/* * Firmware Assisted dump: A robust mechanism to get reliable kernel crash * dump with assistance from firmware. This approach does not use kexec, * instead firmware assists in booting the kdump kernel while preserving * memory contents. The most of the code implementation has been adapted * from phyp assisted dump implementation written by Linas Vepstas and * Manish Ahuja * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * 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. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * * Copyright 2011 IBM Corporation * Author: Mahesh Salgaonkar */ #undef DEBUG #define pr_fmt(fmt) "fadump: " fmt #include #include #include #include #include #include #include #include #include static struct fw_dump fw_dump; static struct fadump_mem_struct fdm; static const struct fadump_mem_struct *fdm_active; static DEFINE_MUTEX(fadump_mutex); /* Scan the Firmware Assisted dump configuration details. */ int __init early_init_dt_scan_fw_dump(unsigned long node, const char *uname, int depth, void *data) { __be32 *sections; int i, num_sections; unsigned long size; const int *token; if (depth != 1 || strcmp(uname, "rtas") != 0) return 0; /* * Check if Firmware Assisted dump is supported. if yes, check * if dump has been initiated on last reboot. */ token = of_get_flat_dt_prop(node, "ibm,configure-kernel-dump", NULL); if (!token) return 0; fw_dump.fadump_supported = 1; fw_dump.ibm_configure_kernel_dump = *token; /* * The 'ibm,kernel-dump' rtas node is present only if there is * dump data waiting for us. */ fdm_active = of_get_flat_dt_prop(node, "ibm,kernel-dump", NULL); if (fdm_active) fw_dump.dump_active = 1; /* Get the sizes required to store dump data for the firmware provided * dump sections. * For each dump section type supported, a 32bit cell which defines * the ID of a supported section followed by two 32 bit cells which * gives teh size of the section in bytes. */ sections = of_get_flat_dt_prop(node, "ibm,configure-kernel-dump-sizes", &size); if (!sections) return 0; num_sections = size / (3 * sizeof(u32)); for (i = 0; i < num_sections; i++, sections += 3) { u32 type = (u32)of_read_number(sections, 1); switch (type) { case FADUMP_CPU_STATE_DATA: fw_dump.cpu_state_data_size = of_read_ulong(§ions[1], 2); break; case FADUMP_HPTE_REGION: fw_dump.hpte_region_size = of_read_ulong(§ions[1], 2); break; } } return 1; } int is_fadump_active(void) { return fw_dump.dump_active; } /* Print firmware assisted dump configurations for debugging purpose. */ static void fadump_show_config(void) { pr_debug("Support for firmware-assisted dump (fadump): %s\n", (fw_dump.fadump_supported ? "present" : "no support")); if (!fw_dump.fadump_supported) return; pr_debug("Fadump enabled : %s\n", (fw_dump.fadump_enabled ? "yes" : "no")); pr_debug("Dump Active : %s\n", (fw_dump.dump_active ? "yes" : "no")); pr_debug("Dump section sizes:\n"); pr_debug(" CPU state data size: %lx\n", fw_dump.cpu_state_data_size); pr_debug(" HPTE region size : %lx\n", fw_dump.hpte_region_size); pr_debug("Boot memory size : %lx\n", fw_dump.boot_memory_size); } static unsigned long init_fadump_mem_struct(struct fadump_mem_struct *fdm, unsigned long addr) { if (!fdm) return 0; memset(fdm, 0, sizeof(struct fadump_mem_struct)); addr = addr & PAGE_MASK; fdm->header.dump_format_version = 0x00000001; fdm->header.dump_num_sections = 3; fdm->header.dump_status_flag = 0; fdm->header.offset_first_dump_section = (u32)offsetof(struct fadump_mem_struct, cpu_state_data); /* * Fields for disk dump option. * We are not using disk dump option, hence set these fields to 0. */ fdm->header.dd_block_size = 0; fdm->header.dd_block_offset = 0; fdm->header.dd_num_blocks = 0; fdm->header.dd_offset_disk_path = 0; /* set 0 to disable an automatic dump-reboot. */ fdm->header.max_time_auto = 0; /* Kernel dump sections */ /* cpu state data section. */ fdm->cpu_state_data.request_flag = FADUMP_REQUEST_FLAG; fdm->cpu_state_data.source_data_type = FADUMP_CPU_STATE_DATA; fdm->cpu_state_data.source_address = 0; fdm->cpu_state_data.source_len = fw_dump.cpu_state_data_size; fdm->cpu_state_data.destination_address = addr; addr += fw_dump.cpu_state_data_size; /* hpte region section */ fdm->hpte_region.request_flag = FADUMP_REQUEST_FLAG; fdm->hpte_region.source_data_type = FADUMP_HPTE_REGION; fdm->hpte_region.source_address = 0; fdm->hpte_region.source_len = fw_dump.hpte_region_size; fdm->hpte_region.destination_address = addr; addr += fw_dump.hpte_region_size; /* RMA region section */ fdm->rmr_region.request_flag = FADUMP_REQUEST_FLAG; fdm->rmr_region.source_data_type = FADUMP_REAL_MODE_REGION; fdm->rmr_region.source_address = RMA_START; fdm->rmr_region.source_len = fw_dump.boot_memory_size; fdm->rmr_region.destination_address = addr; addr += fw_dump.boot_memory_size; return addr; } /** * fadump_calculate_reserve_size(): reserve variable boot area 5% of System RAM * * Function to find the largest memory size we need to reserve during early * boot process. This will be the size of the memory that is required for a * kernel to boot successfully. * * This function has been taken from phyp-assisted dump feature implementation. * * returns larger of 256MB or 5% rounded down to multiples of 256MB. * * TODO: Come up with better approach to find out more accurate memory size * that is required for a kernel to boot successfully. * */ static inline unsigned long fadump_calculate_reserve_size(void) { unsigned long size; /* * Check if the size is specified through fadump_reserve_mem= cmdline * option. If yes, then use that. */ if (fw_dump.reserve_bootvar) return fw_dump.reserve_bootvar; /* divide by 20 to get 5% of value */ size = memblock_end_of_DRAM() / 20; /* round it down in multiples of 256 */ size = size & ~0x0FFFFFFFUL; /* Truncate to memory_limit. We don't want to over reserve the memory.*/ if (memory_limit && size > memory_limit) size = memory_limit; return (size > MIN_BOOT_MEM ? size : MIN_BOOT_MEM); } /* * Calculate the total memory size required to be reserved for * firmware-assisted dump registration. */ static unsigned long get_fadump_area_size(void) { unsigned long size = 0; size += fw_dump.cpu_state_data_size; size += fw_dump.hpte_region_size; size += fw_dump.boot_memory_size; size = PAGE_ALIGN(size); return size; } int __init fadump_reserve_mem(void) { unsigned long base, size, memory_boundary; if (!fw_dump.fadump_enabled) return 0; if (!fw_dump.fadump_supported) { printk(KERN_INFO "Firmware-assisted dump is not supported on" " this hardware\n"); fw_dump.fadump_enabled = 0; return 0; } /* * Initialize boot memory size * If dump is active then we have already calculated the size during * first kernel. */ if (fdm_active) fw_dump.boot_memory_size = fdm_active->rmr_region.source_len; else fw_dump.boot_memory_size = fadump_calculate_reserve_size(); /* * Calculate the memory boundary. * If memory_limit is less than actual memory boundary then reserve * the memory for fadump beyond the memory_limit and adjust the * memory_limit accordingly, so that the running kernel can run with * specified memory_limit. */ if (memory_limit && memory_limit < memblock_end_of_DRAM()) { size = get_fadump_area_size(); if ((memory_limit + size) < memblock_end_of_DRAM()) memory_limit += size; else memory_limit = memblock_end_of_DRAM(); printk(KERN_INFO "Adjusted memory_limit for firmware-assisted" " dump, now %#016llx\n", (unsigned long long)memory_limit); } if (memory_limit) memory_boundary = memory_limit; else memory_boundary = memblock_end_of_DRAM(); if (fw_dump.dump_active) { printk(KERN_INFO "Firmware-assisted dump is active.