[1/1] Only pass the minimum number of syscall arguments

Message ID 20200210201958.352384-2-mail@gms.tf
State New
Headers show
Series
  • Only pass the minimum number of syscall arguments (RISC-V)
Related show

Commit Message

Georg Sauthoff Feb. 10, 2020, 8:19 p.m.
Previously, __internal_syscall() compiled into asm-code that unconditionally
sets the syscall argument registers a0 to a5.

For example, the instruction sequence for a exit syscall looked like
this:

    li    a0, 1   # in ther caller of exit()
    # ...         # in newlib:
    li    a1, 0   # unused arguments
    li    a2, 0
    li    a3, 0
    li    a4, 0
    li    a5, 0
    li    a7, 93  # exit syscall number

(i.e. the binary contains then 5 superfluous instructions for this
one argument syscall)

This commit changes the RISC-V syscall code such that only the required
syscall argument registers are set.

GCC detects that argc is known at compile time and thus evaluates all the
if-statements where argc is used at compile time (tested with -O2 and -Os).
---
 libgloss/riscv/internal_syscall.h | 41 ++++++++++++++++++++++---------
 libgloss/riscv/sys_access.c       |  2 +-
 libgloss/riscv/sys_close.c        |  2 +-
 libgloss/riscv/sys_exit.c         |  2 +-
 libgloss/riscv/sys_faccessat.c    |  2 +-
 libgloss/riscv/sys_fstat.c        |  2 +-
 libgloss/riscv/sys_fstatat.c      |  2 +-
 libgloss/riscv/sys_gettimeofday.c |  2 +-
 libgloss/riscv/sys_link.c         |  2 +-
 libgloss/riscv/sys_lseek.c        |  2 +-
 libgloss/riscv/sys_lstat.c        |  2 +-
 libgloss/riscv/sys_open.c         |  2 +-
 libgloss/riscv/sys_openat.c       |  2 +-
 libgloss/riscv/sys_read.c         |  2 +-
 libgloss/riscv/sys_sbrk.c         |  4 +--
 libgloss/riscv/sys_stat.c         |  2 +-
 libgloss/riscv/sys_unlink.c       |  2 +-
 libgloss/riscv/sys_write.c        |  2 +-
 18 files changed, 48 insertions(+), 29 deletions(-)

-- 
2.24.1

Comments

Kito Cheng Feb. 11, 2020, 6:55 a.m. | #1
Hi Georg:

LGTM, great job, it reduce the code size for libgloss.

Tested rv32gc/rv64gc on qemu.

Thanks :)

On Tue, Feb 11, 2020 at 4:20 AM Georg Sauthoff <mail@gms.tf> wrote:
>

> Previously, __internal_syscall() compiled into asm-code that unconditionally

> sets the syscall argument registers a0 to a5.

>

> For example, the instruction sequence for a exit syscall looked like

> this:

>

>     li    a0, 1   # in ther caller of exit()

>     # ...         # in newlib:

>     li    a1, 0   # unused arguments

>     li    a2, 0

>     li    a3, 0

>     li    a4, 0

>     li    a5, 0

>     li    a7, 93  # exit syscall number

>

> (i.e. the binary contains then 5 superfluous instructions for this

> one argument syscall)

>

> This commit changes the RISC-V syscall code such that only the required

> syscall argument registers are set.

>

> GCC detects that argc is known at compile time and thus evaluates all the

> if-statements where argc is used at compile time (tested with -O2 and -Os).

