From 6b1ab74a9917012d0c559edc4ed299d9228ac89f Mon Sep 17 00:00:00 2001 From: Felix Fietkau Date: Sat, 8 Jul 2017 08:26:47 +0200 Subject: kernel: add the new 'crashlog' feature this tries to store kernel oops/panic logs in a fixed location in RAM to recover them available to user space using debugfs Signed-off-by: Felix Fietkau --- include/linux/crashlog.h | 17 ++++ init/Kconfig | 4 + kernel/Makefile | 1 + kernel/crashlog.c | 213 +++++++++++++++++++++++++++++++++++++++++++++++ kernel/module.c | 3 + mm/bootmem.c | 2 + mm/memblock.c | 5 ++ 7 files changed, 245 insertions(+) create mode 100644 include/linux/crashlog.h create mode 100644 kernel/crashlog.c --- /dev/null +++ b/include/linux/crashlog.h @@ -0,0 +1,17 @@ +#ifndef __CRASHLOG_H +#define __CRASHLOG_H + +#ifdef CONFIG_CRASHLOG +void crashlog_init_bootmem(struct bootmem_data *bdata); +void crashlog_init_memblock(phys_addr_t addr, phys_addr_t size); +#else +static inline void crashlog_init_bootmem(struct bootmem_data *bdata) +{ +} + +static inline void crashlog_init_memblock(phys_addr_t addr, phys_addr_t size) +{ +} +#endif + +#endif --- a/init/Kconfig +++ b/init/Kconfig @@ -1298,6 +1298,10 @@ config RELAY If unsure, say N. +config CRASHLOG + bool "Crash logging" + depends on (!NO_BOOTMEM || HAVE_MEMBLOCK) + config BLK_DEV_INITRD bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support" depends on BROKEN || !FRV --- a/kernel/Makefile +++ b/kernel/Makefile @@ -113,6 +113,7 @@ obj-$(CONFIG_TORTURE_TEST) += torture.o obj-$(CONFIG_MEMBARRIER) += membarrier.o obj-$(CONFIG_HAS_IOMEM) += memremap.o +obj-$(CONFIG_CRASHLOG) += crashlog.o $(obj)/configs.o: $(obj)/config_data.h --- /dev/null +++ b/kernel/crashlog.c @@ -0,0 +1,213 @@ +/* + * Crash information logger + * Copyright (C) 2010 Felix Fietkau + * + * Based on ramoops.c + * Copyright (C) 2010 Marco Stornelli + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * 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. + * + * 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., 51 Franklin St, Fifth Floor, Boston, MA + * 02110-1301 USA + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define CRASHLOG_PAGES 4 +#define CRASHLOG_SIZE (CRASHLOG_PAGES * PAGE_SIZE) +#define CRASHLOG_MAGIC 0xa1eedead + +/* + * Start the log at 1M before the end of RAM, as some boot loaders like + * to use the end of the RAM for stack usage and other things + * If this fails, fall back to using the last part. + */ +#define CRASHLOG_OFFSET (1024 * 1024) + +struct crashlog_data { + u32 magic; + u32 len; + u8 data[]; +}; + +static struct debugfs_blob_wrapper crashlog_blob; +static unsigned long crashlog_addr = 0; +static struct crashlog_data *crashlog_buf; +static struct kmsg_dumper dump; +static bool first = true; + +extern struct list_head *crashlog_modules; + +static bool crashlog_set_addr(phys_addr_t addr, phys_addr_t size) +{ + /* Limit to lower 64 MB to avoid highmem */ + phys_addr_t limit = 64 * 1024 * 1024; + + if (crashlog_addr) + return false; + + if (addr > limit) + return false; + + if (addr + size > limit) + size = limit - addr; + + crashlog_addr = addr; + + if (addr + size > CRASHLOG_OFFSET) + crashlog_addr += size - CRASHLOG_OFFSET; + + return true; +} + +#ifndef CONFIG_NO_BOOTMEM +void __init crashlog_init_bootmem(bootmem_data_t *bdata) +{ + phys_addr_t start, end; + + start = PFN_PHYS(bdata->node_low_pfn); + end = PFN_PHYS(bdata->node_min_pfn); + if (!crashlog_set_addr(start, end - start)) + return; + + if (reserve_bootmem(crashlog_addr, CRASHLOG_SIZE, BOOTMEM_EXCLUSIVE) < 0) { + printk("Crashlog failed to allocate RAM at address 0x%lx\n", + crashlog_addr); + crashlog_addr = 0; + } +} +#endif + +#ifdef CONFIG_HAVE_MEMBLOCK +void __init_memblock crashlog_init_memblock(phys_addr_t