perf llvm: Return -ENOMEM when asprintf() fails

Zhihao sent a patch but it made llvm__compile_bpf() return what
asprintf() returns on error, which is just -1, but since this function
returns -errno, fix it by returning -ENOMEM for this case instead.

Fixes: cb76371441 ("perf llvm: Allow passing options to llc ...")
Fixes: 5eab5a7ee0 ("perf llvm: Display eBPF compiling command ...")
Reported-by: Hulk Robot <hulkci@huawei.com>
Reported-by: Zhihao Cheng <chengzhihao1@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Yu Kuai <yukuai3@huawei.com>
Cc: clang-built-linux@googlegroups.com
Link: http://lore.kernel.org/lkml/20210609115945.2193194-1-chengzhihao1@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/llvm-utils.c

@@ -504,6 +504,7 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
 			goto errout;
 		}
 
+		err = -ENOMEM;
 		if (asprintf(&pipe_template, "%s -emit-llvm | %s -march=bpf %s -filetype=obj -o -",
 			      template, llc_path, opts) < 0) {
 			pr_err("ERROR:\tnot enough memory to setup command line\n");
@@ -524,6 +525,7 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
 
 	pr_debug("llvm compiling command template: %s\n", template);
 
+	err = -ENOMEM;
 	if (asprintf(&command_echo, "echo -n \"%s\"", template) < 0)
 		goto errout;