linux-kernel - [PATCH v2] cpuidle: change enter

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <1594005196-16327-2-git-send-email-neal.liu@mediatek.com>
Date:   Mon, 6 Jul 2020 11:13:16 +0800
From:   Neal Liu <neal.liu@...iatek.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Sami Tolvanen <samitolvanen@...gle.com>
CC:     Neal Liu <neal.liu@...iatek.com>, <linux-acpi@...r.kernel.org>,
        <linux-pm@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        lkml <linux-kernel@...r.kernel.org>, <wsd_upstream@...iatek.com>
Subject: [PATCH v2] cpuidle: change enter_s2idle() prototype

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 <neal.liu@...iatek.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