From 51be5606d9ff9eb27ed6514f6172fbd7578a25d6 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Mon, 9 Jan 2006 20:51:42 -0800 Subject: [PATCH] [PATCH] kdump: export per cpu crash notes pointer through sysfs - Kexec on panic functionality allocates memory for saving cpu registers in case of system crash event. Address of this allocated memory needs to be exported to user space, which is used by kexec-tools. - Previously, a single /sys/kernel/crash_notes entry was being exported as memory allocated was a single continuous array. Now memory allocation being dyanmic and per cpu based, address of per cpu buffer is exported through "/sys/devices/system/cpu/cpuX/crash_notes" Signed-off-by: Vivek Goyal Cc: Greg KH Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/base/cpu.c | 32 ++++++++++++++++++++++++++++++++ kernel/ksysfs.c | 13 ------------- 2 files changed, 32 insertions(+), 13 deletions(-) diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index 281d26784d25..982e6583cd63 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -83,6 +83,33 @@ static inline void register_cpu_control(struct cpu *cpu) } #endif /* CONFIG_HOTPLUG_CPU */ +#ifdef CONFIG_KEXEC +#include + +static ssize_t show_crash_notes(struct sys_device *dev, char *buf) +{ + struct cpu *cpu = container_of(dev, struct cpu, sysdev); + ssize_t rc; + unsigned long long addr; + int cpunum; + + cpunum = cpu->sysdev.id; + + /* + * Might be reading other cpu's data based on which cpu read thread + * has been scheduled. But cpu data (memory) is allocated once during + * boot up and this data does not change there after. Hence this + * operation should be safe. No locking required. + */ + get_cpu(); + addr = __pa(per_cpu_ptr(crash_notes, cpunum)); + rc = sprintf(buf, "%Lx\n", addr); + put_cpu(); + return rc; +} +static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL); +#endif + /* * register_cpu - Setup a driverfs device for a CPU. * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to @@ -108,6 +135,11 @@ int __devinit register_cpu(struct cpu *cpu, int num, struct node *root) register_cpu_control(cpu); if (!error) cpu_sys_devices[num] = &cpu->sysdev; + +#ifdef CONFIG_KEXEC + if (!error) + error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes); +#endif return error; } diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c index 99af8b05eeaa..d5eeae0fa5bc 100644 --- a/kernel/ksysfs.c +++ b/kernel/ksysfs.c @@ -51,16 +51,6 @@ static ssize_t uevent_helper_store(struct subsystem *subsys, const char *page, s KERNEL_ATTR_RW(uevent_helper); #endif -#ifdef CONFIG_KEXEC -#include - -static ssize_t crash_notes_show(struct subsystem *subsys, char *page) -{ - return sprintf(page, "%p\n", (void *)crash_notes); -} -KERNEL_ATTR_RO(crash_notes); -#endif - decl_subsys(kernel, NULL, NULL); EXPORT_SYMBOL_GPL(kernel_subsys); @@ -68,9 +58,6 @@ static struct attribute * kernel_attrs[] = { #ifdef CONFIG_HOTPLUG &uevent_seqnum_attr.attr, &uevent_helper_attr.attr, -#endif -#ifdef CONFIG_KEXEC - &crash_notes_attr.attr, #endif NULL }; -- 2.20.1