addr, phys_addr_t size) +{ + if (!crashlog_set_addr(addr, size)) + return; + + if (memblock_reserve(crashlog_addr, CRASHLOG_SIZE)) { + printk("Crashlog failed to allocate RAM at address 0x%lx\n", + crashlog_addr); + crashlog_addr = 0; + } +} +#endif + +static void __init crashlog_copy(void) +{ + if (crashlog_buf->magic != CRASHLOG_MAGIC) + return; + + if (!crashlog_buf->len || crashlog_buf->len > + CRASHLOG_SIZE - sizeof(*crashlog_buf)) + return; + + crashlog_blob.size = crashlog_buf->len; + crashlog_blob.data = kmemdup(crashlog_buf->data, + crashlog_buf->len, GFP_KERNEL); + + debugfs_create_blob("crashlog", 0700, NULL, &crashlog_blob); +} + +static int get_maxlen(void) +{ + return CRASHLOG_SIZE - sizeof(*crashlog_buf) - crashlog_buf->len; +} + +static void crashlog_printf(const char *fmt, ...) +{ + va_list args; + int len = get_maxlen(); + + if (!len) + return; + + va_start(args, fmt); + crashlog_buf->len += vscnprintf( + &crashlog_buf->data[crashlog_buf->len], + len, fmt, args); + va_end(args); +} + +static void crashlog_do_dump(struct kmsg_dumper *dumper, + enum kmsg_dump_reason reason) +{ + struct timeval tv; + struct module *m; + char *buf; + size_t len; + + if (!first) + crashlog_printf("\n===================================\n"); + + do_gettimeofday(&tv); + crashlog_printf("Time: %lu.%lu\n", + (long)tv.tv_sec, (long)tv.tv_usec); + + if (first) { + crashlog_printf("Modules:"); + list_for_each_entry(m, crashlog_modules, list) { + crashlog_printf("\t%s@%p+%x", m->name, + m->core_layout.base, m->core_layout.size, + m->init_layout.base, m->init_layout.size); + } + crashlog_printf("\n"); + first = false; + } + + buf = (char *)&crashlog_buf->data[crashlog_buf->len]; + + kmsg_dump_get_buffer(dumper, true, buf, get_maxlen(), &len); + + crashlog_buf->len += len; +} + + +int __init crashlog_init_fs(void) +{ + struct page *pages[CRASHLOG_PAGES]; + pgprot_t prot; + int i; + + if (!crashlog_addr) { + printk("No memory allocated for crashlog\n"); + return -ENOMEM; + } + + printk("Crashlog allocated RAM at address 0x%lx\n", (unsigned long) crashlog_addr); + for (i = 0; i < CRASHLOG_PAGES; i++) + pages[i] = pfn_to_page((crashlog_addr >> PAGE_SHIFT) + i); + + prot = pgprot_writecombine(PAGE_KERNEL); + crashlog_buf = vmap(pages, CRASHLOG_PAGES, VM_MAP, prot); + + crashlog_copy(); + + crashlog_buf->magic = CRASHLOG_MAGIC; + crashlog_buf->len = 0; + + dump.max_reason = KMSG_DUMP_OOPS; + dump.dump = crashlog_do_dump; + kmsg_dump_register(&dump); + + return 0; +} +module_init(crashlog_init_fs); --- a/kernel/module.c +++ b/kernel/module.c @@ -253,6 +253,9 @@ static void mod_update_bounds(struct mod #ifdef CONFIG_KGDB_KDB struct list_head *kdb_modules = &modules; /* kdb needs the list of modules */ #endif /* CONFIG_KGDB_KDB */ +#ifdef CONFIG_CRASHLOG +struct list_head *crashlog_modules = &modules; +#endif static void module_assert_mutex(void) { --- a/mm/bootmem.c +++ b/mm/bootmem.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include @@ -174,6 +175,7 @@ static unsigned long __init free_all_boo if (!bdata->node_bootmem_map) return 0; + crashlog_init_bootmem(bdata); map = bdata->node_bootmem_map; start = bdata->node_min_pfn; end = bdata->node_low_pfn; --- a/mm/memblock.c +++ b/mm/memblock.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include @@ -499,6 +500,8 @@ static void __init_memblock memblock_ins memblock_set_region_node(rgn, nid); type->cnt++; type->total_size += size; + if (type == &memblock.memory) + crashlog_init_memblock(base, size); } /** @@ -538,6 +541,8 @@ int __init_memblock memblock_add_range(s type->regions[0].flags = flags; memblock_set_region_node(&type->regions[0], nid); type->total_size = size; + if (type == &memblock.memory) + crashlog_init_memblock(base, size); return 0; } repeat: