* Re: [PATCH] cpufreq: amd-pstate: avoid uninitialized variable use
2023-02-07 16:12 [PATCH] cpufreq: amd-pstate: avoid uninitialized variable use Arnd Bergmann
@ 2023-02-08 14:28 ` Wyes Karny
2023-02-09 2:02 ` Yuan, Perry
` (2 subsequent siblings)
3 siblings, 0 replies; 6+ messages in thread
From: Wyes Karny @ 2023-02-08 14:28 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Huang Rui, Rafael J. Wysocki, Viresh Kumar, Perry Yuan,
Mario Limonciello, Arnd Bergmann, Jinzhou Su, Meng Li, linux-pm,
linux-kernel
On 07 Feb 17:12, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> The new epp support causes warnings about three separate
> but related bugs:
>
> 1) failing before allocation should just return an error:
>
> drivers/cpufreq/amd-pstate.c:951:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (!dev)
> ^~~~
> drivers/cpufreq/amd-pstate.c:1018:9: note: uninitialized use occurs here
> return ret;
> ^~~
>
> 2) wrong variable to store return code:
>
> drivers/cpufreq/amd-pstate.c:963:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (rc)
> ^~
> drivers/cpufreq/amd-pstate.c:1019:9: note: uninitialized use occurs here
> return ret;
> ^~~
> drivers/cpufreq/amd-pstate.c:963:2: note: remove the 'if' if its condition is always false
> if (rc)
> ^~~~~~~
>
> 3) calling amd_pstate_set_epp() in cleanup path after determining
> that it should not be called:
>
> drivers/cpufreq/amd-pstate.c:1055:6: error: variable 'epp' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (cpudata->epp_policy == cpudata->policy)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/cpufreq/amd-pstate.c:1080:30: note: uninitialized use occurs here
> amd_pstate_set_epp(cpudata, epp);
> ^~~
>
> All three are trivial to fix, but most likely there are additional bugs
> in this function when the error handling was not really tested.
>
> Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> drivers/cpufreq/amd-pstate.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 168a28bed6ee..847f5f31396d 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -940,7 +940,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> struct amd_cpudata *cpudata;
> struct device *dev;
> - int rc;
> u64 value;
>
> /*
> @@ -950,7 +949,7 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> amd_perf_ctl_reset(policy->cpu);
> dev = get_cpu_device(policy->cpu);
> if (!dev)
> - goto free_cpudata1;
> + return -ENODEV;
>
> cpudata = kzalloc(sizeof(*cpudata), GFP_KERNEL);
> if (!cpudata)
> @@ -959,8 +958,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> cpudata->cpu = policy->cpu;
> cpudata->epp_policy = 0;
>
> - rc = amd_pstate_init_perf(cpudata);
> - if (rc)
> + ret = amd_pstate_init_perf(cpudata);
> + if (ret)
> goto free_cpudata1;
>
> min_freq = amd_get_min_freq(cpudata);
> @@ -1076,9 +1075,9 @@ static void amd_pstate_epp_init(unsigned int cpu)
> value |= (u64)epp << 24;
> }
>
> + amd_pstate_set_epp(cpudata, epp);
> skip_epp:
> WRITE_ONCE(cpudata->cppc_req_cached, value);
> - amd_pstate_set_epp(cpudata, epp);
> cpufreq_cpu_put(policy);
> }
>
Tested this on AMD Milan (Zen 3) system.
