[GitHub] [incubator-nuttx] pkarashchenko commented on a change in pull request #5782: RISC-V: Implement option to run NuttX in supervisor mode (S-mode)

[GitBox]

pkarashchenko commented on a change in pull request #5782:
URL: https://github.com/apache/incubator-nuttx/pull/5782#discussion_r839531282



##########
File path: arch/risc-v/include/syscall.h
##########
@@ -259,7 +230,15 @@ static inline uintptr_t sys_call2(unsigned int nbr, 
uintptr_t parm1,
 
   asm volatile
     (
+#if defined (CONFIG_ARCH_USE_S_MODE) && defined (__KERNEL__)
+     " addi sp, sp, -16\n"                  /* Make room */
+     " sd   ra, 0(sp)\n"                    /* Save ra */
+     " jal  ra, riscv_syscall_dispatch\n"   /* Dispatch (modifies ra) */
+     " ld   ra, 0(sp)\n"                    /* Restore ra */
+     " addi sp, sp, 16\n"                   /* Restore sp */
+#else
      "ecall"
+#endif

Review comment:
       Those parts seems to be copy pasted few times. Maybe we can
   ```
   #if defined (CONFIG_ARCH_USE_S_MODE) && defined (__KERNEL__)
   #  define ASM_SYS_CALL \
        " addi sp, sp, -16\n"                  /* Make room */ \
        " sd   ra, 0(sp)\n"                    /* Save ra */ \
        " jal  ra, riscv_syscall_dispatch\n"   /* Dispatch (modifies ra) */ \
        " ld   ra, 0(sp)\n"                    /* Restore ra */ \
        " addi sp, sp, 16\n"                   /* Restore sp */
   #else
   #  define ASM_SYS_CALL "ecall"
   #endif
   ...
     __asm__ __volatile__(ASM_SYS_CALL);
   ```




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