alistair23-linux/arch/powerpc/include/asm/book3s/32/pgtable.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_POWERPC_BOOK3S_32_PGTABLE_H
#define _ASM_POWERPC_BOOK3S_32_PGTABLE_H

#define __ARCH_USE_5LEVEL_HACK
#include <asm-generic/pgtable-nopmd.h>

#include <asm/book3s/32/hash.h>

/* And here we include common definitions */
#include <asm/pte-common.h>

#define PTE_INDEX_SIZE	PTE_SHIFT
#define PMD_INDEX_SIZE	0
#define PUD_INDEX_SIZE	0
#define PGD_INDEX_SIZE	(32 - PGDIR_SHIFT)

#define PMD_CACHE_INDEX	PMD_INDEX_SIZE

#ifndef __ASSEMBLY__
#define PTE_TABLE_SIZE	(sizeof(pte_t) << PTE_INDEX_SIZE)
#define PMD_TABLE_SIZE	0
#define PUD_TABLE_SIZE	0
#define PGD_TABLE_SIZE	(sizeof(pgd_t) << PGD_INDEX_SIZE)
#endif	/* __ASSEMBLY__ */

#define PTRS_PER_PTE	(1 << PTE_INDEX_SIZE)
#define PTRS_PER_PGD	(1 << PGD_INDEX_SIZE)

/*
 * The normal case is that PTEs are 32-bits and we have a 1-page
 * 1024-entry pgdir pointing to 1-page 1024-entry PTE pages.  -- paulus
 *
 * For any >32-bit physical address platform, we can use the following
 * two level page table layout where the pgdir is 8KB and the MS 13 bits
 * are an index to the second level table.  The combined pgdir/pmd first
 * level has 2048 entries and the second level has 512 64-bit PTE entries.
 * -Matt
 */
/* PGDIR_SHIFT determines what a top-level page table entry can map */
#define PGDIR_SHIFT	(PAGE_SHIFT + PTE_INDEX_SIZE)
#define PGDIR_SIZE	(1UL << PGDIR_SHIFT)
#define PGDIR_MASK	(~(PGDIR_SIZE-1))

#define USER_PTRS_PER_PGD	(TASK_SIZE / PGDIR_SIZE)
/*
 * This is the bottom of the PKMAP area with HIGHMEM or an arbitrary
 * value (for now) on others, from where we can start layout kernel
 * virtual space that goes below PKMAP and FIXMAP
 */
#ifdef CONFIG_HIGHMEM
#define KVIRT_TOP	PKMAP_BASE
#else
#define KVIRT_TOP	(0xfe000000UL)	/* for now, could be FIXMAP_BASE ? */
#endif

/*
 * ioremap_bot starts at that address. Early ioremaps move down from there,
 * until mem_init() at which point this becomes the top of the vmalloc
 * and ioremap space
 */
#ifdef CONFIG_NOT_COHERENT_CACHE
#define IOREMAP_TOP	((KVIRT_TOP - CONFIG_CONSISTENT_SIZE) & PAGE_MASK)
#else
#define IOREMAP_TOP	KVIRT_TOP
#endif

/*
 * Just any arbitrary offset to the start of the vmalloc VM area: the
 * current 16MB value just means that there will be a 64MB "hole" after the
 * physical memory until the kernel virtual memory starts.  That means that
 * any out-of-bounds memory accesses will hopefully be caught.
 * The vmalloc() routines leaves a hole of 4kB between each vmalloced
 * area for the same reason. ;)
 *
 * We no longer map larger than phys RAM with the BATs so we don't have
 * to worry about the VMALLOC_OFFSET causing problems.  We do have to worry
 * about clashes between our early calls to ioremap() that start growing down
 * from ioremap_base being run into the VM area allocations (growing upwards
 * from VMALLOC_START).  For this reason we have ioremap_bot to check when
 * we actually run into our mappings setup in the early boot with the VM
 * system.  This really does become a problem for machines with good amounts
 * of RAM.  -- Cort
 */
#define VMALLOC_OFFSET (0x1000000) /* 16M */
#ifdef PPC_PIN_SIZE
#define VMALLOC_START (((_ALIGN((long)high_memory, PPC_PIN_SIZE) + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1)))
#else
#define VMALLOC_START ((((long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1)))
#endif
#define VMALLOC_END	ioremap_bot

#ifndef __ASSEMBLY__
#include <linux/sched.h>
#include <linux/threads.h>
#include <asm/io.h>			/* For sub-arch specific PPC_PIN_SIZE */

extern unsigned long ioremap_bot;

/* Bits to mask out from a PGD to get to the PUD page */
#define PGD_MASKED_BITS		0

