csky: Add memory layout 2.5G(user):1.5G(kernel)

There are two ways for translating va to pa for csky:
- Use TLB(Translate Lookup Buffer) and PTW (Page Table Walk)
- Use SSEG0/1 (Simple Segment Mapping)

We use tlb mapping 0-2G and 3G-4G virtual address area and SSEG0/1
are for 2G-2.5G and 2.5G-3G translation. We could disable SSEG0
to use 2G-2.5G as TLB user mapping.

Signed-off-by: Guo Ren <[e-mail]>

arch/csky/Kconfig

···
 endchoice
 
 choice
+	prompt "PAGE OFFSET"
+	default PAGE_OFFSET_80000000
+
+config PAGE_OFFSET_80000000
+	bool "PAGE OFFSET 2G (user:kernel = 2:2)"
+
+config PAGE_OFFSET_A0000000
+	bool "PAGE OFFSET 2.5G (user:kernel = 2.5:1.5)"
+endchoice
+
+config PAGE_OFFSET
+	hex
+	default 0x80000000 if PAGE_OFFSET_80000000
+	default 0xa0000000 if PAGE_OFFSET_A0000000
+choice
+
 	prompt "C-SKY PMU type"
 	depends on PERF_EVENTS
 	depends on CPU_CK807 || CPU_CK810 || CPU_CK860

arch/csky/abiv1/inc/abi/ckmmu.h

···
 	cpwcr("cpcr8", 0x02000000);
 }
 
-static inline void setup_pgd(unsigned long pgd, bool kernel)
+static inline void setup_pgd(pgd_t *pgd)
 {
-	cpwcr("cpcr29", pgd | BIT(0));
+	cpwcr("cpcr29", __pa(pgd) | BIT(0));
 }
 
-static inline unsigned long get_pgd(void)
+static inline pgd_t *get_pgd(void)
 {
-	return cprcr("cpcr29") & ~BIT(0);
+	return __va(cprcr("cpcr29") & ~BIT(0));
 }
 #endif /* __ASM_CSKY_CKMMUV1_H */

arch/csky/abiv2/inc/abi/ckmmu.h

···
 	mtcr("cr<8, 15>", 0x02000000);
 }
 
-static inline void setup_pgd(unsigned long pgd, bool kernel)
+static inline void setup_pgd(pgd_t *pgd)
 {
-	if (kernel)
-		mtcr("cr<28, 15>", pgd | BIT(0));
-	else
-		mtcr("cr<29, 15>", pgd | BIT(0));
+#ifdef CONFIG_CPU_HAS_TLBI
+	mtcr("cr<28, 15>", __pa(pgd) | BIT(0));
+#endif
+	mtcr("cr<29, 15>", __pa(pgd) | BIT(0));
 }
 
-static inline unsigned long get_pgd(void)
+static inline pgd_t *get_pgd(void)
 {
-	return mfcr("cr<29, 15>") & ~BIT(0);
+	return __va(mfcr("cr<29, 15>") & ~BIT(0));
 }
 #endif /* __ASM_CSKY_CKMMUV2_H */

arch/csky/abiv2/inc/abi/entry.h

···
 	stw	tls, (sp, 0)
 	stw	lr, (sp, 4)
 
+	RD_MEH	lr
+	WR_MEH	lr
+
 	mfcr	lr, epc
 	movi	tls, \epc_inc
 	add	lr, tls
···
 	mtcr	\rx, cr<8, 15>
 .endm
 
+#ifdef CONFIG_PAGE_OFFSET_80000000
+#define MSA_SET cr<30, 15>
+#define MSA_CLR cr<31, 15>
+#endif
+
+#ifdef CONFIG_PAGE_OFFSET_A0000000
+#define MSA_SET cr<31, 15>
+#define MSA_CLR cr<30, 15>
+#endif
+
 .macro SETUP_MMU
 	/* Init psr and enable ee */
 	lrw	r6, DEFAULT_PSR_VALUE
···
 	 * 31 - 29 | 28 - 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
 	 *   BA     Reserved  SH  WA  B   SO SEC  C   D   V
 	 */
-	mfcr	r6, cr<30, 15> /* Get MSA0 */
+	mfcr	r6, MSA_SET /* Get MSA */
 2:
 	lsri	r6, 29
 	lsli	r6, 29
 	addi	r6, 0x1ce
-	mtcr	r6, cr<30, 15> /* Set MSA0 */
+	mtcr	r6, MSA_SET /* Set MSA */
 
 	movi    r6, 0
-	mtcr	r6, cr<31, 15> /* Clr MSA1 */
+	mtcr	r6, MSA_CLR /* Clr MSA */
 
