From f764bcffed69d8c62625dc4b6c1a6af21bd6dbc2 Mon Sep 17 00:00:00 2001 From: Joel Stanley Date: Wed, 6 Dec 2017 12:26:21 +1030 Subject: [PATCH] or1k: syscall: Pass arguments on the stack Busybox internally calls syscall(2). - in unistd.h defined something like int syscall(nr, ....) - in syscall.c (common) implemented as int syscall(nr, arg1, arg3, arg3, arg4, arg5, arg6) This will not work, busybox thinks syscall should have varargs calling conventions. But it doesnt in the uclibc implementation so no args go through. Most architectures this will work. But on openrisc varargs are all sent on the stack. Regular args are passed in registers. Commit message and idea from Stafford Horne . Signed-off-by: Joel Stanley --- libc/sysdeps/linux/or1k/Makefile.arch | 2 +- libc/sysdeps/linux/or1k/syscall.c | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 33 insertions(+), 1 deletion(-) create mode 100644 libc/sysdeps/linux/or1k/syscall.c diff --git a/libc/sysdeps/linux/or1k/Makefile.arch b/libc/sysdeps/linux/or1k/Makefile.arch index f6758fa63fa3..191eebafde9d 100644 --- a/libc/sysdeps/linux/or1k/Makefile.arch +++ b/libc/sysdeps/linux/or1k/Makefile.arch @@ -5,5 +5,5 @@ # Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball. # -CSRC-y := __syscall_error.c __init_brk.c brk.c sbrk.c clone.c +CSRC-y := __syscall_error.c __init_brk.c brk.c sbrk.c clone.c syscall.c SSRC-y := __longjmp.S setjmp.S or1k_clone.S diff --git a/libc/sysdeps/linux/or1k/syscall.c b/libc/sysdeps/linux/or1k/syscall.c new file mode 100644 index 000000000000..2f4356737cf8 --- /dev/null +++ b/libc/sysdeps/linux/or1k/syscall.c @@ -0,0 +1,32 @@ +/* + * Copyright (C) 2017 Joel Stanley + * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball. + */ + +#include +#include +#include + +long int syscall (long num, ...) +{ + unsigned long arg1 = 0; + unsigned long arg2 = 0; + unsigned long arg3 = 0; + unsigned long arg4 = 0; + unsigned long arg5 = 0; + unsigned long arg6 = 0; + va_list arg; + + va_start (arg, num); + arg1 = va_arg (arg, unsigned long); + arg2 = va_arg (arg, unsigned long); + arg3 = va_arg (arg, unsigned long); + arg4 = va_arg (arg, unsigned long); + arg5 = va_arg (arg, unsigned long); + arg6 = va_arg (arg, unsigned long); + va_end (arg); + + __asm__ volatile ( "" ::: "memory" ); + + return INLINE_SYSCALL_NCS(num, 6, arg1, arg2, arg3, arg4, arg5, arg6); +} -- 2.14.1