linux/arch
Mike Frysinger 04e4f2b18c 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>
2010-01-06 18:16:02 -08:00
..
alpha alpha: Convert BUG() to use unreachable() 2009-12-18 01:14:52 -05:00
arm Merge branch 'davinci-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/khilman/linux-davinci 2010-01-06 10:46:27 -08:00
avr32 Merge branch 'for-33' of git://repo.or.cz/linux-kbuild 2009-12-17 07:23:42 -08:00
blackfin FDPIC: Respect PT_GNU_STACK exec protection markings when creating NOMMU stack 2010-01-06 18:16:02 -08:00
cris Merge branch 'for-33' of git://repo.or.cz/linux-kbuild 2009-12-17 07:23:42 -08:00
frv FDPIC: Respect PT_GNU_STACK exec protection markings when creating NOMMU stack 2010-01-06 18:16:02 -08:00
h8300 Merge branch 'for-33' of git://repo.or.cz/linux-kbuild 2009-12-17 07:23:42 -08:00
ia64 KVM: ia64: fix build breakage due to host spinlock change 2009-12-27 13:36:33 -02:00
m32r elf: kill USE_ELF_CORE_DUMP 2009-12-16 07:20:12 -08:00
m68k Merge branch 'for-33' of git://repo.or.cz/linux-kbuild 2009-12-17 07:23:42 -08:00
m68knommu Unify sys_mmap* 2009-12-11 06:44:29 -05:00
microblaze Merge branch 'for-33' of git://repo.or.cz/linux-kbuild 2009-12-17 07:23:42 -08:00
mips Merge branch 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus 2009-12-17 16:38:06 -08:00
mn10300 Merge branch 'for-33' of git://repo.or.cz/linux-kbuild 2009-12-17 07:23:42 -08:00
parisc Merge branch 'for-33' of git://repo.or.cz/linux-kbuild 2009-12-17 07:23:42 -08:00
powerpc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 2009-12-30 13:13:24 -08:00
s390 [S390] Update default configuration. 2010-01-04 09:05:58 +01:00
score Merge branch 'for-linus' of git://gitserver.sunplusct.com/linux-2.6-score 2009-12-17 08:08:57 -08:00
sh sh: update defconfigs. 2010-01-04 15:38:50 +09:00
sparc sparc64: Fix Niagara2 perf event handling. 2010-01-04 23:16:03 -08:00
um Merge branch 'for-33' of git://repo.or.cz/linux-kbuild 2009-12-17 07:23:42 -08:00
x86 Revert "x86: Side-step lguest problem by only building cmpxchg8b_emu for pre-Pentium" 2010-01-05 16:01:35 -08:00
xtensa Merge branch 'for-33' of git://repo.or.cz/linux-kbuild 2009-12-17 07:23:42 -08:00
.gitignore
Kconfig hw-breakpoints: Fix hardware breakpoints -> perf events dependency 2009-12-18 13:11:51 +01:00