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>

arch/arc/include/asm/arcregs.h

@@ -13,6 +13,7 @@
 
 /* Build Configuration Registers */
 #define ARC_REG_VECBASE_BCR	0x68
+#define ARC_REG_MMU_BCR		0x6f
 
 /* status32 Bits Positions */
 #define STATUS_H_BIT		0	/* CPU Halted */
@@ -36,6 +37,35 @@
 #define STATUS_U_MASK		(1<<STATUS_U_BIT)
 #define STATUS_L_MASK		(1<<STATUS_L_BIT)
 
+/*
+ * ECR: Exception Cause Reg bits-n-pieces
+ * [23:16] = Exception Vector
+ * [15: 8] = Exception Cause Code
+ * [ 7: 0] = Exception Parameters (for certain types only)
+ */
+#define ECR_VEC_MASK			0xff0000
+#define ECR_CODE_MASK			0x00ff00
+#define ECR_PARAM_MASK			0x0000ff
+
+/* Exception Cause Vector Values */
+#define ECR_V_INSN_ERR			0x02
+#define ECR_V_MACH_CHK			0x20
+#define ECR_V_ITLB_MISS			0x21
+#define ECR_V_DTLB_MISS			0x22
+#define ECR_V_PROTV			0x23
+
+/* Protection Violation Exception Cause Code Values */
+#define ECR_C_PROTV_INST_FETCH		0x00
+#define ECR_C_PROTV_LOAD		0x01
+#define ECR_C_PROTV_STORE		0x02
+#define ECR_C_PROTV_XCHG		0x03
+#define ECR_C_PROTV_MISALIG_DATA	0x04
+
+/* DTLB Miss Exception Cause Code Values */
+#define ECR_C_BIT_DTLB_LD_MISS		8
+#define ECR_C_BIT_DTLB_ST_MISS		9
+
+
 /* Auxiliary registers */
 #define AUX_IDENTITY		4
 #define AUX_INTR_VEC_BASE	0x25
@@ -58,6 +88,44 @@
 #define TIMER_CTRL_IE		(1 << 0) /* Interupt when Count reachs limit */
 #define TIMER_CTRL_NH		(1 << 1) /* Count only when CPU NOT halted */
 
+#if defined(CONFIG_ARC_MMU_V1)
+#define CONFIG_ARC_MMU_VER 1
+#elif defined(CONFIG_ARC_MMU_V2)
+#define CONFIG_ARC_MMU_VER 2
+#elif defined(CONFIG_ARC_MMU_V3)
+#define CONFIG_ARC_MMU_VER 3
+#else
+#error "Error: MMU ver"
+#endif
+
+/* MMU Management regs */
+#define ARC_REG_TLBPD0		0x405
+#define ARC_REG_TLBPD1		0x406
+#define ARC_REG_TLBINDEX	0x407
+#define ARC_REG_TLBCOMMAND	0x408
+#define ARC_REG_PID		0x409
+#define ARC_REG_SCRATCH_DATA0	0x418
+
+/* Bits in MMU PID register */
+#define MMU_ENABLE		(1 << 31)	/* Enable MMU for process */
+
+/* Error code if probe fails */
+#define TLB_LKUP_ERR		0x80000000
+
+/* TLB Commands */
+#define TLBWrite    0x1
+#define TLBRead     0x2
+#define TLBGetIndex 0x3
+#define TLBProbe    0x4
+
+#if (CONFIG_ARC_MMU_VER >= 2)
+#define TLBWriteNI  0x5		/* write JTLB without inv uTLBs */
+#define TLBIVUTLB   0x6		/* explicitly inv uTLBs */
+#else
+#undef TLBWriteNI		/* These cmds don't exist on older MMU */
+#undef TLBIVUTLB
+#endif
+
 /* Instruction cache related Auxiliary registers */
 #define ARC_REG_IC_BCR		0x77	/* Build Config reg */
 #define ARC_REG_IC_IVIC		0x10
@@ -205,6 +273,24 @@ struct arc_fpu {
  * Build Configuration Registers, with encoded hardware config
  */
 
