3 files changed, 32 insertions, 0 deletions
diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index 4c904ef0b47e..477666f3d496 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -286,3 +286,20 @@ tags:
 
 # Delete partially updated (corrupted) files on error
 .DELETE_ON_ERROR:
+
+help:
+	@echo 'libbpf common targets:'
+	@echo '  HINT: use "V=1" to enable verbose build'
+	@echo '  all     - build libraries and pkgconfig'
+	@echo '  clean   - remove all generated files'
+	@echo '  check   - check abi and version info'
+	@echo ''
+	@echo 'libbpf install targets:'
+	@echo '  HINT: use "prefix"(defaults to "/usr/local") or "DESTDIR" (defaults to "/")'
+	@echo '        to adjust target desitantion, e.g. "make prefix=/usr/local install"'
+	@echo '  install          - build and install all headers, libraries and pkgconfig'
+	@echo '  install_headers  - install only headers to include/bpf'
+	@echo ''
+	@echo 'libbpf make targets:'
+	@echo '  tags    - use ctags to make tag information for source code browsing'
+	@echo '  cscope  - use cscope to make interactive source code browsing database'
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index a112e0ed1b19..7468978d3c27 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -409,8 +409,15 @@ LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf,
 				 __u32 *buf_len, __u32 *prog_id, __u32 *fd_type,
 				 __u64 *probe_offset, __u64 *probe_addr);
 
+#ifdef __cplusplus
+/* forward-declaring enums in C++ isn't compatible with pure C enums, so
+ * instead define bpf_enable_stats() as accepting int as an input
+ */
+LIBBPF_API int bpf_enable_stats(int type);
+#else
 enum bpf_stats_type; /* defined in up-to-date linux/bpf.h */
 LIBBPF_API int bpf_enable_stats(enum bpf_stats_type type);
+#endif
 
 struct bpf_prog_bind_opts {
 	size_t sz; /* size of this struct for forward/backward compatibility */
diff --git a/tools/lib/bpf/usdt.c b/tools/lib/bpf/usdt.c
index b8daae265f99..75b411fc2c77 100644
--- a/tools/lib/bpf/usdt.c
+++ b/tools/lib/bpf/usdt.c
@@ -1233,6 +1233,14 @@ static int parse_usdt_arg(const char *arg_str, int arg_num, struct usdt_arg_spec
 		if (reg_off < 0)
 			return reg_off;
 		arg->reg_off = reg_off;
+	} else if (sscanf(arg_str, " %d @ ( %%%15[^)] ) %n", &arg_sz, reg_name, &len) == 2) {
+		/* Memory dereference case without offset, e.g., 8@(%rsp) */
+		arg->arg_type = USDT_ARG_REG_DEREF;
+		arg->val_off = 0;
+		reg_off = calc_pt_regs_off(reg_name);
+		if (reg_off < 0)
+			return reg_off;
+		arg->reg_off = reg_off;
 	} else if (sscanf(arg_str, " %d @ %%%15s %n", &arg_sz, reg_name, &len) == 2) {
 		/* Register read case, e.g., -4@%eax */
 		arg->arg_type = USDT_ARG_REG;