> ---

>  libgloss/riscv/internal_syscall.h | 41 ++++++++++++++++++++++---------

>  libgloss/riscv/sys_access.c       |  2 +-

>  libgloss/riscv/sys_close.c        |  2 +-

>  libgloss/riscv/sys_exit.c         |  2 +-

>  libgloss/riscv/sys_faccessat.c    |  2 +-

>  libgloss/riscv/sys_fstat.c        |  2 +-

>  libgloss/riscv/sys_fstatat.c      |  2 +-

>  libgloss/riscv/sys_gettimeofday.c |  2 +-

>  libgloss/riscv/sys_link.c         |  2 +-

>  libgloss/riscv/sys_lseek.c        |  2 +-

>  libgloss/riscv/sys_lstat.c        |  2 +-

>  libgloss/riscv/sys_open.c         |  2 +-

>  libgloss/riscv/sys_openat.c       |  2 +-

>  libgloss/riscv/sys_read.c         |  2 +-

>  libgloss/riscv/sys_sbrk.c         |  4 +--

>  libgloss/riscv/sys_stat.c         |  2 +-

>  libgloss/riscv/sys_unlink.c       |  2 +-

>  libgloss/riscv/sys_write.c        |  2 +-

>  18 files changed, 48 insertions(+), 29 deletions(-)

>

> diff --git a/libgloss/riscv/internal_syscall.h b/libgloss/riscv/internal_syscall.h

> index e5d5594..1f1f42f 100644

> --- a/libgloss/riscv/internal_syscall.h

> +++ b/libgloss/riscv/internal_syscall.h

> @@ -22,31 +22,50 @@ __syscall_error(long a0)

>  }

>

>  static inline long

> -__internal_syscall(long n, long _a0, long _a1, long _a2, long _a3, long _a4, long _a5)

> +__internal_syscall(long n, int argc, long _a0, long _a1, long _a2, long _a3, long _a4, long _a5)

>  {

> +#ifdef __riscv_32e

> +  register long syscall_id asm("t0") = n;

> +#else

> +  register long syscall_id asm("a7") = n;

> +#endif

> +

>    register long a0 asm("a0") = _a0;

> +  if (argc < 2) {

> +      asm volatile ("ecall" : "+r"(a0) : "r"(syscall_id));

> +      return a0;

> +  }

>    register long a1 asm("a1") = _a1;

> +  if (argc == 2) {

> +      asm volatile ("ecall" : "+r"(a0) : "r"(a1), "r"(syscall_id));

> +      return a0;

> +  }

>    register long a2 asm("a2") = _a2;

> +  if (argc == 3) {

> +      asm volatile ("ecall" : "+r"(a0) : "r"(a1), "r"(a2), "r"(syscall_id));

> +      return a0;

> +  }

>    register long a3 asm("a3") = _a3;

> +  if (argc == 4) {

> +      asm volatile ("ecall" : "+r"(a0) : "r"(a1), "r"(a2), "r"(a3), "r"(syscall_id));

> +      return a0;

> +  }

>    register long a4 asm("a4") = _a4;

> +  if (argc == 5) {

> +      asm volatile ("ecall" : "+r"(a0) : "r"(a1), "r"(a2), "r"(a3), "r"(a4), "r"(syscall_id));

> +      return a0;

> +  }

>    register long a5 asm("a5") = _a5;

>

> -#ifdef __riscv_32e

> -  register long syscall_id asm("t0") = n;

> -#else

> -  register long syscall_id asm("a7") = n;

> -#endif

> -

> -  asm volatile ("scall"

> -               : "+r"(a0) : "r"(a1), "r"(a2), "r"(a3), "r"(a4), "r"(a5), "r"(syscall_id));

> +  asm volatile ("ecall" : "+r"(a0) : "r"(a1), "r"(a2), "r"(a3), "r"(a4), "r"(a5), "r"(syscall_id));

>

>    return a0;

>  }

>

>  static inline long

> -syscall_errno(long n, long _a0, long _a1, long _a2, long _a3, long _a4, long _a5)

> +syscall_errno(long n, int argc, long _a0, long _a1, long _a2, long _a3, long _a4, long _a5)

>  {

> -  long a0 = __internal_syscall (n, _a0, _a1, _a2, _a3, _a4, _a5);

> +  long a0 = __internal_syscall (n, argc, _a0, _a1, _a2, _a3, _a4, _a5);

>

>    if (a0 < 0)

>      return __syscall_error (a0);

> diff --git a/libgloss/riscv/sys_access.c b/libgloss/riscv/sys_access.c

> index ef446d2..45bedb3 100644

> --- a/libgloss/riscv/sys_access.c

> +++ b/libgloss/riscv/sys_access.c

> @@ -5,5 +5,5 @@

>  int

>  _access(const char *file, int mode)