Tested-by: Wyes Karny <wyes.karny@amd.com>
> --
> 2.39.1
>
^ permalink raw reply [flat|nested] 6+ messages in thread* RE: [PATCH] cpufreq: amd-pstate: avoid uninitialized variable use
2023-02-07 16:12 [PATCH] cpufreq: amd-pstate: avoid uninitialized variable use Arnd Bergmann
2023-02-08 14:28 ` Wyes Karny
@ 2023-02-09 2:02 ` Yuan, Perry
2023-02-09 5:03 ` Huang Rui
2023-02-09 9:58 ` Wyes Karny
3 siblings, 0 replies; 6+ messages in thread
From: Yuan, Perry @ 2023-02-09 2:02 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Huang, Ray, Rafael J. Wysocki, Viresh Kumar, Karny, Wyes,
Limonciello, Mario, Meng, Li (Jassmine), linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org, arnd@arndb.de
[AMD Official Use Only - General]
Hi Arnd,
> -----Original Message-----
> From: Arnd Bergmann <arnd@kernel.org>
> Sent: Wednesday, February 8, 2023 12:13 AM
> To: Huang, Ray <Ray.Huang@amd.com>; Rafael J. Wysocki
> <rafael@kernel.org>; Viresh Kumar <viresh.kumar@linaro.org>; Karny, Wyes
> <Wyes.Karny@amd.com>; Yuan, Perry <Perry.Yuan@amd.com>; Limonciello,
> Mario <Mario.Limonciello@amd.com>
> Cc: Arnd Bergmann <arnd@arndb.de>; Yuan, Perry <Perry.Yuan@amd.com>;
> Limonciello, Mario <Mario.Limonciello@amd.com>; Jinzhou Su
> <Jinzhou.Su@amd.com>; Meng, Li (Jassmine) <Li.Meng@amd.com>; linux-
> pm@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: [PATCH] cpufreq: amd-pstate: avoid uninitialized variable use
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> The new epp support causes warnings about three separate but related bugs:
>
> 1) failing before allocation should just return an error:
>
> drivers/cpufreq/amd-pstate.c:951:6: error: variable 'ret' is used uninitialized
> whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (!dev)
> ^~~~
> drivers/cpufreq/amd-pstate.c:1018:9: note: uninitialized use occurs here
> return ret;
> ^~~
>
> 2) wrong variable to store return code:
>
> drivers/cpufreq/amd-pstate.c:963:6: error: variable 'ret' is used uninitialized
> whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (rc)
> ^~
> drivers/cpufreq/amd-pstate.c:1019:9: note: uninitialized use occurs here
> return ret;
> ^~~
> drivers/cpufreq/amd-pstate.c:963:2: note: remove the 'if' if its condition is
> always false
> if (rc)
> ^~~~~~~
>
> 3) calling amd_pstate_set_epp() in cleanup path after determining that it
> should not be called:
>
> drivers/cpufreq/amd-pstate.c:1055:6: error: variable 'epp' is used
> uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-
> uninitialized]
> if (cpudata->epp_policy == cpudata->policy)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/cpufreq/amd-pstate.c:1080:30: note: uninitialized use occurs here
> amd_pstate_set_epp(cpudata, epp);
> ^~~
>
> All three are trivial to fix, but most likely there are additional bugs in this
> function when the error handling was not really tested.
>
> Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support
> for the AMD processors")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> drivers/cpufreq/amd-pstate.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 168a28bed6ee..847f5f31396d 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -940,7 +940,6 @@ static int amd_pstate_epp_cpu_init(struct
> cpufreq_policy *policy)
> int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> struct amd_cpudata *cpudata;
> struct device *dev;
> - int rc;
> u64 value;
>
> /*
> @@ -950,7 +949,7 @@ static int amd_pstate_epp_cpu_init(struct
> cpufreq_policy *policy)
> amd_perf_ctl_reset(policy->cpu);
> dev = get_cpu_device(policy->cpu);
> if (!dev)
> - goto free_cpudata1;
> + return -ENODEV;
>
> cpudata = kzalloc(sizeof(*cpudata), GFP_KERNEL);
> if (!cpudata)
> @@ -959,8 +958,8 @@ static int amd_pstate_epp_cpu_init(struct
> cpufreq_policy *policy)
> cpudata->cpu = policy->cpu;
> cpudata->epp_policy = 0;
>
> - rc = amd_pstate_init_perf(cpudata);
> - if (rc)
> + ret = amd_pstate_init_perf(cpudata);
> + if (ret)
> goto free_cpudata1;
>
> min_freq = amd_get_min_freq(cpudata);
> @@ -1076,9 +1075,9 @@ static void amd_pstate_epp_init(unsigned int cpu)
> value |= (u64)epp << 24;
> }
>
> + amd_pstate_set_epp(cpudata, epp);
> skip_epp:
> WRITE_ONCE(cpudata->cppc_req_cached, value);
> - amd_pstate_set_epp(cpudata, epp);
> cpufreq_cpu_put(policy);
> }
>
> --
> 2.39.1
Thanks for your quick fix patch.
