| Message ID | 20230207161256.271613-1-arnd@kernel.org (mailing list archive) |
|---|---|
| State | Mainlined, archived |
| Headers | show |
| Series | cpufreq: amd-pstate: avoid uninitialized variable use | expand |
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 >
[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>
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 >
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 >
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!
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); }