arm64: Add support for app specific settings

Add support to provide an interface that can be used from
userspace to decide whether app specific settings need to
be applied / cleared when particular processes are running.

CRs-Fixed: 981519 997757
Change-Id: Id81f8b70de64f291a8586150f4d2c7c8f8b4420f
Signed-off-by: Sarangdhar Joshi <spjoshi@codeaurora.org>
[satyap@codeaurora.org: trivial merge conflict resolution and pull
fixes for CR: 997757]
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>

arch/arm64/Kconfig

@@ -513,9 +513,20 @@ config ARM64_64K_PAGES
 
 endchoice
 
+config MSM_APP_API
+	bool "API support to enable / disable app settings for MSM8996"
+	depends on ARCH_MSM8996 && (ENABLE_FP_SIMD_SETTINGS || MSM_APP_SETTINGS)
+	help
+	  Add API support to enable / disable the app settings to be used
+	  at runtime. These APIs are used to enable / disable app setting
+	  when specific aarch32 or aarch64 processes are running.
+
+	  If you are not sure what to do, select 'N' here.
+
 config ENABLE_FP_SIMD_SETTINGS
 	bool "Enable FP(Floating Point) Settings for Qualcomm MSM8996"
 	depends on ARCH_MSM8996
+	select MSM_APP_API
 	help
 	  Enable FP(Floating Point) and SIMD settings for the MSM8996 during
 	  the execution of the aarch32 processes and disable these settings
@@ -523,6 +534,16 @@ config ENABLE_FP_SIMD_SETTINGS
 
 	  If you are not sure what to do, select 'N' here.
 
+config MSM_APP_SETTINGS
+	bool "Support to enable / disable app settings for MSM8996"
+	depends on ARCH_MSM8996
+	select MSM_APP_API
+	help
+	  Expose an interface used by the userspace at runtime to
+	  enable / disable the app specific settings.
+
+	  If you are not sure what to do, select 'N' here.
+
 choice
 	prompt "Virtual address space size"
 	default ARM64_VA_BITS_39 if ARM64_4K_PAGES

arch/arm64/include/asm/app_api.h

@@ -0,0 +1,42 @@
+/* Copyright (c) 2016, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __ASM_APP_API_H
+#define __ASM_APP_API_H
+
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+
+#define APP_SETTING_BIT		30
+#define MAX_ENTRIES		10
+
+/*
+ * APIs to set / clear the app setting bits
+ * in the register.
+ */
+#ifdef CONFIG_MSM_APP_API
+extern void set_app_setting_bit(uint32_t bit);
+extern void clear_app_setting_bit(uint32_t bit);
+#else
+static inline void set_app_setting_bit(uint32_t bit) {}
+static inline void clear_app_setting_bit(uint32_t bit) {}
+#endif
+
+#ifdef CONFIG_MSM_APP_SETTINGS
+extern void switch_app_setting_bit(struct task_struct *prev,
+				   struct task_struct *next);
+extern void apply_app_setting_bit(struct file *file);
+extern bool use_app_setting;
+#endif
+
+#endif

arch/arm64/include/asm/fpsimd.h

@@ -84,13 +84,9 @@ extern void fpsimd_load_partial_state(struct fpsimd_partial_state *state);
 #ifdef CONFIG_ENABLE_FP_SIMD_SETTINGS
 extern void fpsimd_disable_trap(void);
 extern void fpsimd_enable_trap(void);
-extern void fpsimd_settings_disable(void);
-extern void fpsimd_settings_enable(void);
 #else
 static inline void fpsimd_disable_trap(void) {}
 static inline void fpsimd_enable_trap(void) {}
-static inline void fpsimd_settings_disable(void) {}
-static inline void fpsimd_settings_enable(void) {}
 #endif
 
 #endif

arch/arm64/kernel/Makefile

@@ -43,6 +43,8 @@ arm64-obj-$(CONFIG_EFI)			+= efi.o efi-entry.stub.o
 arm64-obj-$(CONFIG_PCI)			+= pci.o
 arm64-obj-$(CONFIG_ARMV8_DEPRECATED)	+= armv8_deprecated.o
 arm64-obj-$(CONFIG_ACPI)		+= acpi.o
+arm64-obj-$(CONFIG_MSM_APP_API)		+= app_api.o
+arm64-obj-$(CONFIG_MSM_APP_SETTINGS)	+= app_setting.o
 
 obj-y					+= $(arm64-obj-y) vdso/
 obj-m					+= $(arm64-obj-m)

