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authorCatalin Marinas <catalin.marinas@arm.com>2010-09-13 16:03:21 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-11-04 15:44:31 +0000
commit247055aa21ffef1c49dd64710d5e94c2aee19b58 (patch)
treee9e026b96597d080de4c16bb88c17b0495c61904 /arch/arm/include/asm/assembler.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/assembler.h')
-rw-r--r--arch/arm/include/asm/assembler.h13
1 files changed, 7 insertions, 6 deletions
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index 062b58c029ab..4e84d09c9c1b 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -18,6 +18,7 @@
#endif
#include <asm/ptrace.h>
+#include <asm/domain.h>
/*
* Endian independent macros for shifting bytes within registers.
@@ -206,12 +207,12 @@
*/
#ifdef CONFIG_THUMB2_KERNEL
- .macro usraccoff, instr, reg, ptr, inc, off, cond, abort
+ .macro usraccoff, instr, reg, ptr, inc, off, cond, abort, t=T()
9999:
.if \inc == 1
- \instr\cond\()bt \reg, [\ptr, #\off]
+ \instr\cond\()b\()\t\().w \reg, [\ptr, #\off]
.elseif \inc == 4
- \instr\cond\()t \reg, [\ptr, #\off]
+ \instr\cond\()\t\().w \reg, [\ptr, #\off]
.else
.error "Unsupported inc macro argument"
.endif
@@ -246,13 +247,13 @@
#else /* !CONFIG_THUMB2_KERNEL */
- .macro usracc, instr, reg, ptr, inc, cond, rept, abort
+ .macro usracc, instr, reg, ptr, inc, cond, rept, abort, t=T()
.rept \rept
9999:
.if \inc == 1
- \instr\cond\()bt \reg, [\ptr], #\inc
+ \instr\cond\()b\()\t \reg, [\ptr], #\inc
.elseif \inc == 4
- \instr\cond\()t \reg, [\ptr], #\inc
+ \instr\cond\()\t \reg, [\ptr], #\inc
.else
.error "Unsupported inc macro argument"
.endif