diff options
| author | Catalin Marinas | 2010-09-13 16:03:21 +0100 |
|---|---|---|
| committer | Russell King | 2010-11-04 15:44:31 +0000 |
| commit | 247055aa21ffef1c49dd64710d5e94c2aee19b58 (patch) | |
| tree | e9e026b96597d080de4c16bb88c17b0495c61904 /arch/arm/include/asm/domain.h | |
| parent | ff8b16d7e15a8ba2a6086645614a483e048e3fbf (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/include/asm/domain.h')
| -rw-r--r-- | arch/arm/include/asm/domain.h | 31 |
1 files changed, 29 insertions, 2 deletions
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 */ |