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a4e92ce8e4
One of the primary issues with Firmware Assisted Dump (fadump) on Power
is that it needs a large amount of memory to be reserved. On large
systems with TeraBytes of memory, this reservation can be quite
significant.
In some cases, fadump fails if the memory reserved is insufficient, or
if the reserved memory was DLPAR hot-removed.
In the normal case, post reboot, the preserved memory is filtered to
extract only relevant areas of interest using the makedumpfile tool.
While the tool provides flexibility to determine what needs to be part
of the dump and what memory to filter out, all supported distributions
default this to "Capture only kernel data and nothing else".
We take advantage of this default and the Linux kernel's Contiguous
Memory Allocator (CMA) to fundamentally change the memory reservation
model for fadump.
Instead of setting aside a significant chunk of memory nobody can use,
this patch uses CMA instead, to reserve a significant chunk of memory
that the kernel is prevented from using (due to MIGRATE_CMA), but
applications are free to use it. With this fadump will still be able
to capture all of the kernel memory and most of the user space memory
except the user pages that were present in CMA region.
Essentially, on a P9 LPAR with 2 cores, 8GB RAM and current upstream:
[root@zzxx-yy10 ~]# free -m
total used free shared buff/cache available
Mem: 7557 193 6822 12 541 6725
Swap: 4095 0 4095
With this patch:
[root@zzxx-yy10 ~]# free -m
total used free shared buff/cache available
Mem: 8133 194 7464 12 475 7338
Swap: 4095 0 4095
Changes made here are completely transparent to how fadump has
traditionally worked.
Thanks to Aneesh Kumar and Anshuman Khandual for helping us understand
CMA and its usage.
TODO:
- Handle case where CMA reservation spans nodes.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
223 lines
6.3 KiB
C
223 lines
6.3 KiB
C
/*
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* Firmware Assisted dump header file.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright 2011 IBM Corporation
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* Author: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
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*/
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#ifndef __PPC64_FA_DUMP_H__
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#define __PPC64_FA_DUMP_H__
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#ifdef CONFIG_FA_DUMP
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/*
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* The RMA region will be saved for later dumping when kernel crashes.
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* RMA is Real Mode Area, the first block of logical memory address owned
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* by logical partition, containing the storage that may be accessed with
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* translate off.
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*/
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#define RMA_START 0x0
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#define RMA_END (ppc64_rma_size)
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/*
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* On some Power systems where RMO is 128MB, it still requires minimum of
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* 256MB for kernel to boot successfully. When kdump infrastructure is
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* configured to save vmcore over network, we run into OOM issue while
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* loading modules related to network setup. Hence we need aditional 64M
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* of memory to avoid OOM issue.
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*/
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#define MIN_BOOT_MEM (((RMA_END < (0x1UL << 28)) ? (0x1UL << 28) : RMA_END) \
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+ (0x1UL << 26))
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/* The upper limit percentage for user specified boot memory size (25%) */
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#define MAX_BOOT_MEM_RATIO 4
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#define memblock_num_regions(memblock_type) (memblock.memblock_type.cnt)
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/* Alignement per CMA requirement. */
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#define FADUMP_CMA_ALIGNMENT (PAGE_SIZE << \
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max_t(unsigned long, MAX_ORDER - 1, pageblock_order))
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/* Firmware provided dump sections */
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#define FADUMP_CPU_STATE_DATA 0x0001
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#define FADUMP_HPTE_REGION 0x0002
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#define FADUMP_REAL_MODE_REGION 0x0011
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/* Dump request flag */
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#define FADUMP_REQUEST_FLAG 0x00000001
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/* FAD commands */
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#define FADUMP_REGISTER 1
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#define FADUMP_UNREGISTER 2
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#define FADUMP_INVALIDATE 3
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/* Dump status flag */
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#define FADUMP_ERROR_FLAG 0x2000
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#define FADUMP_CPU_ID_MASK ((1UL << 32) - 1)
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#define CPU_UNKNOWN (~((u32)0))
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/* Utility macros */
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#define SKIP_TO_NEXT_CPU(reg_entry) \
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({ \
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while (be64_to_cpu(reg_entry->reg_id) != REG_ID("CPUEND")) \
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reg_entry++; \
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reg_entry++; \
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})
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extern int crashing_cpu;
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/* Kernel Dump section info */
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struct fadump_section {
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__be32 request_flag;
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__be16 source_data_type;
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__be16 error_flags;
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__be64 source_address;
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__be64 source_len;
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__be64 bytes_dumped;
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__be64 destination_address;
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};
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/* ibm,configure-kernel-dump header. */
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struct fadump_section_header {
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__be32 dump_format_version;
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__be16 dump_num_sections;
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__be16 dump_status_flag;
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__be32 offset_first_dump_section;
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/* Fields for disk dump option. */
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__be32 dd_block_size;
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__be64 dd_block_offset;
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__be64 dd_num_blocks;
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__be32 dd_offset_disk_path;
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/* Maximum time allowed to prevent an automatic dump-reboot. */
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__be32 max_time_auto;
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};
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/*
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* Firmware Assisted dump memory structure. This structure is required for
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* registering future kernel dump with power firmware through rtas call.
