Add nolibc riscv64 support

Add `lgcc` to avoid undefined reference to `__clzdi2'

Signed-off-by: Michal Biesek <[email protected]>

configure

@@ -389,11 +389,11 @@ liburing_nolibc="no"
 if test "$use_libc" != "yes"; then
 
   #
-  # Currently, CONFIG_NOLIBC only supports x86-64, x86 (32-bit) and aarch64.
+  # Currently, CONFIG_NOLIBC only supports x86-64, x86 (32-bit), aarch64 and riscv64.
   #
   cat > $TMPC << EOF
 int main(void){
-#if defined(__x86_64__) || defined(__i386__) || defined(__aarch64__)
+#if defined(__x86_64__) || defined(__i386__) || defined(__aarch64__) || (defined(__riscv) && __riscv_xlen == 64)
   return 0;
 #else
 #error libc is needed

src/Makefile

@@ -47,7 +47,7 @@ ifeq ($(CONFIG_NOLIBC),y)
 	liburing_srcs += nolibc.c
 	override CFLAGS += -nostdlib -nodefaultlibs -ffreestanding -fno-builtin -fno-stack-protector
 	override CPPFLAGS += -nostdlib -nodefaultlibs -ffreestanding -fno-builtin -fno-stack-protector
-	override LINK_FLAGS += -nostdlib -nodefaultlibs
+	override LINK_FLAGS += -nostdlib -nodefaultlibs -lgcc
 endif
 
 override CPPFLAGS += -MT "$@" -MMD -MP -MF "$@.d"

src/arch/riscv64/lib.h

@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: MIT */
+
+#ifndef LIBURING_ARCH_RISCV64_LIB_H
+#define LIBURING_ARCH_RISCV64_LIB_H
+
+#include <elf.h>
+#include <sys/auxv.h>
+#include "../../syscall.h"
+
+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 < (long) sizeof(buf))
+			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_RISCV64_LIB_H */

src/arch/riscv64/syscall.h

@@ -0,0 +1,100 @@
+/* SPDX-License-Identifier: MIT */
+
+#ifndef LIBURING_ARCH_RISCV64_SYSCALL_H
+#define LIBURING_ARCH_RISCV64_SYSCALL_H
+
+#if defined(__riscv) && __riscv_xlen == 64
+
+#define __do_syscallM(...) ({						\
+	__asm__ volatile (						\
+		"ecall"							\
+		: "=r"(a0)						\
+		: __VA_ARGS__						\
+		: "memory", "a1");					\
+	(long) a0;							\
+})
+
+#define __do_syscallN(...) ({						\
+	__asm__ volatile (						\
+		"ecall"							\
+		: "=r"(a0)						\
+		: __VA_ARGS__						\
+		: "memory");					\
+	(long) a0;							\
+})
+
+#define __do_syscall0(__n) ({						\
+	register long a7 __asm__("a7") = __n;				\
+	register long a0 __asm__("a0");					\
+									\
+	__do_syscallM("r" (a7));					\
+})
+
+#define __do_syscall1(__n, __a) ({					\
+	register long a7 __asm__("a7") = __n;				\
+	register __typeof__(__a) a0 __asm__("a0") = __a;		\
+									\
+	__do_syscallM("r" (a7), "0" (a0));				\
+})
+
+#define __do_syscall2(__n, __a, __b) ({					\
+	register long a7 __asm__("a7") = __n;				\
+	register __typeof__(__a) a0 __asm__("a0") = __a;		\
+	register __typeof__(__b) a1 __asm__("a1") = __b;		\
+									\
+	__do_syscallN("r" (a7), "0" (a0), "r" (a1));			\
+})
+
+#define __do_syscall3(__n, __a, __b, __c) ({				\
+	register long a7 __asm__("a7") = __n;				\
+	register __typeof__(__a) a0 __asm__("a0") = __a;		\
+	register __typeof__(__b) a1 __asm__("a1") = __b;		\
+	register __typeof__(__c) a2 __asm__("a2") = __c;		\
+									\
+	__do_syscallN("r" (a7), "0" (a0), "r" (a1), "r" (a2));		\
+})
+
+#define __do_syscall4(__n, __a, __b, __c, __d) ({			\
+	register long a7 __asm__("a7") = __n;				\
+	register __typeof__(__a) a0 __asm__("a0") = __a;		\
+	register __typeof__(__b) a1 __asm__("a1") = __b;		\
+	register __typeof__(__c) a2 __asm__("a2") = __c;		\
+	register __typeof__(__d) a3 __asm__("a3") = __d;		\
+									\
+	__do_syscallN("r" (a7), "0" (a0), "r" (a1), "r" (a2), "r" (a3));\
+})
+
+#define __do_syscall5(__n, __a, __b, __c, __d, __e) ({			\
+	register long a7 __asm__("a7") = __n;				\
+	register __typeof__(__a) a0 __asm__("a0") = __a;		\
+	register __typeof__(__b) a1 __asm__("a1") = __b;		\
+	register __typeof__(__c) a2 __asm__("a2") = __c;		\
+	register __typeof__(__d) a3 __asm__("a3") = __d;		\
+	register __typeof__(__e) a4 __asm__("a4") = __e;		\
+									\
+	__do_syscallN("r" (a7), "0" (a0), "r" (a1), "r" (a2), "r" (a3),	\
+			"r"(a4));					\
+})
+
+#define __do_syscall6(__n, __a, __b, __c, __d, __e, __f) ({		\
+	register long a7 __asm__("a7") = __n;				\
+	register __typeof__(__a) a0 __asm__("a0") = __a;		\
+	register __typeof__(__b) a1 __asm__("a1") = __b;		\
+	register __typeof__(__c) a2 __asm__("a2") = __c;		\
+	register __typeof__(__d) a3 __asm__("a3") = __d;		\
+	register __typeof__(__e) a4 __asm__("a4") = __e;		\
+	register __typeof__(__f) a5 __asm__("a5") = __f;		\
+									\
+	__do_syscallN("r" (a7), "0" (a0), "r" (a1), "r" (a2), "r" (a3),	\
+			"r" (a4), "r"(a5));				\
+})
+
+#include "../syscall-defs.h"
+
+#else /* #if defined(__riscv) && __riscv_xlen == 64 */
+
+#include "../generic/syscall.h"
+
+#endif /*  #if defined(__riscv) && __riscv_xlen == 64 */
+
+#endif /* #ifndef LIBURING_ARCH_RISCV64_SYSCALL_H */

