diff options
| author | Mike Frysinger <vapier@gentoo.org> | 2010-01-06 17:23:17 +0000 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-01-06 18:16:02 -0800 |
| commit | 04e4f2b18c8de1389d1e00fef0f42a8099910daf (patch) | |
| tree | cd1ae20d055552a7ea9b9a21ee01a052589a66f5 /arch | |
| parent | 93939f4e5df30e6229a0b5257fdcaf3faf88471c (diff) | |
FDPIC: Respect PT_GNU_STACK exec protection markings when creating NOMMU stack
The current code will load the stack size and protection markings, but
then only use the markings in the MMU code path. The NOMMU code path
always passes PROT_EXEC to the mmap() call. While this doesn't matter
to most people whilst the code is running, it will cause a pointless
icache flush when starting every FDPIC application. Typically this
icache flush will be of a region on the order of 128KB in size, or may
be the entire icache, depending on the facilities available on the CPU.
In the case where the arch default behaviour seems to be desired
(EXSTACK_DEFAULT), we probe VM_STACK_FLAGS for VM_EXEC to determine
whether we should be setting PROT_EXEC or not.
For arches that support an MPU (Memory Protection Unit - an MMU without
the virtual mapping capability), setting PROT_EXEC or not will make an
important difference.
It should be noted that this change also affects the executability of
the brk region, since ELF-FDPIC has that share with the stack. However,
this is probably irrelevant as NOMMU programs aren't likely to use the
brk region, preferring instead allocation via mmap().
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/blackfin/include/asm/page.h | 5 | ||||
| -rw-r--r-- | arch/frv/include/asm/page.h | 2 |
2 files changed, 5 insertions, 2 deletions
diff --git a/arch/blackfin/include/asm/page.h b/arch/blackfin/include/asm/page.h index 944a07c6cfd..1d04e407834 100644 --- a/arch/blackfin/include/asm/page.h +++ b/arch/blackfin/include/asm/page.h @@ -10,4 +10,9 @@ #include <asm-generic/page.h> #define MAP_NR(addr) (((unsigned long)(addr)-PAGE_OFFSET) >> PAGE_SHIFT) +#define VM_DATA_DEFAULT_FLAGS \ + (VM_READ | VM_WRITE | \ + ((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0 ) | \ + VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC) + #endif diff --git a/arch/frv/include/asm/page.h b/arch/frv/include/asm/page.h index 25c6a500235..8c97068ac8f 100644 --- a/arch/frv/include/asm/page.h +++ b/arch/frv/include/asm/page.h @@ -63,12 +63,10 @@ extern unsigned long max_pfn; #define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT) -#ifdef CONFIG_MMU #define VM_DATA_DEFAULT_FLAGS \ (VM_READ | VM_WRITE | \ ((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0 ) | \ VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC) -#endif #endif /* __ASSEMBLY__ */ |