ret_from_exception
|
||||
|
||||
ARC_EXIT EV_TLBMissD
|
||||
|
||||
ARC_ENTRY EV_TLBMissB ; Bogus entry to measure sz of DTLBMiss hdlr
|
||||
Loading…
Reference in New Issue
Block a user