+struct bcr_mmu_1_2 {
+#ifdef CONFIG_CPU_BIG_ENDIAN
+	unsigned int ver:8, ways:4, sets:4, u_itlb:8, u_dtlb:8;
+#else
+	unsigned int u_dtlb:8, u_itlb:8, sets:4, ways:4, ver:8;
+#endif
+};
+
+struct bcr_mmu_3 {
+#ifdef CONFIG_CPU_BIG_ENDIAN
+	unsigned int ver:8, ways:4, sets:4, osm:1, reserv:3, pg_sz:4,
+		     u_itlb:4, u_dtlb:4;
+#else
+	unsigned int u_dtlb:4, u_itlb:4, pg_sz:4, reserv:3, osm:1, sets:4,
+		     ways:4, ver:8;
+#endif
+};
+
 struct bcr_cache {
 #ifdef CONFIG_CPU_BIG_ENDIAN
 	unsigned int pad:12, line_len:4, sz:4, config:4, ver:8;
@@ -218,12 +304,17 @@ struct bcr_cache {
  * Generic structures to hold build configuration used at runtime
  */
 
+struct cpuinfo_arc_mmu {
+	unsigned int ver, pg_sz, sets, ways, u_dtlb, u_itlb, num_tlb;
+};
+
 struct cpuinfo_arc_cache {
 	unsigned int has_aliasing, sz, line_len, assoc, ver;
 };
 
 struct cpuinfo_arc {
 	struct cpuinfo_arc_cache icache, dcache;
+	struct cpuinfo_arc_mmu mmu;
 };
 
 extern struct cpuinfo_arc cpuinfo_arc700[];