#define pte_ERROR(e) \
	pr_err("%s:%d: bad pte %llx.\n", __FILE__, __LINE__, \
		(unsigned long long)pte_val(e))
#define pgd_ERROR(e) \
	pr_err("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
/*
 * Bits in a linux-style PTE.  These match the bits in the
 * (hardware-defined) PowerPC PTE as closely as possible.
 */

#define pte_clear(mm, addr, ptep) \
	do { pte_update(ptep, ~_PAGE_HASHPTE, 0); } while (0)

#define pmd_none(pmd)		(!pmd_val(pmd))
#define	pmd_bad(pmd)		(pmd_val(pmd) & _PMD_BAD)
#define	pmd_present(pmd)	(pmd_val(pmd) & _PMD_PRESENT_MASK)
static inline void pmd_clear(pmd_t *pmdp)
{
	*pmdp = __pmd(0);
}


/*
 * When flushing the tlb entry for a page, we also need to flush the hash
 * table entry.  flush_hash_pages is assembler (for speed) in hashtable.S.
 */
extern int flush_hash_pages(unsigned context, unsigned long va,
			    unsigned long pmdval, int count);

/* Add an HPTE to the hash table */
extern void add_hash_page(unsigned context, unsigned long va,
			  unsigned long pmdval);

/* Flush an entry from the TLB/hash table */
extern void flush_hash_entry(struct mm_struct *mm, pte_t *ptep,
			     unsigned long address);

/*
 * PTE updates. This function is called whenever an existing
 * valid PTE is updated. This does -not- include set_pte_at()
 * which nowadays only sets a new PTE.
 *
 * Depending on the type of MMU, we may need to use atomic updates
 * and the PTE may be either 32 or 64 bit wide. In the later case,
 * when using atomic updates, only the low part of the PTE is
 * accessed atomically.
 *
 * In addition, on 44x, we also maintain a global flag indicating
 * that an executable user mapping was modified, which is needed
 * to properly flush the virtually tagged instruction cache of
 * those implementations.
 */
#ifndef CONFIG_PTE_64BIT
static inline unsigned long pte_update(pte_t *p,
				       unsigned long clr,
				       unsigned long set)
{
	unsigned long old, tmp;

	__asm__ __volatile__("\
1:	lwarx	%0,0,%3\n\
	andc	%1,%0,%4\n\
	or	%1,%1,%5\n"
	PPC405_ERR77(0,%3)
"	stwcx.	%1,0,%3\n\
	bne-	1b"
	: "=&r" (old), "=&r" (tmp), "=m" (*p)
	: "r" (p), "r" (clr), "r" (set), "m" (*p)
	: "cc" );

	return old;
}
#else /* CONFIG_PTE_64BIT */
static inline unsigned long long pte_update(pte_t *p,
					    unsigned long clr,
					    unsigned long set)
{
	unsigned long long old;
	unsigned long tmp;

	__asm__ __volatile__("\
1:	lwarx	%L0,0,%4\n\
	lwzx	%0,0,%3\n\
	andc	%1,%L0,%5\n\
	or	%1,%1,%6\n"
	PPC405_ERR77(0,%3)
"	stwcx.	%1,0,%4\n\
	bne-	1b"
	: "=&r" (old), "=&r" (tmp), "=m" (*p)
	: "r" (p), "r" ((unsigned long)(p) + 4), "r" (clr), "r" (set), "m" (*p)
	: "cc" );

	return old;
}
#endif /* CONFIG_PTE_64BIT */

/*
 * 2.6 calls this without flushing the TLB entry; this is wrong
 * for our hash-based implementation, we fix that up here.
 */
#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
static inline int __ptep_test_and_clear_young(unsigned int context, unsigned long addr, pte_t *ptep)
{
	unsigned long old;
	old = pte_update(ptep, _PAGE_ACCESSED, 0);
	if (old & _PAGE_HASHPTE) {
		unsigned long ptephys = __pa(ptep) & PAGE_MASK;
		flush_hash_pages(context, addr, ptephys, 1);
	}
	return (old & _PAGE_ACCESSED) != 0;
}
#define ptep_test_and_clear_young(__vma, __addr, __ptep) \
	__ptep_test_and_clear_young((__vma)->vm_mm->context.id, __addr, __ptep)

#define __HAVE_ARCH_PTEP_GET_AND_CLEAR
static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
				       pte_t *ptep)
{
	return __pte(pte_update(ptep, ~_PAGE_HASHPTE, 0));
}

#define __HAVE_ARCH_PTEP_SET_WRPROTECT
static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr,
				      pte_t *ptep)
{
	pte_update(ptep, (_PAGE_RW | _PAGE_HWWRITE), _PAGE_RO);
}
static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
					   unsigned long addr, pte_t *ptep)
{
	ptep_set_wrprotect(mm, addr, ptep);
}


static inline void __ptep_set_access_flags(struct mm_struct *mm,
					   pte_t *ptep, pte_t entry,
					   unsigned long address)
{
	unsigned long set = pte_val(entry) &
		(_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC);
	unsigned long clr = ~pte_val(entry) & _PAGE_RO;

	pte_update(ptep, clr, set);
}

#define __HAVE_ARCH_PTE_SAME
#define pte_same(A,B)	(((pte_val(A) ^ pte_val(B)) & ~_PAGE_HASHPTE) == 0)

