bianbu-repo-mirror/bianbu-linux-6.6
1
0
Fork 0
mirror of https://gitee.com/bianbu-linux/linux-6.6 synced 2025-04-24 14:07:52 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions
bianbu-linux-6.6/arch/sh/include/asm/pgtable_32.h
Rick Edgecombe 2f0584f3f4 mm: Rename arch pte_mkwrite()'s to pte_mkwrite_novma() 
The x86 Shadow stack feature includes a new type of memory called shadow
stack. This shadow stack memory has some unusual properties, which requires
some core mm changes to function properly.

One of these unusual properties is that shadow stack memory is writable,
but only in limited ways. These limits are applied via a specific PTE
bit combination. Nevertheless, the memory is writable, and core mm code
will need to apply the writable permissions in the typical paths that
call pte_mkwrite(). The goal is to make pte_mkwrite() take a VMA, so
that the x86 implementation of it can know whether to create regular
writable or shadow stack mappings.

But there are a couple of challenges to this. Modifying the signatures of
each arch pte_mkwrite() implementation would be error prone because some
are generated with macros and would need to be re-implemented. Also, some
pte_mkwrite() callers operate on kernel memory without a VMA.

So this can be done in a three step process. First pte_mkwrite() can be
renamed to pte_mkwrite_novma() in each arch, with a generic pte_mkwrite()
added that just calls pte_mkwrite_novma(). Next callers without a VMA can
be moved to pte_mkwrite_novma(). And lastly, pte_mkwrite() and all callers
can be changed to take/pass a VMA.

Start the process by renaming pte_mkwrite() to pte_mkwrite_novma() and
adding the pte_mkwrite() wrapper in linux/pgtable.h. Apply the same
pattern for pmd_mkwrite(). Since not all archs have a pmd_mkwrite_novma(),
create a new arch config HAS_HUGE_PAGE that can be used to tell if
pmd_mkwrite() should be defined. Otherwise in the !HAS_HUGE_PAGE cases the
compiler would not be able to find pmd_mkwrite_novma().

No functional change.

Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/lkml/CAHk-=wiZjSu7c9sFYZb3q04108stgHff2wfbokGCCgW7riz+8Q@mail.gmail.com/
Link: https://lore.kernel.org/all/20230613001108.3040476-2-rick.p.edgecombe%40intel.com
2023-07-11 14:10:56 -07:00

491 lines
17 KiB
C
Raw Blame History

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_SH_PGTABLE_32_H
#define __ASM_SH_PGTABLE_32_H
/*
* Linux PTEL encoding.
*
* Hardware and software bit definitions for the PTEL value (see below for
* notes on SH-X2 MMUs and 64-bit PTEs):
*
* - Bits 0 and 7 are reserved on SH-3 (_PAGE_WT and _PAGE_SZ1 on SH-4).
*
* - Bit 1 is the SH-bit, but is unused on SH-3 due to an MMU bug (the
* hardware PTEL value can't have the SH-bit set when MMUCR.IX is set,
* which is the default in cpu-sh3/mmu_context.h:MMU_CONTROL_INIT).
*
* In order to keep this relatively clean, do not use these for defining
* SH-3 specific flags until all of the other unused bits have been
* exhausted.
*
* - Bit 9 is reserved by everyone and used by _PAGE_PROTNONE.
*
* - Bits 10 and 11 are low bits of the PPN that are reserved on >= 4K pages.
* Bit 10 is used for _PAGE_ACCESSED, and bit 11 is used for _PAGE_SPECIAL.
*
* - On 29 bit platforms, bits 31 to 29 are used for the space attributes
* and timing control which (together with bit 0) are moved into the
* old-style PTEA on the parts that support it.
*
* SH-X2 MMUs and extended PTEs
*
* SH-X2 supports an extended mode TLB with split data arrays due to the
* number of bits needed for PR and SZ (now EPR and ESZ) encodings. The PR and
* SZ bit placeholders still exist in data array 1, but are implemented as
* reserved bits, with the real logic existing in data array 2.
*
* The downside to this is that we can no longer fit everything in to a 32-bit
* PTE encoding, so a 64-bit pte_t is necessary for these parts. On the plus
* side, this gives us quite a few spare bits to play with for future usage.
