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bianbu-linux-6.6/arch/nios2/include/asm/pgtable.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

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/*
* Copyright (C) 2011 Tobias Klauser <tklauser@distanz.ch>
* Copyright (C) 2009 Wind River Systems Inc
*
* Based on asm/pgtable-32.h from mips which is:
*
* Copyright (C) 1994, 95, 96, 97, 98, 99, 2000, 2003 Ralf Baechle
* Copyright (C) 1999, 2000, 2001 Silicon Graphics, Inc.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#ifndef _ASM_NIOS2_PGTABLE_H
#define _ASM_NIOS2_PGTABLE_H
#include <linux/io.h>
#include <linux/bug.h>
#include <asm/page.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/pgtable-bits.h>
#include <asm-generic/pgtable-nopmd.h>
#define VMALLOC_START CONFIG_NIOS2_KERNEL_MMU_REGION_BASE
#define VMALLOC_END (CONFIG_NIOS2_KERNEL_REGION_BASE - 1)
struct mm_struct;
/* Helper macro */
#define MKP(x, w, r) __pgprot(_PAGE_PRESENT | _PAGE_CACHED | \
((x) ? _PAGE_EXEC : 0) | \
((r) ? _PAGE_READ : 0) | \
((w) ? _PAGE_WRITE : 0))
/*
* These are the macros that generic kernel code needs
* (to populate protection_map[])
*/
/* Remove W bit on private pages for COW support */
/* Shared pages can have exact HW mapping */
/* Used all over the kernel */
#define PAGE_KERNEL __pgprot(_PAGE_PRESENT | _PAGE_CACHED | _PAGE_READ | \
_PAGE_WRITE | _PAGE_EXEC | _PAGE_GLOBAL)
#define PAGE_SHARED __pgprot(_PAGE_PRESENT | _PAGE_CACHED | _PAGE_READ | \
_PAGE_WRITE | _PAGE_ACCESSED)
#define PAGE_COPY MKP(0, 0, 1)
#define PTRS_PER_PGD (PAGE_SIZE / sizeof(pgd_t))
#define PTRS_PER_PTE (PAGE_SIZE / sizeof(pte_t))
#define USER_PTRS_PER_PGD \
(CONFIG_NIOS2_KERNEL_MMU_REGION_BASE / PGDIR_SIZE)
#define PGDIR_SHIFT 22
#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
#define PGDIR_MASK (~(PGDIR_SIZE-1))
/*
* ZERO_PAGE is a global shared page that is always zero: used
* for zero-mapped memory areas etc..
*/
extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
extern pte_t invalid_pte_table[PAGE_SIZE/sizeof(pte_t)];
/*
* (pmds are folded into puds so this doesn't get actually called,
* but the define is needed for a generic inline function.)
*/
static inline void set_pmd(pmd_t *pmdptr, pmd_t pmdval)
{
*pmdptr = pmdval;
}
static inline int pte_write(pte_t pte) \
{ return pte_val(pte) & _PAGE_WRITE; }
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; }
#define pgprot_noncached pgprot_noncached
static inline pgprot_t pgprot_noncached(pgprot_t _prot)
{
unsigned long prot = pgprot_val(_prot);
prot &= ~_PAGE_CACHED;
return __pgprot(prot);
}
static inline int pte_none(pte_t pte)
{
return !(pte_val(pte) & ~(_PAGE_GLOBAL|0xf));
}
static inline int pte_present(pte_t pte) \
{ return pte_val(pte) & _PAGE_PRESENT; }
/*
* The following only work if pte_present() is true.
* Undefined behaviour if not..