/*
 * Note that on Book E processors, the pmd contains the kernel virtual
 * (lowmem) address of the pte page.  The physical address is less useful
 * because everything runs with translation enabled (even the TLB miss
 * handler).  On everything else the pmd contains the physical address
 * of the pte page.  -- paulus
 */
#ifndef CONFIG_BOOKE
#define pmd_page_vaddr(pmd)	\
	((unsigned long) __va(pmd_val(pmd) & PAGE_MASK))
#define pmd_page(pmd)		\
	pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)
#else
#define pmd_page_vaddr(pmd)	\
	((unsigned long) (pmd_val(pmd) & PAGE_MASK))
#define pmd_page(pmd)		\
	pfn_to_page((__pa(pmd_val(pmd)) >> PAGE_SHIFT))
#endif

/* to find an entry in a kernel page-table-directory */
#define pgd_offset_k(address) pgd_offset(&init_mm, address)

/* to find an entry in a page-table-directory */
#define pgd_index(address)	 ((address) >> PGDIR_SHIFT)
#define pgd_offset(mm, address)	 ((mm)->pgd + pgd_index(address))

/* Find an entry in the third-level page table.. */
#define pte_index(address)		\
	(((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
#define pte_offset_kernel(dir, addr)	\
	((pte_t *) pmd_page_vaddr(*(dir)) + pte_index(addr))
#define pte_offset_map(dir, addr)		\
	((pte_t *) kmap_atomic(pmd_page(*(dir))) + pte_index(addr))
#define pte_unmap(pte)		kunmap_atomic(pte)

/*
 * Encode and decode a swap entry.
 * Note that the bits we use in a PTE for representing a swap entry
 * must not include the _PAGE_PRESENT bit or the _PAGE_HASHPTE bit (if used).
 *   -- paulus
 */
#define __swp_type(entry)		((entry).val & 0x1f)
#define __swp_offset(entry)		((entry).val >> 5)
#define __swp_entry(type, offset)	((swp_entry_t) { (type) | ((offset) << 5) })
#define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val(pte) >> 3 })
#define __swp_entry_to_pte(x)		((pte_t) { (x).val << 3 })

int map_kernel_page(unsigned long va, phys_addr_t pa, int flags);

/* Generic accessors to PTE bits */
static inline int pte_write(pte_t pte)		{ return !!(pte_val(pte) & _PAGE_RW);}
static inline int pte_read(pte_t pte)		{ return 1; }
static inline int pte_dirty(pte_t pte)		{ return !!(pte_val(pte) & _PAGE_DIRTY); }
static inline int pte_young(pte_t pte)		{ return !!(pte_val(pte) & _PAGE_ACCESSED); }
static inline int pte_special(pte_t pte)	{ return !!(pte_val(pte) & _PAGE_SPECIAL); }
static inline int pte_none(pte_t pte)		{ return (pte_val(pte) & ~_PTE_NONE_MASK) == 0; }
static inline pgprot_t pte_pgprot(pte_t pte)	{ return __pgprot(pte_val(pte) & PAGE_PROT_BITS); }

static inline int pte_present(pte_t pte)
{
	return pte_val(pte) & _PAGE_PRESENT;
}

/* Conversion functions: convert a page and protection to a page entry,
 * and a page entry and page directory to the page they refer to.
 *
 * Even if PTEs can be unsigned long long, a PFN is always an unsigned
 * long for now.
 */
static inline pte_t pfn_pte(unsigned long pfn, pgprot_t pgprot)
{
	return __pte(((pte_basic_t)(pfn) << PTE_RPN_SHIFT) |
		     pgprot_val(pgprot));
}

static inline unsigned long pte_pfn(pte_t pte)
{
	return pte_val(pte) >> PTE_RPN_SHIFT;
}

/* Generic modifiers for PTE bits */
static inline pte_t pte_wrprotect(pte_t pte)
{
	return __pte(pte_val(pte) & ~_PAGE_RW);
}

static inline pte_t pte_mkclean(pte_t pte)
{
	return __pte(pte_val(pte) & ~_PAGE_DIRTY);
}

static inline pte_t pte_mkold(pte_t pte)
{
	return __pte(pte_val(pte) & ~_PAGE_ACCESSED);
}

static inline pte_t pte_mkwrite(pte_t pte)
{
	return __pte(pte_val(pte) | _PAGE_RW);
}

static inline pte_t pte_mkdirty(pte_t pte)
{
	return __pte(pte_val(pte) | _PAGE_DIRTY);
}

static inline pte_t pte_mkyoung(pte_t pte)
{
	return __pte(pte_val(pte) | _PAGE_ACCESSED);
}

static inline pte_t pte_mkspecial(pte_t pte)
{
	return __pte(pte_val(pte) | _PAGE_SPECIAL);
}

static inline pte_t pte_mkhuge(pte_t pte)
{
	return pte;
}

static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
	return __pte((pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot));
}