\n"); /* * If last boot has crashed then reserve all the memory * above boot_memory_size so that we don't touch it until * dump is written to disk by userspace tool. This memory * will be released for general use once the dump is saved. */ base = fw_dump.boot_memory_size; size = memory_boundary - base; memblock_reserve(base, size); printk(KERN_INFO "Reserved %ldMB of memory at %ldMB " "for saving crash dump\n", (unsigned long)(size >> 20), (unsigned long)(base >> 20)); } else { /* Reserve the memory at the top of memory. */ size = get_fadump_area_size(); base = memory_boundary - size; memblock_reserve(base, size); printk(KERN_INFO "Reserved %ldMB of memory at %ldMB " "for firmware-assisted dump\n", (unsigned long)(size >> 20), (unsigned long)(base >> 20)); } fw_dump.reserve_dump_area_start = base; fw_dump.reserve_dump_area_size = size; return 1; } /* Look for fadump= cmdline option. */ static int __init early_fadump_param(char *p) { if (!p) return 1; if (strncmp(p, "on", 2) == 0) fw_dump.fadump_enabled = 1; else if (strncmp(p, "off", 3) == 0) fw_dump.fadump_enabled = 0; return 0; } early_param("fadump", early_fadump_param); /* Look for fadump_reserve_mem= cmdline option */ static int __init early_fadump_reserve_mem(char *p) { if (p) fw_dump.reserve_bootvar = memparse(p, &p); return 0; } early_param("fadump_reserve_mem", early_fadump_reserve_mem); static void register_fw_dump(struct fadump_mem_struct *fdm) { int rc; unsigned int wait_time; pr_debug("Registering for firmware-assisted kernel dump...\n"); /* TODO: Add upper time limit for the delay */ do { rc = rtas_call(fw_dump.ibm_configure_kernel_dump, 3, 1, NULL, FADUMP_REGISTER, fdm, sizeof(struct fadump_mem_struct)); wait_time = rtas_busy_delay_time(rc); if (wait_time) mdelay(wait_time); } while (wait_time); switch (rc) { case -1: printk(KERN_ERR "Failed to register firmware-assisted kernel" " dump. Hardware Error(%d).\n", rc); break; case -3: printk(KERN_ERR "Failed to register firmware-assisted kernel" " dump. Parameter Error(%d).\n", rc); break; case -9: printk(KERN_ERR "firmware-assisted kernel dump is already " " registered."); fw_dump.dump_registered = 1; break; case 0: printk(KERN_INFO "firmware-assisted kernel dump registration" " is successful\n"); fw_dump.dump_registered = 1; break; } } static void register_fadump(void) { /* * If no memory is reserved then we can not register for firmware- * assisted dump. */ if (!fw_dump.reserve_dump_area_size) return; /* register the future kernel dump with firmware. */ register_fw_dump(&fdm); } static int fadump_unregister_dump(struct fadump_mem_struct *fdm) { int rc = 0; unsigned int wait_time; pr_debug("Un-register firmware-assisted dump\n"); /* TODO: Add upper time limit for the delay */ do { rc = rtas_call(fw_dump.ibm_configure_kernel_dump, 3, 1, NULL, FADUMP_UNREGISTER, fdm, sizeof(struct fadump_mem_struct)); wait_time = rtas_busy_delay_time(rc); if (wait_time) mdelay(wait_time); } while (wait_time); if (rc) { printk(KERN_ERR "Failed to un-register firmware-assisted dump." " unexpected error(%d).