From 247055aa21ffef1c49dd64710d5e94c2aee19b58 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Mon, 13 Sep 2010 16:03:21 +0100 Subject: ARM: 6384/1: Remove the domain switching on ARMv6k/v7 CPUs This patch removes the domain switching functionality via the set_fs and __switch_to functions on cores that have a TLS register. Currently, the ioremap and vmalloc areas share the same level 1 page tables and therefore have the same domain (DOMAIN_KERNEL). When the kernel domain is modified from Client to Manager (via the __set_fs or in the __switch_to function), the XN (eXecute Never) bit is overridden and newer CPUs can speculatively prefetch the ioremap'ed memory. Linux performs the kernel domain switching to allow user-specific functions (copy_to/from_user, get/put_user etc.) to access kernel memory. In order for these functions to work with the kernel domain set to Client, the patch modifies the LDRT/STRT and related instructions to the LDR/STR ones. The user pages access rights are also modified for kernel read-only access rather than read/write so that the copy-on-write mechanism still works. CPU_USE_DOMAINS gets disabled only if the hardware has a TLS register (CPU_32v6K is defined) since writing the TLS value to the high vectors page isn't possible. The user addresses passed to the kernel are checked by the access_ok() function so that they do not point to the kernel space. Tested-by: Anton Vorontsov Cc: Tony Lindgren Signed-off-by: Catalin Marinas Signed-off-by: Russell King --- arch/arm/include/asm/futex.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'arch/arm/include/asm/futex.h') diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h index 540a044153a5..b33fe7065b38 100644 --- a/arch/arm/include/asm/futex.h +++ b/arch/arm/include/asm/futex.h @@ -13,12 +13,13 @@ #include #include #include +#include #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \ __asm__ __volatile__( \ - "1: ldrt %1, [%2]\n" \ + "1: " T(ldr) " %1, [%2]\n" \ " " insn "\n" \ - "2: strt %0, [%2]\n" \ + "2: " T(str) " %0, [%2]\n" \ " mov %0, #0\n" \ "3:\n" \ " .pushsection __ex_table,\"a\"\n" \ @@ -97,10 +98,10 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) pagefault_disable(); /* implies preempt_disable() */ __asm__ __volatile__("@futex_atomic_cmpxchg_inatomic\n" - "1: ldrt %0, [%3]\n" + "1: " T(ldr) " %0, [%3]\n" " teq %0, %1\n" " it eq @ explicit IT needed for the 2b label\n" - "2: streqt %2, [%3]\n" + "2: " T(streq) " %2, [%3]\n" "3:\n" " .pushsection __ex_table,\"a\"\n" " .align 3\n" -- cgit v1.2.2