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authorCatalin Marinas <catalin.marinas@arm.com>2010-09-13 11:03:21 -0400
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-11-04 11:44:31 -0400
commit247055aa21ffef1c49dd64710d5e94c2aee19b58 (patch)
treee9e026b96597d080de4c16bb88c17b0495c61904 /arch/arm/include/asm/domain.h
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/include/asm/domain.h')
-rw-r--r--arch/arm/include/asm/domain.h31
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 @@
45 */ 45 */
46#define DOMAIN_NOACCESS 0 46#define DOMAIN_NOACCESS 0
47#define DOMAIN_CLIENT 1 47#define DOMAIN_CLIENT 1
48#ifdef CONFIG_CPU_USE_DOMAINS
48#define DOMAIN_MANAGER 3 49#define DOMAIN_MANAGER 3
50#else
51#define DOMAIN_MANAGER 1
52#endif
49 53
50#define domain_val(dom,type) ((type) << (2*(dom))) 54#define domain_val(dom,type) ((type) << (2*(dom)))
51 55
52#ifndef __ASSEMBLY__ 56#ifndef __ASSEMBLY__
53 57
54#ifdef CONFIG_MMU 58#ifdef CONFIG_CPU_USE_DOMAINS
55#define set_domain(x) \ 59#define set_domain(x) \
56 do { \ 60 do { \
57 __asm__ __volatile__( \ 61 __asm__ __volatile__( \
@@ -74,5 +78,28 @@
74#define modify_domain(dom,type) do { } while (0) 78#define modify_domain(dom,type) do { } while (0)
75#endif 79#endif
76 80
81/*
82 * Generate the T (user) versions of the LDR/STR and related
83 * instructions (inline assembly)
84 */
85#ifdef CONFIG_CPU_USE_DOMAINS
86#define T(instr) #instr "t"
87#else
88#define T(instr) #instr
77#endif 89#endif
78#endif /* !__ASSEMBLY__ */ 90
91#else /* __ASSEMBLY__ */
92
93/*
94 * Generate the T (user) versions of the LDR/STR and related
95 * instructions
96 */
97#ifdef CONFIG_CPU_USE_DOMAINS
98#define T(instr) instr ## t
99#else
100#define T(instr) instr
101#endif
102
103#endif /* __ASSEMBLY__ */
104
105#endif /* !__ASM_PROC_DOMAIN_H */