>  {

> -  return syscall_errno (SYS_access, file, mode, 0, 0, 0, 0);

> +  return syscall_errno (SYS_access, 2, file, mode, 0, 0, 0, 0);

>  }

> diff --git a/libgloss/riscv/sys_close.c b/libgloss/riscv/sys_close.c

> index 80b10c6..c1691d8 100644

> --- a/libgloss/riscv/sys_close.c

> +++ b/libgloss/riscv/sys_close.c

> @@ -5,5 +5,5 @@

>  int

>  _close(int file)

>  {

> -  return syscall_errno (SYS_close, file, 0, 0, 0, 0, 0);

> +  return syscall_errno (SYS_close, 1, file, 0, 0, 0, 0, 0);

>  }

> diff --git a/libgloss/riscv/sys_exit.c b/libgloss/riscv/sys_exit.c

> index 03e1c34..995dd65 100644

> --- a/libgloss/riscv/sys_exit.c

> +++ b/libgloss/riscv/sys_exit.c

> @@ -5,6 +5,6 @@

>  void

>  _exit(int exit_status)

>  {

> -  syscall_errno (SYS_exit, exit_status, 0, 0, 0, 0, 0);

> +  syscall_errno (SYS_exit, 1, exit_status, 0, 0, 0, 0, 0);

>    while (1);

>  }

> diff --git a/libgloss/riscv/sys_faccessat.c b/libgloss/riscv/sys_faccessat.c

> index e966a4a..6418ef4 100644

> --- a/libgloss/riscv/sys_faccessat.c

> +++ b/libgloss/riscv/sys_faccessat.c

> @@ -4,5 +4,5 @@

>  /* Permissions of a file (by name) in a given directory.  */

>  int _faccessat(int dirfd, const char *file, int mode, int flags)

>  {

> -  return syscall_errno (SYS_faccessat, dirfd, file, mode, flags, 0, 0);

> +  return syscall_errno (SYS_faccessat, 4, dirfd, file, mode, flags, 0, 0);

>  }

> diff --git a/libgloss/riscv/sys_fstat.c b/libgloss/riscv/sys_fstat.c

> index 13a0bca..d97ba44 100644

> --- a/libgloss/riscv/sys_fstat.c

> +++ b/libgloss/riscv/sys_fstat.c

> @@ -9,7 +9,7 @@ int

>  _fstat(int file, struct stat *st)

>  {

>    struct kernel_stat kst;

> -  int rv = syscall_errno (SYS_fstat, file, &kst, 0, 0, 0, 0);

> +  int rv = syscall_errno (SYS_fstat, 2, file, &kst, 0, 0, 0, 0);

>    _conv_stat (st, &kst);

>    return rv;

>  }

> diff --git a/libgloss/riscv/sys_fstatat.c b/libgloss/riscv/sys_fstatat.c

> index 0e4ea42..bf03355 100644

> --- a/libgloss/riscv/sys_fstatat.c

> +++ b/libgloss/riscv/sys_fstatat.c

> @@ -8,7 +8,7 @@ int

>  _fstatat(int dirfd, const char *file, struct stat *st, int flags)

>  {

>    struct kernel_stat kst;

> -  int rv = syscall_errno (SYS_fstatat, dirfd, file, &kst, flags, 0, 0);

> +  int rv = syscall_errno (SYS_fstatat, 4, dirfd, file, &kst, flags, 0, 0);

>    _conv_stat (st, &kst);

>    return rv;

>  }

> diff --git a/libgloss/riscv/sys_gettimeofday.c b/libgloss/riscv/sys_gettimeofday.c

> index 457dcbc..daa14e4 100644

> --- a/libgloss/riscv/sys_gettimeofday.c

> +++ b/libgloss/riscv/sys_gettimeofday.c

> @@ -6,5 +6,5 @@

>  int

>  _gettimeofday(struct timeval *tp, void *tzp)

>  {

> -  return syscall_errno (SYS_gettimeofday, tp, 0, 0, 0, 0, 0);

