The new veneer support for loadable modules on ARM uses the
__opcode_to_mem_thumb32() function to count R_ARM_THM_CALL
and R_ARM_THM_JUMP24 relocations.

However, this function is not defined for big-endian kernels
on ARMv5 or before, causing a compile-time error:

arch/arm/kernel/module-plts.c: In function 'count_plts':
arch/arm/kernel/module-plts.c:124:9: error: implicit declaration of function '__opcode_to_mem_thumb32' [-Werror=implicit-function-declaration]
         __opcode_to_mem_thumb32(0x07ff2fff)))
         ^

As we know that this part of the function is only needed for
Thumb2 kernels, and that those can never happen with BE32,
we can avoid the error by enclosing the code in an #ifdef.

Fixes: 7d485f64 ("ARM: 8220/1: allow modules outside of bl range")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Loading modules far away from the kernel in memory is problematic
because the 'bl' instruction only has limited reach, and modules are not
built with PLTs. Instead of using the -mlong-calls option (which affects
all compiler emitted bl instructions, but not the ones in assembler),
this patch allocates some additional space at module load time, and
populates it with PLT like veneers when encountering relocations that
are out of range.

This should work with all relocations against symbols exported by the
kernel, including those resulting from GCC generated implicit function
calls for ftrace etc.

The module memory size increases by about 5% on average, regardless of
whether any PLT entries were actually needed. However, due to the page
based rounding that occurs when allocating module memory, the average
memory footprint increase is negligible.
Reviewed-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>