[PATCH liburing v3 00/10] aarch64 support

[PATCH liburing v3 00/10] aarch64 support

[Ammar Faizi]

From: Ammar Faizi <ammarfaizi2@gnuweeb.org>

Hi Jens,

This is v3 revision of aarch64 support.

This series contains nolibc support for aarch64 and one extra irrelevant
cleanup (patch #1). The missing bit from aarch64 is get_page_size()
which is a bit complicated to implement without libc.

aarch64 supports three values of page size: 4K, 16K, and 64K which are
selected at kernel compilation time. Therefore, we can't hard code the
page size for this arch. In this series we utilize open(), read() and
close() syscall to find the page size from /proc/self/auxv.

The auxiliary vector contains information about the page size, it is
located at `AT_PAGESZ` keyval pair.

For more details about the auxv data structure, check the link below.

Link: https://github.com/torvalds/linux/blob/v5.19-rc4/fs/binfmt_elf.c#L260
Link: https://lwn.net/Articles/631631/

There are 10 patches in this series. Summary:

- Patch 1 is just a trivial changelog fix.
- Patch 2 and 3 are to add open() and read() syscall.
- Patch 4 is to remove __INTERNAL__LIBURING_SYSCALL_H checks.
- Patch 5 is to add get_page_size() function.
- Patch 6 is just a trivial style fixup for #ifdef and friends.
- Patch 7 is to enable the nolibc support for aarch64.
- Patch 8 is to add nolibc test.
- Patch 9 is for GitHub bot build.
- Patch 10 is to update the CHANGELOG to note aarch64 nolibc support.

I have built it with GitHub bot and it compiles just fine. But I don't
have an aarch64 machine to run the tests. Since you are using aarch64,
I can rely on you to test it.

How to test this?

  make clean;
  ./configure --nolibc;
  make -j8;

  ldd src/liburing.so.2.3;
  # Make sure you don't see libc.so from the `ldd` command.

  make runtests;

Please give it a test, thanks!

## Changelog

v2 -> v3:
  - No need to init the static var to zero.
  - Split style fixup into a separate patch.
  - Add nolibc test to test get_page_size() function.
  - Use __NR_openat when __NR_open is not defined on the arch.
  - Split open/read/close in get_page_size() into a new function.
  - Cache the get_page_size() fallback value when we fail on the
    syscalls.

v1 -> v2:
  - Drop aarch64 renaming directory patch.
  - Fallback the page size to 4K if we fail to get it.
  - Cache the page size after we read it from /proc/self/auxv.
  - Massage commit messages.
  - Note aarch64 nolibc support in CHANGELOG.

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---

Ammar Faizi (10):
  CHANGELOG: Fixup missing space
  arch: syscall: Add `__sys_open()` syscall
  arch: syscall: Add `__sys_read()` syscall
  arch: Remove `__INTERNAL__LIBURING_LIB_H` checks
  arch/aarch64: lib: Add `get_page_size()` function
  lib: Style fixup for #if / #elif / #else / #endif
  lib: Enable nolibc support for aarch64
  test: Add nolibc test
  .github: Enable aarch64 nolibc build for GitHub bot
  CHANGELOG: Note about aarch64 support

 .github/workflows/build.yml |  2 +-
 CHANGELOG                   |  7 ++++-
 src/arch/aarch64/lib.h      | 51 +++++++++++++++++++++++++++++++
 src/arch/aarch64/syscall.h  |  4 ---
 src/arch/generic/lib.h      |  4 ---
 src/arch/generic/syscall.h  | 20 ++++++++++---
 src/arch/syscall-defs.h     | 19 ++++++++++++
 src/arch/x86/lib.h          |  4 ---
 src/arch/x86/syscall.h      |  4 ---
 src/lib.h                   | 32 ++++++++++----------
 src/syscall.h               |  2 --
 test/Makefile               |  1 +
 test/nolibc.c               | 60 +++++++++++++++++++++++++++++++++++++
 13 files changed, 170 insertions(+), 40 deletions(-)
 create mode 100644 src/arch/aarch64/lib.h
 create mode 100644 test/nolibc.c


base-commit: f8eb5f804288e10ae7ef442ef482e4dd8b18fee7
-- 
Ammar Faizi

[PATCH liburing v3 01/10] CHANGELOG: Fixup missing space

[Ammar Faizi]

