From: Sumit Gupta <sumitg@nvidia.com>
To: <rafael@kernel.org>, <lenb@kernel.org>, <viresh.kumar@linaro.org>,
<linux-acpi@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-pm@vger.kernel.org>
Cc: <linux-tegra@vger.kernel.org>, <treding@nvidia.com>,
<jonathanh@nvidia.com>, <bbasu@nvidia.com>, <sumitg@nvidia.com>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>
Subject: [PATCH] ACPI: CPPC: Check cpc_read() return values consistently
Date: Wed, 18 Mar 2026 15:20:05 +0530 [thread overview]
Message-ID: <20260318095005.2437960-1-sumitg@nvidia.com> (raw)
Callers of cpc_read() ignore its return value, which can lead
to using uninitialized or stale values when the read fails.
Fix this by consistently checking cpc_read() return values in
cppc_get_perf_caps(), cppc_get_perf_ctrs(), and cppc_get_perf().
Depends-on: https://lore.kernel.org/lkml/20260206142658.72583-2-sumitg@nvidia.com/
Link: https://lore.kernel.org/lkml/48bdf87e-39f1-402f-a7dc-1a0e1e7a819d@nvidia.com/
Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---
drivers/acpi/cppc_acpi.c | 99 +++++++++++++++++++++++++++++-----------
1 file changed, 72 insertions(+), 27 deletions(-)
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 5ad922eb937a..053fc6765a59 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -1394,45 +1394,66 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
}
}
- cpc_read(cpunum, highest_reg, &high);
+ ret = cpc_read(cpunum, highest_reg, &high);
+ if (ret)
+ goto out_err;
perf_caps->highest_perf = high;
- cpc_read(cpunum, lowest_reg, &low);
+ ret = cpc_read(cpunum, lowest_reg, &low);
+ if (ret)
+ goto out_err;
perf_caps->lowest_perf = low;
- cpc_read(cpunum, nominal_reg, &nom);
+ ret = cpc_read(cpunum, nominal_reg, &nom);
+ if (ret)
+ goto out_err;
perf_caps->nominal_perf = nom;
/*
* If reference perf register is not supported then we should
* use the nominal perf value
*/
- if (CPC_SUPPORTED(reference_reg))
- cpc_read(cpunum, reference_reg, &ref);
- else
+ if (CPC_SUPPORTED(reference_reg)) {
+ ret = cpc_read(cpunum, reference_reg, &ref);
+ if (ret)
+ goto out_err;
+ } else {
ref = nom;
+ }
perf_caps->reference_perf = ref;
if (guaranteed_reg->type != ACPI_TYPE_BUFFER ||
IS_NULL_REG(&guaranteed_reg->cpc_entry.reg)) {
perf_caps->guaranteed_perf = 0;
} else {
- cpc_read(cpunum, guaranteed_reg, &guaranteed);
+ ret = cpc_read(cpunum, guaranteed_reg, &guaranteed);
+ if (ret)
+ goto out_err;
perf_caps->guaranteed_perf = guaranteed;
}
- cpc_read(cpunum, lowest_non_linear_reg, &min_nonlinear);
+ ret = cpc_read(cpunum, lowest_non_linear_reg, &min_nonlinear);
+ if (ret)
+ goto out_err;
perf_caps->lowest_nonlinear_perf = min_nonlinear;
- if (!high || !low || !nom || !ref || !min_nonlinear)
+ if (!high || !low || !nom || !ref || !min_nonlinear) {
ret = -EFAULT;
+ goto out_err;
+ }
/* Read optional lowest and nominal frequencies if present */
- if (CPC_SUPPORTED(low_freq_reg))
- cpc_read(cpunum, low_freq_reg, &low_f);
+ if (CPC_SUPPORTED(low_freq_reg)) {
+ ret = cpc_read(cpunum, low_freq_reg, &low_f);
+ if (ret)
+ goto out_err;
+ }
- if (CPC_SUPPORTED(nom_freq_reg))
- cpc_read(cpunum, nom_freq_reg, &nom_f);
+ if (CPC_SUPPORTED(nom_freq_reg)) {
+ ret = cpc_read(cpunum, nom_freq_reg, &nom_f);
+ if (ret)
+ goto out_err;
+ }
perf_caps->lowest_freq = low_f;
perf_caps->nominal_freq = nom_f;
@@ -1526,16 +1547,25 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
}
}
- cpc_read(cpunum, delivered_reg, &delivered);
- cpc_read(cpunum, reference_reg, &reference);
+ ret = cpc_read(cpunum, delivered_reg, &delivered);
+ if (ret)
+ goto out_err;
+
+ ret = cpc_read(cpunum, reference_reg, &reference);
+ if (ret)
+ goto out_err;
+
/*
* Per spec, if ctr_wrap_time optional register is unsupported, then the
* performance counters are assumed to never wrap during the lifetime of
* platform
*/
ctr_wrap_time = (u64)(~((u64)0));
- if (CPC_SUPPORTED(ctr_wrap_reg))
- cpc_read(cpunum, ctr_wrap_reg, &ctr_wrap_time);
+ if (CPC_SUPPORTED(ctr_wrap_reg)) {
+ ret = cpc_read(cpunum, ctr_wrap_reg, &ctr_wrap_time);
+ if (ret)
+ goto out_err;
+ }
if (!delivered || !reference) {
ret = -EFAULT;
@@ -1811,24 +1841,39 @@ int cppc_get_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
}
/* Read optional elements if present */
- if (CPC_SUPPORTED(max_perf_reg))
- cpc_read(cpu, max_perf_reg, &max);
+ if (CPC_SUPPORTED(max_perf_reg)) {
+ ret = cpc_read(cpu, max_perf_reg, &max);
+ if (ret)
+ goto out_err;
+ }
perf_ctrls->max_perf = max;
- if (CPC_SUPPORTED(min_perf_reg))
- cpc_read(cpu, min_perf_reg, &min);
+ if (CPC_SUPPORTED(min_perf_reg)) {
+ ret = cpc_read(cpu, min_perf_reg, &min);
+ if (ret)
+ goto out_err;
+ }
perf_ctrls->min_perf = min;
- if (CPC_SUPPORTED(desired_perf_reg))
- cpc_read(cpu, desired_perf_reg, &desired_perf);
+ if (CPC_SUPPORTED(desired_perf_reg)) {
+ ret = cpc_read(cpu, desired_perf_reg, &desired_perf);
+ if (ret)
+ goto out_err;
+ }
perf_ctrls->desired_perf = desired_perf;
- if (CPC_SUPPORTED(energy_perf_reg))
- cpc_read(cpu, energy_perf_reg, &energy_perf);
+ if (CPC_SUPPORTED(energy_perf_reg)) {
+ ret = cpc_read(cpu, energy_perf_reg, &energy_perf);
+ if (ret)
+ goto out_err;
+ }
perf_ctrls->energy_perf = energy_perf;
- if (CPC_SUPPORTED(auto_sel_reg))
- cpc_read(cpu, auto_sel_reg, &auto_sel);
+ if (CPC_SUPPORTED(auto_sel_reg)) {
+ ret = cpc_read(cpu, auto_sel_reg, &auto_sel);
+ if (ret)
+ goto out_err;
+ }
perf_ctrls->auto_sel = (bool)auto_sel;
out_err:
--
2.34.1
reply other threads:[~2026-03-18 9:50 UTC|newest]
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