Reviewed-by: Yuan Perry <Perry.Yuan@amd.com>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] cpufreq: amd-pstate: avoid uninitialized variable use
2023-02-07 16:12 [PATCH] cpufreq: amd-pstate: avoid uninitialized variable use Arnd Bergmann
2023-02-08 14:28 ` Wyes Karny
2023-02-09 2:02 ` Yuan, Perry
@ 2023-02-09 5:03 ` Huang Rui
2023-02-09 19:22 ` Rafael J. Wysocki
2023-02-09 9:58 ` Wyes Karny
3 siblings, 1 reply; 6+ messages in thread
From: Huang Rui @ 2023-02-09 5:03 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Rafael J. Wysocki, Viresh Kumar, Karny, Wyes, Yuan, Perry,
Limonciello, Mario, Arnd Bergmann, Jinzhou Su,
Meng, Li (Jassmine), linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org
On Wed, Feb 08, 2023 at 12:12:51AM +0800, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> The new epp support causes warnings about three separate
> but related bugs:
>
> 1) failing before allocation should just return an error:
>
> drivers/cpufreq/amd-pstate.c:951:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (!dev)
> ^~~~
> drivers/cpufreq/amd-pstate.c:1018:9: note: uninitialized use occurs here
> return ret;
> ^~~
>
> 2) wrong variable to store return code:
>
> drivers/cpufreq/amd-pstate.c:963:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (rc)
> ^~
> drivers/cpufreq/amd-pstate.c:1019:9: note: uninitialized use occurs here
> return ret;
> ^~~
> drivers/cpufreq/amd-pstate.c:963:2: note: remove the 'if' if its condition is always false
> if (rc)
> ^~~~~~~
>
> 3) calling amd_pstate_set_epp() in cleanup path after determining
> that it should not be called:
>
> drivers/cpufreq/amd-pstate.c:1055:6: error: variable 'epp' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (cpudata->epp_policy == cpudata->policy)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/cpufreq/amd-pstate.c:1080:30: note: uninitialized use occurs here
> amd_pstate_set_epp(cpudata, epp);
> ^~~
>
> All three are trivial to fix, but most likely there are additional bugs
> in this function when the error handling was not really tested.
>
> Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Thanks!