*/
/* Legacy and compat mode bits */
#define _PAGE_WT 0x001 /* WT-bit on SH-4, 0 on SH-3 */
#define _PAGE_HW_SHARED 0x002 /* SH-bit : shared among processes */
#define _PAGE_DIRTY 0x004 /* D-bit : page changed */
#define _PAGE_CACHABLE 0x008 /* C-bit : cachable */
#define _PAGE_SZ0 0x010 /* SZ0-bit : Size of page */
#define _PAGE_RW 0x020 /* PR0-bit : write access allowed */
#define _PAGE_USER 0x040 /* PR1-bit : user space access allowed*/
#define _PAGE_SZ1 0x080 /* SZ1-bit : Size of page (on SH-4) */
#define _PAGE_PRESENT 0x100 /* V-bit : page is valid */
#define _PAGE_PROTNONE 0x200 /* software: if not present */
#define _PAGE_ACCESSED 0x400 /* software: page referenced */
#define _PAGE_SPECIAL 0x800 /* software: special page */
#define _PAGE_SZ_MASK (_PAGE_SZ0 | _PAGE_SZ1)
#define _PAGE_PR_MASK (_PAGE_RW | _PAGE_USER)
/* Extended mode bits */
#define _PAGE_EXT_ESZ0 0x0010 /* ESZ0-bit: Size of page */
#define _PAGE_EXT_ESZ1 0x0020 /* ESZ1-bit: Size of page */
#define _PAGE_EXT_ESZ2 0x0040 /* ESZ2-bit: Size of page */
#define _PAGE_EXT_ESZ3 0x0080 /* ESZ3-bit: Size of page */
#define _PAGE_EXT_USER_EXEC 0x0100 /* EPR0-bit: User space executable */
#define _PAGE_EXT_USER_WRITE 0x0200 /* EPR1-bit: User space writable */
#define _PAGE_EXT_USER_READ 0x0400 /* EPR2-bit: User space readable */
#define _PAGE_EXT_KERN_EXEC 0x0800 /* EPR3-bit: Kernel space executable */
#define _PAGE_EXT_KERN_WRITE 0x1000 /* EPR4-bit: Kernel space writable */
#define _PAGE_EXT_KERN_READ 0x2000 /* EPR5-bit: Kernel space readable */
#define _PAGE_EXT_WIRED 0x4000 /* software: Wire TLB entry */
/* Wrapper for extended mode pgprot twiddling */
#define _PAGE_EXT(x) ((unsigned long long)(x) << 32)
#ifdef CONFIG_X2TLB
#define _PAGE_PCC_MASK 0x00000000 /* No legacy PTEA support */
#else
/* software: moves to PTEA.TC (Timing Control) */
#define _PAGE_PCC_AREA5 0x00000000 /* use BSC registers for area5 */
#define _PAGE_PCC_AREA6 0x80000000 /* use BSC registers for area6 */
/* software: moves to PTEA.SA[2:0] (Space Attributes) */
#define _PAGE_PCC_IODYN 0x00000001 /* IO space, dynamically sized bus */
#define _PAGE_PCC_IO8 0x20000000 /* IO space, 8 bit bus */
#define _PAGE_PCC_IO16 0x20000001 /* IO space, 16 bit bus */
#define _PAGE_PCC_COM8 0x40000000 /* Common Memory space, 8 bit bus */
#define _PAGE_PCC_COM16 0x40000001 /* Common Memory space, 16 bit bus */
