/* * 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 static struct fw_dump fw_dump; /* 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. */ if (of_get_flat_dt_prop(node, "ibm,kernel-dump", NULL)) 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; } /** * 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 */ 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);