> +  return syscall_errno (SYS_gettimeofday, 1, tp, 0, 0, 0, 0, 0);

>  }

> diff --git a/libgloss/riscv/sys_link.c b/libgloss/riscv/sys_link.c

> index eaeb22b..83cd1b2 100644

> --- a/libgloss/riscv/sys_link.c

> +++ b/libgloss/riscv/sys_link.c

> @@ -4,5 +4,5 @@

>  /* Establish a new name for an existing file.  */

>  int _link(const char *old_name, const char *new_name)

>  {

> -  return syscall_errno (SYS_link, old_name, new_name, 0, 0, 0, 0);

> +  return syscall_errno (SYS_link, 2, old_name, new_name, 0, 0, 0, 0);

>  }

> diff --git a/libgloss/riscv/sys_lseek.c b/libgloss/riscv/sys_lseek.c

> index 7486a3a..8eb8b81 100644

> --- a/libgloss/riscv/sys_lseek.c

> +++ b/libgloss/riscv/sys_lseek.c

> @@ -6,5 +6,5 @@

>  off_t

>  _lseek(int file, off_t ptr, int dir)

>  {

> -  return syscall_errno (SYS_lseek, file, ptr, dir, 0, 0, 0);

> +  return syscall_errno (SYS_lseek, 3, file, ptr, dir, 0, 0, 0);

>  }

> diff --git a/libgloss/riscv/sys_lstat.c b/libgloss/riscv/sys_lstat.c

> index 2eeabcc..dd5dc52 100644

> --- a/libgloss/riscv/sys_lstat.c

> +++ b/libgloss/riscv/sys_lstat.c

> @@ -7,7 +7,7 @@

>  int _lstat(const char *file, struct stat *st)

>  {

>    struct kernel_stat kst;

> -  int rv = syscall_errno (SYS_lstat, file, &kst, 0, 0, 0, 0);

> +  int rv = syscall_errno (SYS_lstat, 2, file, &kst, 0, 0, 0, 0);

>    _conv_stat (st, &kst);

>    return rv;

>  }

> diff --git a/libgloss/riscv/sys_open.c b/libgloss/riscv/sys_open.c

> index 4fd5d67..eb1a99b 100644

> --- a/libgloss/riscv/sys_open.c

> +++ b/libgloss/riscv/sys_open.c

> @@ -5,5 +5,5 @@

>  int

>  _open(const char *name, int flags, int mode)

>  {

> -  return syscall_errno (SYS_open, name, flags, mode, 0, 0, 0);

> +  return syscall_errno (SYS_open, 3, name, flags, mode, 0, 0, 0);

>  }

> diff --git a/libgloss/riscv/sys_openat.c b/libgloss/riscv/sys_openat.c

> index cf429b7..652ab2e 100644

> --- a/libgloss/riscv/sys_openat.c

> +++ b/libgloss/riscv/sys_openat.c

> @@ -4,5 +4,5 @@

>  /* Open file relative to given directory.  */

>  int _openat(int dirfd, const char *name, int flags, int mode)

>  {

> -  return syscall_errno (SYS_openat, dirfd, name, flags, mode, 0, 0);

> +  return syscall_errno (SYS_openat, 4, dirfd, name, flags, mode, 0, 0);

>  }

> diff --git a/libgloss/riscv/sys_read.c b/libgloss/riscv/sys_read.c

> index 7367e26..dd3bc33 100644

> --- a/libgloss/riscv/sys_read.c

> +++ b/libgloss/riscv/sys_read.c

> @@ -5,5 +5,5 @@

>  /* Read from a file.  */

>  ssize_t _read(int file, void *ptr, size_t len)

>  {

> -  return syscall_errno (SYS_read, file, ptr, len, 0, 0, 0);

> +  return syscall_errno (SYS_read, 3, file, ptr, len, 0, 0, 0);

>  }

> diff --git a/libgloss/riscv/sys_sbrk.c b/libgloss/riscv/sys_sbrk.c

> index f91c2c5..086509e 100644

> --- a/libgloss/riscv/sys_sbrk.c

> +++ b/libgloss/riscv/sys_sbrk.c

> @@ -41,13 +41,13 @@ _sbrk(ptrdiff_t incr)

