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[ARM] latencytop support

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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: Nicolas Pitre <nico@marvell.com>
Tested-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
This commit is contained in:
Nicolas Pitre 2008-04-24 01:31:46 -04:00 committed by Lennert Buytenhek
parent b0bfcce930
commit f76e915473
2 changed files with 35 additions and 4 deletions
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5
arch/arm/Kconfig
View File

@ -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

34
arch/arm/kernel/stacktrace.c
View File

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