arch: add loongarch support.

arch/arch-loongarch.h

@@ -0,0 +1,38 @@
+#ifndef ARCH_LOONGARCH_H
+#define ARCH_LOONGARCH_H
+
+#define FIO_ARCH	(arch_loongarch)
+
+#define read_barrier()		__asm__ __volatile__("dbar 0": : :"memory")
+#define write_barrier()		__asm__ __volatile__("dbar 0": : :"memory")
+#define nop			__asm__ __volatile__("nop")
+
+static inline int arch_ffz(unsigned long bitmask)
+{
+	unsigned long count;
+	if (~bitmask == 0)	/* ffz() in lib/ffz.h does this. */
+#if __loongarch_xlen == 64
+		return 63;
+#define CTZ "ctz.d"
+#define CTO "cto.d"
+#else
+		return 31;
+#define CTZ "ctz.w"
+#define CTO "cto.w"
+#endif
+
+	__asm__ __volatile__ (CTZ " %0, %1\n\t"
+			      "bnez %0, 0f\n\t"
+			      CTO " %0, %1\n\t"
+			      "b 1f\n\t"
+			      "0: move %0, $zero\n\t"
+			      "1:\n\t"
+			      :"=&r"(count)
+			      :"r"(bitmask));
+
+	return count;
+}
+
+#define ARCH_HAVE_FFZ
+
+#endif

arch/arch.h

@@ -19,6 +19,7 @@ enum {
 	arch_hppa,
 	arch_mips,
 	arch_aarch64,
+	arch_loongarch,
 
 	arch_generic,
 
@@ -77,6 +78,8 @@ extern unsigned long arch_flags;
 #include "arch-hppa.h"
 #elif defined(__aarch64__)
 #include "arch-aarch64.h"
+#elif defined(__loongarch__)
+#include "arch-loongarch.h"
 #else
 #warning "Unknown architecture, attempting to use generic model."
 #include "arch-generic.h"

os/os-linux-syscall.h

@@ -263,8 +263,8 @@
 #define __NR_sys_vmsplice	294
 #endif
 
-/* Linux syscalls for aarch64 */
-#elif defined(ARCH_AARCH64_H)
+/* Linux syscalls for aarch64 and loongarch */
+#elif defined(ARCH_AARCH64_H) || defined(ARCH_LOONGARCH_H)
 #ifndef __NR_ioprio_set
 #define __NR_ioprio_set		30
 #define __NR_ioprio_get		31