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authorSteven Rostedt <rostedt@goodmis.org>2008-10-01 10:52:51 -0400
committerIngo Molnar <mingo@elte.hu>2008-10-14 10:39:07 +0200
commit7104f300c5a69b46dda00d898034dd05c9f21739 (patch)
treea8c885bd61fb1e269f277837b2e521179faf8739 /kernel/trace/trace.h
parent797d3712a9dd75c720558612be05f42c031a7bb5 (diff)
ftrace: type cast filter+verifier
The mmiotrace map had a bug that would typecast the entry from the trace to the wrong type. That is a known danger of C typecasts, there's absolutely zero checking done on them. Help that problem a bit by using a GCC extension to implement a type filter that restricts the types that a trace record can be cast into, and by adding a dynamic check (in debug mode) to verify the type of the entry. This patch adds a macro to assign all entries of ftrace using the type of the variable and checking the entry id. The typecasts are now done in the macro for only those types that it knows about, which should be all the types that are allowed to be read from the tracer. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace/trace.h')
-rw-r--r--kernel/trace/trace.h42
1 files changed, 42 insertions, 0 deletions
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index a921ba5d292..f02042d0d82 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -177,6 +177,48 @@ struct trace_array {
struct trace_array_cpu *data[NR_CPUS];
};
+#define FTRACE_CMP_TYPE(var, type) \
+ __builtin_types_compatible_p(typeof(var), type *)
+
+#undef IF_ASSIGN
+#define IF_ASSIGN(var, entry, etype, id) \
+ if (FTRACE_CMP_TYPE(var, etype)) { \
+ var = (typeof(var))(entry); \
+ WARN_ON(id && (entry)->type != id); \
+ break; \
+ }
+
+/* Will cause compile errors if type is not found. */
+extern void __ftrace_bad_type(void);
+
+/*
+ * The trace_assign_type is a verifier that the entry type is
+ * the same as the type being assigned. To add new types simply
+ * add a line with the following format:
+ *
+ * IF_ASSIGN(var, ent, type, id);
+ *
+ * Where "type" is the trace type that includes the trace_entry
+ * as the "ent" item. And "id" is the trace identifier that is
+ * used in the trace_type enum.
+ *
+ * If the type can have more than one id, then use zero.
+ */
+#define trace_assign_type(var, ent) \
+ do { \
+ IF_ASSIGN(var, ent, struct ftrace_entry, TRACE_FN); \
+ IF_ASSIGN(var, ent, struct ctx_switch_entry, 0); \
+ IF_ASSIGN(var, ent, struct trace_field_cont, TRACE_CONT); \
+ IF_ASSIGN(var, ent, struct stack_entry, TRACE_STACK); \
+ IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT); \
+ IF_ASSIGN(var, ent, struct special_entry, 0); \
+ IF_ASSIGN(var, ent, struct trace_mmiotrace_rw, \
+ TRACE_MMIO_RW); \
+ IF_ASSIGN(var, ent, struct trace_mmiotrace_map, \
+ TRACE_MMIO_MAP); \
+ IF_ASSIGN(var, ent, struct trace_boot, TRACE_BOOT); \
+ __ftrace_bad_type(); \
+ } while (0)
/* Return values for print_line callback */
enum print_line_t {