[PATCH v5 09/14] tools/nolibc: add missing my_syscall6() for mips

From: Zhangjin Wu
Date: Wed Jun 28 2023 - 09:39:34 EST


It is able to pass the 6th argument like the 5th argument via the stack
for mips, let's add a new my_syscall6() now, see [1] for details:

The mips/o32 system call convention passes arguments 5 through 8 on
the user stack.

Both mmap() and pselect6() require my_syscall6().

[1]: https://man7.org/linux/man-pages/man2/syscall.2.html

Signed-off-by: Zhangjin Wu <falcon@xxxxxxxxxxx>
---
tools/include/nolibc/arch-mips.h | 25 +++++++++++++++++++++++++
tools/include/nolibc/nolibc.h | 9 ++++-----
2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/tools/include/nolibc/arch-mips.h b/tools/include/nolibc/arch-mips.h
index 55a9f01825e0..a8b33d6914a4 100644
--- a/tools/include/nolibc/arch-mips.h
+++ b/tools/include/nolibc/arch-mips.h
@@ -176,6 +176,31 @@ struct sys_stat_struct {
_arg4 ? -_num : _num; \
})

+#define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
+({ \
+ register long _num __asm__ ("v0") = (num); \
+ register long _arg1 __asm__ ("a0") = (long)(arg1); \
+ register long _arg2 __asm__ ("a1") = (long)(arg2); \
+ register long _arg3 __asm__ ("a2") = (long)(arg3); \
+ register long _arg4 __asm__ ("a3") = (long)(arg4); \
+ register long _arg5 = (long)(arg5); \
+ register long _arg6 = (long)(arg6); \
+ \
+ __asm__ volatile ( \
+ "addiu $sp, $sp, -32\n" \
+ "sw %7, 16($sp)\n" \
+ "sw %8, 20($sp)\n" \
+ "syscall\n " \
+ "addiu $sp, $sp, 32\n" \
+ : "=r" (_num), "=r"(_arg4) \
+ : "0"(_num), \
+ "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \
+ "r"(_arg6) \
+ : SYSCALL_CLOBBERLIST \
+ ); \
+ _arg4 ? -_num : _num; \
+})
+
char **environ __attribute__((weak));
const unsigned long *_auxv __attribute__((weak));

diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h
index 05a228a6ee78..1f8d821000ac 100644
--- a/tools/include/nolibc/nolibc.h
+++ b/tools/include/nolibc/nolibc.h
@@ -13,11 +13,10 @@
* Syscalls are split into 3 levels:
* - The lower level is the arch-specific syscall() definition, consisting in
* assembly code in compound expressions. These are called my_syscall0() to
- * my_syscall6() depending on the number of arguments. The MIPS
- * implementation is limited to 5 arguments. All input arguments are cast
- * to a long stored in a register. These expressions always return the
- * syscall's return value as a signed long value which is often either a
- * pointer or the negated errno value.
+ * my_syscall6() depending on the number of arguments. All input arguments
+ * are castto a long stored in a register. These expressions always return
+ * the syscall's return value as a signed long value which is often either
+ * a pointer or the negated errno value.
*
* - The second level is mostly architecture-independent. It is made of
* static functions called sys_<name>() which rely on my_syscallN()
--
2.25.1