[PATCH liburing v4 02/10] arch: syscall: Add `__sys_open()` syscall

Ammar Faizi
2022-07-04T19:32:30Z

A prep patch to support aarch64 nolibc. We will use this to get the
page size by reading /proc/self/auxv. For some reason __NR_open is
not defined, so also define it in aarch64 syscall specific file.

v3:
- Use __NR_openat if __NR_open is not defined.

Reviewed-by: Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org>
Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
src/arch/generic/syscall.h | 9 +++++++++
src/arch/syscall-defs.h | 14 ++++++++++++++
2 files changed, 23 insertions(+)

diff --git a/src/arch/generic/syscall.h b/src/arch/generic/syscall.h
index fa93064..71b2234 100644
--- a/src/arch/generic/syscall.h
+++ b/src/arch/generic/syscall.h
@@ -7,6 +7,8 @@
#ifndef LIBURING_ARCH_GENERIC_SYSCALL_H
#define LIBURING_ARCH_GENERIC_SYSCALL_H

+#include <fcntl.h>
+
static inline int ____sys_io_uring_register(int fd, unsigned opcode,
const void *arg, unsigned nr_args)
{
@@ -41,6 +43,13 @@ static inline int ____sys_io_uring_enter(int fd, unsigned to_submit,
_NSIG / 8);
}

+static inline int __sys_open(const char *pathname, int flags, mode_t mode)
+{
+ int ret;
+ ret = open(pathname, flags, mode);
+ return (ret < 0) ? -errno : ret;
+}
+
static inline void *__sys_mmap(void *addr, size_t length, int prot, int flags,
int fd, off_t offset)
{
diff --git a/src/arch/syscall-defs.h b/src/arch/syscall-defs.h
index 1e8ae1b..9d4424d 100644
--- a/src/arch/syscall-defs.h
+++ b/src/arch/syscall-defs.h
@@ -3,6 +3,20 @@
#ifndef LIBURING_ARCH_SYSCALL_DEFS_H
#define LIBURING_ARCH_SYSCALL_DEFS_H

+#include <fcntl.h>
+
+static inline int __sys_open(const char *pathname, int flags, mode_t mode)
+{
+ /*
+ * Some architectures don't have __NR_open, but __NR_openat.
+ */
+#ifdef __NR_open
+ return __do_syscall3(__NR_open, pathname, flags, mode);
+#else
+ return __do_syscall4(__NR_openat, AT_FDCWD, pathname, flags, mode);
+#endif
+}
+
static inline void *__sys_mmap(void *addr, size_t length, int prot, int flags,
int fd, off_t offset)
{
--
Ammar Faizi