From: Ammar Faizi <ammarfaizi2@gnuweeb.org>

  s/reducingthe/reducing the/

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 CHANGELOG | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CHANGELOG b/CHANGELOG
index 01cb677..efb3ff3 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -6,7 +6,7 @@ liburing-2.2 release
 - Add support for multishot accept.
 - io_uring_register_files() will set RLIMIT_NOFILE if necessary.
 - Add support for registered ring fds, io_uring_register_ring_fd(),
-  reducingthe overhead of an io_uring_enter() system call.
+  reducing the overhead of an io_uring_enter() system call.
 - Add support for the message ring opcode.
 - Add support for newer request cancelation features.
 - Add support for IORING_SETUP_COOP_TASKRUN, which can help reduce the
-- 
Ammar Faizi

[PATCH liburing v3 02/10] arch: syscall: Add `__sys_open()` syscall

[Ammar Faizi]

From: Ammar Faizi <ammarfaizi2@gnuweeb.org>

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.

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

[PATCH liburing v3 03/10] arch: syscall: Add `__sys_read()` syscall

[Ammar Faizi]

From: Ammar Faizi <ammarfaizi2@gnuweeb.org>

A prep patch to support aarch64 nolibc. We will use this to get the
page size by reading /proc/self/auxv.

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 src/arch/generic/syscall.h | 7 +++++++
 src/arch/syscall-defs.h    | 5 +++++
 2 files changed, 12 insertions(+)

diff --git a/src/arch/generic/syscall.h b/src/arch/generic/syscall.h
index 71b2234..22252a1 100644
--- a/src/arch/generic/syscall.h
+++ b/src/arch/generic/syscall.h
@@ -50,6 +50,13 @@ static inline int __sys_open(const char *pathname, int flags, mode_t mode)
 	return (ret < 0) ? -errno : ret;
 }
 
+static inline ssize_t __sys_read(int fd, void *buffer, size_t size)
+{
+	ssize_t ret;
+	ret = read(fd, buffer, size);
+	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 9d4424d..32750b5 100644
--- a/src/arch/syscall-defs.h
+++ b/src/arch/syscall-defs.h
@@ -17,6 +17,11 @@ static inline int __sys_open(const char *pathname, int flags, mode_t mode)
 #endif
 }
 
+static inline int __sys_read(int fd, void *buffer, size_t size)
+{
+	return (int) __do_syscall3(__NR_read, fd, buffer, size);
+}
+
 static inline void *__sys_mmap(void *addr, size_t length, int prot, int flags,
 			       int fd, off_t offset)
 {
-- 
Ammar Faizi

[PATCH liburing v3 04/10] arch: Remove `__INTERNAL__LIBURING_LIB_H` checks

[Ammar Faizi]

From: Ammar Faizi <ammarfaizi2@gnuweeb.org>

We will include the syscall.h from another place as well. This check
was added by me when adding the x86 syscalls. For aarch64 we will
include this header from lib.h but we are restricted by this check.
Let's just remove it for all archs. User shouldn't touch this code
directly anyway.

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 src/arch/aarch64/syscall.h | 4 ----
 src/arch/generic/lib.h     | 4 ----
 src/arch/generic/syscall.h | 4 ----
 src/arch/x86/lib.h         | 4 ----
 src/arch/x86/syscall.h     | 4 ----
 src/lib.h                  | 2 --
 src/syscall.h              | 2 --
 7 files changed, 24 deletions(-)

diff --git a/src/arch/aarch64/syscall.h b/src/arch/aarch64/syscall.h
index c0ab7e2..b00e90b 100644
--- a/src/arch/aarch64/syscall.h
+++ b/src/arch/aarch64/syscall.h
@@ -1,9 +1,5 @@
 /* SPDX-License-Identifier: MIT */
 
