From 14f0aa359365e8a93a77b71e3b840274b9b4dcb1 Mon Sep 17 00:00:00 2001 From: Russell King Date: Sat, 23 May 2009 11:36:20 +0100 Subject: [ARM] disable NX support for OABI-supporting kernels Our signal syscall restart handling for these kernels still uses the userspace stack to build code for restarting the syscall. Unfortunately, fixing this is non-trivial, and so for the time being, we resolve the problem by disabling NX support. Signed-off-by: Russell King --- arch/arm/kernel/elf.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'arch/arm/kernel') diff --git a/arch/arm/kernel/elf.c b/arch/arm/kernel/elf.c index d4a0da1e48f4..950391f194c4 100644 --- a/arch/arm/kernel/elf.c +++ b/arch/arm/kernel/elf.c @@ -78,6 +78,15 @@ int arm_elf_read_implies_exec(const struct elf32_hdr *x, int executable_stack) return 1; if (cpu_architecture() < CPU_ARCH_ARMv6) return 1; +#if !defined(CONFIG_AEABI) || defined(CONFIG_OABI_COMPAT) + /* + * If we have support for OABI programs, we can never allow NX + * support - our signal syscall restart mechanism relies upon + * being able to execute code placed on the user stack. + */ + return 1; +#else return 0; +#endif } EXPORT_SYMBOL(arm_elf_read_implies_exec); -- cgit v1.2.3 From bac4e960b5ce2453d862beaf20e59aa68af3b43a Mon Sep 17 00:00:00 2001 From: Russell King Date: Mon, 25 May 2009 20:58:00 +0100 Subject: [ARM] barriers: improve xchg, bitops and atomic SMP barriers Mathieu Desnoyers pointed out that the ARM barriers were lacking: - cmpxchg, xchg and atomic add return need memory barriers on architectures which can reorder the relative order in which memory read/writes can be seen between CPUs, which seems to include recent ARM architectures. Those barriers are currently missing on ARM. - test_and_xxx_bit were missing SMP barriers. So put these barriers in. Provide separate atomic_add/atomic_sub operations which do not require barriers. Reported-Reviewed-and-Acked-by: Mathieu Desnoyers Signed-off-by: Russell King --- arch/arm/kernel/entry-armv.S | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'arch/arm/kernel') diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index d662a2f1fd85..83b1da6b7baa 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -815,10 +815,7 @@ __kuser_helper_start: */ __kuser_memory_barrier: @ 0xffff0fa0 - -#if __LINUX_ARM_ARCH__ >= 6 && defined(CONFIG_SMP) - mcr p15, 0, r0, c7, c10, 5 @ dmb -#endif + smp_dmb usr_ret lr .align 5 -- cgit v1.2.3