 	/* enable MMU */
 	mfcr    r6, cr18

arch/csky/include/asm/memory.h

···
 
 #define FIXADDR_TOP	_AC(0xffffc000, UL)
 #define PKMAP_BASE	_AC(0xff800000, UL)
-#define VMALLOC_START	_AC(0xc0008000, UL)
+#define VMALLOC_START	(PAGE_OFFSET + LOWMEM_LIMIT + (PAGE_SIZE * 8))
 #define VMALLOC_END	(PKMAP_BASE - (PAGE_SIZE * 2))
 
 #ifdef CONFIG_HAVE_TCM

arch/csky/include/asm/mmu_context.h

···
 #include <linux/sched.h>
 #include <abi/ckmmu.h>
 
-#define TLBMISS_HANDLER_SETUP_PGD(pgd) \
-	setup_pgd(__pa(pgd), false)
-
-#define TLBMISS_HANDLER_SETUP_PGD_KERNEL(pgd) \
-	setup_pgd(__pa(pgd), true)
-
 #define ASID_MASK		((1 << CONFIG_CPU_ASID_BITS) - 1)
 #define cpu_asid(mm)		(atomic64_read(&mm->context.asid) & ASID_MASK)
 
···
 	if (prev != next)
 		check_and_switch_context(next, cpu);
 
-	TLBMISS_HANDLER_SETUP_PGD(next->pgd);
+	setup_pgd(next->pgd);
 	write_mmu_entryhi(next->context.asid.counter);
 
 	flush_icache_deferred(next);

arch/csky/include/asm/page.h

···
  * address region. We use them mapping kernel 1GB direct-map address area and
  * for more than 1GB of memory we use highmem.
  */
-#define PAGE_OFFSET	0x80000000
+#define PAGE_OFFSET	CONFIG_PAGE_OFFSET
 #define SSEG_SIZE	0x20000000
 #define LOWMEM_LIMIT	(SSEG_SIZE * 2)
 

arch/csky/include/asm/pgalloc.h

···
 } while (0)
 
 extern void pagetable_init(void);
-extern void pre_mmu_init(void);
+extern void mmu_init(unsigned long min_pfn, unsigned long max_pfn);
 extern void pre_trap_init(void);
 
 #endif /* __ASM_CSKY_PGALLOC_H */

arch/csky/include/asm/pgtable.h

···
 #define PGDIR_SIZE		(1UL << PGDIR_SHIFT)
 #define PGDIR_MASK		(~(PGDIR_SIZE-1))
 
-#define USER_PTRS_PER_PGD	(0x80000000UL/PGDIR_SIZE)
+#define USER_PTRS_PER_PGD	(PAGE_OFFSET/PGDIR_SIZE)
 #define FIRST_USER_ADDRESS	0UL
 
 /*

arch/csky/include/asm/processor.h

···
  * for a 64 bit kernel expandable to 8192EB, of which the current CSKY
  * implementations will "only" be able to use 1TB ...
  */
-#define TASK_SIZE       0x7fff8000UL
+#define TASK_SIZE	(PAGE_OFFSET - (PAGE_SIZE * 8))
 
 #ifdef __KERNEL__
 #define STACK_TOP       TASK_SIZE

arch/csky/include/asm/segment.h

···
 
 #define KERNEL_DS		((mm_segment_t) { 0xFFFFFFFF })
 