arch/arm64/kernel/app_api.c

@@ -0,0 +1,75 @@
+/* Copyright (c) 2016, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/bitops.h>
+#include <linux/spinlock.h>
+#include <linux/cpu.h>
+#include <linux/export.h>
+
+#include <asm/app_api.h>
+
+static spinlock_t spinlock;
+static DEFINE_PER_CPU(int, app_config_applied);
+static unsigned long app_config_set[NR_CPUS];
+static unsigned long app_config_clear[NR_CPUS];
+
+void set_app_setting_bit(uint32_t bit)
+{
+	unsigned long flags;
+	uint64_t reg;
+	int cpu;
+
+	spin_lock_irqsave(&spinlock, flags);
+	asm volatile("mrs %0, S3_1_C15_C15_0" : "=r" (reg));
+	reg = reg | BIT(bit);
+	isb();
+	asm volatile("msr S3_1_C15_C15_0, %0" : : "r" (reg));
+	isb();
+	if (bit == APP_SETTING_BIT) {
+		cpu = raw_smp_processor_id();
+		app_config_set[cpu]++;
+
+		this_cpu_write(app_config_applied, 1);
+	}
+	spin_unlock_irqrestore(&spinlock, flags);
+
+}
+EXPORT_SYMBOL(set_app_setting_bit);
+
+void clear_app_setting_bit(uint32_t bit)
+{
+	unsigned long flags;
+	uint64_t reg;
+	int cpu;
+
+	spin_lock_irqsave(&spinlock, flags);
+	asm volatile("mrs %0, S3_1_C15_C15_0" : "=r" (reg));
+	reg = reg & ~BIT(bit);
+	isb();
+	asm volatile("msr S3_1_C15_C15_0, %0" : : "r" (reg));
+	isb();
+	if (bit == APP_SETTING_BIT) {
+		cpu = raw_smp_processor_id();
+		app_config_clear[cpu]++;
+
+		this_cpu_write(app_config_applied, 0);
+	}
+	spin_unlock_irqrestore(&spinlock, flags);
+}
+EXPORT_SYMBOL(clear_app_setting_bit);
+
+static int __init init_app_api(void)
+{
+	spin_lock_init(&spinlock);
+	return 0;
+}
+early_initcall(init_app_api);

arch/arm64/kernel/app_setting.c

@@ -0,0 +1,120 @@
+/* Copyright (c) 2016, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/cpu.h>
+#include <linux/slab.h>
+#include <linux/notifier.h>
+
+#include <asm/app_api.h>
+
+#define MAX_LEN		100
+
+static char *lib_names[MAX_ENTRIES];
+static unsigned int count;
+static struct mutex mutex;
+
+static char lib_str[MAX_LEN] = "";
+static struct kparam_string kps = {
+	.string			= lib_str,
+	.maxlen			= MAX_LEN,
+};
+static int set_name(const char *str, struct kernel_param *kp);
+module_param_call(lib_name, set_name, param_get_string, &kps, S_IWUSR);
+
+bool use_app_setting = true;
+module_param(use_app_setting, bool, 0644);
+MODULE_PARM_DESC(use_app_setting, "control use of app specific settings");
+
+static int set_name(const char *str, struct kernel_param *kp)
+{
+	int len = strlen(str);
+	char *name;
+
+	if (len >= MAX_LEN) {
+		pr_err("app_setting: name string too long\n");
+		return -ENOSPC;
+	}
+
+	/*
+	 * echo adds '\n' which we need to chop off later
+	 */
+	name = kzalloc(len + 1, GFP_KERNEL);
+	if (!name)
+		return -ENOMEM;
+
+	strlcpy(name, str, len + 1);
+
+	if (name[len - 1] == '\n')
+		name[len - 1] = '\0';
+
+	mutex_lock(&mutex);
+	if (count < MAX_ENTRIES) {
+		lib_names[count] = name;
+		/*
+		 * mb to ensure that the new lib_names entry is present
+		 * before updating the view presented by get_lib_names
+		 */
+		mb();
+		count++;
+	} else {
+		pr_err("app_setting: set name failed. Max entries reached\n");
+		kfree(name);
+		mutex_unlock(&mutex);
+		return -EPERM;
+	}
+	mutex_unlock(&mutex);
+
+	return 0;
+}
+
+void switch_app_setting_bit(struct task_struct *prev, struct task_struct *next)
+{
+	if (prev->mm && unlikely(prev->mm->app_setting))
+		clear_app_setting_bit(APP_SETTING_BIT);
+
+	if (next->mm && unlikely(next->mm->app_setting))
+		set_app_setting_bit(APP_SETTING_BIT);
+}
+EXPORT_SYMBOL(switch_app_setting_bit);
+
+void apply_app_setting_bit(struct file *file)
+{
+	bool found = false;
+	int i;
+
+	if (file && file->f_path.dentry) {
+		const char *name = file->f_path.dentry->d_name.name;
+
+		for (i = 0; i < count; i++) {
+			if (unlikely(!strcmp(name, lib_names[i]))) {
+				found = true;
+				break;
+			}
+		}
+		if (found) {
+			preempt_disable();
+			set_app_setting_bit(APP_SETTING_BIT);
+			/* This will take care of child processes as well */
+			current->mm->app_setting = 1;
+			preempt_enable();
+		}
+	}
+}
+EXPORT_SYMBOL(apply_app_setting_bit);
+
+static int __init app_setting_init(void)
+{
+	mutex_init(&mutex);
+	return 0;
+}
+module_init(app_setting_init);

