From 1e4f63aecb53e48468661e922fc2fa3b83e55722 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Sun, 26 Jan 2020 23:40:11 +0100 Subject: cpufreq: Avoid creating excessively large stack frames In the process of modifying a cpufreq policy, the cpufreq core makes a copy of it including all of the internals which is stored on the CPU stack. Because struct cpufreq_policy is relatively large, this may cause the size of the stack frame to exceed the 2 KB limit and so the GCC complains when -Wframe-larger-than= is used. In fact, it is not necessary to copy the entire policy structure in order to modify it, however. First, because cpufreq_set_policy() obtains the min and max policy limits from frequency QoS now, it is not necessary to pass the limits to it from the callers. The only things that need to be passed to it from there are the new governor pointer or (if there is a built-in governor in the driver) the "policy" value representing the governor choice. They both can be passed as individual arguments, though, so make cpufreq_set_policy() take them this way and rework its callers accordingly. This avoids making copies of cpufreq policies in the callers of cpufreq_set_policy(). Second, cpufreq_set_policy() still needs to pass the new policy data to the ->verify() callback of the cpufreq driver whose task is to sanitize the min and max policy limits. It still does not need to make a full copy of struct cpufreq_policy for this purpose, but it needs to pass a few items from it to the driver in case they are needed (different drivers have different needs in that respect and all of them have to be covered). For this reason, introduce struct cpufreq_policy_data to hold copies of the members of struct cpufreq_policy used by the existing ->verify() driver callbacks and pass a pointer to a temporary structure of that type to ->verify() (instead of passing a pointer to full struct cpufreq_policy to it). While at it, notice that intel_pstate and longrun don't really need to verify the "policy" value in struct cpufreq_policy, so drop those check from them to avoid copying "policy" into struct cpufreq_policy_data (which allows it to be slightly smaller). Also while at it fix up white space in a couple of places and make cpufreq_set_policy() static (as it can be so). Fixes: 3000ce3c52f8 ("cpufreq: Use per-policy frequency QoS") Link: https://lore.kernel.org/linux-pm/CAMuHMdX6-jb1W8uC2_237m8ctCpsnGp=JCxqt8pCWVqNXHmkVg@mail.gmail.com Reported-by: kbuild test robot Reported-by: Geert Uytterhoeven Cc: 5.4+ # 5.4+ Signed-off-by: Rafael J. Wysocki Acked-by: Viresh Kumar --- drivers/cpufreq/cpufreq.c | 147 ++++++++++++++++++++++------------------------ 1 file changed, 70 insertions(+), 77 deletions(-) (limited to 'drivers/cpufreq/cpufreq.c') diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 77114a3897fb..4adac3a8c265 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -74,6 +74,9 @@ static void cpufreq_exit_governor(struct cpufreq_policy *policy); static int cpufreq_start_governor(struct cpufreq_policy *policy); static void cpufreq_stop_governor(struct cpufreq_policy *policy); static void cpufreq_governor_limits(struct cpufreq_policy *policy); +static int cpufreq_set_policy(struct cpufreq_policy *policy, + struct cpufreq_governor *new_gov, + unsigned int new_pol); /** * Two notifier lists: the "policy" list is involved in the @@ -616,25 +619,22 @@ static struct cpufreq_governor *find_governor(const char *str_governor) return NULL; } -static int cpufreq_parse_policy(char *str_governor, - struct cpufreq_policy *policy) +static unsigned int cpufreq_parse_policy(char *str_governor) { - if (!strncasecmp(str_governor, "performance", CPUFREQ_NAME_LEN)) { - policy->policy = CPUFREQ_POLICY_PERFORMANCE; - return 0; - } - if (!strncasecmp(str_governor, "powersave", CPUFREQ_NAME_LEN)) { - policy->policy = CPUFREQ_POLICY_POWERSAVE; - return 0; - } - return -EINVAL; + if (!strncasecmp(str_governor, "performance", CPUFREQ_NAME_LEN)) + return CPUFREQ_POLICY_PERFORMANCE; + + if (!strncasecmp(str_governor, "powersave", CPUFREQ_NAME_LEN)) + return CPUFREQ_POLICY_POWERSAVE; + + return CPUFREQ_POLICY_UNKNOWN; } /** * cpufreq_parse_governor - parse a governor string only for has_target() + * @str_governor: Governor name. */ -static int cpufreq_parse_governor(char *str_governor, - struct cpufreq_policy *policy) +static struct cpufreq_governor *cpufreq_parse_governor(char *str_governor) { struct cpufreq_governor *t; @@ -648,7 +648,7 @@ static int cpufreq_parse_governor(char *str_governor, ret = request_module("cpufreq_%s", str_governor); if (ret) - return -EINVAL; + return NULL; mutex_lock(&cpufreq_governor_mutex); @@ -659,12 +659,7 @@ static int cpufreq_parse_governor(char *str_governor, mutex_unlock(&cpufreq_governor_mutex); - if (t) { - policy->governor = t; - return 0; - } - - return -EINVAL; + return t; } /** @@ -765,28 +760,33 @@ static ssize_t show_scaling_governor(struct cpufreq_policy *policy, char *buf) static ssize_t store_scaling_governor(struct cpufreq_policy *policy, const char *buf, size_t count) { + char str_governor[16]; int ret; - char str_governor[16]; - struct cpufreq_policy new_policy; - - memcpy(&new_policy, policy, sizeof(*policy)); ret = sscanf(buf, "%15s", str_governor); if (ret != 1) return -EINVAL; if (cpufreq_driver->setpolicy) { - if (cpufreq_parse_policy(str_governor, &new_policy)) + unsigned int new_pol; + + new_pol = cpufreq_parse_policy(str_governor); + if (!new_pol) return -EINVAL; + + ret = cpufreq_set_policy(policy, NULL, new_pol); } else { - if (cpufreq_parse_governor(str_governor, &new_policy)) + struct cpufreq_governor *new_gov; + + new_gov = cpufreq_parse_governor(str_governor); + if (!new_gov) return -EINVAL; - } - ret = cpufreq_set_policy(policy, &new_policy); + ret = cpufreq_set_policy(policy, new_gov, + CPUFREQ_POLICY_UNKNOWN); - if (new_policy.governor) - module_put(new_policy.governor->owner); + module_put(new_gov->owner); + } return ret ? ret : count; } @@ -1053,40 +1053,33 @@ __weak struct cpufreq_governor *cpufreq_default_governor(void) static int cpufreq_init_policy(struct cpufreq_policy *policy) { - struct cpufreq_governor *gov = NULL, *def_gov = NULL; - struct cpufreq_policy new_policy; - - memcpy(&new_policy, policy, sizeof(*policy)); - - def_gov = cpufreq_default_governor(); + struct cpufreq_governor *def_gov = cpufreq_default_governor(); + struct cpufreq_governor *gov = NULL; + unsigned int pol = CPUFREQ_POLICY_UNKNOWN; if (has_target()) { - /* - * Update governor of new_policy to the governor used before - * hotplug - */ + /* Update policy governor to the one used before hotplug. */ gov = find_governor(policy->last_governor); if (gov) { pr_debug("Restoring governor %s for cpu %d\n", - policy->governor->name, policy->cpu); - } else { - if (!def_gov) - return -ENODATA; + policy->governor->name, policy->cpu); + } else if (def_gov) { gov = def_gov; + } else { + return -ENODATA; } - new_policy.governor = gov; } else { /* Use the default policy if there is no last_policy. */ if (policy->last_policy) { - new_policy.policy = policy->last_policy; + pol = policy->last_policy; + } else if (def_gov) { + pol = cpufreq_parse_policy(def_gov->name); } else { - if (!def_gov) - return -ENODATA; - cpufreq_parse_policy(def_gov->name, &new_policy); + return -ENODATA; } } - return cpufreq_set_policy(policy, &new_policy); + return cpufreq_set_policy(policy, gov, pol); } static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu) @@ -1114,13 +1107,10 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp void refresh_frequency_limits(struct cpufreq_policy *policy) { - struct cpufreq_policy new_policy; - if (!policy_is_inactive(policy)) { - new_policy = *policy; pr_debug("updating policy for CPU %u\n", policy->cpu); - cpufreq_set_policy(policy, &new_policy); + cpufreq_set_policy(policy, policy->governor, policy->policy); } } EXPORT_SYMBOL(refresh_frequency_limits); @@ -2364,46 +2354,49 @@ EXPORT_SYMBOL(cpufreq_get_policy); /** * cpufreq_set_policy - Modify cpufreq policy parameters. * @policy: Policy object to modify. - * @new_policy: New policy data. + * @new_gov: Policy governor pointer. + * @new_pol: Policy value (for drivers with built-in governors). * - * Pass @new_policy to the cpufreq driver's ->verify() callback. Next, copy the - * min and max parameters of @new_policy to @policy and either invoke the - * driver's ->setpolicy() callback (if present) or carry out a governor update - * for @policy. That is, run the current governor's ->limits() callback (if the - * governor field in @new_policy points to the same object as the one in - * @policy) or replace the governor for @policy with the new one stored in - * @new_policy. + * Invoke the cpufreq driver's ->verify() callback to sanity-check the frequency + * limits to be set for the policy, update @policy with the verified limits + * values and either invoke the driver's ->setpolicy() callback (if present) or + * carry out a governor update for @policy. That is, run the current governor's + * ->limits() callback (if @new_gov points to the same object as the one in + * @policy) or replace the governor for @policy with @new_gov. * * The cpuinfo part of @policy is not updated by this function. */ -int cpufreq_set_policy(struct cpufreq_policy *policy, - struct cpufreq_policy *new_policy) +static int cpufreq_set_policy(struct cpufreq_policy *policy, + struct cpufreq_governor *new_gov, + unsigned int new_pol) { + struct cpufreq_policy_data new_data; struct cpufreq_governor *old_gov; int ret; - pr_debug("setting new policy for CPU %u: %u - %u kHz\n", - new_policy->cpu, new_policy->min, new_policy->max); - - memcpy(&new_policy->cpuinfo, &policy->cpuinfo, sizeof(policy->cpuinfo)); - + memcpy(&new_data.cpuinfo, &policy->cpuinfo, sizeof(policy->cpuinfo)); + new_data.freq_table = policy->freq_table; + new_data.cpu = policy->cpu; /* * PM QoS framework collects all the requests from users and provide us * the final aggregated value here. */ - new_policy->min = freq_qos_read_value(&policy->constraints, FREQ_QOS_MIN); - new_policy->max = freq_qos_read_value(&policy->constraints, FREQ_QOS_MAX); + new_data.min = freq_qos_read_value(&policy->constraints, FREQ_QOS_MIN); + new_data.max = freq_qos_read_value(&policy->constraints, FREQ_QOS_MAX); + + pr_debug("setting new policy for CPU %u: %u - %u kHz\n", + new_data.cpu, new_data.min, new_data.max); /* * Verify that the CPU speed can be set within these limits and make sure * that min <= max. */ - ret = cpufreq_driver->verify(new_policy); + ret = cpufreq_driver->verify(&new_data); if (ret) return ret; - policy->min = new_policy->min; - policy->max = new_policy->max; + policy->min = new_data.min; + policy->max = new_data.max; trace_cpu_frequency_limits(policy); policy->cached_target_freq = UINT_MAX; @@ -2412,12 +2405,12 @@ int cpufreq_set_policy(struct cpufreq_policy *policy, policy->min, policy->max); if (cpufreq_driver->setpolicy) { - policy->policy = new_policy->policy; + policy->policy = new_pol; pr_debug("setting range\n"); return cpufreq_driver->setpolicy(policy); } - if (new_policy->governor == policy->governor) { + if (new_gov == policy->governor) { pr_debug("governor limits update\n"); cpufreq_governor_limits(policy); return 0; @@ -2434,7 +2427,7 @@ int cpufreq_set_policy(struct cpufreq_policy *policy, } /* start new governor */ - policy->governor = new_policy->governor; + policy->governor = new_gov; ret = cpufreq_init_governor(policy); if (!ret) { ret = cpufreq_start_governor(policy); -- cgit v1.2.3