#define _PAGE_PCC_ATR8 0x60000000 /* Attribute Memory space, 8 bit bus */
#define _PAGE_PCC_ATR16 0x60000001 /* Attribute Memory space, 6 bit bus */
#define _PAGE_PCC_MASK 0xe0000001
/* copy the ptea attributes */
static inline unsigned long copy_ptea_attributes(unsigned long x)
{
return ((x >> 28) & 0xe) | (x & 0x1);
}
#endif
/* Mask which drops unused bits from the PTEL value */
#if defined(CONFIG_CPU_SH3)
#define _PAGE_CLEAR_FLAGS (_PAGE_PROTNONE | _PAGE_ACCESSED| \
_PAGE_SZ1 | _PAGE_HW_SHARED)
#elif defined(CONFIG_X2TLB)
/* Get rid of the legacy PR/SZ bits when using extended mode */
#define _PAGE_CLEAR_FLAGS (_PAGE_PROTNONE | _PAGE_ACCESSED | \
_PAGE_PR_MASK | _PAGE_SZ_MASK)
#else
#define _PAGE_CLEAR_FLAGS (_PAGE_PROTNONE | _PAGE_ACCESSED)
#endif
#define _PAGE_FLAGS_HARDWARE_MASK (phys_addr_mask() & ~(_PAGE_CLEAR_FLAGS))
/* Hardware flags, page size encoding */
#if !defined(CONFIG_MMU)
# define _PAGE_FLAGS_HARD 0ULL
#elif defined(CONFIG_X2TLB)
# if defined(CONFIG_PAGE_SIZE_4KB)
# define _PAGE_FLAGS_HARD _PAGE_EXT(_PAGE_EXT_ESZ0)
# elif defined(CONFIG_PAGE_SIZE_8KB)
# define _PAGE_FLAGS_HARD _PAGE_EXT(_PAGE_EXT_ESZ1)
# elif defined(CONFIG_PAGE_SIZE_64KB)
# define _PAGE_FLAGS_HARD _PAGE_EXT(_PAGE_EXT_ESZ2)
# endif
#else
# if defined(CONFIG_PAGE_SIZE_4KB)
# define _PAGE_FLAGS_HARD _PAGE_SZ0
# elif defined(CONFIG_PAGE_SIZE_64KB)
# define _PAGE_FLAGS_HARD _PAGE_SZ1
# endif
#endif
#if defined(CONFIG_X2TLB)
# if defined(CONFIG_HUGETLB_PAGE_SIZE_64K)
# define _PAGE_SZHUGE (_PAGE_EXT_ESZ2)
# elif defined(CONFIG_HUGETLB_PAGE_SIZE_256K)
# define _PAGE_SZHUGE (_PAGE_EXT_ESZ0 | _PAGE_EXT_ESZ2)
# elif defined(CONFIG_HUGETLB_PAGE_SIZE_1MB)
# define _PAGE_SZHUGE (_PAGE_EXT_ESZ0 | _PAGE_EXT_ESZ1 | _PAGE_EXT_ESZ2)
# elif defined(CONFIG_HUGETLB_PAGE_SIZE_4MB)
# define _PAGE_SZHUGE (_PAGE_EXT_ESZ3)
# elif defined(CONFIG_HUGETLB_PAGE_SIZE_64MB)
# define _PAGE_SZHUGE (_PAGE_EXT_ESZ2 | _PAGE_EXT_ESZ3)
# endif
# define _PAGE_WIRED (_PAGE_EXT(_PAGE_EXT_WIRED))
#else
# if defined(CONFIG_HUGETLB_PAGE_SIZE_64K)
# define _PAGE_SZHUGE (_PAGE_SZ1)
# elif defined(CONFIG_HUGETLB_PAGE_SIZE_1MB)
# define _PAGE_SZHUGE (_PAGE_SZ0 | _PAGE_SZ1)
# endif
# define _PAGE_WIRED (0)
#endif
/*
* Stub out _PAGE_SZHUGE if we don't have a good definition for it,
* to make pte_mkhuge() happy.
*/
#ifndef _PAGE_SZHUGE
# define _PAGE_SZHUGE (_PAGE_FLAGS_HARD)
#endif
/*
* Mask of bits that are to be preserved across pgprot changes.
