changes since v2:
- add more comments on enter_s2idle to explain why it is necessary to return
int even if its return value is never used.
changes since v1:
- add more description in commit message.
*** BLURB HERE ***
Neal Liu (1):
cpuidle: change enter_s2idle() prototype
drivers/acpi/processor_idle.c | 6 ++++--
drivers/cpuidle/cpuidle-tegra.c | 8 +++++---
drivers/idle/intel_idle.c | 6 ++++--
include/linux/cpuidle.h | 9 ++++++---
4 files changed, 19 insertions(+), 10 deletions(-)
--
2.18.0
Control Flow Integrity(CFI) is a security mechanism that disallows
changes to the original control flow graph of a compiled binary,
making it significantly harder to perform such attacks.
init_state_node() assign same function callback to different
function pointer declarations.
static int init_state_node(struct cpuidle_state *idle_state,
const struct of_device_id *matches,
struct device_node *state_node) { ...
idle_state->enter = match_id->data; ...
idle_state->enter_s2idle = match_id->data; }
Function declarations:
struct cpuidle_state { ...
int (*enter) (struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index);
void (*enter_s2idle) (struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index); };
In this case, either enter() or enter_s2idle() would cause CFI check
failed since they use same callee.
Align function prototype of enter() since it needs return value for
some use cases. The return value of enter_s2idle() is no
need currently.
Signed-off-by: Neal Liu <[email protected]>
Reviewed-by: Sami Tolvanen <[email protected]>
---
drivers/acpi/processor_idle.c | 6 ++++--
drivers/cpuidle/cpuidle-tegra.c | 8 +++++---
drivers/idle/intel_idle.c | 6 ++++--
include/linux/cpuidle.h | 9 ++++++---
4 files changed, 19 insertions(+), 10 deletions(-)
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 75534c5..6ffb6c9 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -655,8 +655,8 @@ static int acpi_idle_enter(struct cpuidle_device *dev,
return index;
}
-static void acpi_idle_enter_s2idle(struct cpuidle_device *dev,
- struct cpuidle_driver *drv, int index)
+static int acpi_idle_enter_s2idle(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
{
struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu);
@@ -674,6 +674,8 @@ static void acpi_idle_enter_s2idle(struct cpuidle_device *dev,
}
}
acpi_idle_do_entry(cx);
+
+ return 0;
}
static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
diff --git a/drivers/cpuidle/cpuidle-tegra.c b/drivers/cpuidle/cpuidle-tegra.c
index 1500458..a12fb14 100644
--- a/drivers/cpuidle/cpuidle-tegra.c
+++ b/drivers/cpuidle/cpuidle-tegra.c
@@ -253,11 +253,13 @@ static int tegra_cpuidle_enter(struct cpuidle_device *dev,
return err ? -1 : index;
}
-static void tegra114_enter_s2idle(struct cpuidle_device *dev,
- struct cpuidle_driver *drv,
- int index)
+static int tegra114_enter_s2idle(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv,
+ int index)
{
tegra_cpuidle_enter(dev, drv, index);
+
+ return 0;
}
/*
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index f449584..b178da3 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -175,13 +175,15 @@ static __cpuidle int intel_idle(struct cpuidle_device *dev,
* Invoked as a suspend-to-idle callback routine with frozen user space, frozen
* scheduler tick and suspended scheduler clock on the target CPU.
*/
-static __cpuidle void intel_idle_s2idle(struct cpuidle_device *dev,
- struct cpuidle_driver *drv, int index)
+static __cpuidle int intel_idle_s2idle(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
{
unsigned long eax = flg2MWAIT(drv->states[index].flags);
unsigned long ecx = 1; /* break on interrupt flag */
mwait_idle_with_hints(eax, ecx);
+
+ return 0;
}
/*
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index ec2ef63..b65909a 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -65,10 +65,13 @@ struct cpuidle_state {
* CPUs execute ->enter_s2idle with the local tick or entire timekeeping
* suspended, so it must not re-enable interrupts at any point (even
* temporarily) or attempt to change states of clock event devices.
+ *
+ * This callback may point to the same function as ->enter if all of
+ * the above requirements are met by it.
*/
- void (*enter_s2idle) (struct cpuidle_device *dev,
- struct cpuidle_driver *drv,
- int index);
+ int (*enter_s2idle)(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv,
+ int index);
};
/* Idle State Flags */
--
1.7.9.5
On Mon, Jul 27, 2020 at 5:25 AM Neal Liu <[email protected]> wrote:
>
> Control Flow Integrity(CFI) is a security mechanism that disallows
> changes to the original control flow graph of a compiled binary,
> making it significantly harder to perform such attacks.
