On Wed, Sep 21, 2022 at 7:56 PM Chen Zhongjin <chenzhongjin@xxxxxxxxxx> wrote: > > Hi, > > Sorry to bother again, I just finished the test with your patches on > mine patch set. > > On 2022/9/21 17:53, Guo Ren wrote: > > On Wed, Sep 21, 2022 at 4:34 PM Chen Zhongjin <chenzhongjin@xxxxxxxxxx> wrote: > >> Hi, > >> > >> On 2022/9/18 23:52, guoren@xxxxxxxxxx wrote: > >>> diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S > >>> index 5f49517cd3a2..426529b84db0 100644 > >>> --- a/arch/riscv/kernel/entry.S > >>> +++ b/arch/riscv/kernel/entry.S > >>> @@ -332,6 +332,33 @@ ENTRY(ret_from_kernel_thread) > >>> tail syscall_exit_to_user_mode > >>> ENDPROC(ret_from_kernel_thread) > >>> > >>> +#ifdef CONFIG_IRQ_STACKS > >>> +ENTRY(call_on_stack) > >>> + /* Create a frame record to save our ra and fp */ > >>> + addi sp, sp, -RISCV_SZPTR > >>> + REG_S ra, (sp) > >>> + addi sp, sp, -RISCV_SZPTR > >>> + REG_S fp, (sp) > >>> + > >>> + /* Save sp in fp */ > >>> + move fp, sp > >>> + > > Considering that s0 points to previous sp normally, I think here we > should have 'addi fp, sp, 2*RISCV_SZPTR'. > > An example below: > > addi sp, sp, -16 > sd ra, 8(sp) > sd s0, 0(sp) > addi s0, sp, 16 <- s0 is set to previous sp > ... > > ld ra,8(sp) > ld s0,0(sp) > addi sp,sp,16 > > So maybe it's better to save the stack frame as below: > > addi sp, sp, -2*RISCV_SZPTR > REG_S ra, RISCV_SZPTR(sp) > REG_S s0, (sp) > > /* Save sp in fp */ > addi s0, sp, 2*RISCV_SZPTR > > ... > > /* > * Restore sp from prev fp, and fp, ra from the frame > */ > addi sp, s0, -2*RISCV_SZPTR > REG_L ra, RISCV_SZPTR(sp) > REG_L s0, (sp) > addi sp, sp, 2*RISCV_SZPTR > > > Anyway, lets set fp as sp + 2 * RISCV_SZPTR, so that unwinder can > connect two stacks same as normal function. > > I tested this with my patch and the unwinder works properly. Thx, you got it. My patch broke the fp chain. I would fix it in the next version. > > > Thanks for your time! > > Best, > > Chen > > >>> + /* Move to the new stack and call the function there */ > >>> + li a3, IRQ_STACK_SIZE > >>> + add sp, a1, a3 > >>> + jalr a2 > >>> + > >>> + /* > >>> + * Restore sp from prev fp, and fp, ra from the frame > >>> + */ > >>> + move sp, fp > >>> + REG_L fp, (sp) > >>> + addi sp, sp, RISCV_SZPTR > >>> + REG_L ra, (sp) > >>> + addi sp, sp, RISCV_SZPTR > >>> + ret > >>> +ENDPROC(call_on_stack) > >>> +#endif > >> Seems my compiler (riscv64-linux-gnu-gcc 8.4.0, cross compiling from > >> x86) cannot recognize the register `fp`. > > The whole entry.S uses s0 instead of fp, so I approve of your advice. Thx. > > > >> After I changed it to `s0` this can pass compiling. > >> > >> > >> Seems there is nowhere else using `fp`, can this just using `s0` instead? > >> > >> Best, > >> > >> Chen > >> > >> -- Best Regards Guo Ren
