perf tools: Refactor out kernel symbol argument sanity checking

User supplied values for vmlinux and kallsyms are checked before
continuing. Refactor this into a function so that it can be used
elsewhere.
Reviewed-by: NDenis Nikitin <denik@chromium.org>
Signed-off-by: NJames Clark <james.clark@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20211018134844.2627174-2-james.clark@arm.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-report.c

@@ -1378,18 +1378,9 @@ int cmd_report(int argc, const char **argv)
 	if (quiet)
 		perf_quiet_option();
 
-	if (symbol_conf.vmlinux_name &&
-	    access(symbol_conf.vmlinux_name, R_OK)) {
-		pr_err("Invalid file: %s\n", symbol_conf.vmlinux_name);
-		ret = -EINVAL;
-		goto exit;
-	}
-	if (symbol_conf.kallsyms_name &&
-	    access(symbol_conf.kallsyms_name, R_OK)) {
-		pr_err("Invalid file: %s\n", symbol_conf.kallsyms_name);
-		ret = -EINVAL;
+	ret = symbol__validate_sym_arguments();
+	if (ret)
 		goto exit;
-	}
 
 	if (report.inverted_callchain)
 		callchain_param.order = ORDER_CALLER;

tools/perf/util/symbol.c

@@ -2634,3 +2634,25 @@ struct mem_info *mem_info__new(void)
 		refcount_set(&mi->refcnt, 1);
 	return mi;
 }
+
+/*
+ * Checks that user supplied symbol kernel files are accessible because
+ * the default mechanism for accessing elf files fails silently. i.e. if
+ * debug syms for a build ID aren't found perf carries on normally. When
+ * they are user supplied we should assume that the user doesn't want to
+ * silently fail.
+ */
+int symbol__validate_sym_arguments(void)
+{
+	if (symbol_conf.vmlinux_name &&
+	    access(symbol_conf.vmlinux_name, R_OK)) {
+		pr_err("Invalid file: %s\n", symbol_conf.vmlinux_name);
+		return -EINVAL;
+	}
+	if (symbol_conf.kallsyms_name &&
+	    access(symbol_conf.kallsyms_name, R_OK)) {
+		pr_err("Invalid file: %s\n", symbol_conf.kallsyms_name);
+		return -EINVAL;
+	}
+	return 0;
+}

tools/perf/util/symbol.h

@@ -286,4 +286,6 @@ static inline void __mem_info__zput(struct mem_info **mi)
 
 #define mem_info__zput(mi) __mem_info__zput(&mi)
 
+int symbol__validate_sym_arguments(void);
+
 #endif /* __PERF_SYMBOL */