*/
#define _PAGE_CHG_MASK \
(PTE_MASK | _PAGE_ACCESSED | _PAGE_CACHABLE | \
_PAGE_DIRTY | _PAGE_SPECIAL)
#ifndef __ASSEMBLY__
#if defined(CONFIG_X2TLB) /* SH-X2 TLB */
#define PAGE_NONE __pgprot(_PAGE_PROTNONE | _PAGE_CACHABLE | \
_PAGE_ACCESSED | _PAGE_FLAGS_HARD)
#define PAGE_SHARED __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
_PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
_PAGE_EXT(_PAGE_EXT_KERN_READ | \
_PAGE_EXT_KERN_WRITE | \
_PAGE_EXT_USER_READ | \
_PAGE_EXT_USER_WRITE))
#define PAGE_EXECREAD __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
_PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
_PAGE_EXT(_PAGE_EXT_KERN_EXEC | \
_PAGE_EXT_KERN_READ | \
_PAGE_EXT_USER_EXEC | \
_PAGE_EXT_USER_READ))
#define PAGE_COPY PAGE_EXECREAD
#define PAGE_READONLY __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
_PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
_PAGE_EXT(_PAGE_EXT_KERN_READ | \
_PAGE_EXT_USER_READ))
#define PAGE_WRITEONLY __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
_PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
_PAGE_EXT(_PAGE_EXT_KERN_WRITE | \
_PAGE_EXT_USER_WRITE))
#define PAGE_RWX __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
_PAGE_CACHABLE | _PAGE_FLAGS_HARD | \
_PAGE_EXT(_PAGE_EXT_KERN_WRITE | \
_PAGE_EXT_KERN_READ | \
_PAGE_EXT_KERN_EXEC | \
_PAGE_EXT_USER_WRITE | \
_PAGE_EXT_USER_READ | \
_PAGE_EXT_USER_EXEC))
#define PAGE_KERNEL __pgprot(_PAGE_PRESENT | _PAGE_CACHABLE | \
_PAGE_DIRTY | _PAGE_ACCESSED | \
_PAGE_HW_SHARED | _PAGE_FLAGS_HARD | \
_PAGE_EXT(_PAGE_EXT_KERN_READ | \
_PAGE_EXT_KERN_WRITE | \
_PAGE_EXT_KERN_EXEC))
#define PAGE_KERNEL_NOCACHE \
__pgprot(_PAGE_PRESENT | _PAGE_DIRTY | \
_PAGE_ACCESSED | _PAGE_HW_SHARED | \
_PAGE_FLAGS_HARD | \
_PAGE_EXT(_PAGE_EXT_KERN_READ | \
_PAGE_EXT_KERN_WRITE | \
_PAGE_EXT_KERN_EXEC))
#define PAGE_KERNEL_RO __pgprot(_PAGE_PRESENT | _PAGE_CACHABLE | \
_PAGE_DIRTY | _PAGE_ACCESSED | \
_PAGE_HW_SHARED | _PAGE_FLAGS_HARD | \
_PAGE_EXT(_PAGE_EXT_KERN_READ | \
_PAGE_EXT_KERN_EXEC))
#define PAGE_KERNEL_PCC(slot, type) \
__pgprot(0)
#elif defined(CONFIG_MMU) /* SH-X TLB */
#define PAGE_NONE __pgprot(_PAGE_PROTNONE | _PAGE_CACHABLE | \
_PAGE_ACCESSED | _PAGE_FLAGS_HARD)
#define PAGE_SHARED __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | \
_PAGE_CACHABLE | _PAGE_ACCESSED | \
_PAGE_FLAGS_HARD)
#define PAGE_COPY __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_CACHABLE | \
_PAGE_ACCESSED | _PAGE_FLAGS_HARD)
#define PAGE_READONLY __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_CACHABLE | \
_PAGE_ACCESSED | _PAGE_FLAGS_HARD)
#define PAGE_EXECREAD PAGE_READONLY
#define PAGE_RWX PAGE_SHARED
#define PAGE_WRITEONLY PAGE_SHARED
#define PAGE_KERNEL __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_CACHABLE | \
_PAGE_DIRTY | _PAGE_ACCESSED | \
_PAGE_HW_SHARED | _PAGE_FLAGS_HARD)
#define PAGE_KERNEL_NOCACHE \
__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | \
_PAGE_ACCESSED | _PAGE_HW_SHARED | \
_PAGE_FLAGS_HARD)
#define PAGE_KERNEL_RO __pgprot(_PAGE_PRESENT | _PAGE_CACHABLE | \
_PAGE_DIRTY | _PAGE_ACCESSED | \
_PAGE_HW_SHARED | _PAGE_FLAGS_HARD)
#define PAGE_KERNEL_PCC(slot, type) \
__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | \
_PAGE_ACCESSED | _PAGE_FLAGS_HARD | \
(slot ? _PAGE_PCC_AREA5 : _PAGE_PCC_AREA6) | \
(type))
#else /* no mmu */
#define PAGE_NONE __pgprot(0)
#define PAGE_SHARED __pgprot(0)
#define PAGE_COPY __pgprot(0)
#define PAGE_EXECREAD __pgprot(0)
#define PAGE_RWX __pgprot(0)
#define PAGE_READONLY __pgprot(0)
#define PAGE_WRITEONLY __pgprot(0)
#define PAGE_KERNEL __pgprot(0)
#define PAGE_KERNEL_NOCACHE __pgprot(0)
#define PAGE_KERNEL_RO __pgprot(0)
#define PAGE_KERNEL_PCC(slot, type) \
__pgprot(0)
#endif
#endif /* __ASSEMBLY__ */
#ifndef __ASSEMBLY__
/*
* Certain architectures need to do special things when PTEs
* within a page table are directly modified. Thus, the following
* hook is made available.
