[PATCH] cpuidle: change enter_s2idle() prototype

Neal Liu
2020-06-29T09:11:14Z

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() assigns same function pointer to idle_state->enter
and idle_state->enter_s2idle. This definitely causes CFI failure
when calling either enter() or enter_s2idle().

Align enter_s2idle() with enter() function prototype to fix CFI
failure.

Signed-off-by: Neal Liu <neal.liu@mediatek.com>
---
drivers/acpi/processor_idle.c | 6 ++++--
drivers/cpuidle/cpuidle-tegra.c | 8 +++++---
drivers/idle/intel_idle.c | 6 ++++--
include/linux/cpuidle.h | 6 +++---
4 files changed, 16 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..bee10c0 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -66,9 +66,9 @@ struct cpuidle_state {
* suspended, so it must not re-enable interrupts at any point (even
* temporarily) or attempt to change states of clock event devices.
*/
- 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