-#define USER_DS			((mm_segment_t) { 0x80000000UL })
+#define USER_DS			((mm_segment_t) { PAGE_OFFSET })
 #define get_fs()		(current_thread_info()->addr_limit)
 #define set_fs(x)		(current_thread_info()->addr_limit = (x))
 #define uaccess_kernel()	(get_fs().seg == KERNEL_DS.seg)

arch/csky/kernel/atomic.S

···
  */
 ENTRY(csky_cmpxchg)
 	USPTOKSP
+
+	RD_MEH	a3
+	WR_MEH	a3
+
 	mfcr	a3, epc
 	addi	a3, TRAP0_SIZE
 

arch/csky/kernel/entry.S

···
 
 	RD_PGDR	r6
 	RD_MEH	a3
+	WR_MEH	a3
 #ifdef CONFIG_CPU_HAS_TLBI
 	tlbi.vaas a3
 	sync.is
···
 	WR_MCIR	a2
 #endif
 	bclri   r6, 0
+	lrw	a2, PAGE_OFFSET
+	add	r6, a2
 	lrw	a2, va_pa_offset
 	ld.w	a2, (a2, 0)
 	subu	r6, a2
-	bseti	r6, 31
 
 	mov     a2, a3
 	lsri    a2, _PGDIR_SHIFT
···
 	addu    r6, a2
 	ldw     r6, (r6)
 
+	lrw	a2, PAGE_OFFSET
+	add	r6, a2
 	lrw	a2, va_pa_offset
 	ld.w	a2, (a2, 0)
 	subu	r6, a2
-	bseti	r6, 31
 
 	lsri    a3, PTE_INDX_SHIFT
 	lrw     a2, PTE_INDX_MSK
···
  */
 ENTRY(csky_get_tls)
 	USPTOKSP
+
+	RD_MEH	a0
+	WR_MEH	a0
 
 	/* increase epc for continue */
 	mfcr	a0, epc

arch/csky/kernel/head.S

···
 ENTRY(_start_smp_secondary)
 	SETUP_MMU
 
-	/* copy msa1 from CPU0 */
-	lrw     r6, secondary_msa1
+#ifdef CONFIG_PAGE_OFFSET_80000000
+	lrw	r6, secondary_msa1
 	ld.w	r6, (r6, 0)
 	mtcr	r6, cr<31, 15>
+#endif
+
+	lrw     r6, secondary_pgd
+	ld.w	r6, (r6, 0)
+	mtcr	r6, cr<28, 15>
+	mtcr	r6, cr<29, 15>
 
 	/* set stack point */
 	lrw     r6, secondary_stack

arch/csky/kernel/setup.c

···
 
 	if (size >= lowmem_size) {
 		max_low_pfn = min_low_pfn + lowmem_size;
+#ifdef CONFIG_PAGE_OFFSET_80000000
 		write_mmu_msa1(read_mmu_msa0() + SSEG_SIZE);
+#endif
 	} else if (size > sseg_size) {
 		max_low_pfn = min_low_pfn + sseg_size;
 	}
 
 	max_zone_pfn[ZONE_NORMAL] = max_low_pfn;
+
+	mmu_init(min_low_pfn, max_low_pfn);
 
 #ifdef CONFIG_HIGHMEM
 	max_zone_pfn[ZONE_HIGHMEM] = max_pfn;
···
 unsigned long va_pa_offset;
 EXPORT_SYMBOL(va_pa_offset);
 
+static inline unsigned long read_mmu_msa(void)
+{
+#ifdef CONFIG_PAGE_OFFSET_80000000
+	return read_mmu_msa0();
+#endif
+
+#ifdef CONFIG_PAGE_OFFSET_A0000000
+	return read_mmu_msa1();
+#endif
+}
+
 asmlinkage __visible void __init csky_start(unsigned int unused,
 					    void *dtb_start)
 {
 	/* Clean up bss section */
 	memset(__bss_start, 0, __bss_stop - __bss_start);
 
-	va_pa_offset = read_mmu_msa0() & ~(SSEG_SIZE - 1);
+	va_pa_offset = read_mmu_msa() & ~(SSEG_SIZE - 1);
 
 	pre_trap_init();
-	pre_mmu_init();
 
 	if (dtb_start == NULL)
 		early_init_dt_scan(__dtb_start);

arch/csky/kernel/smp.c

···
 volatile unsigned int secondary_hint2;
 volatile unsigned int secondary_ccr;
 volatile unsigned int secondary_stack;
-
-unsigned long secondary_msa1;
+volatile unsigned int secondary_msa1;
+volatile unsigned int secondary_pgd;
 
