From: Florian Fainelli <f.fainelli@gmail.com> To: linux-arm-kernel@lists.infradead.org Cc: Florian Fainelli <f.fainelli@gmail.com>, Russell King <linux@armlinux.org.uk>, bcm-kernel-feedback-list@broadcom.com (maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE), Jonathan Austin <jonathan.austin@arm.com>, Vladimir Murzin <vladimir.murzin@arm.com>, Thomas Gleixner <tglx@linutronix.de>, Zhaoxiu Zeng <zhaoxiu.zeng@gmail.com>, Mark Rutland <mark.rutland@arm.com>, Nicolas Pitre <nico@linaro.org>, Sebastian Andrzej Siewior <bigeasy@linutronix.de>, Anna-Maria Gleixner <anna-maria@linutronix.de>, linux-kernel@vger.kernel.org (open list), will.deacon@arm.com Subject: [PATCH 6/7] ARM: B15: Register reboot notifier for KEXEC Date: Wed, 18 Jan 2017 12:29:25 -0800 [thread overview] Message-ID: <20170118202927.28740-7-f.fainelli@gmail.com> (raw) In-Reply-To: <20170118202927.28740-1-f.fainelli@gmail.com> During kexec, we will go through kernel_kexec() -> syscore_suspend() if CONFIG_KEXEC_JUMP is set, if not, down the road we end-up calling kernel_restart_prepare() which invokes reboot notifiers with SYS_RESTART. We register a reboot notifier to make sure that the B15 read-ahead cache is disabled, since it is another level of instruction and data cache, and we want to avoid any potential side effects with booting a new kernel with such a cache still turned on. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> --- arch/arm/mm/cache-b15-rac.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/arch/arm/mm/cache-b15-rac.c b/arch/arm/mm/cache-b15-rac.c index ef5e93e4b5c2..148d51fdfc3d 100644 --- a/arch/arm/mm/cache-b15-rac.c +++ b/arch/arm/mm/cache-b15-rac.c @@ -16,6 +16,7 @@ #include <linux/notifier.h> #include <linux/cpu.h> #include <linux/syscore_ops.h> +#include <linux/reboot.h> #include <asm/cacheflush.h> #include <asm/hardware/cache-b15-rac.h> @@ -151,6 +152,29 @@ static void b15_rac_enable(void) __b15_rac_enable(enable); } +static int b15_rac_reboot_notifier(struct notifier_block *nb, + unsigned long action, + void *data) +{ + /* During kexec, we are not yet migrated on the boot CPU, so we need to + * make sure we are SMP safe here. Once the RAC is disabled, flag it as + * suspended such that the hotplug notifier returns early. + */ + if (action == SYS_RESTART) { + spin_lock(&rac_lock); + b15_rac_disable_and_flush(); + clear_bit(RAC_ENABLED, &b15_rac_flags); + set_bit(RAC_SUSPENDED, &b15_rac_flags); + spin_unlock(&rac_lock); + } + + return NOTIFY_DONE; +} + +static struct notifier_block b15_rac_reboot_nb = { + .notifier_call = b15_rac_reboot_notifier, +}; + #ifdef CONFIG_HOTPLUG_CPU /* The CPU hotplug case is the most interesting one, we basically need to make * sure that the RAC is disabled for the entire system prior to having a CPU @@ -191,6 +215,12 @@ static void b15_rac_enable(void) /* Running on the dying CPU */ static int b15_rac_dying_cpu(unsigned int cpu) { + /* During kexec/reboot, the RAC is disabled via the reboot notifier + * return early here. + */ + if (test_bit(RAC_SUSPENDED, &b15_rac_flags)) + return 0; + spin_lock(&rac_lock); /* Indicate that we are starting a hotplug procedure */ @@ -207,6 +237,12 @@ static int b15_rac_dying_cpu(unsigned int cpu) /* Running on a non-dying CPU */ static int b15_rac_dead_cpu(unsigned int cpu) { + /* During kexec/reboot, the RAC is disabled via the reboot notifier + * return early here. + */ + if (test_bit(RAC_SUSPENDED, &b15_rac_flags)) + return 0; + spin_lock(&rac_lock); /* And enable it */ @@ -272,6 +308,13 @@ static int __init b15_rac_init(void) goto out; } + ret = register_reboot_notifier(&b15_rac_reboot_nb); + if (ret) { + pr_err("failed to register reboot notifier\n"); + iounmap(b15_rac_base); + goto out; + } + #ifdef CONFIG_HOTPLUG_CPU ret = cpuhp_setup_state_nocalls(CPUHP_AP_ARM_CACHE_B15_RAC_DEAD, "arm/cache-b15-rac:dead", @@ -308,6 +351,7 @@ static int __init b15_rac_init(void) out_cpu_dead: cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CACHE_B15_RAC_DYING); out_unmap: + unregister_reboot_notifier(&b15_rac_reboot_nb); iounmap(b15_rac_base); out: of_node_put(dn); -- 2.9.3
WARNING: multiple messages have this Message-ID (diff)
