tools/include/nolibc/arch-riscv.h

   1 /* SPDX-License-Identifier: LGPL-2.1 OR MIT */
   2 /*
   3  * RISCV (32 and 64) specific definitions for NOLIBC
   4  * Copyright (C) 2017-2022 Willy Tarreau <w@1wt.eu>
   5  */
   6
   7 #ifndef _NOLIBC_ARCH_RISCV_H
   8 #define _NOLIBC_ARCH_RISCV_H
   9
  10 #include "compiler.h"
  11 #include "crt.h"
  12
  13 /* Syscalls for RISCV :
  14  *   - stack is 16-byte aligned
  15  *   - syscall number is passed in a7
  16  *   - arguments are in a0, a1, a2, a3, a4, a5
  17  *   - the system call is performed by calling ecall
  18  *   - syscall return comes in a0
  19  *   - the arguments are cast to long and assigned into the target
  20  *     registers which are then simply passed as registers to the asm code,
  21  *     so that we don't have to experience issues with register constraints.
  22  */
  23
  24 #define my_syscall0(num)                                                      \
  25 ({                                                                            \
  26         register long _num  __asm__ ("a7") = (num);                           \
  27         register long _arg1 __asm__ ("a0");                                   \
  28                                                                               \
  29         __asm__ volatile (                                                    \
  30                 "ecall\n\t"                                                   \
  31                 : "=r"(_arg1)                                                 \
  32                 : "r"(_num)                                                   \
  33                 : "memory", "cc"                                              \
  34         );                                                                    \
  35         _arg1;                                                                \
  36 })
  37
  38 #define my_syscall1(num, arg1)                                                \
  39 ({                                                                            \
  40         register long _num  __asm__ ("a7") = (num);                           \
  41         register long _arg1 __asm__ ("a0") = (long)(arg1);                    \
  42                                                                               \
  43         __asm__ volatile (                                                    \
  44                 "ecall\n"                                                     \
  45                 : "+r"(_arg1)                                                 \
  46                 : "r"(_num)                                                   \
  47                 : "memory", "cc"                                              \
  48         );                                                                    \
  49         _arg1;                                                                \
  50 })
  51
  52 #define my_syscall2(num, arg1, arg2)                                          \
  53 ({                                                                            \
  54         register long _num  __asm__ ("a7") = (num);                           \
  55         register long _arg1 __asm__ ("a0") = (long)(arg1);                    \
  56         register long _arg2 __asm__ ("a1") = (long)(arg2);                    \
  57                                                                               \
  58         __asm__ volatile (                                                    \
  59                 "ecall\n"                                                     \
  60                 : "+r"(_arg1)                                                 \
  61                 : "r"(_arg2),                                                 \
  62                   "r"(_num)                                                   \
  63                 : "memory", "cc"                                              \
  64         );                                                                    \
  65         _arg1;                                                                \
  66 })
  67
  68 #define my_syscall3(num, arg1, arg2, arg3)                                    \
  69 ({                                                                            \
  70         register long _num  __asm__ ("a7") = (num);                           \
  71         register long _arg1 __asm__ ("a0") = (long)(arg1);                    \
  72         register long _arg2 __asm__ ("a1") = (long)(arg2);                    \
  73         register long _arg3 __asm__ ("a2") = (long)(arg3);                    \
  74                                                                               \
  75         __asm__ volatile (                                                    \
  76                 "ecall\n\t"                                                   \
  77                 : "+r"(_arg1)                                                 \
  78                 : "r"(_arg2), "r"(_arg3),                                     \
  79                   "r"(_num)                                                   \
  80                 : "memory", "cc"                                              \
  81         );                                                                    \
  82         _arg1;                                                                \
  83 })
  84
  85 #define my_syscall4(num, arg1, arg2, arg3, arg4)                              \
  86 ({                                                                            \
  87         register long _num  __asm__ ("a7") = (num);                           \
  88         register long _arg1 __asm__ ("a0") = (long)(arg1);                    \
  89         register long _arg2 __asm__ ("a1") = (long)(arg2);                    \
  90         register long _arg3 __asm__ ("a2") = (long)(arg3);                    \
  91         register long _arg4 __asm__ ("a3") = (long)(arg4);                    \
  92                                                                               \
  93         __asm__ volatile (                                                    \
  94                 "ecall\n"                                                     \
  95                 : "+r"(_arg1)                                                 \
  96                 : "r"(_arg2), "r"(_arg3), "r"(_arg4),                         \
  97                   "r"(_num)                                                   \
  98                 : "memory", "cc"                                              \
  99         );                                                                    \
 100         _arg1;                                                                \
 101 })
 102
 103 #define my_syscall5(num, arg1, arg2, arg3, arg4, arg5)                        \
 104 ({                                                                            \
 105         register long _num  __asm__ ("a7") = (num);                           \
 106         register long _arg1 __asm__ ("a0") = (long)(arg1);                    \
 107         register long _arg2 __asm__ ("a1") = (long)(arg2);                    \
 108         register long _arg3 __asm__ ("a2") = (long)(arg3);                    \
 109         register long _arg4 __asm__ ("a3") = (long)(arg4);                    \
 110         register long _arg5 __asm__ ("a4") = (long)(arg5);                    \
 111                                                                               \
 112         __asm__ volatile (                                                    \
 113                 "ecall\n"                                                     \
 114                 : "+r"(_arg1)                                                 \
 115                 : "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5),             \
 116                   "r"(_num)                                                   \
 117                 : "memory", "cc"                                              \
 118         );                                                                    \
 119         _arg1;                                                                \
 120 })
 121
 122 #define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6)                  \
 123 ({                                                                            \
 124         register long _num  __asm__ ("a7") = (num);                           \
 125         register long _arg1 __asm__ ("a0") = (long)(arg1);                    \
 126         register long _arg2 __asm__ ("a1") = (long)(arg2);                    \
 127         register long _arg3 __asm__ ("a2") = (long)(arg3);                    \
 128         register long _arg4 __asm__ ("a3") = (long)(arg4);                    \
 129         register long _arg5 __asm__ ("a4") = (long)(arg5);                    \
 130         register long _arg6 __asm__ ("a5") = (long)(arg6);                    \
 131                                                                               \
 132         __asm__ volatile (                                                    \
 133                 "ecall\n"                                                     \
 134                 : "+r"(_arg1)                                                 \
 135                 : "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), "r"(_arg6), \
 136                   "r"(_num)                                                   \
 137                 : "memory", "cc"                                              \
 138         );                                                                    \
 139         _arg1;                                                                \
 140 })
 141
 142 /* startup code */
 143 void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
 144 {
 145         __asm__ volatile (
 146                 ".option push\n"
 147                 ".option norelax\n"
 148                 "lla  gp, __global_pointer$\n"
 149                 ".option pop\n"
 150                 "mv   a0, sp\n"           /* save stack pointer to a0, as arg1 of _start_c */
 151                 "andi sp, a0, -16\n"      /* sp must be 16-byte aligned                    */
 152                 "call _start_c\n"         /* transfer to c runtime                         */
 153         );
 154         __builtin_unreachable();
 155 }
 156
 157 #endif /* _NOLIBC_ARCH_RISCV_H */