 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 {
···
 	secondary_hint2 = mfcr("cr<21, 1>");
 	secondary_ccr  = mfcr("cr18");
 	secondary_msa1 = read_mmu_msa1();
+	secondary_pgd = mfcr("cr<29, 15>");
 
 	/*
 	 * Because other CPUs are in reset status, we must flush data
···
 
 	flush_tlb_all();
 	write_mmu_pagemask(0);
-	TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir);
-	TLBMISS_HANDLER_SETUP_PGD_KERNEL(swapper_pg_dir);
 
 #ifdef CONFIG_CPU_HAS_FPU
 	init_fpu();

arch/csky/kernel/vmlinux.lds.S

···
 
 	.text : AT(ADDR(.text) - LOAD_OFFSET) {
 		_text = .;
+		VBR_BASE
 		IRQENTRY_TEXT
 		SOFTIRQENTRY_TEXT
 		TEXT_TEXT
···
 
 	EXCEPTION_TABLE(L1_CACHE_BYTES)
 	BSS_SECTION(L1_CACHE_BYTES, PAGE_SIZE, L1_CACHE_BYTES)
-	VBR_BASE
 	_end = . ;
 
 	STABS_DEBUG

arch/csky/mm/fault.c

···
 
 	si_code = SEGV_MAPERR;
 
-#ifndef CONFIG_CPU_HAS_TLBI
 	/*
 	 * We fault-in kernel-space virtual memory on-demand. The
 	 * 'reference' page table is init_mm.pgd.
···
 		pmd_t *pmd, *pmd_k;
 		pte_t *pte_k;
 
-		unsigned long pgd_base;
-
-		pgd_base = (unsigned long)__va(get_pgd());
-		pgd = (pgd_t *)pgd_base + offset;
+		pgd = get_pgd() + offset;
 		pgd_k = init_mm.pgd + offset;
 
 		if (!pgd_present(*pgd_k))
···
 			goto no_context;
 		return;
 	}
-#endif
 
 	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 	/*

arch/csky/mm/init.c

···
 #include <asm/mmu_context.h>
 #include <asm/sections.h>
 #include <asm/tlb.h>
+#include <asm/cacheflush.h>
 
 pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
 pte_t invalid_pte_table[PTRS_PER_PTE] __page_aligned_bss;
+pte_t kernel_pte_tables[(PTRS_PER_PGD - USER_PTRS_PER_PGD)*PTRS_PER_PTE] __page_aligned_bss;
+
 EXPORT_SYMBOL(invalid_pte_table);
 unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
 						__page_aligned_bss;
···
 
 	for (i = 0; i < PTRS_PER_PGD; i++)
 		p[i] = __pa(invalid_pte_table);
+
+	flush_tlb_all();
+	local_icache_inv_all(NULL);
 }
 
-void __init pre_mmu_init(void)
+void __init mmu_init(unsigned long min_pfn, unsigned long max_pfn)
 {
-	/*
-	 * Setup page-table and enable TLB-hardrefill
-	 */
+	int i;
+
+	for (i = 0; i < USER_PTRS_PER_PGD; i++)
+		swapper_pg_dir[i].pgd = __pa(invalid_pte_table);
+
+	for (i = USER_PTRS_PER_PGD; i < PTRS_PER_PGD; i++)
+		swapper_pg_dir[i].pgd =
+			__pa(kernel_pte_tables + (PTRS_PER_PTE * (i - USER_PTRS_PER_PGD)));
+
+	for (i = min_pfn; i < max_pfn; i++)
+		set_pte(&kernel_pte_tables[i - PFN_DOWN(va_pa_offset)], pfn_pte(i, PAGE_KERNEL));
+
 	flush_tlb_all();
-	pgd_init((unsigned long *)swapper_pg_dir);
-	TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir);
-	TLBMISS_HANDLER_SETUP_PGD_KERNEL(swapper_pg_dir);
+	local_icache_inv_all(NULL);
 
 	/* Setup page mask to 4k */
 	write_mmu_pagemask(0);
+
+	setup_pgd(swapper_pg_dir);
 }
 
 void __init fixrange_init(unsigned long start, unsigned long end,