Oops, there is no warning with 6.0-rc3. But it's a bug, I fixed that by:

diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c
index afc8c030c222..5871eccbbd94 100644
--- a/arch/riscv/kernel/signal.c
+++ b/arch/riscv/kernel/signal.c
@@ -12,6 +12,7 @@
 #include <linux/syscalls.h>
 #include <linux/resume_user_mode.h>
 #include <linux/linkage.h>
+#include <linux/entry-common.h>

 #include <asm/ucontext.h>
 #include <asm/vdso.h>
@@ -272,7 +273,7 @@ static void handle_signal(struct ksignal *ksig,
struct pt_regs *regs)
        signal_setup_done(ret, ksig, 0);
 }

-void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal)
+void arch_do_signal_or_restart(struct pt_regs *regs)
 {
        struct ksignal ksig;

On Sun, Sep 4, 2022 at 1:59 AM kernel test robot <lkp@intel.com> wrote:
>
> Hi,
>
> I love your patch! Perhaps something to improve:
>
> [auto build test WARNING on soc/for-next]
> [also build test WARNING on linus/master v6.0-rc3 next-20220901]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url:    https://github.com/intel-lab-lkp/linux/commits/guoren-kernel-org/riscv-Add-GENERIC_ENTRY-IRQ_STACKS-support/20220904-003954
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git for-next
> config: riscv-allyesconfig (https://download.01.org/0day-ci/archive/20220904/202209040118.GmG1Lby1-lkp@intel.com/config)
> compiler: riscv64-linux-gcc (GCC) 12.1.0
> 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://github.com/intel-lab-lkp/linux/commit/6ed1ef93b372116f7d4586b13bfd352e19453740
>         git remote add linux-review https://github.com/intel-lab-lkp/linux
>         git fetch --no-tags linux-review guoren-kernel-org/riscv-Add-GENERIC_ENTRY-IRQ_STACKS-support/20220904-003954
>         git checkout 6ed1ef93b372116f7d4586b13bfd352e19453740
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash arch/riscv/
>
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <lkp@intel.com>
>
> All warnings (new ones prefixed by >>):
>
> >> arch/riscv/kernel/irq.c:48:6: warning: no previous prototype for 'do_softirq_own_stack' [-Wmissing-prototypes]
>       48 | void do_softirq_own_stack(void)
>          |      ^~~~~~~~~~~~~~~~~~~~
>    arch/riscv/kernel/irq.c:74:25: warning: no previous prototype for 'handle_riscv_irq' [-Wmissing-prototypes]
>       74 | asmlinkage void noinstr handle_riscv_irq(struct pt_regs *regs)
>          |                         ^~~~~~~~~~~~~~~~
>    arch/riscv/kernel/irq.c:85:25: warning: no previous prototype for 'do_riscv_irq' [-Wmissing-prototypes]
>       85 | asmlinkage void noinstr do_riscv_irq(struct pt_regs *regs)
>          |                         ^~~~~~~~~~~~
>
>
> vim +/do_softirq_own_stack +48 arch/riscv/kernel/irq.c
>
>     47
>   > 48  void do_softirq_own_stack(void)
>     49  {
>     50          ulong *sp = per_cpu(irq_stack_ptr, smp_processor_id());
>     51
>     52          call_on_stack(NULL, sp, do_riscv_softirq, 0);
>     53  }
>     54  #endif /* CONFIG_PREEMPT_RT */
>     55
>
> --
> 0-DAY CI Kernel Test Service
> https://01.org/lkp



-- 
Best Regards
 Guo Ren