Acked-by: Huang Rui <ray.huang@amd.com>
> ---
> drivers/cpufreq/amd-pstate.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 168a28bed6ee..847f5f31396d 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -940,7 +940,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> struct amd_cpudata *cpudata;
> struct device *dev;
> - int rc;
> u64 value;
>
> /*
> @@ -950,7 +949,7 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> amd_perf_ctl_reset(policy->cpu);
> dev = get_cpu_device(policy->cpu);
> if (!dev)
> - goto free_cpudata1;
> + return -ENODEV;
>
> cpudata = kzalloc(sizeof(*cpudata), GFP_KERNEL);
> if (!cpudata)
> @@ -959,8 +958,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> cpudata->cpu = policy->cpu;
> cpudata->epp_policy = 0;
>
> - rc = amd_pstate_init_perf(cpudata);
> - if (rc)
> + ret = amd_pstate_init_perf(cpudata);
> + if (ret)
> goto free_cpudata1;
>
> min_freq = amd_get_min_freq(cpudata);
> @@ -1076,9 +1075,9 @@ static void amd_pstate_epp_init(unsigned int cpu)
> value |= (u64)epp << 24;
> }
>
> + amd_pstate_set_epp(cpudata, epp);
> skip_epp:
> WRITE_ONCE(cpudata->cppc_req_cached, value);
> - amd_pstate_set_epp(cpudata, epp);
> cpufreq_cpu_put(policy);
> }
>
> --
> 2.39.1
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] cpufreq: amd-pstate: avoid uninitialized variable use
2023-02-09 5:03 ` Huang Rui
@ 2023-02-09 19:22 ` Rafael J. Wysocki
0 siblings, 0 replies; 6+ messages in thread
From: Rafael J. Wysocki @ 2023-02-09 19:22 UTC (permalink / raw)
To: Huang Rui, Arnd Bergmann
Cc: Rafael J. Wysocki, Viresh Kumar, Karny, Wyes, Yuan, Perry,
Limonciello, Mario, Arnd Bergmann, Jinzhou Su,
Meng, Li (Jassmine), linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org
On Thu, Feb 9, 2023 at 6:04 AM Huang Rui <ray.huang@amd.com> wrote:
>
> On Wed, Feb 08, 2023 at 12:12:51AM +0800, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > The new epp support causes warnings about three separate
> > but related bugs:
> >
> > 1) failing before allocation should just return an error:
> >
> > drivers/cpufreq/amd-pstate.c:951:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> > if (!dev)
> > ^~~~
> > drivers/cpufreq/amd-pstate.c:1018:9: note: uninitialized use occurs here
> > return ret;
> > ^~~
> >
> > 2) wrong variable to store return code:
> >
> > drivers/cpufreq/amd-pstate.c:963:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> > if (rc)
> > ^~
> > drivers/cpufreq/amd-pstate.c:1019:9: note: uninitialized use occurs here
> > return ret;
> > ^~~
> > drivers/cpufreq/amd-pstate.c:963:2: note: remove the 'if' if its condition is always false
> > if (rc)
> > ^~~~~~~
> >
> > 3) calling amd_pstate_set_epp() in cleanup path after determining
> > that it should not be called:
> >
> > drivers/cpufreq/amd-pstate.c:1055:6: error: variable 'epp' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> > if (cpudata->epp_policy == cpudata->policy)
> > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > drivers/cpufreq/amd-pstate.c:1080:30: note: uninitialized use occurs here
> > amd_pstate_set_epp(cpudata, epp);
> > ^~~
> >
> > All three are trivial to fix, but most likely there are additional bugs
> > in this function when the error handling was not really tested.
> >
> > Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors")
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>
> Thanks!
>
> Acked-by: Huang Rui <ray.huang@amd.com>
>
> > ---
> > drivers/cpufreq/amd-pstate.c | 9 ++++-----
> > 1 file changed, 4 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> > index 168a28bed6ee..847f5f31396d 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -940,7 +940,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> > int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> > struct amd_cpudata *cpudata;
> > struct device *dev;
> > - int rc;
> > u64 value;
> >
> > /*
> > @@ -950,7 +949,7 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> > amd_perf_ctl_reset(policy->cpu);
> > dev = get_cpu_device(policy->cpu);
> > if (!dev)
> > - goto free_cpudata1;
> > + return -ENODEV;
> >
> > cpudata = kzalloc(sizeof(*cpudata), GFP_KERNEL);
> > if (!cpudata)
> > @@ -959,8 +958,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> > cpudata->cpu = policy->cpu;
> > cpudata->epp_policy = 0;
> >
> > - rc = amd_pstate_init_perf(cpudata);
> > - if (rc)
> > + ret = amd_pstate_init_perf(cpudata);
> > + if (ret)
> > goto free_cpudata1;
> >
> > min_freq = amd_get_min_freq(cpudata);
> > @@ -1076,9 +1075,9 @@ static void amd_pstate_epp_init(unsigned int cpu)
> > value |= (u64)epp << 24;
> > }
> >
> > + amd_pstate_set_epp(cpudata, epp);
> > skip_epp:
> > WRITE_ONCE(cpudata->cppc_req_cached, value);
> > - amd_pstate_set_epp(cpudata, epp);
> > cpufreq_cpu_put(policy);
> > }
> >
> > --
Applied, thanks!