/* This low level function performs the actual PTE insertion
 * Setting the PTE depends on the MMU type and other factors. It's
 * an horrible mess that I'm not going to try to clean up now but
 * I'm keeping it in one place rather than spread around
 */
static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
				pte_t *ptep, pte_t pte, int percpu)
{
#if defined(CONFIG_PPC_STD_MMU_32) && defined(CONFIG_SMP) && !defined(CONFIG_PTE_64BIT)
	/* First case is 32-bit Hash MMU in SMP mode with 32-bit PTEs. We use the
	 * helper pte_update() which does an atomic update. We need to do that
	 * because a concurrent invalidation can clear _PAGE_HASHPTE. If it's a
	 * per-CPU PTE such as a kmap_atomic, we do a simple update preserving
	 * the hash bits instead (ie, same as the non-SMP case)
	 */
	if (percpu)
		*ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
			      | (pte_val(pte) & ~_PAGE_HASHPTE));
	else
		pte_update(ptep, ~_PAGE_HASHPTE, pte_val(pte));

#elif defined(CONFIG_PPC32) && defined(CONFIG_PTE_64BIT)
	/* Second case is 32-bit with 64-bit PTE.  In this case, we
	 * can just store as long as we do the two halves in the right order
	 * with a barrier in between. This is possible because we take care,
	 * in the hash code, to pre-invalidate if the PTE was already hashed,
	 * which synchronizes us with any concurrent invalidation.
	 * In the percpu case, we also fallback to the simple update preserving
	 * the hash bits
	 */
	if (percpu) {
		*ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
			      | (pte_val(pte) & ~_PAGE_HASHPTE));
		return;
	}
	if (pte_val(*ptep) & _PAGE_HASHPTE)
		flush_hash_entry(mm, ptep, addr);
	__asm__ __volatile__("\
		stw%U0%X0 %2,%0\n\
		eieio\n\
		stw%U0%X0 %L2,%1"
	: "=m" (*ptep), "=m" (*((unsigned char *)ptep+4))
	: "r" (pte) : "memory");

#elif defined(CONFIG_PPC_STD_MMU_32)
	/* Third case is 32-bit hash table in UP mode, we need to preserve
	 * the _PAGE_HASHPTE bit since we may not have invalidated the previous
	 * translation in the hash yet (done in a subsequent flush_tlb_xxx())
	 * and see we need to keep track that this PTE needs invalidating
	 */
	*ptep = __pte((pte_val(*ptep) & _PAGE_HASHPTE)
		      | (pte_val(pte) & ~_PAGE_HASHPTE));

#else
#error "Not supported "
#endif
}

/*
 * Macro to mark a page protection value as "uncacheable".
 */

#define _PAGE_CACHE_CTL	(_PAGE_COHERENT | _PAGE_GUARDED | _PAGE_NO_CACHE | \
			 _PAGE_WRITETHRU)

#define pgprot_noncached pgprot_noncached
static inline pgprot_t pgprot_noncached(pgprot_t prot)
{
	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
			_PAGE_NO_CACHE | _PAGE_GUARDED);
}

#define pgprot_noncached_wc pgprot_noncached_wc
static inline pgprot_t pgprot_noncached_wc(pgprot_t prot)
{
	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
			_PAGE_NO_CACHE);
}

#define pgprot_cached pgprot_cached
static inline pgprot_t pgprot_cached(pgprot_t prot)
{
	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
			_PAGE_COHERENT);
}

#define pgprot_cached_wthru pgprot_cached_wthru
static inline pgprot_t pgprot_cached_wthru(pgprot_t prot)
{
	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
			_PAGE_COHERENT | _PAGE_WRITETHRU);
}

#define pgprot_cached_noncoherent pgprot_cached_noncoherent
static inline pgprot_t pgprot_cached_noncoherent(pgprot_t prot)
{
	return __pgprot(pgprot_val(prot) & ~_PAGE_CACHE_CTL);
}

#define pgprot_writecombine pgprot_writecombine
static inline pgprot_t pgprot_writecombine(pgprot_t prot)
{
	return pgprot_noncached_wc(prot);
}

#endif /* !__ASSEMBLY__ */

#endif /*  _ASM_POWERPC_BOOK3S_32_PGTABLE_H */