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/domain.h | 31 +++++++++++++++++++++++++++++-- 1 file changed, 29 insertions(+), 2 deletions(-) (limited to 'arch/arm/include/asm/domain.h') diff --git a/arch/arm/include/asm/domain.h b/arch/arm/include/asm/domain.h index cc7ef4080711..af18ceaacf5d 100644 --- a/arch/arm/include/asm/domain.h +++ b/arch/arm/include/asm/domain.h @@ -45,13 +45,17 @@ */ #define DOMAIN_NOACCESS 0 #define DOMAIN_CLIENT 1 +#ifdef CONFIG_CPU_USE_DOMAINS #define DOMAIN_MANAGER 3 +#else +#define DOMAIN_MANAGER 1 +#endif #define domain_val(dom,type) ((type) << (2*(dom))) #ifndef __ASSEMBLY__ -#ifdef CONFIG_MMU +#ifdef CONFIG_CPU_USE_DOMAINS #define set_domain(x) \ do { \ __asm__ __volatile__( \ @@ -74,5 +78,28 @@ #define modify_domain(dom,type) do { } while (0) #endif +/* + * Generate the T (user) versions of the LDR/STR and related + * instructions (inline assembly) + */ +#ifdef CONFIG_CPU_USE_DOMAINS +#define T(instr) #instr "t" +#else +#define T(instr) #instr #endif -#endif /* !__ASSEMBLY__ */ + +#else /* __ASSEMBLY__ */ + +/* + * Generate the T (user) versions of the LDR/STR and related + * instructions + */ +#ifdef CONFIG_CPU_USE_DOMAINS +#define T(instr) instr ## t +#else +#define T(instr) instr +#endif + +#endif /* __ASSEMBLY__ */ + +#endif /* !__ASM_PROC_DOMAIN_H */ -- cgit