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] cpufreq: amd-pstate: avoid uninitialized variable use
2023-02-07 16:12 [PATCH] cpufreq: amd-pstate: avoid uninitialized variable use Arnd Bergmann
` (2 preceding siblings ...)
2023-02-09 5:03 ` Huang Rui
@ 2023-02-09 9:58 ` Wyes Karny
3 siblings, 0 replies; 6+ messages in thread
From: Wyes Karny @ 2023-02-09 9:58 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Huang Rui, Rafael J. Wysocki, Viresh Kumar, Perry Yuan,
Mario Limonciello, Arnd Bergmann, Jinzhou Su, Meng Li, linux-pm,
linux-kernel
Hi Arnd, Ray, Perry,
On 07 Feb 17:12, Arnd Bergmann wrote:
> @@ -1076,9 +1075,9 @@ static void amd_pstate_epp_init(unsigned int cpu)
> value |= (u64)epp << 24;
> }
>
> + amd_pstate_set_epp(cpudata, epp);
> skip_epp:
> WRITE_ONCE(cpudata->cppc_req_cached, value);
> - amd_pstate_set_epp(cpudata, epp);
> cpufreq_cpu_put(policy);
> }
I see an issue here with MSR-based systems.
Here EPP is being set before updating `cppc_req_cached` and for MSR
based systems while updating EPP value, MIN_PERF and MAX_PERF also
updated. So, here whatever value MSR_AMD_CPPC_REQ had for min and max
perf that will be rewritten instead of highest and lowest perf from
MSR_AMD_CPPC_CAP1.
Can we do something like this:
@@ -1053,32 +1052,34 @@ static void amd_pstate_epp_init(unsigned int
cpu)
value &= ~AMD_CPPC_DES_PERF(~0L);
value |= AMD_CPPC_DES_PERF(0);
+ /* No need to set epp again if previous and current policy is same */
if (cpudata->epp_policy == cpudata->policy)
goto skip_epp;
cpudata->epp_policy = cpudata->policy;
- if (cpudata->policy == CPUFREQ_POLICY_PERFORMANCE) {
- epp = amd_pstate_get_epp(cpudata, value);
- if (epp < 0)
- goto skip_epp;
- /* force the epp value to be zero for performance policy */
- epp = 0;
- } else {
- /* Get BIOS pre-defined epp value */
- epp = amd_pstate_get_epp(cpudata, value);
- if (epp)
- goto skip_epp;
+ /* Get BIOS pre-defined epp value */
+ epp = amd_pstate_get_epp(cpudata, value);
+ if (epp < 0) {
+ /**
+ * This return value can only be negative for shared_memory
+ * systems where EPP register read/write not supported.
+ */
+ goto skip_epp;
}
+
+ if (cpudata->policy == CPUFREQ_POLICY_PERFORMANCE)
+ epp = 0;
+
/* Set initial EPP value */
if (boot_cpu_has(X86_FEATURE_CPPC)) {
value &= ~GENMASK_ULL(31, 24);
value |= (u64)epp << 24;
}
-skip_epp:
WRITE_ONCE(cpudata->cppc_req_cached, value);
amd_pstate_set_epp(cpudata, epp);
+skip_epp:
cpufreq_cpu_put(policy);
}
>
> --
> 2.39.1
>
^ permalink raw reply [flat|nested] 6+ messages in thread