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Commit db59504d authored by Li Zefan's avatar Li Zefan Committed by Ingo Molnar
Browse files

ksym_tracer: Extract trace entry from struct trace_ksym 



struct trace_ksym is used as an entry in hbp list, and is also
used as trace_entry stored in ring buffer.

This is not necessary and is a waste of memory in ring buffer.

There is also a bug that dereferencing field->ksym_hbp in
ksym_trace_output() can be invalid.

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: "K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A52E2A4.4050007@cn.fujitsu.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 9d22b536

kernel/trace/trace.h

+4 −9
Original line number Diff line number Diff line
@@ -215,17 +215,12 @@ struct syscall_trace_exit { 
#define KSYM_SELFTEST_ENTRY "ksym_selftest_dummy"

extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr);



struct trace_ksym {

struct ksym_trace_entry {

	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;

	unsigned char		type;

	char			ksym_name[KSYM_NAME_LEN];

	char			p_name[TASK_COMM_LEN];

	char			cmd[TASK_COMM_LEN];

};



/*
@@ -343,7 +338,7 @@ extern void __ftrace_bad_type(void); 
			  TRACE_SYSCALL_ENTER);				\

		IF_ASSIGN(var, ent, struct syscall_trace_exit,		\

			  TRACE_SYSCALL_EXIT);				\

		IF_ASSIGN(var, ent, struct trace_ksym, TRACE_KSYM);	\

		IF_ASSIGN(var, ent, struct ksym_trace_entry, TRACE_KSYM);\

		__ftrace_bad_type();					\

	} while (0)

kernel/trace/trace_ksym.c

+18 −8
Original line number Diff line number Diff line
@@ -37,6 +37,15 @@ 
#define KSYM_TRACER_OP_LEN 3 /* rw- */

#define KSYM_FILTER_ENTRY_LEN (KSYM_NAME_LEN + KSYM_TRACER_OP_LEN + 1)



struct trace_ksym {

	struct hw_breakpoint	*ksym_hbp;

	unsigned long		ksym_addr;

#ifdef CONFIG_PROFILE_KSYM_TRACER

	unsigned long		counter;

#endif

	struct hlist_node	ksym_hlist;

};



static struct trace_array *ksym_trace_array;



static unsigned int ksym_filter_entry_count;
@@ -71,7 +80,7 @@ void ksym_hbp_handler(struct hw_breakpoint *hbp, struct pt_regs *regs) 
{

	struct ring_buffer_event *event;

	struct trace_array *tr;

	struct trace_ksym *entry;

	struct ksym_trace_entry *entry;

	int pc;



	if (!ksym_tracing_enabled)
@@ -86,10 +95,11 @@ void ksym_hbp_handler(struct hw_breakpoint *hbp, struct pt_regs *regs) 
		return;



	entry		= ring_buffer_event_data(event);

	strlcpy(entry->ksym_name, hbp->info.name, KSYM_SYMBOL_LEN);

	entry->ksym_hbp = hbp;

	entry->ip	= instruction_pointer(regs);

	strlcpy(entry->p_name, current->comm, TASK_COMM_LEN);

	entry->type	= hbp->info.type;

	strlcpy(entry->ksym_name, hbp->info.name, KSYM_SYMBOL_LEN);

	strlcpy(entry->cmd, current->comm, TASK_COMM_LEN);



#ifdef CONFIG_PROFILE_KSYM_TRACER

	ksym_collect_stats(hbp->info.address);

#endif /* CONFIG_PROFILE_KSYM_TRACER */
@@ -380,7 +390,7 @@ static enum print_line_t ksym_trace_output(struct trace_iterator *iter) 
{

	struct trace_entry *entry = iter->ent;

	struct trace_seq *s = &iter->seq;

	struct trace_ksym *field;

	struct ksym_trace_entry *field;

	char str[KSYM_SYMBOL_LEN];

	int ret;
@@ -389,12 +399,12 @@ static enum print_line_t ksym_trace_output(struct trace_iterator *iter) 


	trace_assign_type(field, entry);



	ret = trace_seq_printf(s, "%-15s %-5d %-3d %-20s ", field->p_name,

	ret = trace_seq_printf(s, "%-15s %-5d %-3d %-20s ", field->cmd,

				entry->pid, iter->cpu, field->ksym_name);

	if (!ret)

		return TRACE_TYPE_PARTIAL_LINE;



	switch (field->ksym_hbp->info.type) {

	switch (field->type) {

	case HW_BREAKPOINT_WRITE:

		ret = trace_seq_printf(s, " W  ");

		break;