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| author | Catalin Marinas <catalin.marinas@arm.com> | 2010-09-13 19:03:21 +0400 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2010-11-04 18:44:31 +0300 |
| commit | 247055aa21ffef1c49dd64710d5e94c2aee19b58 (patch) | |
| tree | e9e026b96597d080de4c16bb88c17b0495c61904 /arch/arm/mm/proc-v7.S | |
| parent | ff8b16d7e15a8ba2a6086645614a483e048e3fbf (diff) | |
| download | linux-247055aa21ffef1c49dd64710d5e94c2aee19b58.tar.xz | |
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/mm/proc-v7.S')
| -rw-r--r-- | arch/arm/mm/proc-v7.S | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S index 53cbe2225153..cfc11afab1fb 100644 --- a/arch/arm/mm/proc-v7.S +++ b/arch/arm/mm/proc-v7.S @@ -148,8 +148,11 @@ ENTRY(cpu_v7_set_pte_ext) tst r1, #L_PTE_USER orrne r3, r3, #PTE_EXT_AP1 +#ifdef CONFIG_CPU_USE_DOMAINS + @ allow kernel read/write access to read-only user pages tstne r3, #PTE_EXT_APX bicne r3, r3, #PTE_EXT_APX | PTE_EXT_AP0 +#endif tst r1, #L_PTE_EXEC orreq r3, r3, #PTE_EXT_XN @@ -273,8 +276,6 @@ __v7_setup: ALT_SMP(orr r4, r4, #TTB_FLAGS_SMP) ALT_UP(orr r4, r4, #TTB_FLAGS_UP) mcr p15, 0, r4, c2, c0, 1 @ load TTB1 - mov r10, #0x1f @ domains 0, 1 = manager - mcr p15, 0, r10, c3, c0, 0 @ load domain access register /* * Memory region attributes with SCTLR.TRE=1 * |