Subject: Re: [tip:core/rseq 25/39] include/linux/rseq_entry.h:132:3: error: invalid operand for instruction

From: Thomas Gleixner <[email-masked]>
Date: Mon, 24 Nov 2025 20:15:46 +0100

On Tue, Nov 25 2025 at 01:37, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core/rseq
> head:   21782b3a5cd40892cb2995aa1ec3e74dd1112f1d
> commit: abc850e7616c91ebaa3f5ba3617ab0a104d45039 [25/39] rseq: Provide and use rseq_update_user_cs()
> config: powerpc-randconfig-002-20251124 (https://download.01.org/0day-ci/archive/20251125/[email-masked]/config)
> compiler: clang version 16.0.6 (https://github.com/llvm/llvm-project 7cbf1a2591520c2491aa35339f227775f4d3adf6)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251125/[email-masked]/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <[email-masked]>
> | Closes: https://lore.kernel.org/oe-kbuild-all/[email-masked]/
>
> All errors (new ones prefixed by >>):
>
>    In file included from kernel/rseq.c:75:
>>> include/linux/rseq_entry.h:132:3: error: invalid operand for instruction
>                    unsafe_get_user(start_ip, &ucs->start_ip, efault);
>                    ^
>    include/linux/uaccess.h:606:2: note: expanded from macro 'unsafe_get_user'
>            arch_unsafe_get_user(x, ptr, local_label);      \
>            ^
>    arch/powerpc/include/asm/uaccess.h:458:2: note: expanded from macro 'arch_unsafe_get_user'
>            __get_user_size_goto(__gu_val, __gu_addr, sizeof(*(p)), e); \
>            ^
>    arch/powerpc/include/asm/uaccess.h:282:2: note: expanded from macro '__get_user_size_goto'
>            __get_user_size_allowed(x, ptr, size, __gus_retval);    \
>            ^
>    arch/powerpc/include/asm/uaccess.h:273:10: note: expanded from macro '__get_user_size_allowed'
>            case 8: __get_user_asm2(x, (u64 __user *)ptr, retval);  break;  \
>                    ^
>    arch/powerpc/include/asm/uaccess.h:256:4: note: expanded from macro '__get_user_asm2'
>                    "       li %1+1,0\n"                    \
>                     ^
>    <inline asm>:7:5: note: instantiated into assembly here
>            li 31+1,0

Definitely not a problem of tip core/rseq. It just ends up in
__get_user_asm2() and then the compiler gets unhappy about the PowerPC
inline assembly for whatever reason.

Thanks,

        tglx