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/lib/getuser.S | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'arch/arm/lib/getuser.S') 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 #include +#include 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) -- cgit v1.2.3