[PATCH 0/1] Only pass the minimum number of syscall arguments (RISC-V)

[Georg Sauthoff]

As is, the RISC-V syscall code unconditionally sets all possible syscall
arguments even if the syscall requires fewer.

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

Georg Sauthoff (1):
  Only pass the minimum number of syscall arguments

 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