Merge branch 'for-6.15/amd_sfh' into for-linus

From: Mario Limonciello <mario.limonciello@amd.com>

Some platforms include a human presence detection (HPD) sensor. When
enabled and a user is detected a wake event will be emitted from the
sensor fusion hub that software can react to.

Example use cases are "wake from suspend on approach" or to "lock
when leaving".

This is currently enabled by default on supported systems, but users
can't control it. This essentially means that wake on approach is
enabled which is a really surprising behavior to users that don't
expect it.

Instead of defaulting to enabled add a sysfs knob that users can
use to enable the feature if desirable and set it to disabled by
default.

1 files changed, 26 insertions, 2 deletions

diff --git a/lib/fault-inject.c b/lib/fault-inject.c
index 52eb6ba296984..999053fa133e3 100644
--- a/lib/fault-inject.c
+++ b/lib/fault-inject.c
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-only
 #include <linux/kernel.h>
 #include <linux/init.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 #include <linux/debugfs.h>
 #include <linux/sched.h>
 #include <linux/stat.h>
@@ -13,6 +13,24 @@
 #include <linux/fault-inject.h>
 
 /*
+ * The should_fail() functions use prandom instead of the normal Linux RNG
+ * since they don't need cryptographically secure random numbers.
+ */
+static DEFINE_PER_CPU(struct rnd_state, fault_rnd_state);
+
+static u32 fault_prandom_u32_below_100(void)
+{
+	struct rnd_state *state;
+	u32 res;
+
+	state = &get_cpu_var(fault_rnd_state);
+	res = prandom_u32_state(state);
+	put_cpu_var(fault_rnd_state);
+
+	return res % 100;
+}
+
+/*
  * setup_fault_attr() is a helper function for various __setup handlers, so it
  * returns 0 on error, because that is what __setup handlers do.
  */
@@ -31,6 +49,8 @@ int setup_fault_attr(struct fault_attr *attr, char *str)
 		return 0;
 	}
 
+	prandom_init_once(&fault_rnd_state);
+
 	attr->probability = probability;
 	attr->interval = interval;
 	atomic_set(&attr->times, times);
@@ -146,7 +166,7 @@ bool should_fail_ex(struct fault_attr *attr, ssize_t size, int flags)
 			return false;
 	}
 
-	if (attr->probability <= get_random_u32_below(100))
+	if (attr->probability <= fault_prandom_u32_below_100())
 		return false;
 
 fail:
@@ -219,6 +239,8 @@ struct dentry *fault_create_debugfs_attr(const char *name,
 	if (IS_ERR(dir))
 		return dir;
 
+	prandom_init_once(&fault_rnd_state);
+
 	debugfs_create_ul("probability", mode, dir, &attr->probability);
 	debugfs_create_ul("interval", mode, dir, &attr->interval);
 	debugfs_create_atomic_t("times", mode, dir, &attr->times);
@@ -431,6 +453,8 @@ static const struct config_item_type fault_config_type = {
 
 void fault_config_init(struct fault_config *config, const char *name)
 {
+	prandom_init_once(&fault_rnd_state);
+
 	config_group_init_type_name(&config->group, name, &fault_config_type);
 }
 EXPORT_SYMBOL_GPL(fault_config_init);