-#ifndef __INTERNAL__LIBURING_SYSCALL_H
-	#error "This file should be included from src/syscall.h (liburing)"
-#endif
-
 #ifndef LIBURING_ARCH_AARCH64_SYSCALL_H
 #define LIBURING_ARCH_AARCH64_SYSCALL_H
 
diff --git a/src/arch/generic/lib.h b/src/arch/generic/lib.h
index 737e795..6b006c6 100644
--- a/src/arch/generic/lib.h
+++ b/src/arch/generic/lib.h
@@ -1,9 +1,5 @@
 /* SPDX-License-Identifier: MIT */
 
-#ifndef __INTERNAL__LIBURING_LIB_H
-	#error "This file should be included from src/lib.h (liburing)"
-#endif
-
 #ifndef LIBURING_ARCH_GENERIC_LIB_H
 #define LIBURING_ARCH_GENERIC_LIB_H
 
diff --git a/src/arch/generic/syscall.h b/src/arch/generic/syscall.h
index 22252a1..e637890 100644
--- a/src/arch/generic/syscall.h
+++ b/src/arch/generic/syscall.h
@@ -1,9 +1,5 @@
 /* SPDX-License-Identifier: MIT */
 
-#ifndef __INTERNAL__LIBURING_SYSCALL_H
-	#error "This file should be included from src/syscall.h (liburing)"
-#endif
-
 #ifndef LIBURING_ARCH_GENERIC_SYSCALL_H
 #define LIBURING_ARCH_GENERIC_SYSCALL_H
 
diff --git a/src/arch/x86/lib.h b/src/arch/x86/lib.h
index e6a74f3..6ece2d4 100644
--- a/src/arch/x86/lib.h
+++ b/src/arch/x86/lib.h
@@ -1,9 +1,5 @@
 /* SPDX-License-Identifier: MIT */
 
-#ifndef __INTERNAL__LIBURING_LIB_H
-	#error "This file should be included from src/lib.h (liburing)"
-#endif
-
 #ifndef LIBURING_ARCH_X86_LIB_H
 #define LIBURING_ARCH_X86_LIB_H
 
diff --git a/src/arch/x86/syscall.h b/src/arch/x86/syscall.h
index 43c576b..cb8fb91 100644
--- a/src/arch/x86/syscall.h
+++ b/src/arch/x86/syscall.h
@@ -1,9 +1,5 @@
 /* SPDX-License-Identifier: MIT */
 
-#ifndef __INTERNAL__LIBURING_SYSCALL_H
-	#error "This file should be included from src/syscall.h (liburing)"
-#endif
-
 #ifndef LIBURING_ARCH_X86_SYSCALL_H
 #define LIBURING_ARCH_X86_SYSCALL_H
 
diff --git a/src/lib.h b/src/lib.h
index 89a40f2..7bbacb9 100644
--- a/src/lib.h
+++ b/src/lib.h
@@ -6,7 +6,6 @@
 #include <string.h>
 #include <unistd.h>
 
-#define __INTERNAL__LIBURING_LIB_H
 #if defined(__x86_64__) || defined(__i386__)
 	#include "arch/x86/lib.h"
 #else
@@ -19,7 +18,6 @@
 	/* libc wrappers. */
 	#include "arch/generic/lib.h"
 #endif
-#undef __INTERNAL__LIBURING_LIB_H
 
 
 #ifndef offsetof
diff --git a/src/syscall.h b/src/syscall.h
index 214789d..73b04b4 100644
--- a/src/syscall.h
+++ b/src/syscall.h
@@ -70,7 +70,6 @@ static inline bool IS_ERR(const void *ptr)
 	return uring_unlikely((uintptr_t) ptr >= (uintptr_t) -4095UL);
 }
 
-#define __INTERNAL__LIBURING_SYSCALL_H
 #if defined(__x86_64__) || defined(__i386__)
 #include "arch/x86/syscall.h"
 #elif defined(__aarch64__)
@@ -86,7 +85,6 @@ static inline bool IS_ERR(const void *ptr)
 /* libc syscall wrappers. */
 #include "arch/generic/syscall.h"
 #endif
-#undef __INTERNAL__LIBURING_SYSCALL_H
 
