[patch 1/5] mm: Allow architectures to define additional protection bits
From: Dave Kleikamp <hidden>
Date: 2008-07-07 14:28:51
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 <redacted> Acked-by: Andrew Morton <akpm@linux-foundation.org> Cc: Hugh Dickins <redacted> --- include/linux/mman.h | 29 ++++++++++++++++++++++++++++- mm/mmap.c | 5 +++-- mm/mprotect.c | 2 +- 3 files changed, 32 insertions(+), 4 deletions(-) Index: b/include/linux/mman.h ===================================================================
--- a/include/linux/mman.h
+++ b/include/linux/mman.h@@ -34,6 +34,32 @@ } /* + * 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 * but this version is faster.
@@ -51,7 +77,8 @@ { 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); } /*
Index: b/mm/mmap.c ===================================================================
--- a/mm/mmap.c
+++ b/mm/mmap.c@@ -72,8 +72,9 @@ 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);
Index: b/mm/mprotect.c ===================================================================
--- a/mm/mprotect.c
+++ b/mm/mprotect.c@@ -239,7 +239,7 @@ 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;
--
Dave Kleikamp
IBM Linux Technology Center