arch/arc/include/asm/tlb-mmu1.h

@@ -0,0 +1,104 @@
+/*
+ * 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.
+ */
+
+#ifndef __ASM_TLB_MMU_V1_H__
+#define __ASM_TLB_MMU_V1_H__
+
+#if defined(__ASSEMBLY__) && defined(CONFIG_ARC_MMU_VER == 1)
+
+#include <asm/tlb.h>
+
+.macro TLB_WRITE_HEURISTICS
+
+#define JH_HACK1
+#undef JH_HACK2
+#undef JH_HACK3
+
+#ifdef JH_HACK3
+; Calculate set index for 2-way MMU
+; -avoiding use of GetIndex from MMU
+;   and its unpleasant LFSR pseudo-random sequence
+;
+; r1 = TLBPD0 from TLB_RELOAD above
+;
+; -- jh_ex_way_set not cleared on startup
+;    didn't want to change setup.c
+;    hence extra instruction to clean
+;
+; -- should be in cache since in same line
+;    as r0/r1 saves above
+;
+ld  r0,[jh_ex_way_sel]  ; victim pointer
+and r0,r0,1         ; clean
+xor.f   r0,r0,1         ; flip
+st  r0,[jh_ex_way_sel]  ; store back
+asr r0,r1,12        ; get set # <<1, note bit 12=R=0
+or.nz   r0,r0,1         ; set way bit
+and r0,r0,0xff      ; clean
+sr  r0,[ARC_REG_TLBINDEX]
+#endif
+
+#ifdef JH_HACK2
+; JH hack #2
+;  Faster than hack #1 in non-thrash case, but hard-coded for 2-way MMU
+;  Slower in thrash case (where it matters) because more code is executed
+;  Inefficient due to two-register paradigm of this miss handler
+;
+/* r1 = data TLBPD0 at this point */
+lr      r0,[eret]               /* instruction address */
+xor     r0,r0,r1                /* compare set #       */
+and.f   r0,r0,0x000fe000        /* 2-way MMU mask      */
+bne     88f                     /* not in same set - no need to probe */
+
+lr      r0,[eret]               /* instruction address */
+and     r0,r0,PAGE_MASK         /* VPN of instruction address */
+; lr  r1,[ARC_REG_TLBPD0]     /* Data VPN+ASID - already in r1 from TLB_RELOAD*/
+and     r1,r1,0xff              /* Data ASID */
+or      r0,r0,r1                /* Instruction address + Data ASID */
+
+lr      r1,[ARC_REG_TLBPD0]     /* save TLBPD0 containing data TLB*/
+sr      r0,[ARC_REG_TLBPD0]     /* write instruction address to TLBPD0 */
+sr      TLBProbe, [ARC_REG_TLBCOMMAND] /* Look for instruction */
+lr      r0,[ARC_REG_TLBINDEX]   /* r0 = index where instruction is, if at all */
+sr      r1,[ARC_REG_TLBPD0]     /* restore TLBPD0 */
+
+xor     r0,r0,1                 /* flip bottom bit of data index */
+b.d     89f
+sr      r0,[ARC_REG_TLBINDEX]   /* and put it back */
+88:
+sr  TLBGetIndex, [ARC_REG_TLBCOMMAND]
+89:
+#endif
+
+#ifdef JH_HACK1
+;
+; Always checks whether instruction will be kicked out by dtlb miss
+;
+mov_s   r3, r1                  ; save PD0 prepared by TLB_RELOAD in r3
+lr      r0,[eret]               /* instruction address */
+and     r0,r0,PAGE_MASK         /* VPN of instruction address */
+bmsk    r1,r3,7                 /* Data ASID, bits 7-0 */
+or_s    r0,r0,r1                /* Instruction address + Data ASID */
+
+sr      r0,[ARC_REG_TLBPD0]     /* write instruction address to TLBPD0 */
+sr      TLBProbe, [ARC_REG_TLBCOMMAND] /* Look for instruction */
+lr      r0,[ARC_REG_TLBINDEX]   /* r0 = index where instruction is, if at all */
+sr      r3,[ARC_REG_TLBPD0]     /* restore TLBPD0 */
+
+sr      TLBGetIndex, [ARC_REG_TLBCOMMAND]
+lr      r1,[ARC_REG_TLBINDEX]   /* r1 = index where MMU wants to put data */
+cmp     r0,r1                   /* if no match on indices, go around */
+xor.eq  r1,r1,1                 /* flip bottom bit of data index */
+sr      r1,[ARC_REG_TLBINDEX]   /* and put it back */
+#endif
+
+.endm
+
+#endif
+
+#endif

arch/arc/include/asm/tlb.h

@@ -0,0 +1,41 @@
+/*
+ * 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.
+ */
+
+#ifndef _ASM_ARC_TLB_H
+#define _ASM_ARC_TLB_H
+
+#ifdef __KERNEL__
+
+#include <asm/pgtable.h>
+
+/* Masks for actual TLB "PD"s */
+#define PTE_BITS_IN_PD0	(_PAGE_GLOBAL | _PAGE_PRESENT)
+#define PTE_BITS_IN_PD1	(PAGE_MASK | _PAGE_CACHEABLE | \
+			 _PAGE_EXECUTE | _PAGE_WRITE | _PAGE_READ | \
+			 _PAGE_K_EXECUTE | _PAGE_K_WRITE | _PAGE_K_READ)
+
+#ifndef __ASSEMBLY__
+
+#include <linux/pagemap.h>
+#include <asm-generic/tlb.h>
+
+#ifdef CONFIG_ARC_DBG_TLB_PARANOIA
+void tlb_paranoid_check(unsigned int pid_sw, unsigned long address);
+#else
+#define tlb_paranoid_check(a, b)
+#endif
+
+void arc_mmu_init(void);
+extern char *arc_mmu_mumbojumbo(int cpu_id, char *buf, int len);
+void __init read_decode_mmu_bcr(void);
+
+#endif	/* __ASSEMBLY__ */
+
+#endif	/* __KERNEL__ */
+
+#endif /* _ASM_ARC_TLB_H */