libbpf: Add LoongArch support to bpf_tracing.h

Add PT_REGS macros for LoongArch ([0]).

  [0]: https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.htmlSigned-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Link: https://lore.kernel.org/bpf/20221231100757.3177034-1-hengqi.chen@gmail.com

tools/lib/bpf/bpf_tracing.h

@@ -32,6 +32,9 @@
 #elif defined(__TARGET_ARCH_arc)
 	#define bpf_target_arc
 	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_loongarch)
+	#define bpf_target_loongarch
+	#define bpf_target_defined
 #else
 
 /* Fall back to what the compiler says */
@@ -62,6 +65,9 @@
 #elif defined(__arc__)
 	#define bpf_target_arc
 	#define bpf_target_defined
+#elif defined(__loongarch__)
+	#define bpf_target_loongarch
+	#define bpf_target_defined
 #endif /* no compiler target */
 
 #endif
@@ -258,6 +264,23 @@ struct pt_regs___arm64 {
 /* arc does not select ARCH_HAS_SYSCALL_WRAPPER. */
 #define PT_REGS_SYSCALL_REGS(ctx) ctx
 
+#elif defined(bpf_target_loongarch)
+
+/* https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html */
+
+#define __PT_PARM1_REG regs[4]
+#define __PT_PARM2_REG regs[5]
+#define __PT_PARM3_REG regs[6]
+#define __PT_PARM4_REG regs[7]
+#define __PT_PARM5_REG regs[8]
+#define __PT_RET_REG regs[1]
+#define __PT_FP_REG regs[22]
+#define __PT_RC_REG regs[4]
+#define __PT_SP_REG regs[3]
+#define __PT_IP_REG csr_era
+/* loongarch does not select ARCH_HAS_SYSCALL_WRAPPER. */
+#define PT_REGS_SYSCALL_REGS(ctx) ctx
+
 #endif
 
 #if defined(bpf_target_defined)