>
> init_state_node() assign same function callback to different
> function pointer declarations.
>
> static int init_state_node(struct cpuidle_state *idle_state,
> const struct of_device_id *matches,
> struct device_node *state_node) { ...
> idle_state->enter = match_id->data; ...
> idle_state->enter_s2idle = match_id->data; }
>
> Function declarations:
>
> struct cpuidle_state { ...
> int (*enter) (struct cpuidle_device *dev,
> struct cpuidle_driver *drv,
> int index);
>
> void (*enter_s2idle) (struct cpuidle_device *dev,
> struct cpuidle_driver *drv,
> int index); };
>
> In this case, either enter() or enter_s2idle() would cause CFI check
> failed since they use same callee.
>
> Align function prototype of enter() since it needs return value for
> some use cases. The return value of enter_s2idle() is no
> need currently.
>
> Signed-off-by: Neal Liu <[email protected]>
> Reviewed-by: Sami Tolvanen <[email protected]>
> ---
> drivers/acpi/processor_idle.c | 6 ++++--
> drivers/cpuidle/cpuidle-tegra.c | 8 +++++---
> drivers/idle/intel_idle.c | 6 ++++--
> include/linux/cpuidle.h | 9 ++++++---
> 4 files changed, 19 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index 75534c5..6ffb6c9 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -655,8 +655,8 @@ static int acpi_idle_enter(struct cpuidle_device *dev,
> return index;
> }
>
> -static void acpi_idle_enter_s2idle(struct cpuidle_device *dev,
> - struct cpuidle_driver *drv, int index)
> +static int acpi_idle_enter_s2idle(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv, int index)
> {
> struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu);
>
> @@ -674,6 +674,8 @@ static void acpi_idle_enter_s2idle(struct cpuidle_device *dev,
> }
> }
> acpi_idle_do_entry(cx);
> +
> + return 0;
> }
>
> static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
> diff --git a/drivers/cpuidle/cpuidle-tegra.c b/drivers/cpuidle/cpuidle-tegra.c
> index 1500458..a12fb14 100644
> --- a/drivers/cpuidle/cpuidle-tegra.c
> +++ b/drivers/cpuidle/cpuidle-tegra.c
> @@ -253,11 +253,13 @@ static int tegra_cpuidle_enter(struct cpuidle_device *dev,
> return err ? -1 : index;
> }
>
> -static void tegra114_enter_s2idle(struct cpuidle_device *dev,
> - struct cpuidle_driver *drv,
> - int index)
> +static int tegra114_enter_s2idle(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv,
> + int index)
> {
> tegra_cpuidle_enter(dev, drv, index);
> +
> + return 0;
> }
>
> /*
> diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
> index f449584..b178da3 100644
> --- a/drivers/idle/intel_idle.c
> +++ b/drivers/idle/intel_idle.c
> @@ -175,13 +175,15 @@ static __cpuidle int intel_idle(struct cpuidle_device *dev,
> * Invoked as a suspend-to-idle callback routine with frozen user space, frozen
> * scheduler tick and suspended scheduler clock on the target CPU.
> */
> -static __cpuidle void intel_idle_s2idle(struct cpuidle_device *dev,
> - struct cpuidle_driver *drv, int index)
> +static __cpuidle int intel_idle_s2idle(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv, int index)
> {
> unsigned long eax = flg2MWAIT(drv->states[index].flags);
> unsigned long ecx = 1; /* break on interrupt flag */
>
> mwait_idle_with_hints(eax, ecx);
> +
> + return 0;
> }
>
> /*
> diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
> index ec2ef63..b65909a 100644
> --- a/include/linux/cpuidle.h
> +++ b/include/linux/cpuidle.h
> @@ -65,10 +65,13 @@ struct cpuidle_state {
> * CPUs execute ->enter_s2idle with the local tick or entire timekeeping
> * suspended, so it must not re-enable interrupts at any point (even
> * temporarily) or attempt to change states of clock event devices.
> + *
> + * This callback may point to the same function as ->enter if all of
> + * the above requirements are met by it.
> */
> - void (*enter_s2idle) (struct cpuidle_device *dev,
> - struct cpuidle_driver *drv,
> - int index);
> + int (*enter_s2idle)(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv,
> + int index);
> };
>
> /* Idle State Flags */
> --
Applied as 5.9 material, thanks!