*/
#ifdef CONFIG_X2TLB
static inline void set_pte(pte_t *ptep, pte_t pte)
{
ptep->pte_high = pte.pte_high;
smp_wmb();
ptep->pte_low = pte.pte_low;
}
#else
#define set_pte(pteptr, pteval) (*(pteptr) = pteval)
#endif
#define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
/*
* (pmds are folded into pgds so this doesn't get actually called,
* but the define is needed for a generic inline function.)
*/
#define set_pmd(pmdptr, pmdval) (*(pmdptr) = pmdval)
#define pfn_pte(pfn, prot) \
__pte(((unsigned long long)(pfn) << PAGE_SHIFT) | pgprot_val(prot))
#define pfn_pmd(pfn, prot) \
__pmd(((unsigned long long)(pfn) << PAGE_SHIFT) | pgprot_val(prot))
#define pte_none(x) (!pte_val(x))
#define pte_present(x) ((x).pte_low & (_PAGE_PRESENT | _PAGE_PROTNONE))
#define pte_clear(mm,addr,xp) do { set_pte_at(mm, addr, xp, __pte(0)); } while (0)
#define pmd_none(x) (!pmd_val(x))
#define pmd_present(x) (pmd_val(x))
#define pmd_clear(xp) do { set_pmd(xp, __pmd(0)); } while (0)
#define pmd_bad(x) (pmd_val(x) & ~PAGE_MASK)
#define pages_to_mb(x) ((x) >> (20-PAGE_SHIFT))
#define pte_page(x) pfn_to_page(pte_pfn(x))
/*
* The following only work if pte_present() is true.
* Undefined behaviour if not..
*/
#define pte_not_present(pte) (!((pte).pte_low & _PAGE_PRESENT))
#define pte_dirty(pte) ((pte).pte_low & _PAGE_DIRTY)
#define pte_young(pte) ((pte).pte_low & _PAGE_ACCESSED)
#define pte_special(pte) ((pte).pte_low & _PAGE_SPECIAL)
#ifdef CONFIG_X2TLB
#define pte_write(pte) \
((pte).pte_high & (_PAGE_EXT_USER_WRITE | _PAGE_EXT_KERN_WRITE))
#else
#define pte_write(pte) ((pte).pte_low & _PAGE_RW)
#endif
#define PTE_BIT_FUNC(h,fn,op) \
static inline pte_t pte_##fn(pte_t pte) { pte.pte_##h op; return pte; }
#ifdef CONFIG_X2TLB
/*
* We cheat a bit in the SH-X2 TLB case. As the permission bits are
* individually toggled (and user permissions are entirely decoupled from
* kernel permissions), we attempt to couple them a bit more sanely here.
*/
PTE_BIT_FUNC(high, wrprotect, &= ~(_PAGE_EXT_USER_WRITE | _PAGE_EXT_KERN_WRITE));
PTE_BIT_FUNC(high, mkwrite_novma, |= _PAGE_EXT_USER_WRITE | _PAGE_EXT_KERN_WRITE);
PTE_BIT_FUNC(high, mkhuge, |= _PAGE_SZHUGE);
#else
PTE_BIT_FUNC(low, wrprotect, &= ~_PAGE_RW);
PTE_BIT_FUNC(low, mkwrite_novma, |= _PAGE_RW);
PTE_BIT_FUNC(low, mkhuge, |= _PAGE_SZHUGE);
#endif
PTE_BIT_FUNC(low, mkclean, &= ~_PAGE_DIRTY);
PTE_BIT_FUNC(low, mkdirty, |= _PAGE_DIRTY);
PTE_BIT_FUNC(low, mkold, &= ~_PAGE_ACCESSED);
PTE_BIT_FUNC(low, mkyoung, |= _PAGE_ACCESSED);
PTE_BIT_FUNC(low, mkspecial, |= _PAGE_SPECIAL);
/*
* Macro and implementation to make a page protection as uncachable.