 /*
  * For backward compatibility.
-- 
Ammar Faizi

[PATCH liburing v3 05/10] arch/aarch64: lib: Add `get_page_size()` function

[Ammar Faizi]

From: Ammar Faizi <ammarfaizi2@gnuweeb.org>

A prep patch to add aarch64 nolibc support.

aarch64 supports three values of page size: 4K, 16K, and 64K which are
selected at kernel compilation time. Therefore, we can't hard code the
page size for this arch. Utilize open(), read() and close() syscall to
find the page size from /proc/self/auxv. For more details about the
auxv data structure, check the link below [1].

v3:
  - Split open/read/close in get_page_size() into a new function.
  - Cache the fallback value when we fail on the syscalls.
  - No need to init the static var to zero.

v2:
  - Fallback to 4K if the syscall fails.
  - Cache the page size after read as suggested by Jens.

Link: https://github.com/torvalds/linux/blob/v5.19-rc4/fs/binfmt_elf.c#L260 [1]
Link: https://lore.kernel.org/io-uring/3895dbe1-8d5f-cf53-e94b-5d1545466de1@kernel.dk
Link: https://lore.kernel.org/io-uring/8bfba71c-55d7-fb49-6593-4d0f9d9c3611@kernel.dk
Link: https://lore.kernel.org/io-uring/49ed1c4c-46ca-15c4-f288-f6808401b0ff@kernel.dk
Suggested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 src/arch/aarch64/lib.h | 51 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 src/arch/aarch64/lib.h

diff --git a/src/arch/aarch64/lib.h b/src/arch/aarch64/lib.h
new file mode 100644
index 0000000..eb7e4cb
--- /dev/null
+++ b/src/arch/aarch64/lib.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: MIT */
+
+#ifndef LIBURING_ARCH_AARCH64_LIB_H
+#define LIBURING_ARCH_AARCH64_LIB_H
+
+#include <elf.h>
+#include <sys/auxv.h>
+#include "../../syscall.h"
+
+static inline long __get_page_size(void)
+{
+	static const long fallback_ret = 4096;
+	Elf64_Off buf[2];
+	long ret;
+	int fd;
+
+	fd = __sys_open("/proc/self/auxv", O_RDONLY, 0);
+	if (fd < 0)
+		return fallback_ret;
+
+	while (1) {
+		ssize_t x;
+
+		x = __sys_read(fd, buf, sizeof(buf));
+		if (x < sizeof(buf)) {
+			ret = fallback_ret;
+			break;
+		}
+
+		if (buf[0] == AT_PAGESZ) {
+			ret = buf[1];
+			break;
+		}
+	}
+
+	__sys_close(fd);
+	return ret;
+}
+
+static inline long get_page_size(void)
+{
+	static long cache_val;
+
+	if (cache_val)
+		return cache_val;
+
+	cache_val = __get_page_size();
+	return cache_val;
+}
+
+#endif /* #ifndef LIBURING_ARCH_AARCH64_LIB_H */
-- 
Ammar Faizi

[PATCH liburing v3 06/10] lib: Style fixup for #if / #elif / #else / #endif

[Ammar Faizi]

From: Ammar Faizi <ammarfaizi2@gnuweeb.org>

Don't indent the block inside #if / #elif / #else / #endif.

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 src/lib.h | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/src/lib.h b/src/lib.h
index 7bbacb9..a966c77 100644
--- a/src/lib.h
+++ b/src/lib.h
@@ -7,28 +7,28 @@
 #include <unistd.h>
 
 #if defined(__x86_64__) || defined(__i386__)
-	#include "arch/x86/lib.h"
+#include "arch/x86/lib.h"
 #else
-	/*
-	 * We don't have nolibc support for this arch. Must use libc!
-	 */
-	#ifdef CONFIG_NOLIBC
-		#error "This arch doesn't support building liburing without libc"
-	#endif
-	/* libc wrappers. */
-	#include "arch/generic/lib.h"
+/*
+ * We don't have nolibc support for this arch. Must use libc!
+ */
+#ifdef CONFIG_NOLIBC
+#error "This arch doesn't support building liburing without libc"
+#endif
+/* libc wrappers. */
+#include "arch/generic/lib.h"
 #endif
 
