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mm: Allow architectures to define additional protection bits

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This patch allows architectures to define functions to deal with
additional protections bits for mmap() and mprotect().

arch_calc_vm_prot_bits() maps additonal protection bits to vm_flags
arch_vm_get_page_prot() maps additional vm_flags to the vma's vm_page_prot
arch_validate_prot() checks for valid values of the protection bits

Note: vm_get_page_prot() is now pretty ugly, but the generated code
should be identical for architectures that don't define additional
protection bits.

Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Dave Kleikamp 2008-07-08 00:28:51 +10:00 committed by Benjamin Herrenschmidt
parent e5093ff05d
commit b845f313d7
3 changed files with 32 additions and 4 deletions
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29
include/linux/mman.h
View File

@ -33,6 +33,32 @@ static inline void vm_unacct_memory(long pages)
vm_acct_memory(-pages);
}
/*
* Allow architectures to handle additional protection bits
*/
#ifndef arch_calc_vm_prot_bits
#define arch_calc_vm_prot_bits(prot) 0
#endif
#ifndef arch_vm_get_page_prot
#define arch_vm_get_page_prot(vm_flags) __pgprot(0)
#endif
#ifndef arch_validate_prot
/*
* This is called from mprotect(). PROT_GROWSDOWN and PROT_GROWSUP have
* already been masked out.
*
* Returns true if the prot flags are valid
*/
static inline int arch_validate_prot(unsigned long prot)
{
return (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM)) == 0;
}
#define arch_validate_prot arch_validate_prot
#endif
/*
* Optimisation macro. It is equivalent to:
* (x & bit1) ? bit2 : 0
@ -51,7 +77,8 @@ calc_vm_prot_bits(unsigned long prot)
{
return _calc_vm_trans(prot, PROT_READ, VM_READ ) |
_calc_vm_trans(prot, PROT_WRITE, VM_WRITE) |
_calc_vm_trans(prot, PROT_EXEC, VM_EXEC );
_calc_vm_trans(prot, PROT_EXEC, VM_EXEC) |
arch_calc_vm_prot_bits(prot);
}
/*

5
mm/mmap.c
View File

@ -72,8 +72,9 @@ pgprot_t protection_map[16] = {
pgprot_t vm_get_page_prot(unsigned long vm_flags)
{
return protection_map[vm_flags &
(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
return __pgprot(pgprot_val(protection_map[vm_flags &
(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
pgprot_val(arch_vm_get_page_prot(vm_flags)));
}
EXPORT_SYMBOL(vm_get_page_prot);

2
mm/mprotect.c
View File

@ -239,7 +239,7 @@ sys_mprotect(unsigned long start, size_t len, unsigned long prot)
end = start + len;
if (end <= start)
return -ENOMEM;
if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM))
if (!arch_validate_prot(prot))
return -EINVAL;
reqprot = prot;