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Commit f76e9154 authored by Nicolas Pitre's avatar Nicolas Pitre Committed by Lennert Buytenhek
Browse files

[ARM] latencytop support 



Available for !SMP only at the moment.

From Russell:

|Basically, if a thread is running on a CPU, thread_saved_fp() is invalid.
|So, the question is: what guarantees do we have here that 'tsk' is not
|running on another CPU?

Signed-off-by: default avatarNicolas Pitre <nico@marvell.com>
Tested-by: default avatarLennert Buytenhek <buytenh@marvell.com>
Signed-off-by: default avatarLennert Buytenhek <buytenh@marvell.com>
parent b0bfcce9

arch/arm/Kconfig

+5 −0
Original line number Diff line number Diff line
@@ -84,6 +84,11 @@ config STACKTRACE_SUPPORT 
	bool

	default y



config HAVE_LATENCYTOP_SUPPORT

	bool

	depends on !SMP

	default y



config LOCKDEP_SUPPORT

	bool

	default y

arch/arm/kernel/stacktrace.c

+30 −4
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ EXPORT_SYMBOL(walk_stackframe); 
#ifdef CONFIG_STACKTRACE

struct stack_trace_data {

	struct stack_trace *trace;

	unsigned int no_sched_functions;

	unsigned int skip;

};
@@ -43,27 +44,52 @@ static int save_trace(struct stackframe *frame, void *d) 
{

	struct stack_trace_data *data = d;

	struct stack_trace *trace = data->trace;

	unsigned long addr = frame->lr;



	if (data->no_sched_functions && in_sched_functions(addr))

		return 0;

	if (data->skip) {

		data->skip--;

		return 0;

	}



	trace->entries[trace->nr_entries++] = frame->lr;

	trace->entries[trace->nr_entries++] = addr;



	return trace->nr_entries >= trace->max_entries;

}



void save_stack_trace(struct stack_trace *trace)

void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)

{

	struct stack_trace_data data;

	unsigned long fp, base;



	data.trace = trace;

	data.skip = trace->skip;

	base = (unsigned long)task_stack_page(current);

	base = (unsigned long)task_stack_page(tsk);



	if (tsk != current) {

#ifdef CONFIG_SMP

		/*

		 * What guarantees do we have here that 'tsk'

		 * is not running on another CPU?

		 */

		BUG();

#else

		data.no_sched_functions = 1;

		fp = thread_saved_fp(tsk);

#endif

	} else {

		data.no_sched_functions = 0;

		asm("mov %0, fp" : "=r" (fp));

	}



	walk_stackframe(fp, base, base + THREAD_SIZE, save_trace, &data);

	if (trace->nr_entries < trace->max_entries)

		trace->entries[trace->nr_entries++] = ULONG_MAX;

}



void save_stack_trace(struct stack_trace *trace)

{

	save_stack_trace_tsk(current, trace);

}

#endif