hw-breakpoints: ftrace plugin for kernel symbol tracing using HW Breakpoint interfaces
This patch adds an ftrace plugin to detect and profile memory access over kernel
variables. It uses HW Breakpoint interfaces to 'watch memory addresses.
Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 6e735d4..7d5cc37 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -15,6 +15,10 @@
#include <linux/trace_seq.h>
#include <linux/ftrace_event.h>
+#ifdef CONFIG_KSYM_TRACER
+#include <asm/hw_breakpoint.h>
+#endif
+
enum trace_type {
__TRACE_FIRST_TYPE = 0,
@@ -40,6 +44,7 @@
TRACE_KMEM_FREE,
TRACE_POWER,
TRACE_BLK,
+ TRACE_KSYM,
__TRACE_LAST_TYPE,
};
@@ -207,6 +212,21 @@
unsigned long ret;
};
+#define KSYM_SELFTEST_ENTRY "ksym_selftest_dummy"
+extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr);
+
+struct trace_ksym {
+ struct trace_entry ent;
+ struct hw_breakpoint *ksym_hbp;
+ unsigned long ksym_addr;
+ unsigned long ip;
+#ifdef CONFIG_PROFILE_KSYM_TRACER
+ unsigned long counter;
+#endif
+ struct hlist_node ksym_hlist;
+ char ksym_name[KSYM_NAME_LEN];
+ char p_name[TASK_COMM_LEN];
+};
/*
* trace_flag_type is an enumeration that holds different
@@ -323,6 +343,7 @@
TRACE_SYSCALL_ENTER); \
IF_ASSIGN(var, ent, struct syscall_trace_exit, \
TRACE_SYSCALL_EXIT); \
+ IF_ASSIGN(var, ent, struct trace_ksym, TRACE_KSYM); \
__ftrace_bad_type(); \
} while (0)
@@ -540,6 +561,8 @@
struct trace_array *tr);
extern int trace_selftest_startup_hw_branches(struct tracer *trace,
struct trace_array *tr);
+extern int trace_selftest_startup_ksym(struct tracer *trace,
+ struct trace_array *tr);
#endif /* CONFIG_FTRACE_STARTUP_TEST */
extern void *head_page(struct trace_array_cpu *data);