Provide uaccess_save_and_enable() and uaccess_restore() to permit
control of userspace visibility to the kernel, and hook these into
the appropriate places in the kernel where we need to access
userspace.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This moves all fixup snippets to the .text.fixup section, which is
a special section that gets emitted along with the .text section
for each input object file, i.e., the snippets are kept much closer
to the code they refer to, which helps prevent linker failure on
large kernels.
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The memory copy functions(memcpy, __copy_from_user, __copy_to_user)
never had unwinding annotations added. Currently, when accessing
invalid pointer by these functions occurs the backtrace shown will
stop at these functions or some completely unrelated function.
Add unwinding annotations in hopes of getting a more useful backtrace
in following cases:
1. die on accessing invalid pointer by these functions
2. kprobe trapped at any instruction within these functions
3. interrupted at any instruction within these functions
Signed-off-by: Lin Yongting <linyongting@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The patch adds the ENDPROC declarations for the __copy_to_user_std and
__clear_user_std functions. Without these, the compiler generates BXL to
ARM when compiling the kernel in Thumb-2 mode.
Reported-by: Kyungmin Park <kmpark@infradead.org>
Tested-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Russell 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: Russell King <rmk+kernel@arm.linux.org.uk>
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: Nicolas Pitre <nico@marvell.com>
This declaration specifies the "function" type and size for various
assembly functions, mainly needed for generating the correct branch
instructions in Thumb-2.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell 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: Russell King <rmk+kernel@arm.linux.org.uk>
Patch from Nicolas Pitre
This patch provides a preemption safe implementation of copy_to_user
and copy_from_user based on the copy template also used for memcpy.
It is enabled unconditionally when CONFIG_PREEMPT=y. Otherwise if the
configured architecture is not ARMv3 then it is enabled as well as it
gives better performances at least on StrongARM and XScale cores. If
ARMv3 is not too affected or if it doesn't matter too much then
uaccess.S could be removed altogether.
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Russell King