>

>    if (heap_end == 0)

>      {

> -      long brk = __internal_syscall (SYS_brk, 0, 0, 0, 0, 0, 0);

> +      long brk = __internal_syscall (SYS_brk, 1, 0, 0, 0, 0, 0, 0);

>        if (brk == -1)

>          return (void *)__syscall_error (-ENOMEM);

>        heap_end = brk;

>      }

>

> -  if (__internal_syscall (SYS_brk, heap_end + incr, 0, 0, 0, 0, 0) != heap_end + incr)

> +  if (__internal_syscall (SYS_brk, 1, heap_end + incr, 0, 0, 0, 0, 0) != heap_end + incr)

>      return (void *)__syscall_error (-ENOMEM);

>

>    heap_end += incr;

> diff --git a/libgloss/riscv/sys_stat.c b/libgloss/riscv/sys_stat.c

> index a193b10..1e03700 100644

> --- a/libgloss/riscv/sys_stat.c

> +++ b/libgloss/riscv/sys_stat.c

> @@ -8,7 +8,7 @@ int

>  _stat(const char *file, struct stat *st)

>  {

>    struct kernel_stat kst;

> -  int rv = syscall_errno (SYS_stat, file, &kst, 0, 0, 0, 0);

> +  int rv = syscall_errno (SYS_stat, 2, file, &kst, 0, 0, 0, 0);

>    _conv_stat (st, &kst);

>    return rv;

>  }

> diff --git a/libgloss/riscv/sys_unlink.c b/libgloss/riscv/sys_unlink.c

> index b55fe1e..1cf6bbe 100644

> --- a/libgloss/riscv/sys_unlink.c

> +++ b/libgloss/riscv/sys_unlink.c

> @@ -5,5 +5,5 @@

>  int

>  _unlink(const char *name)

>  {

> -  return syscall_errno (SYS_unlink, name, 0, 0, 0, 0, 0);

> +  return syscall_errno (SYS_unlink, 1, name, 0, 0, 0, 0, 0);

>  }

> diff --git a/libgloss/riscv/sys_write.c b/libgloss/riscv/sys_write.c

> index b972734..ce2edd3 100644

> --- a/libgloss/riscv/sys_write.c

> +++ b/libgloss/riscv/sys_write.c

> @@ -6,5 +6,5 @@

>  ssize_t

>  _write(int file, const void *ptr, size_t len)

>  {

> -  return syscall_errno (SYS_write, file, ptr, len, 0, 0, 0);

> +  return syscall_errno (SYS_write, 3, file, ptr, len, 0, 0, 0);

>  }

> --

> 2.24.1

>

Patch

diff --git a/libgloss/riscv/internal_syscall.h b/libgloss/riscv/internal_syscall.h
index e5d5594..1f1f42f 100644
--- a/libgloss/riscv/internal_syscall.h
+++ b/libgloss/riscv/internal_syscall.h
@@ -22,31 +22,50 @@  __syscall_error(long a0)
 }
 
 static inline long
-__internal_syscall(long n, long _a0, long _a1, long _a2, long _a3, long _a4, long _a5)
+__internal_syscall(long n, int argc, long _a0, long _a1, long _a2, long _a3, long _a4, long _a5)
 {
+#ifdef __riscv_32e
+  register long syscall_id asm("t0") = n;
+#else
+  register long syscall_id asm("a7") = n;
+#endif
+
   register long a0 asm("a0") = _a0;
+  if (argc < 2) {
+      asm volatile ("ecall" : "+r"(a0) : "r"(syscall_id));
+      return a0;
+  }
   register long a1 asm("a1") = _a1;
+  if (argc == 2) {
+      asm volatile ("ecall" : "+r"(a0) : "r"(a1), "r"(syscall_id));
+      return a0;
+  }
   register long a2 asm("a2") = _a2;
+  if (argc == 3) {
+      asm volatile ("ecall" : "+r"(a0) : "r"(a1), "r"(a2), "r"(syscall_id));
+      return a0;
+  }
   register long a3 asm("a3") = _a3;
+  if (argc == 4) {
+      asm volatile ("ecall" : "+r"(a0) : "r"(a1), "r"(a2), "r"(a3), "r"(syscall_id));
+      return a0;
+  }
   register long a4 asm("a4") = _a4;
+  if (argc == 5) {
+      asm volatile ("ecall" : "+r"(a0) : "r"(a1), "r"(a2), "r"(a3), "r"(a4), "r"(syscall_id));
+      return a0;
+  }
   register long a5 asm("a5") = _a5;
 