arch/arm64/kernel/entry-fpsimd.S

@@ -78,22 +78,6 @@ ENTRY(fpsimd_disable_trap)
 	msr cpacr_el1, x0
 	ret
 ENDPROC(fpsimd_disable_trap)
-ENTRY(fpsimd_settings_enable)
-	mrs x0, s3_1_c15_c15_0
-	orr x0, x0, #(1 << 31)
-	isb
-	msr s3_1_c15_c15_0, x0
-	isb
-	ret
-ENDPROC(fpsimd_settings_enable)
-ENTRY(fpsimd_settings_disable)
-	mrs x0, s3_1_c15_c15_0
-	bic x0, x0, #(1 << 31)
-	isb
-	msr s3_1_c15_c15_0, x0
-	isb
-	ret
-ENDPROC(fpsimd_settings_disable)
 #endif
 
 #endif

arch/arm64/kernel/fpsimd.c

@@ -28,6 +28,7 @@
 
 #include <asm/fpsimd.h>
 #include <asm/cputype.h>
+#include <asm/app_api.h>
 
 #define FPEXC_IOF	(1 << 0)
 #define FPEXC_DZF	(1 << 1)
@@ -36,6 +37,8 @@
 #define FPEXC_IXF	(1 << 4)
 #define FPEXC_IDF	(1 << 7)
 
+#define FP_SIMD_BIT	31
+
 /*
  * In order to reduce the number of times the FPSIMD state is needlessly saved
  * and restored, we need to keep track of two things:
@@ -94,6 +97,16 @@ static DEFINE_PER_CPU(int, fpsimd_stg_enable);
 static int fpsimd_settings = 0x1; /* default = 0x1 */
 module_param(fpsimd_settings, int, 0644);
 
+void fpsimd_settings_enable(void)
+{
+	set_app_setting_bit(FP_SIMD_BIT);
+}
+
+void fpsimd_settings_disable(void)
+{
+	clear_app_setting_bit(FP_SIMD_BIT);
+}
+
 /*
  * Trapped FP/ASIMD access.
  */

include/linux/mm_types.h

@@ -522,6 +522,10 @@ struct mm_struct {
 #ifdef CONFIG_HUGETLB_PAGE
 	atomic_long_t hugetlb_usage;
 #endif
+#ifdef CONFIG_MSM_APP_SETTINGS
+	int app_setting;
+#endif
+
 };
 
 static inline void mm_init_cpumask(struct mm_struct *mm)

kernel/sched/core.c

@@ -85,6 +85,9 @@
 #ifdef CONFIG_PARAVIRT
 #include <asm/paravirt.h>
 #endif
+#ifdef CONFIG_MSM_APP_SETTINGS
+#include <asm/app_api.h>
+#endif
 
 #include "sched.h"
 #include "../workqueue_internal.h"
@@ -5874,6 +5877,11 @@ prepare_task_switch(struct rq *rq, struct task_struct *prev,
 	fire_sched_out_preempt_notifiers(prev, next);
 	prepare_lock_switch(rq, next);
 	prepare_arch_switch(next);
+
+#ifdef CONFIG_MSM_APP_SETTINGS
+	if (use_app_setting)
+		switch_app_setting_bit(prev, next);
+#endif
 }
 
 /**

mm/mmap.c

@@ -48,6 +48,10 @@
 #include <asm/tlb.h>
 #include <asm/mmu_context.h>
 
+#ifdef CONFIG_MSM_APP_SETTINGS
+#include <asm/app_api.h>
+#endif
+
 #include "internal.h"
 
 #ifndef arch_mmap_check
@@ -1297,6 +1301,11 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
 	if (!len)
 		return -EINVAL;
 
+#ifdef CONFIG_MSM_APP_SETTINGS
+	if (use_app_setting)
+		apply_app_setting_bit(file);
+#endif
+
 	/*
 	 * Does the application expect PROT_READ to imply PROT_EXEC?
 	 *