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| author |   Catalin Marinas <catalin.marinas@arm.com> | 2010-09-13 16:03:21 +0100 |
|---|---|---|
| committer |   Russell King <rmk+kernel@arm.linux.org.uk> | 2010-11-04 15:44:31 +0000 |
| commit | 247055aa21ffef1c49dd64710d5e94c2aee19b58 (patch) | |
| tree | e9e026b96597d080de4c16bb88c17b0495c61904 /arch/arm/include/asm/assembler.h | |
| parent | vmstat: fix offset calculation on void* (diff) | |
| download | linux-dev-247055aa21ffef1c49dd64710d5e94c2aee19b58.tar.xz linux-dev-247055aa21ffef1c49dd64710d5e94c2aee19b58.zip | |
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.h | 13 |
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 |