-#ifdef __riscv_32e
-  register long syscall_id asm("t0") = n;
-#else
-  register long syscall_id asm("a7") = n;
-#endif
-
-  asm volatile ("scall"
-		: "+r"(a0) : "r"(a1), "r"(a2), "r"(a3), "r"(a4), "r"(a5), "r"(syscall_id));
+  asm volatile ("ecall" : "+r"(a0) : "r"(a1), "r"(a2), "r"(a3), "r"(a4), "r"(a5), "r"(syscall_id));
 
   return a0;
 }
 
 static inline long
-syscall_errno(long n, long _a0, long _a1, long _a2, long _a3, long _a4, long _a5)
+syscall_errno(long n, int argc, long _a0, long _a1, long _a2, long _a3, long _a4, long _a5)
 {
-  long a0 = __internal_syscall (n, _a0, _a1, _a2, _a3, _a4, _a5);
+  long a0 = __internal_syscall (n, argc, _a0, _a1, _a2, _a3, _a4, _a5);
 
   if (a0 < 0)
     return __syscall_error (a0);
diff --git a/libgloss/riscv/sys_access.c b/libgloss/riscv/sys_access.c
index ef446d2..45bedb3 100644
--- a/libgloss/riscv/sys_access.c
+++ b/libgloss/riscv/sys_access.c
@@ -5,5 +5,5 @@ 
 int
 _access(const char *file, int mode)
 {
-  return syscall_errno (SYS_access, file, mode, 0, 0, 0, 0);
+  return syscall_errno (SYS_access, 2, file, mode, 0, 0, 0, 0);
 }
diff --git a/libgloss/riscv/sys_close.c b/libgloss/riscv/sys_close.c
index 80b10c6..c1691d8 100644
--- a/libgloss/riscv/sys_close.c
+++ b/libgloss/riscv/sys_close.c
@@ -5,5 +5,5 @@ 
 int
 _close(int file)
 {
-  return syscall_errno (SYS_close, file, 0, 0, 0, 0, 0);
+  return syscall_errno (SYS_close, 1, file, 0, 0, 0, 0, 0);
 }
diff --git a/libgloss/riscv/sys_exit.c b/libgloss/riscv/sys_exit.c
index 03e1c34..995dd65 100644
--- a/libgloss/riscv/sys_exit.c
+++ b/libgloss/riscv/sys_exit.c
@@ -5,6 +5,6 @@ 
 void
 _exit(int exit_status)
 {
-  syscall_errno (SYS_exit, exit_status, 0, 0, 0, 0, 0);
+  syscall_errno (SYS_exit, 1, exit_status, 0, 0, 0, 0, 0);
   while (1);
 }
diff --git a/libgloss/riscv/sys_faccessat.c b/libgloss/riscv/sys_faccessat.c
index e966a4a..6418ef4 100644
--- a/libgloss/riscv/sys_faccessat.c
+++ b/libgloss/riscv/sys_faccessat.c
@@ -4,5 +4,5 @@ 
 /* Permissions of a file (by name) in a given directory.  */
 int _faccessat(int dirfd, const char *file, int mode, int flags)
 {
-  return syscall_errno (SYS_faccessat, dirfd, file, mode, flags, 0, 0);
+  return syscall_errno (SYS_faccessat, 4, dirfd, file, mode, flags, 0, 0);
 }
diff --git a/libgloss/riscv/sys_fstat.c b/libgloss/riscv/sys_fstat.c
index 13a0bca..d97ba44 100644
--- a/libgloss/riscv/sys_fstat.c
+++ b/libgloss/riscv/sys_fstat.c
@@ -9,7 +9,7 @@  int
 _fstat(int file, struct stat *st)
 {
   struct kernel_stat kst;
-  int rv = syscall_errno (SYS_fstat, file, &kst, 0, 0, 0, 0);
+  int rv = syscall_errno (SYS_fstat, 2, file, &kst, 0, 0, 0, 0);
   _conv_stat (st, &kst);
   return rv;
 }
diff --git a/libgloss/riscv/sys_fstatat.c b/libgloss/riscv/sys_fstatat.c
index 0e4ea42..bf03355 100644
--- a/libgloss/riscv/sys_fstatat.c
+++ b/libgloss/riscv/sys_fstatat.c
@@ -8,7 +8,7 @@  int
 _fstatat(int dirfd, const char *file, struct stat *st, int flags)
 {
   struct kernel_stat kst;
-  int rv = syscall_errno (SYS_fstatat, dirfd, file, &kst, flags, 0, 0);
+  int rv = syscall_errno (SYS_fstatat, 4, dirfd, file, &kst, flags, 0, 0);