From: f.fainelli@gmail.com (Florian Fainelli) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 6/7] ARM: B15: Register reboot notifier for KEXEC Date: Wed, 18 Jan 2017 12:29:25 -0800 [thread overview] Message-ID: <20170118202927.28740-7-f.fainelli@gmail.com> (raw) In-Reply-To: <20170118202927.28740-1-f.fainelli@gmail.com> During kexec, we will go through kernel_kexec() -> syscore_suspend() if CONFIG_KEXEC_JUMP is set, if not, down the road we end-up calling kernel_restart_prepare() which invokes reboot notifiers with SYS_RESTART. We register a reboot notifier to make sure that the B15 read-ahead cache is disabled, since it is another level of instruction and data cache, and we want to avoid any potential side effects with booting a new kernel with such a cache still turned on. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> --- arch/arm/mm/cache-b15-rac.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/arch/arm/mm/cache-b15-rac.c b/arch/arm/mm/cache-b15-rac.c index ef5e93e4b5c2..148d51fdfc3d 100644 --- a/arch/arm/mm/cache-b15-rac.c +++ b/arch/arm/mm/cache-b15-rac.c @@ -16,6 +16,7 @@ #include <linux/notifier.h> #include <linux/cpu.h> #include <linux/syscore_ops.h> +#include <linux/reboot.h> #include <asm/cacheflush.h> #include <asm/hardware/cache-b15-rac.h> @@ -151,6 +152,29 @@ static void b15_rac_enable(void) __b15_rac_enable(enable); } +static int b15_rac_reboot_notifier(struct notifier_block *nb, + unsigned long action, + void *data) +{ + /* During kexec, we are not yet migrated on the boot CPU, so we need to + * make sure we are SMP safe here. Once the RAC is disabled, flag it as + * suspended such that the hotplug notifier returns early. + */ + if (action == SYS_RESTART) { + spin_lock(&rac_lock); + b15_rac_disable_and_flush(); + clear_bit(RAC_ENABLED, &b15_rac_flags); + set_bit(RAC_SUSPENDED, &b15_rac_flags); + spin_unlock(&rac_lock); + } + + return NOTIFY_DONE; +} + +static struct notifier_block b15_rac_reboot_nb = { + .notifier_call = b15_rac_reboot_notifier, +}; + #ifdef CONFIG_HOTPLUG_CPU /* The CPU hotplug case is the most interesting one, we basically need to make * sure that the RAC is disabled for the entire system prior to having a CPU @@ -191,6 +215,12 @@ static void b15_rac_enable(void) /* Running on the dying CPU */ static int b15_rac_dying_cpu(unsigned int cpu) { + /* During kexec/reboot, the RAC is disabled via the reboot notifier + * return early here. + */ + if (test_bit(RAC_SUSPENDED, &b15_rac_flags)) + return 0; + spin_lock(&rac_lock); /* Indicate that we are starting a hotplug procedure */ @@ -207,6 +237,12 @@ static int b15_rac_dying_cpu(unsigned int cpu) /* Running on a non-dying CPU */ static int b15_rac_dead_cpu(unsigned int cpu) { + /* During kexec/reboot, the RAC is disabled via the reboot notifier + * return early here. + */ + if (test_bit(RAC_SUSPENDED, &b15_rac_flags)) + return 0; + spin_lock(&rac_lock); /* And enable it */ @@ -272,6 +308,13 @@ static int __init b15_rac_init(void) goto out; } + ret = register_reboot_notifier(&b15_rac_reboot_nb); + if (ret) { + pr_err("failed to register reboot notifier\n"); + iounmap(b15_rac_base); + goto out; + } + #ifdef CONFIG_HOTPLUG_CPU ret = cpuhp_setup_state_nocalls(CPUHP_AP_ARM_CACHE_B15_RAC_DEAD, "arm/cache-b15-rac:dead", @@ -308,6 +351,7 @@ static int __init b15_rac_init(void) out_cpu_dead: cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CACHE_B15_RAC_DYING); out_unmap: + unregister_reboot_notifier(&b15_rac_reboot_nb); iounmap(b15_rac_base); out: of_node_put(dn); -- 2.9.3
next prev parent reply other threads:[~2017-01-18 20:31 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-01-18 20:29 [PATCH 0/7] ARM: Broadcom Brahma-B15 readahead cache support Florian Fainelli 2017-01-18 20:29 ` Florian Fainelli 2017-01-18 20:29 ` [PATCH 1/7] ARM: v7: allow setting different cache functions Florian Fainelli 2017-01-18 20:29 ` Florian Fainelli 2017-01-18 20:29 ` [PATCH 2/7] ARM: Add Broadcom Brahma-B15 readahead cache support Florian Fainelli 2017-01-18 20:29 ` Florian Fainelli 2017-01-18 22:56 ` Russell King - ARM Linux 2017-01-18 22:56 ` Russell King - ARM Linux 2017-01-19 0:18 ` Florian Fainelli 2017-01-19 0:18 ` Florian Fainelli 2017-01-18 20:29 ` [PATCH 3/7] ARM: Hook B15 readahead cache functions based on processor Florian Fainelli 2017-01-18 20:29 ` Florian Fainelli 2017-01-18 20:29 ` [PATCH 4/7] ARM: B15: Add CPU hotplug awareness Florian Fainelli 2017-01-18 20:29 ` Florian Fainelli 2017-01-18 20:29 ` [PATCH 5/7] ARM: B15: Add suspend/resume hooks Florian Fainelli 2017-01-18 20:29 ` Florian Fainelli 2017-01-18 20:29 ` Florian Fainelli [this message] 2017-01-18 20:29 ` [PATCH 6/7] ARM: B15: Register reboot notifier for KEXEC Florian Fainelli 2017-01-18 20:29 ` [PATCH 7/7] MAINTAINERS: Update brcmstb entries to cover B15 code Florian Fainelli 2017-01-18 20:29 ` Florian Fainelli 2017-01-18 20:29 ` [PATCH 8/8] ARM: smp: Remove CPU: shutdown notice Florian Fainelli 2017-01-18 20:29 ` Florian Fainelli
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