 
 #ifndef offsetof
-	#define offsetof(TYPE, FIELD) ((size_t) &((TYPE *)0)->FIELD)
+#define offsetof(TYPE, FIELD) ((size_t) &((TYPE *)0)->FIELD)
 #endif
 
 #ifndef container_of
-	#define container_of(PTR, TYPE, FIELD) ({			\
-		__typeof__(((TYPE *)0)->FIELD) *__FIELD_PTR = (PTR);	\
-		(TYPE *)((char *) __FIELD_PTR - offsetof(TYPE, FIELD));	\
-	})
+#define container_of(PTR, TYPE, FIELD) ({			\
+	__typeof__(((TYPE *)0)->FIELD) *__FIELD_PTR = (PTR);	\
+	(TYPE *)((char *) __FIELD_PTR - offsetof(TYPE, FIELD));	\
+})
 #endif
 
 #define __maybe_unused		__attribute__((__unused__))
-- 
Ammar Faizi

[PATCH liburing v3 07/10] lib: Enable nolibc support for aarch64

[Ammar Faizi]

From: Ammar Faizi <ammarfaizi2@gnuweeb.org>

A previous patch adds get_page_size() function which is the missing bit
for aarch64 nolibc support. Now we have a full set of functions to
enable nolibc build support for aarch64.

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 src/lib.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/lib.h b/src/lib.h
index a966c77..f347191 100644
--- a/src/lib.h
+++ b/src/lib.h
@@ -8,6 +8,8 @@
 
 #if defined(__x86_64__) || defined(__i386__)
 #include "arch/x86/lib.h"
+#elif defined(__aarch64__)
+#include "arch/aarch64/lib.h"
 #else
 /*
  * We don't have nolibc support for this arch. Must use libc!
-- 
Ammar Faizi

[PATCH liburing v3 08/10] test: Add nolibc test

[Ammar Faizi]

From: Ammar Faizi <ammarfaizi2@gnuweeb.org>

This test is used to test liburing nolibc functionality. The first use
case is test get_page_size() function, especially for aarch64 which
relies on reading /proc/self/auxv. We don't seem to have a test that
tests that function, so let's do it here.

We may add more nolibc tests in this file in the future.

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 test/Makefile |  1 +
 test/nolibc.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+)
 create mode 100644 test/nolibc.c

diff --git a/test/Makefile b/test/Makefile
index 9590e1e..45674c3 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -101,6 +101,7 @@ test_srcs := \
 	mkdir.c \
 	msg-ring.c \
 	multicqes_drain.c \
+	nolibc.c \
 	nop-all-sizes.c \
 	nop.c \
 	openat2.c \
diff --git a/test/nolibc.c b/test/nolibc.c
new file mode 100644
index 0000000..e996f40
--- /dev/null
+++ b/test/nolibc.c
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Test liburing nolibc functionality.
+ *
+ * Currently, supported architectures are:
+ *   1) x86
+ *   2) x86-64
+ *   3) aarch64
+ *
+ */
+#include "helpers.h"
+
+#if !defined(__x86_64__) && !defined(__i386__) && !defined(__aarch64__)
+
+/*
+ * This arch doesn't support nolibc.
+ */
+int main(void)
+{
+	return T_EXIT_SKIP;
+}
+
+#else /* #if !defined(__x86_64__) && !defined(__i386__) && !defined(__aarch64__) */
+
+#ifndef CONFIG_NOLIBC
+#define CONFIG_NOLIBC
+#endif
+
+#include <stdio.h>
+#include <unistd.h>
+#include "../src/lib.h"
+
+static int test_get_page_size(void)
+{
+	long a, b;
+
+	a = sysconf(_SC_PAGESIZE);
+	b = get_page_size();
+	if (a != b) {
+		fprintf(stderr, "get_page_size() fails, %ld != %ld", a, b);
+		return -1;
+	}
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret;
+
+	if (argc > 1)
+		return T_EXIT_SKIP;
+
+	ret = test_get_page_size();
+	if (ret)
+		return T_EXIT_FAIL;
+
+	return T_EXIT_PASS;
+}
+
+#endif /* #if !defined(__x86_64__) && !defined(__i386__) && !defined(__aarch64__) */
-- 
Ammar Faizi