   _conv_stat (st, &kst);
   return rv;
 }
diff --git a/libgloss/riscv/sys_gettimeofday.c b/libgloss/riscv/sys_gettimeofday.c
index 457dcbc..daa14e4 100644
--- a/libgloss/riscv/sys_gettimeofday.c
+++ b/libgloss/riscv/sys_gettimeofday.c
@@ -6,5 +6,5 @@ 
 int
 _gettimeofday(struct timeval *tp, void *tzp)
 {
-  return syscall_errno (SYS_gettimeofday, tp, 0, 0, 0, 0, 0);
+  return syscall_errno (SYS_gettimeofday, 1, tp, 0, 0, 0, 0, 0);
 }
diff --git a/libgloss/riscv/sys_link.c b/libgloss/riscv/sys_link.c
index eaeb22b..83cd1b2 100644
--- a/libgloss/riscv/sys_link.c
+++ b/libgloss/riscv/sys_link.c
@@ -4,5 +4,5 @@ 
 /* Establish a new name for an existing file.  */
 int _link(const char *old_name, const char *new_name)
 {
-  return syscall_errno (SYS_link, old_name, new_name, 0, 0, 0, 0);
+  return syscall_errno (SYS_link, 2, old_name, new_name, 0, 0, 0, 0);
 }
diff --git a/libgloss/riscv/sys_lseek.c b/libgloss/riscv/sys_lseek.c
index 7486a3a..8eb8b81 100644
--- a/libgloss/riscv/sys_lseek.c
+++ b/libgloss/riscv/sys_lseek.c
@@ -6,5 +6,5 @@ 
 off_t
 _lseek(int file, off_t ptr, int dir)
 {
-  return syscall_errno (SYS_lseek, file, ptr, dir, 0, 0, 0);
+  return syscall_errno (SYS_lseek, 3, file, ptr, dir, 0, 0, 0);
 }
diff --git a/libgloss/riscv/sys_lstat.c b/libgloss/riscv/sys_lstat.c
index 2eeabcc..dd5dc52 100644
--- a/libgloss/riscv/sys_lstat.c
+++ b/libgloss/riscv/sys_lstat.c
@@ -7,7 +7,7 @@ 
 int _lstat(const char *file, struct stat *st)
 {
   struct kernel_stat kst;
-  int rv = syscall_errno (SYS_lstat, file, &kst, 0, 0, 0, 0);
+  int rv = syscall_errno (SYS_lstat, 2, file, &kst, 0, 0, 0, 0);
   _conv_stat (st, &kst);
   return rv;
 }
diff --git a/libgloss/riscv/sys_open.c b/libgloss/riscv/sys_open.c
index 4fd5d67..eb1a99b 100644
--- a/libgloss/riscv/sys_open.c
+++ b/libgloss/riscv/sys_open.c
@@ -5,5 +5,5 @@ 
 int
 _open(const char *name, int flags, int mode)
 {
-  return syscall_errno (SYS_open, name, flags, mode, 0, 0, 0);
+  return syscall_errno (SYS_open, 3, name, flags, mode, 0, 0, 0);
 }
diff --git a/libgloss/riscv/sys_openat.c b/libgloss/riscv/sys_openat.c
index cf429b7..652ab2e 100644
--- a/libgloss/riscv/sys_openat.c
+++ b/libgloss/riscv/sys_openat.c
@@ -4,5 +4,5 @@ 
 /* Open file relative to given directory.  */
 int _openat(int dirfd, const char *name, int flags, int mode)
 {
-  return syscall_errno (SYS_openat, dirfd, name, flags, mode, 0, 0);
+  return syscall_errno (SYS_openat, 4, dirfd, name, flags, mode, 0, 0);
 }
diff --git a/libgloss/riscv/sys_read.c b/libgloss/riscv/sys_read.c
index 7367e26..dd3bc33 100644
--- a/libgloss/riscv/sys_read.c
+++ b/libgloss/riscv/sys_read.c
@@ -5,5 +5,5 @@ 
 /* Read from a file.  */
 ssize_t _read(int file, void *ptr, size_t len)
 {
-  return syscall_errno (SYS_read, file, ptr, len, 0, 0, 0);
+  return syscall_errno (SYS_read, 3, file, ptr, len, 0, 0, 0);
 }
diff --git a/libgloss/riscv/sys_sbrk.c b/libgloss/riscv/sys_sbrk.c
index f91c2c5..086509e 100644
--- a/libgloss/riscv/sys_sbrk.c
+++ b/libgloss/riscv/sys_sbrk.c
@@ -41,13 +41,13 @@  _sbrk(ptrdiff_t incr)
 
