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Commit e3f996c2 authored by Rusty Russell's avatar Rusty Russell Committed by Dave Jones
Browse files

[CPUFREQ] cpumask: avoid cpumask games in arch/x86/kernel/cpu/cpufreq/speedstep-centrino.c 



Impact: don't play with current's cpumask

It's generally a very bad idea to mug some process's cpumask: it could
legitimately and reasonably be changed by root, which could break us
(if done before our code) or them (if we restore the wrong value).

Use rdmsr_on_cpu and wrmsr_on_cpu instead.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
To: cpufreq@vger.kernel.org
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: default avatarDave Jones <davej@redhat.com>
parent 394122ab

arch/x86/kernel/cpu/cpufreq/speedstep-centrino.c

+17 −43
Original line number Diff line number Diff line
@@ -323,14 +323,8 @@ static unsigned int get_cur_freq(unsigned int cpu) 
{

	unsigned l, h;

	unsigned clock_freq;

	cpumask_t saved_mask;



	saved_mask = current->cpus_allowed;

	set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu));

	if (smp_processor_id() != cpu)

		return 0;



	rdmsr(MSR_IA32_PERF_STATUS, l, h);

	rdmsr_on_cpu(cpu, MSR_IA32_PERF_STATUS, &l, &h);

	clock_freq = extract_clock(l, cpu, 0);



	if (unlikely(clock_freq == 0)) {
@@ -340,11 +334,9 @@ static unsigned int get_cur_freq(unsigned int cpu) 
		 * P-state transition (like TM2). Get the last freq set 

		 * in PERF_CTL.

		 */

		rdmsr(MSR_IA32_PERF_CTL, l, h);

		rdmsr_on_cpu(cpu, MSR_IA32_PERF_CTL, &l, &h);

		clock_freq = extract_clock(l, cpu, 1);

	}



	set_cpus_allowed_ptr(current, &saved_mask);

	return clock_freq;

}
@@ -467,15 +459,10 @@ static int centrino_target (struct cpufreq_policy *policy, 
	struct cpufreq_freqs	freqs;

	int			retval = 0;

	unsigned int		j, k, first_cpu, tmp;

	cpumask_var_t saved_mask, covered_cpus;

	cpumask_var_t covered_cpus;



	if (unlikely(!alloc_cpumask_var(&saved_mask, GFP_KERNEL)))

	if (unlikely(!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL)))

		return -ENOMEM;

	if (unlikely(!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL))) {

		free_cpumask_var(saved_mask);

		return -ENOMEM;

	}

	cpumask_copy(saved_mask, &current->cpus_allowed);



	if (unlikely(per_cpu(centrino_model, cpu) == NULL)) {

		retval = -ENODEV;
@@ -493,7 +480,7 @@ static int centrino_target (struct cpufreq_policy *policy, 


	first_cpu = 1;

	for_each_cpu(j, policy->cpus) {

		const struct cpumask *mask;

		int good_cpu;



		/* cpufreq holds the hotplug lock, so we are safe here */

		if (!cpu_online(j))
@@ -504,32 +491,30 @@ static int centrino_target (struct cpufreq_policy *policy, 
		 * Make sure we are running on CPU that wants to change freq

		 */

		if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)

			mask = policy->cpus;

			good_cpu = cpumask_any_and(policy->cpus,

						   cpu_online_mask);

		else

			mask = cpumask_of(j);

			good_cpu = j;



		set_cpus_allowed_ptr(current, mask);

		preempt_disable();

		if (unlikely(!cpu_isset(smp_processor_id(), *mask))) {

		if (good_cpu >= nr_cpu_ids) {

			dprintk("couldn't limit to CPUs in this domain\n");

			retval = -EAGAIN;

			if (first_cpu) {

				/* We haven't started the transition yet. */

				goto migrate_end;

				goto out;

			}

			preempt_enable();

			break;

		}



		msr = per_cpu(centrino_model, cpu)->op_points[newstate].index;



		if (first_cpu) {

			rdmsr(MSR_IA32_PERF_CTL, oldmsr, h);

			rdmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, &oldmsr, &h);

			if (msr == (oldmsr & 0xffff)) {

				dprintk("no change needed - msr was and needs "

					"to be %x\n", oldmsr);

				retval = 0;

				goto migrate_end;

				goto out;

			}



			freqs.old = extract_clock(oldmsr, cpu, 0);
@@ -553,14 +538,11 @@ static int centrino_target (struct cpufreq_policy *policy, 
			oldmsr |= msr;

		}



		wrmsr(MSR_IA32_PERF_CTL, oldmsr, h);

		if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) {

			preempt_enable();

		wrmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, oldmsr, h);

		if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)

			break;

		}



		cpu_set(j, *covered_cpus);

		preempt_enable();

		cpumask_set_cpu(j, covered_cpus);

	}



	for_each_cpu(k, policy->cpus) {
@@ -578,10 +560,8 @@ static int centrino_target (struct cpufreq_policy *policy, 
		 * Best effort undo..

		 */



		for_each_cpu_mask_nr(j, *covered_cpus) {

			set_cpus_allowed_ptr(current, &cpumask_of_cpu(j));

			wrmsr(MSR_IA32_PERF_CTL, oldmsr, h);

		}

		for_each_cpu(j, covered_cpus)

			wrmsr_on_cpu(j, MSR_IA32_PERF_CTL, oldmsr, h);



		tmp = freqs.new;

		freqs.new = freqs.old;
@@ -593,15 +573,9 @@ static int centrino_target (struct cpufreq_policy *policy, 
			cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

		}

	}

	set_cpus_allowed_ptr(current, saved_mask);

	retval = 0;

	goto out;



migrate_end:

	preempt_enable();

	set_cpus_allowed_ptr(current, saved_mask);

out:

	free_cpumask_var(saved_mask);

	free_cpumask_var(covered_cpus);

	return retval;

}