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SubjectRe: [linux-stable-rc:linux-5.4.y 665/2391] drivers/android/binder.c:3776: Error: unrecognized keyword/register name `l.lwz
+openrisc folks

On Thu, Oct 15, 2020 at 11:28 PM kernel test robot <lkp@intel.com> wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-5.4.y
> head: 85b0841aab15c12948af951d477183ab3df7de14
> commit: c5665cafbedd2e2a523fe933e452391a02d3adb3 [665/2391] binder: Prevent context manager from incrementing ref 0
> config: openrisc-randconfig-r002-20201014 (attached as .config)
> compiler: or1k-linux-gcc (GCC) 9.3.0
> reproduce (this is a W=1 build):
> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/commit/?id=c5665cafbedd2e2a523fe933e452391a02d3adb3
> git remote add linux-stable-rc https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git
> git fetch --no-tags linux-stable-rc linux-5.4.y
> git checkout c5665cafbedd2e2a523fe933e452391a02d3adb3
> # save the attached .config to linux build tree
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=openrisc
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
>
> All errors (new ones prefixed by >>):
>
> drivers/android/binder.c: Assembler messages:
> >> drivers/android/binder.c:3776: Error: unrecognized keyword/register name `l.lwz ?ap,4(r25)'
> drivers/android/binder.c:3781: Error: unrecognized keyword/register name `l.addi ?ap,r0,0'

binder is basically doing this:

u64 data_ptr;
if (get_user(data_ptr, (u64 __user *)ptr))
return -EFAULT;

and GCC complains that that doesn't turn into valid assembly on
openrisc, where get_user() of size 8 expands into this:

#define __get_user_asm2(x, addr, err) \
{ \
unsigned long long __gu_tmp; \
__asm__ __volatile__( \
"1: l.lwz %1,0(%2)\n" \
"2: l.lwz %H1,4(%2)\n" \
"3:\n" \
".section .fixup,\"ax\"\n" \
"4: l.addi %0,r0,%3\n" \
" l.addi %1,r0,0\n" \
" l.addi %H1,r0,0\n" \
" l.j 3b\n" \
" l.nop\n" \
".previous\n" \
".section __ex_table,\"a\"\n" \
" .align 2\n" \
" .long 1b,4b\n" \
" .long 2b,4b\n" \
".previous" \
: "=r"(err), "=&r"(__gu_tmp) \
: "r"(addr), "i"(-EFAULT), "0"(err)); \
(x) = (__typeof__(*(addr)))( \
(__typeof__((x)-(x)))__gu_tmp); \
}

and apparently the "l.lwz %H1,4(%2)" and "l.addi %H1,r0,0" don't turn
into valid assembly when %H1 expands to "?ap"?

I don't know anything about OpenRISC, but this seems like it's
probably an issue in the get_user() implementation.

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