*/
#define pgprot_writecombine(prot) \
__pgprot(pgprot_val(prot) & ~_PAGE_CACHABLE)
#define pgprot_noncached pgprot_writecombine
/*
* Conversion functions: convert a page and protection to a page entry,
* and a page entry and page directory to the page they refer to.
*
* extern pte_t mk_pte(struct page *page, pgprot_t pgprot)
*/
#define mk_pte(page, pgprot) pfn_pte(page_to_pfn(page), (pgprot))
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
pte.pte_low &= _PAGE_CHG_MASK;
pte.pte_low |= pgprot_val(newprot);
#ifdef CONFIG_X2TLB
pte.pte_high |= pgprot_val(newprot) >> 32;
#endif
return pte;
}
static inline unsigned long pmd_page_vaddr(pmd_t pmd)
{
return (unsigned long)pmd_val(pmd);
}
#define pmd_pfn(pmd) (__pa(pmd_val(pmd)) >> PAGE_SHIFT)
#define pmd_page(pmd) (virt_to_page(pmd_val(pmd)))
#ifdef CONFIG_X2TLB
#define pte_ERROR(e) \
printk("%s:%d: bad pte %p(%08lx%08lx).\n", __FILE__, __LINE__, \
&(e), (e).pte_high, (e).pte_low)
#define pgd_ERROR(e) \
printk("%s:%d: bad pgd %016llx.\n", __FILE__, __LINE__, pgd_val(e))
#else
#define pte_ERROR(e) \
printk("%s:%d: bad pte %08lx.\n", __FILE__, __LINE__, pte_val(e))
#define pgd_ERROR(e) \
printk("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
#endif
/*
* Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that
* are !pte_none() && !pte_present().
*
* Constraints:
* _PAGE_PRESENT at bit 8
* _PAGE_PROTNONE at bit 9
*
* For the normal case, we encode the swap type and offset into the swap PTE
* such that bits 8 and 9 stay zero. For the 64-bit PTE case, we use the
* upper 32 for the swap offset and swap type, following the same approach as
* x86 PAE. This keeps the logic quite simple.
*
* As is evident by the Alpha code, if we ever get a 64-bit unsigned
* long (swp_entry_t) to match up with the 64-bit PTEs, this all becomes
* much cleaner..
*/
#ifdef CONFIG_X2TLB
/*
* Format of swap PTEs:
*
* 6 6 6 6 5 5 5 5 5 5 5 5 5 5 4 4 4 4 4 4 4 4 4 4 3 3 3 3 3 3 3 3
* 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2
* <--------------------- offset ----------------------> < type ->
*
* 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1
* 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
* <------------------- zeroes --------------------> E 0 0 0 0 0 0
*/
#define __swp_type(x) ((x).val & 0x1f)
#define __swp_offset(x) ((x).val >> 5)
#define __swp_entry(type, offset) ((swp_entry_t){ ((type) & 0x1f) | (offset) << 5})
#define __pte_to_swp_entry(pte) ((swp_entry_t){ (pte).pte_high })
#define __swp_entry_to_pte(x) ((pte_t){ 0, (x).val })
#else
/*
* Format of swap PTEs:
*
* 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1
* 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
* <--------------- offset ----------------> 0 0 0 0 E < type -> 0
*
* E is the exclusive marker that is not stored in swap entries.
*/
#define __swp_type(x) ((x).val & 0x1f)
#define __swp_offset(x) ((x).val >> 10)
#define __swp_entry(type, offset) ((swp_entry_t){((type) & 0x1f) | (offset) << 10})
#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) >> 1 })
#define __swp_entry_to_pte(x) ((pte_t) { (x).val << 1 })
#endif
/* In both cases, we borrow bit 6 to store the exclusive marker in swap PTEs. */
#define _PAGE_SWP_EXCLUSIVE _PAGE_USER
static inline int pte_swp_exclusive(pte_t pte)
{
return pte.pte_low & _PAGE_SWP_EXCLUSIVE;
}
PTE_BIT_FUNC(low, swp_mkexclusive, |= _PAGE_SWP_EXCLUSIVE);
PTE_BIT_FUNC(low, swp_clear_exclusive, &= ~_PAGE_SWP_EXCLUSIVE);
#endif /* __ASSEMBLY__ */
#endif /* __ASM_SH_PGTABLE_32_H */
Reference in a new issue View git blame Copy permalink