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arm64: Move PTE_RDONLY bit handling out of set_pte_at() 

Currently PTE_RDONLY is treated as a hardware only bit and not handled
by the pte_mkwrite(), pte_wrprotect() or the user PAGE_* definitions.
The set_pte_at() function is responsible for setting this bit based on
the write permission or dirty state. This patch moves the PTE_RDONLY
handling out of set_pte_at into the pte_mkwrite()/pte_wrprotect()
functions. The PAGE_* definitions to need to be updated to explicitly
include PTE_RDONLY when !PTE_WRITE.

The patch also removes the redundant PAGE_COPY(_EXEC) definitions as
they are identical to the corresponding PAGE_READONLY(_EXEC).

Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Catalin Marinas 2017-07-04 19:04:18 +01:00
parent 0966253d7c
commit 73e86cb03c
4 changed files with 21 additions and 41 deletions
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18
arch/arm64/include/asm/pgtable-prot.h
View File

@ -63,23 +63,21 @@
#define PAGE_S2 __pgprot(PROT_DEFAULT | PTE_S2_MEMATTR(MT_S2_NORMAL) | PTE_S2_RDONLY)
#define PAGE_S2_DEVICE __pgprot(PROT_DEFAULT | PTE_S2_MEMATTR(MT_S2_DEVICE_nGnRE) | PTE_S2_RDONLY | PTE_UXN)
#define PAGE_NONE __pgprot(((_PAGE_DEFAULT) & ~PTE_VALID) | PTE_PROT_NONE | PTE_PXN | PTE_UXN)
#define PAGE_NONE __pgprot(((_PAGE_DEFAULT) & ~PTE_VALID) | PTE_PROT_NONE | PTE_RDONLY | PTE_PXN | PTE_UXN)
#define PAGE_SHARED __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_WRITE)
#define PAGE_SHARED_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_WRITE)
#define PAGE_COPY __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)
#define PAGE_COPY_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN)
#define PAGE_READONLY __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)
#define PAGE_READONLY_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN)
#define PAGE_EXECONLY __pgprot(_PAGE_DEFAULT | PTE_NG | PTE_PXN)
#define PAGE_READONLY __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_RDONLY | PTE_NG | PTE_PXN | PTE_UXN)
#define PAGE_READONLY_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_RDONLY | PTE_NG | PTE_PXN)
#define PAGE_EXECONLY __pgprot(_PAGE_DEFAULT | PTE_RDONLY | PTE_NG | PTE_PXN)
#define __P000 PAGE_NONE
#define __P001 PAGE_READONLY
#define __P010 PAGE_COPY
#define __P011 PAGE_COPY
#define __P010 PAGE_READONLY
#define __P011 PAGE_READONLY
#define __P100 PAGE_EXECONLY
#define __P101 PAGE_READONLY_EXEC
#define __P110 PAGE_COPY_EXEC
#define __P111 PAGE_COPY_EXEC
#define __P110 PAGE_READONLY_EXEC
#define __P111 PAGE_READONLY_EXEC
#define __S000 PAGE_NONE
#define __S001 PAGE_READONLY

32
arch/arm64/include/asm/pgtable.h
View File

@ -125,12 +125,16 @@ static inline pte_t set_pte_bit(pte_t pte, pgprot_t prot)
static inline pte_t pte_wrprotect(pte_t pte)
{
return clear_pte_bit(pte, __pgprot(PTE_WRITE));
pte = clear_pte_bit(pte, __pgprot(PTE_WRITE));
pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
return pte;
}
static inline pte_t pte_mkwrite(pte_t pte)
{
return set_pte_bit(pte, __pgprot(PTE_WRITE));
pte = set_pte_bit(pte, __pgprot(PTE_WRITE));
pte = clear_pte_bit(pte, __pgprot(PTE_RDONLY));
return pte;
}
static inline pte_t pte_mkclean(pte_t pte)
@ -169,16 +173,6 @@ static inline pte_t pte_mknoncont(pte_t pte)
return clear_pte_bit(pte, __pgprot(PTE_CONT));
}
static inline pte_t pte_clear_rdonly(pte_t pte)
{
return clear_pte_bit(pte, __pgprot(PTE_RDONLY));
}
static inline pte_t pte_set_rdonly(pte_t pte)
{
return set_pte_bit(pte, __pgprot(PTE_RDONLY));
}
static inline pte_t pte_mkpresent(pte_t pte)
{
return set_pte_bit(pte, __pgprot(PTE_VALID));
@ -226,14 +220,8 @@ extern void __sync_icache_dcache(pte_t pteval, unsigned long addr);
static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
if (pte_present(pte)) {
if (pte_sw_dirty(pte) && pte_write(pte))
pte_val(pte) &= ~PTE_RDONLY;
else
pte_val(pte) |= PTE_RDONLY;
if (pte_user_exec(pte) && !pte_special(pte))
if (pte_present(pte) && pte_user_exec(pte) && !pte_special(pte))
__sync_icache_dcache(pte, addr);
}
/*
* If the existing pte is valid, check for potential race with
@ -659,12 +647,10 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
old_pte = pte;
/*
* If hardware-dirty (PTE_WRITE/DBM bit set and PTE_RDONLY
* clear), set the PTE_DIRTY and PTE_RDONLY bits.
* clear), set the PTE_DIRTY bit.
*/
if (pte_hw_dirty(pte)) {
if (pte_hw_dirty(pte))
pte = pte_mkdirty(pte);
pte = pte_set_rdonly(pte);
}
pte = pte_wrprotect(pte);
pte_val(pte) = cmpxchg_relaxed(&pte_val(*ptep),
pte_val(old_pte), pte_val(pte));

4
arch/arm64/kernel/hibernate.c
View File

@ -330,7 +330,7 @@ static void _copy_pte(pte_t *dst_pte, pte_t *src_pte, unsigned long addr)
* read only (code, rodata). Clear the RDONLY bit from
* the temporary mappings we use during restore.
*/
set_pte(dst_pte, pte_clear_rdonly(pte));
set_pte(dst_pte, pte_mkwrite(pte));
} else if (debug_pagealloc_enabled() && !pte_none(pte)) {
/*
* debug_pagealloc will removed the PTE_VALID bit if
@ -343,7 +343,7 @@ static void _copy_pte(pte_t *dst_pte, pte_t *src_pte, unsigned long addr)
*/
BUG_ON(!pfn_valid(pte_pfn(pte)));
set_pte(dst_pte, pte_mkpresent(pte_clear_rdonly(pte)));
set_pte(dst_pte, pte_mkpresent(pte_mkwrite(pte)));
}
}

6
arch/arm64/mm/fault.c
View File

@ -204,11 +204,7 @@ int ptep_set_access_flags(struct vm_area_struct *vma,
return 0;
/* only preserve the access flags and write permission */
pte_val(entry) &= PTE_AF | PTE_WRITE | PTE_DIRTY;
/* set PTE_RDONLY if actual read-only or clean PTE */
if (!pte_write(entry) || !pte_sw_dirty(entry))
entry = pte_set_rdonly(entry);
pte_val(entry) &= PTE_RDONLY | PTE_AF | PTE_WRITE | PTE_DIRTY;
/*
* Setting the flags must be done atomically to avoid racing with the