\n", rc); return rc; } fw_dump.dump_registered = 0; return 0; } static ssize_t fadump_enabled_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sprintf(buf, "%d\n", fw_dump.fadump_enabled); } static ssize_t fadump_register_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { return sprintf(buf, "%d\n", fw_dump.dump_registered); } static ssize_t fadump_register_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { int ret = 0; if (!fw_dump.fadump_enabled || fdm_active) return -EPERM; mutex_lock(&fadump_mutex); switch (buf[0]) { case '0': if (fw_dump.dump_registered == 0) { ret = -EINVAL; goto unlock_out; } /* Un-register Firmware-assisted dump */ fadump_unregister_dump(&fdm); break; case '1': if (fw_dump.dump_registered == 1) { ret = -EINVAL; goto unlock_out; } /* Register Firmware-assisted dump */ register_fadump(); break; default: ret = -EINVAL; break; } unlock_out: mutex_unlock(&fadump_mutex); return ret < 0 ? ret : count; } static int fadump_region_show(struct seq_file *m, void *private) { const struct fadump_mem_struct *fdm_ptr; if (!fw_dump.fadump_enabled) return 0; if (fdm_active) fdm_ptr = fdm_active; else fdm_ptr = &fdm; seq_printf(m, "CPU : [%#016llx-%#016llx] %#llx bytes, " "Dumped: %#llx\n", fdm_ptr->cpu_state_data.destination_address, fdm_ptr->cpu_state_data.destination_address + fdm_ptr->cpu_state_data.source_len - 1, fdm_ptr->cpu_state_data.source_len, fdm_ptr->cpu_state_data.bytes_dumped); seq_printf(m, "HPTE: [%#016llx-%#016llx] %#llx bytes, " "Dumped: %#llx\n", fdm_ptr->hpte_region.destination_address, fdm_ptr->hpte_region.destination_address + fdm_ptr->hpte_region.source_len - 1, fdm_ptr->hpte_region.source_len, fdm_ptr->hpte_region.bytes_dumped); seq_printf(m, "DUMP: [%#016llx-%#016llx] %#llx bytes, " "Dumped: %#llx\n", fdm_ptr->rmr_region.destination_address, fdm_ptr->rmr_region.destination_address + fdm_ptr->rmr_region.source_len - 1, fdm_ptr->rmr_region.source_len, fdm_ptr->rmr_region.bytes_dumped); if (!fdm_active || (fw_dump.reserve_dump_area_start == fdm_ptr->cpu_state_data.destination_address)) return 0; /* Dump is active. Show reserved memory region. */ seq_printf(m, " : [%#016llx-%#016llx] %#llx bytes, " "Dumped: %#llx\n", (unsigned long long)fw_dump.reserve_dump_area_start, fdm_ptr->cpu_state_data.destination_address - 1, fdm_ptr->cpu_state_data.destination_address - fw_dump.reserve_dump_area_start, fdm_ptr->cpu_state_data.destination_address - fw_dump.reserve_dump_area_start); return 0; } static struct kobj_attribute fadump_attr = __ATTR(fadump_enabled, 0444, fadump_enabled_show, NULL); static struct kobj_attribute fadump_register_attr = __ATTR(fadump_registered, 0644, fadump_register_show, fadump_register_store); static int fadump_region_open(struct inode *inode, struct file *file) { return single_open(file, fadump_region_show, inode->i_private); } static const struct file_operations fadump_region_fops = { .open = fadump_region_open, .read = seq_read, .llseek = seq_lseek, .release = single_release, }; static void fadump_init_files(void) { struct dentry *debugfs_file; int rc = 0; rc = sysfs_create_file(kernel_kobj, &fadump_attr.attr); if (rc) printk(KERN_ERR "fadump: unable to create sysfs file" " fadump_enabled (%d)\n", rc); rc = sysfs_create_file(kernel_kobj, &fadump_register_attr.attr); if (rc) printk(KERN_ERR "fadump: unable to create sysfs file" " fadump_registered (%d)\n", rc); debugfs_file = debugfs_create_file("fadump_region", 0444, powerpc_debugfs_root, NULL, &fadump_region_fops); if (!debugfs_file) printk(KERN_ERR "fadump: unable to create debugfs file" " fadump_region\n"); return; } /* * Prepare for firmware-assisted dump. */ int __init setup_fadump(void) { if (!fw_dump.fadump_enabled) return 0; if (!fw_dump.fadump_supported) { printk(KERN_ERR "Firmware-assisted dump is not supported on" " this hardware\n"); return 0; } fadump_show_config(); /* Initialize the kernel dump memory structure for FAD registration. */ if (fw_dump.reserve_dump_area_size) init_fadump_mem_struct(&fdm, fw_dump.reserve_dump_area_start); fadump_init_files(); return 1; } subsys_initcall(setup_fadump);