[PATCH liburing v3 09/10] .github: Enable aarch64 nolibc build for GitHub bot

[Ammar Faizi]

From: Ammar Faizi <ammarfaizi2@gnuweeb.org>

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 .github/workflows/build.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 88192ff..fc119cb 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -114,7 +114,7 @@ jobs:
 
     - name: Build nolibc
       run: |
-        if [[ "${{matrix.arch}}" == "x86_64" || "${{matrix.arch}}" == "i686" ]]; then \
+        if [[ "${{matrix.arch}}" == "x86_64" || "${{matrix.arch}}" == "i686" || "${{matrix.arch}}" == "aarch64" ]]; then \
             make clean; \
             ./configure --cc=${{matrix.cc}} --cxx=${{matrix.cxx}} --nolibc; \
             make -j$(nproc) V=1 CPPFLAGS="-Werror" CFLAGS="$FLAGS" CXXFLAGS="$FLAGS"; \
-- 
Ammar Faizi

[PATCH liburing v3 10/10] CHANGELOG: Note about aarch64 support

[Ammar Faizi]

From: Ammar Faizi <ammarfaizi2@gnuweeb.org>

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 CHANGELOG | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/CHANGELOG b/CHANGELOG
index efb3ff3..9c054b0 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,8 @@
+liburing-2.3 release
+
+- Support non-libc build for aarch64.
+
+
 liburing-2.2 release
 
 - Support non-libc builds.
-- 
Ammar Faizi

Re: [PATCH liburing v3 02/10] arch: syscall: Add `__sys_open()` syscall

[Alviro Iskandar Setiawan]

On Tue, Jul 5, 2022 at 12:54 AM Ammar Faizi wrote:
> From: Ammar Faizi <ammarfaizi2@gnuweeb.org>
>
> 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.
>
> Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>

Reviewed-by: Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org>

tq

-- Viro

Re: [PATCH liburing v3 03/10] arch: syscall: Add `__sys_read()` syscall

[Alviro Iskandar Setiawan]

On Tue, Jul 5, 2022 at 12:54 AM Ammar Faizi wrote:
> From: Ammar Faizi <ammarfaizi2@gnuweeb.org>
>
> A prep patch to support aarch64 nolibc. We will use this to get the
> page size by reading /proc/self/auxv.
>
> Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
[...]
> +static inline int __sys_read(int fd, void *buffer, size_t size)
> +{
> +       return (int) __do_syscall3(__NR_read, fd, buffer, size);
> +}

__sys_read should return ssize_t and the cast should also (ssize_t).

With that fixed:

Reviewed-by: Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org>

tq

-- Viro

Re: [PATCH liburing v3 03/10] arch: syscall: Add `__sys_read()` syscall

[Ammar Faizi]

On 7/5/22 1:12 AM, Alviro Iskandar Setiawan wrote:
> On Tue, Jul 5, 2022 at 12:54 AM Ammar Faizi wrote:
>> From: Ammar Faizi <ammarfaizi2@gnuweeb.org>
>>
>> A prep patch to support aarch64 nolibc. We will use this to get the
>> page size by reading /proc/self/auxv.
>>
>> Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
> [...]
>> +static inline int __sys_read(int fd, void *buffer, size_t size)
>> +{
>> +       return (int) __do_syscall3(__NR_read, fd, buffer, size);
>> +}
> 
> __sys_read should return ssize_t and the cast should also (ssize_t).

Ah right, I missed it. Will fix in v4.

> With that fixed:
> 
> Reviewed-by: Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org>

Thanks!