*/
static inline pte_t pte_wrprotect(pte_t pte)
{
pte_val(pte) &= ~_PAGE_WRITE;
return pte;
}
static inline pte_t pte_mkclean(pte_t pte)
{
pte_val(pte) &= ~_PAGE_DIRTY;
return pte;
}
static inline pte_t pte_mkold(pte_t pte)
{
pte_val(pte) &= ~_PAGE_ACCESSED;
return pte;
}
static inline pte_t pte_mkwrite_novma(pte_t pte)
{
pte_val(pte) |= _PAGE_WRITE;
return pte;
}
static inline pte_t pte_mkdirty(pte_t pte)
{
pte_val(pte) |= _PAGE_DIRTY;
return pte;
}
static inline pte_t pte_mkyoung(pte_t pte)
{
pte_val(pte) |= _PAGE_ACCESSED;
return pte;
}
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
const unsigned long mask = _PAGE_READ | _PAGE_WRITE | _PAGE_EXEC;
pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask);
return pte;
}
static inline int pmd_present(pmd_t pmd)
{
return (pmd_val(pmd) != (unsigned long) invalid_pte_table)
&& (pmd_val(pmd) != 0UL);
}
static inline void pmd_clear(pmd_t *pmdp)
{
pmd_val(*pmdp) = (unsigned long) invalid_pte_table;
}
#define pte_pfn(pte) (pte_val(pte) & 0xfffff)
#define pfn_pte(pfn, prot) (__pte(pfn | pgprot_val(prot)))
#define pte_page(pte) (pfn_to_page(pte_pfn(pte)))
/*
* Store a linux PTE into the linux page table.
*/
static inline void set_pte(pte_t *ptep, pte_t pteval)
{
*ptep = pteval;
}
static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pteval)
{
unsigned long paddr = (unsigned long)page_to_virt(pte_page(pteval));
flush_dcache_range(paddr, paddr + PAGE_SIZE);
set_pte(ptep, pteval);
}
static inline int pmd_none(pmd_t pmd)
{
return (pmd_val(pmd) ==
(unsigned long) invalid_pte_table) || (pmd_val(pmd) == 0UL);
}
#define pmd_bad(pmd) (pmd_val(pmd) & ~PAGE_MASK)
static inline void pte_clear(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
pte_t null;
pte_val(null) = (addr >> PAGE_SHIFT) & 0xf;
set_pte_at(mm, addr, ptep, null);
}
/*
* Conversion functions: convert a page and protection to a page entry,
* and a page entry and page directory to the page they refer to.
*/
#define mk_pte(page, prot) (pfn_pte(page_to_pfn(page), prot))
/*
* Conversion functions: convert a page and protection to a page entry,
* and a page entry and page directory to the page they refer to.
*/
#define pmd_phys(pmd) virt_to_phys((void *)pmd_val(pmd))
#define pmd_pfn(pmd) (pmd_phys(pmd) >> PAGE_SHIFT)
#define pmd_page(pmd) (pfn_to_page(pmd_phys(pmd) >> PAGE_SHIFT))
static inline unsigned long pmd_page_vaddr(pmd_t pmd)
{
return pmd_val(pmd);
}
#define pte_ERROR(e) \
pr_err("%s:%d: bad pte %08lx.\n", \
__FILE__, __LINE__, pte_val(e))
#define pgd_ERROR(e) \
pr_err("%s:%d: bad pgd %08lx.\n", \
__FILE__, __LINE__, pgd_val(e))
/*
* Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that
* are !pte_none() && !pte_present().
*
* 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
* E < type -> 0 0 0 0 0 0 <-------------- offset --------------->
*
* E is the exclusive marker that is not stored in swap entries.
*
* Note that the offset field is always non-zero if the swap type is 0, thus
* !pte_none() is always true.
*/
#define __swp_type(swp) (((swp).val >> 26) & 0x1f)
#define __swp_offset(swp) ((swp).val & 0xfffff)
#define __swp_entry(type, off) ((swp_entry_t) { (((type) & 0x1f) << 26) \
| ((off) & 0xfffff) })
#define __swp_entry_to_pte(swp) ((pte_t) { (swp).val })
#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) })
static inline int pte_swp_exclusive(pte_t pte)
{
return pte_val(pte) & _PAGE_SWP_EXCLUSIVE;
}
static inline pte_t pte_swp_mkexclusive(pte_t pte)
{
pte_val(pte) |= _PAGE_SWP_EXCLUSIVE;
return pte;
}
static inline pte_t pte_swp_clear_exclusive(pte_t pte)
{
pte_val(pte) &= ~_PAGE_SWP_EXCLUSIVE;
return pte;
}
extern void __init paging_init(void);
extern void __init mmu_init(void);
extern void update_mmu_cache(struct vm_area_struct *vma,
unsigned long address, pte_t *pte);
#endif /* _ASM_NIOS2_PGTABLE_H */
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