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authorCatalin Marinas <catalin.marinas@arm.com>2010-09-13 16:03:21 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-11-04 15:44:31 +0000
commit247055aa21ffef1c49dd64710d5e94c2aee19b58 (patch)
treee9e026b96597d080de4c16bb88c17b0495c61904 /arch/arm/lib/getuser.S
parentff8b16d7e15a8ba2a6086645614a483e048e3fbf (diff)
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 <cbouatmailru@gmail.com> Cc: Tony Lindgren <tony@atomide.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/lib/getuser.S')
-rw-r--r--arch/arm/lib/getuser.S13
1 files changed, 7 insertions, 6 deletions
diff --git a/arch/arm/lib/getuser.S b/arch/arm/lib/getuser.S
index b1631a7dbe75..1b049cd7a49a 100644
--- a/arch/arm/lib/getuser.S
+++ b/arch/arm/lib/getuser.S
@@ -28,20 +28,21 @@
*/
#include <linux/linkage.h>
#include <asm/errno.h>
+#include <asm/domain.h>
ENTRY(__get_user_1)
-1: ldrbt r2, [r0]
+1: T(ldrb) r2, [r0]
mov r0, #0
mov pc, lr
ENDPROC(__get_user_1)
ENTRY(__get_user_2)
#ifdef CONFIG_THUMB2_KERNEL
-2: ldrbt r2, [r0]
-3: ldrbt r3, [r0, #1]
+2: T(ldrb) r2, [r0]
+3: T(ldrb) r3, [r0, #1]
#else
-2: ldrbt r2, [r0], #1
-3: ldrbt r3, [r0]
+2: T(ldrb) r2, [r0], #1
+3: T(ldrb) r3, [r0]
#endif
#ifndef __ARMEB__
orr r2, r2, r3, lsl #8
@@ -53,7 +54,7 @@ ENTRY(__get_user_2)
ENDPROC(__get_user_2)
ENTRY(__get_user_4)
-4: ldrt r2, [r0]
+4: T(ldr) r2, [r0]
mov r0, #0
mov pc, lr
ENDPROC(__get_user_4)