-- 
Ammar Faizi

Re: [PATCH liburing v3 05/10] arch/aarch64: lib: Add `get_page_size()` function

[Alviro Iskandar Setiawan]

On Tue, Jul 5, 2022 at 12:54 AM Ammar Faizi wrote:
> From: Ammar Faizi <ammarfaizi2@gnuweeb.org>
>
> A prep patch to add aarch64 nolibc support.
>
> aarch64 supports three values of page size: 4K, 16K, and 64K which are
> selected at kernel compilation time. Therefore, we can't hard code the
> page size for this arch. Utilize open(), read() and close() syscall to
> find the page size from /proc/self/auxv. For more details about the
> auxv data structure, check the link below [1].
>
> v3:
>   - Split open/read/close in get_page_size() into a new function.
>   - Cache the fallback value when we fail on the syscalls.
>   - No need to init the static var to zero.
>
> v2:
>   - Fallback to 4K if the syscall fails.
>   - Cache the page size after read as suggested by Jens.
>
> Link: https://github.com/torvalds/linux/blob/v5.19-rc4/fs/binfmt_elf.c#L260 [1]
> Link: https://lore.kernel.org/io-uring/3895dbe1-8d5f-cf53-e94b-5d1545466de1@kernel.dk
> Link: https://lore.kernel.org/io-uring/8bfba71c-55d7-fb49-6593-4d0f9d9c3611@kernel.dk
> Link: https://lore.kernel.org/io-uring/49ed1c4c-46ca-15c4-f288-f6808401b0ff@kernel.dk
> Suggested-by: Jens Axboe <axboe@kernel.dk>
> Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
[...]
> +static inline long __get_page_size(void)
> +{
> +       static const long fallback_ret = 4096;
> +       Elf64_Off buf[2];
> +       long ret;
> +       int fd;
> +
> +       fd = __sys_open("/proc/self/auxv", O_RDONLY, 0);
> +       if (fd < 0)
> +               return fallback_ret;
> +
> +       while (1) {
> +               ssize_t x;
> +
> +               x = __sys_read(fd, buf, sizeof(buf));
> +               if (x < sizeof(buf)) {
> +                       ret = fallback_ret;
> +                       break;
> +               }
> +
> +               if (buf[0] == AT_PAGESZ) {
> +                       ret = buf[1];
> +                       break;
> +               }
> +       }
> +
> +       __sys_close(fd);
> +       return ret;
> +}

fallback_ret var is not needed, just do this, simpler:

static inline long __get_page_size(void)
{
        Elf64_Off buf[2];
        long ret = 4096;
        int fd;

        fd = __sys_open("/proc/self/auxv", O_RDONLY, 0);
        if (fd < 0)
                return ret;

        while (1) {
                ssize_t x;

                x = __sys_read(fd, buf, sizeof(buf));
                if (x < sizeof(buf))
                        break;

                if (buf[0] == AT_PAGESZ) {
                        ret = buf[1];
                        break;
                }
        }

        __sys_close(fd);
        return ret;
}

with that simplification:

Reviewed-by: Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org>

tq

-- Viro

Re: [PATCH liburing v3 05/10] arch/aarch64: lib: Add `get_page_size()` function

[Ammar Faizi]

On 7/5/22 1:18 AM, Alviro Iskandar Setiawan wrote:
> fallback_ret var is not needed, just do this, simpler:
> 
> static inline long __get_page_size(void)
> {
>          Elf64_Off buf[2];
>          long ret = 4096;
>          int fd;
> 
>          fd = __sys_open("/proc/self/auxv", O_RDONLY, 0);
>          if (fd < 0)
>                  return ret;
> 
>          while (1) {
>                  ssize_t x;
> 
>                  x = __sys_read(fd, buf, sizeof(buf));
>                  if (x < sizeof(buf))
>                          break;
> 
>                  if (buf[0] == AT_PAGESZ) {
>                          ret = buf[1];
>                          break;
>                  }
>          }
> 
>          __sys_close(fd);
>          return ret;
> }

Agree with that, will fold this in for v4.

> with that simplification:
> 
> Reviewed-by: Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org>

Thanks!

-- 
Ammar Faizi