[PATCH v5 4/8] riscv/runtime-const: Replace open-coded placeholder with RUNTIME_MAGIC

[Guo Ren]

On Tue, Jun 30, 2026 at 12:57 PM K Prateek Nayak <kprateek.nayak at amd.com> wrote:
>
> Define the placeholder used for lui + addi[w] patching sequence as
> RUNTIME_MAGIC and use that instead of open coding the constants in the
> inline assembly.
>
> No functional changes intended.
>
> Suggested-by: Guo Ren <guoren at kernel.org>
> Reviewed-by: Charlie Jenkins <thecharlesjenkins at gmail.com>
> Tested-by: Charlie Jenkins <thecharlesjenkins at gmail.com>
> Signed-off-by: K Prateek Nayak <kprateek.nayak at amd.com>
> ---
> changelog v4..v5:
>
> o Collected tags from Charlie (Thanks a ton!)
> ---
>  arch/riscv/include/asm/runtime-const.h | 38 ++++++++++++++------------
>  1 file changed, 20 insertions(+), 18 deletions(-)
>
> diff --git a/arch/riscv/include/asm/runtime-const.h b/arch/riscv/include/asm/runtime-const.h
> index 900db0a103d05..1ce02605d2e43 100644
> --- a/arch/riscv/include/asm/runtime-const.h
> +++ b/arch/riscv/include/asm/runtime-const.h
> @@ -15,21 +15,23 @@
>
>  #include <linux/uaccess.h>
>
> +#define RUNTIME_MAGIC __ASM_STR(0x89ABCDEF)
> +
>  #ifdef CONFIG_32BIT
> -#define runtime_const_ptr(sym)                                 \
> -({                                                             \
> -       typeof(sym) __ret;                                      \
> -       asm_inline(".option push\n\t"                           \
> -               ".option norvc\n\t"                             \
> -               "1:\t"                                          \
> -               "lui    %[__ret],0x89abd\n\t"                   \
> -               "addi   %[__ret],%[__ret],-0x211\n\t"           \
> -               ".option pop\n\t"                               \
> -               ".pushsection runtime_ptr_" #sym ",\"a\"\n\t"   \
> -               ".long 1b - .\n\t"                              \
> -               ".popsection"                                   \
> -               : [__ret] "=r" (__ret));                        \
> -       __ret;                                                  \
> +#define runtime_const_ptr(sym)                                         \
> +({                                                                     \
> +       typeof(sym) __ret;                                              \
> +       asm_inline(".option push\n\t"                                   \
> +               ".option norvc\n\t"                                     \
> +               "1:\t"                                                  \
> +               "lui    %[__ret], %%hi(" RUNTIME_MAGIC ")\n\t"          \
> +               "addi   %[__ret],%[__ret], %%lo(" RUNTIME_MAGIC ")\n\t" \
> +               ".option pop\n\t"                                       \
> +               ".pushsection runtime_ptr_" #sym ",\"a\"\n\t"           \
> +               ".long 1b - .\n\t"                                      \
> +               ".popsection"                                           \
> +               : [__ret] "=r" (__ret));                                \
> +       __ret;                                                          \
>  })
>  #else
>  /*
> @@ -46,10 +48,10 @@
>         ".option push\n\t"                                      \
>         ".option norvc\n\t"                                     \
>         "1:\t"                                                  \
> -       "lui    %[__ret],0x89abd\n\t"                           \
> -       "lui    %[__tmp],0x1234\n\t"                            \
> -       "addiw  %[__ret],%[__ret],-0x211\n\t"                   \
> -       "addiw  %[__tmp],%[__tmp],0x567\n\t"                    \
> +       "lui    %[__ret], %%hi(" RUNTIME_MAGIC ")\n\t"          \
> +       "lui    %[__tmp], %%hi(" RUNTIME_MAGIC ")\n\t"          \
> +       "addiw  %[__ret],%[__ret], %%lo(" RUNTIME_MAGIC ")\n\t" \
> +       "addiw  %[__tmp],%[__tmp], %%lo(" RUNTIME_MAGIC ")\n\t" \
LGTM!

Reviewed-by: Guo Ren <guoren at kernel.org>

-- 
Best Regards
 Guo Ren