tracing: Show address when function names are not found

Currently, when a function is not found in kallsyms, instead of simply showing the function address, it shows nothing at all: # echo ':mod:kvm_intel' > /sys/kernel/tracing/set_ftrace_filter # echo function > /sys/kernel/tracing/set_ftrace_filter # qemu -enable-kvm /home/my-qemu-image <Ctrl-C> # rmmod kvm_intel # cat /sys/kernel/tracing/trace qemu-system-x86-2408 [001] d..2 135.013238: <-kvm_arch_hardware_enable qemu-system-x86-2408 [001] .... 135.014574: <-kvm_arch_vm_ioctl qemu-system-x86-2408 [001] .... 135.015420: <-kvm_vm_ioctl_check_extension qemu-system-x86-2408 [001] .... 135.045411: <-__do_cpuid_ent qemu-system-x86-2408 [001] .... 135.045412: <-__do_cpuid_ent qemu-system-x86-2408 [001] .... 135.045412: <-__do_cpuid_ent qemu-system-x86-2408 [001] .... 135.045412: <-__do_cpuid_ent qemu-system-x86-2408 [001] ...1 135.045413: <-__do_cpuid_ent qemu-system-x86-2408 [001] .... 135.045413: <-__do_cpuid_ent When it should show: qemu-system-x86-2408 [001] d..2 135.013238: 0xffffffffa02a39f0 <-kvm_arch_hardware_enable qemu-system-x86-2408 [001] .... 135.014574: 0xffffffffa02a2ba0 <-kvm_arch_vm_ioctl qemu-system-x86-2408 [001] .... 135.015420: 0xffffffffa029e4e0 <-kvm_vm_ioctl_check_extension qemu-system-x86-2408 [001] .... 135.045411: 0xffffffffa02a1380 <-__do_cpuid_ent qemu-system-x86-2408 [001] .... 135.045412: 0xffffffffa029e160 <-__do_cpuid_ent qemu-system-x86-2408 [001] .... 135.045412: 0xffffffffa029e180 <-__do_cpuid_ent qemu-system-x86-2408 [001] .... 135.045412: 0xffffffffa029e520 <-__do_cpuid_ent qemu-system-x86-2408 [001] ...1 135.045413: 0xffffffffa02a13b0 <-__do_cpuid_ent qemu-system-x86-2408 [001] .... 135.045413: 0xffffffffa02a1380 <-__do_cpuid_ent instead. Signed-off-by: Steven Rostedt (VMware) <[email protected]>
CamonZ · Jun 22, 2017 · feaf128 · feaf128
1 parent d0ba52f
commit feaf128
Showing 1 changed file with 14 additions and 4 deletions.
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
@@ -340,31 +340,41 @@ static inline const char *kretprobed(const char *name)
 static void
 seq_print_sym_short(struct trace_seq *s, const char *fmt, unsigned long address)
 {
-#ifdef CONFIG_KALLSYMS
 	char str[KSYM_SYMBOL_LEN];
+#ifdef CONFIG_KALLSYMS
 	const char *name;
 
 	kallsyms_lookup(address, NULL, NULL, NULL, str);
 
 	name = kretprobed(str);
 
-	trace_seq_printf(s, fmt, name);
+	if (name && strlen(name)) {
+		trace_seq_printf(s, fmt, name);
+		return;
+	}
 #endif
+	snprintf(str, KSYM_SYMBOL_LEN, "0x%08lx", address);
+	trace_seq_printf(s, fmt, str);
 }
 
 static void
 seq_print_sym_offset(struct trace_seq *s, const char *fmt,
 		     unsigned long address)
 {
-#ifdef CONFIG_KALLSYMS
 	char str[KSYM_SYMBOL_LEN];
+#ifdef CONFIG_KALLSYMS
 	const char *name;
 
 	sprint_symbol(str, address);
 	name = kretprobed(str);
 
-	trace_seq_printf(s, fmt, name);
+	if (name && strlen(name)) {
+		trace_seq_printf(s, fmt, name);
+		return;
+	}
 #endif
+	snprintf(str, KSYM_SYMBOL_LEN, "0x%08lx", address);
+	trace_seq_printf(s, fmt, str);
 }
 
 #ifndef CONFIG_64BIT