   if (heap_end == 0)
     {
-      long brk = __internal_syscall (SYS_brk, 0, 0, 0, 0, 0, 0);
+      long brk = __internal_syscall (SYS_brk, 1, 0, 0, 0, 0, 0, 0);
       if (brk == -1)
         return (void *)__syscall_error (-ENOMEM);
       heap_end = brk;
     }
 
-  if (__internal_syscall (SYS_brk, heap_end + incr, 0, 0, 0, 0, 0) != heap_end + incr)
+  if (__internal_syscall (SYS_brk, 1, heap_end + incr, 0, 0, 0, 0, 0) != heap_end + incr)
     return (void *)__syscall_error (-ENOMEM);
 
   heap_end += incr;
diff --git a/libgloss/riscv/sys_stat.c b/libgloss/riscv/sys_stat.c
index a193b10..1e03700 100644
--- a/libgloss/riscv/sys_stat.c
+++ b/libgloss/riscv/sys_stat.c
@@ -8,7 +8,7 @@  int
 _stat(const char *file, struct stat *st)
 {
   struct kernel_stat kst;
-  int rv = syscall_errno (SYS_stat, file, &kst, 0, 0, 0, 0);
+  int rv = syscall_errno (SYS_stat, 2, file, &kst, 0, 0, 0, 0);
   _conv_stat (st, &kst);
   return rv;
 }
diff --git a/libgloss/riscv/sys_unlink.c b/libgloss/riscv/sys_unlink.c
index b55fe1e..1cf6bbe 100644
--- a/libgloss/riscv/sys_unlink.c
+++ b/libgloss/riscv/sys_unlink.c
@@ -5,5 +5,5 @@ 
 int
 _unlink(const char *name)
 {
-  return syscall_errno (SYS_unlink, name, 0, 0, 0, 0, 0);
+  return syscall_errno (SYS_unlink, 1, name, 0, 0, 0, 0, 0);
 }
diff --git a/libgloss/riscv/sys_write.c b/libgloss/riscv/sys_write.c
index b972734..ce2edd3 100644
--- a/libgloss/riscv/sys_write.c
+++ b/libgloss/riscv/sys_write.c
@@ -6,5 +6,5 @@ 
 ssize_t
 _write(int file, const void *ptr, size_t len)
 {
-  return syscall_errno (SYS_write, file, ptr, len, 0, 0, 0);
+  return syscall_errno (SYS_write, 3, file, ptr, len, 0, 0, 0);
 }