With CONFIG_MMU=y get_fs() returns current_thread_info()->addr_limit
which is initialized as USER_DS (which in turn is defined to TASK_SIZE)
for userspace processes. At least theoretically
current_thread_info()->addr_limit is changable by set_fs() to a
different limit, so checking for KERNEL_DS is more robust.

With !CONFIG_MMU get_fs returns KERNEL_DS. To see what the old variant
did you'd have to find out that USER_DS == KERNEL_DS which isn't needed
any more with the variant this patch introduces. So it's a bit easier to
understand, too.

Also if the limit was changed this limit should be returned, not
TASK_SIZE.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>

According to arm procedure call standart r2 register is call-cloberred.
So after the result of x expression was put into r2 any following
function call in p may overwrite r2. To fix this, the result of p
expression must be saved to the temporary variable before the
assigment x expression to __r2.
Signed-off-by: NAndrey Ryabinin <a.ryabinin@samsung.com>
Reviewed-by: NNicolas Pitre <nico@linaro.org>
Cc: stable@vger.kernel.org
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Now that we select HAVE_EFFICIENT_UNALIGNED_ACCESS for ARMv6+ CPUs,
replace the __LINUX_ARM_ARCH__ check in uaccess.h with the new symbol.
Signed-off-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

BTRFS is now relying on those since v3.12-rc1.
Signed-off-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

On NOMMU ARM, the __addr_ok() and __range_ok() macros do not evaluate
their arguments, which may lead to harmless build warnings in some
code where the variables are not used otherwise. Adding a cast to void
gets rid of the warning and does not make any semantic changes.

Without this patch, building at91x40_defconfig results in:

fs/read_write.c: In function 'rw_copy_check_uvector':
fs/read_write.c:684:9: warning: unused variable 'buf' [-Wunused-variable]
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NGreg Ungerer <gerg@uclinux.org>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>

The user access functions may generate a fault, resulting in invocation
of a handler that may sleep.

This patch annotates the accessors with might_fault() so that we print a
warning if they are invoked from atomic context and help lockdep keep
track of mmap_sem.
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

The {get,put}_user macros don't perform range checking on the provided
__user address when !CPU_HAS_DOMAINS.

This patch reworks the out-of-line assembly accessors to check the user
address against a specified limit, returning -EFAULT if is is out of
range.

[will: changed get_user register allocation to match put_user]
[rmk: fixed building on older ARM architectures]
Reported-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Cc: stable@vger.kernel.org
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This patch implements the word-at-a-time interface for ARM using the
same algorithm as x86. We use the fls macro from ARMv5 onwards, where
we have a clz instruction available which saves us a mov instruction
when targetting Thumb-2. For older CPUs, we use the magic 0x0ff0001
constant. Big-endian configurations make use of the implementation from
asm-generic.

With this implemented, we can replace our byte-at-a-time strnlen_user
and strncpy_from_user functions with the optimised generic versions.
Reviewed-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Disintegrate asm/system.h for ARM.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
cc: Russell King <linux@arm.linux.org.uk>
cc: linux-arm-kernel@lists.infradead.org

This macro is used to generate unprivileged accesses (LDRT/STRT) to user
space.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

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: NAnton Vorontsov <cbouatmailru@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

/tmp/ccJ3ssZW.s: Assembler messages:
/tmp/ccJ3ssZW.s:1952: Error: can't resolve `.text' {.text section} - `.LFB1077'

This is caused because:

	.section .data
	.section .text
	.section .text
	.previous

does not return us to the .text section, but the .data section; this
makes use of .previous dangerous if the ordering of previous sections
is not known.

Fix up the other users of .previous; .pushsection and .popsection are
a safer pairing to use than .section and .previous.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This patch adds the ARM/Thumb-2 unified support for the arch/arm/lib/*
files.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

This allows for optional alternative implementations of __copy_to_user
and __clear_user, with a possible runtime fallback to the standard
version when the alternative provides no gain over that standard
version. This is done by making the standard __copy_to_user into a weak
alias for the symbol __copy_to_user_std.  Same thing for __clear_user.

Those two functions are particularly good candidates to have alternative
implementations for, since they rely on the STRT instruction which has
lower performances than STM instructions on some CPU cores such as
the ARM1176 and Marvell Feroceon.
Signed-off-by: NNicolas Pitre <nico@marvell.com>

... and fix those drivers that were incorrectly relying upon
that include.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

As suggested by Andrew Morton, remove memzero() - it's not supported
on other architectures so use of it is a potential build breaking bug.
Since the compiler optimizes memset(x,0,n) to __memzero() perfectly
well, we don't miss out on the underlying benefits of memzero().
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

The post-index immediate value is optional if it is 0 and this patch
removes it. The reason is to allow such instructions to compile to
Thumb-2 where only pre-indexed LDRT/STRT instructions are allowed.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Move platform independent header files to arch/arm/include/asm, leaving
those in asm/arch* and asm/plat* alone.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

The C99 specification states in section 6.11.5:

The placement of a storage-class specifier other than at the
beginning of the declaration specifiers in a declaration is an
obsolescent feature.
Signed-off-by: NTobias Klauser <tklauser@distanz.ch>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

Rename the variable "sum" in the __range_ok macros to avoid name collisions
causing lots of "symbol shadows an earlier one" warnings by sparse.
Signed-off-by: NTilman Schmidt <tilman@imap.cc>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Andi Kleen <ak@suse.de>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Acked-by: NIan Molton <spyro@f2s.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

MMUless systems have only one address space for all threads, so
both the usual access_ok() checks, and the exception handling do
not make much sense.

Hence, discard the fixup and exception tables at link time, use
memcpy/memset for the user copy/clearing functions, and define
the permission check macros to be constants.

Some of this patch was derived from the equivalent patch by
Hyok S. Choi.
Signed-off-by: NHyok S. Choi <hyok.choi@samsung.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Back in the days when we had armo (26-bit) and armv (32-bit) combined,
we had an additional layer to the uaccess macros to ensure correct
typing.  Since we no longer have 26-bit in this tree, we no longer
need this layer, so eliminate it.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Unfortunately, later gcc versions error out when our get_user is passed
a const pointer, since we write to a temporary variable declared as
typeof(*(p)) which propagates the const-ness.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Remove the deprecated (and unused) verify_area() from various uaccess.h
headers.
Signed-off-by: NJesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!