src/lib.h

@@ -10,6 +10,8 @@
 #include "arch/x86/lib.h"
 #elif defined(__aarch64__)
 #include "arch/aarch64/lib.h"
+#elif defined(__riscv) && __riscv_xlen == 64
+#include "arch/riscv64/lib.h"
 #else
 /*
  * We don't have nolibc support for this arch. Must use libc!

src/syscall.h

@@ -37,6 +37,8 @@ static inline bool IS_ERR(const void *ptr)
 #include "arch/x86/syscall.h"
 #elif defined(__aarch64__)
 #include "arch/aarch64/syscall.h"
+#elif defined(__riscv) && __riscv_xlen == 64
+#include "arch/riscv64/syscall.h"
 #else
 /*
  * We don't have native syscall wrappers

test/nolibc.c

@@ -6,11 +6,13 @@
  *   1) x86
  *   2) x86-64
  *   3) aarch64
+ *   4) riscv64
  *
  */
 #include "helpers.h"
 
-#if !defined(__x86_64__) && !defined(__i386__) && !defined(__aarch64__)
+#if !defined(__x86_64__) && !defined(__i386__) && !defined(__aarch64__) && (!defined(__riscv) && __riscv_xlen != 64)
+
 
 /*
  * This arch doesn't support nolibc.
@@ -20,7 +22,7 @@ int main(void)
 	return T_EXIT_SKIP;
 }
 
-#else /* #if !defined(__x86_64__) && !defined(__i386__) && !defined(__aarch64__) */
+#else /* #if !defined(__x86_64__) && !defined(__i386__) && !defined(__aarch64__) && (!defined(__riscv) && __riscv_xlen != 64) */
 
 #ifndef CONFIG_NOLIBC
 #define CONFIG_NOLIBC
@@ -57,4 +59,4 @@ int main(int argc, char *argv[])
 	return T_EXIT_PASS;
 }
 
-#endif /* #if !defined(__x86_64__) && !defined(__i386__) && !defined(__aarch64__) */
+#endif /* #if !defined(__x86_64__) && !defined(__i386__) && !defined(__aarch64__) && (!defined(__riscv) && __riscv_xlen != 64) */