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*
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* No disk dump option. Hence disk dump path string section is not included.
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*/
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struct fadump_mem_struct {
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struct fadump_section_header header;
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/* Kernel dump sections */
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struct fadump_section cpu_state_data;
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struct fadump_section hpte_region;
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struct fadump_section rmr_region;
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};
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/* Firmware-assisted dump configuration details. */
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struct fw_dump {
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unsigned long cpu_state_data_size;
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unsigned long hpte_region_size;
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unsigned long boot_memory_size;
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unsigned long reserve_dump_area_start;
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unsigned long reserve_dump_area_size;
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/* cmd line option during boot */
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unsigned long reserve_bootvar;
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unsigned long fadumphdr_addr;
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unsigned long cpu_notes_buf;
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unsigned long cpu_notes_buf_size;
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int ibm_configure_kernel_dump;
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unsigned long fadump_enabled:1;
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unsigned long fadump_supported:1;
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unsigned long dump_active:1;
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unsigned long dump_registered:1;
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unsigned long nocma:1;
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};
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/*
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* Copy the ascii values for first 8 characters from a string into u64
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* variable at their respective indexes.
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* e.g.
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* The string "FADMPINF" will be converted into 0x4641444d50494e46
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*/
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static inline u64 str_to_u64(const char *str)
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{
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u64 val = 0;
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int i;
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for (i = 0; i < sizeof(val); i++)
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val = (*str) ? (val << 8) | *str++ : val << 8;
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return val;
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}
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#define STR_TO_HEX(x) str_to_u64(x)
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#define REG_ID(x) str_to_u64(x)
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#define FADUMP_CRASH_INFO_MAGIC STR_TO_HEX("FADMPINF")
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#define REGSAVE_AREA_MAGIC STR_TO_HEX("REGSAVE")
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/* The firmware-assisted dump format.
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*
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* The register save area is an area in the partition's memory used to preserve
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* the register contents (CPU state data) for the active CPUs during a firmware
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* assisted dump. The dump format contains register save area header followed
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* by register entries. Each list of registers for a CPU starts with
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* "CPUSTRT" and ends with "CPUEND".
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*/
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/* Register save area header. */
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struct fadump_reg_save_area_header {
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__be64 magic_number;
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__be32 version;
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__be32 num_cpu_offset;
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};
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/* Register entry. */
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struct fadump_reg_entry {
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__be64 reg_id;
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__be64 reg_value;
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};
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/* fadump crash info structure */
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struct fadump_crash_info_header {
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u64 magic_number;
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u64 elfcorehdr_addr;
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u32 crashing_cpu;
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struct pt_regs regs;
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struct cpumask online_mask;
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};
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struct fad_crash_memory_ranges {
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unsigned long long base;
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unsigned long long size;
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};
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extern int is_fadump_boot_memory_area(u64 addr, ulong size);
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extern int early_init_dt_scan_fw_dump(unsigned long node,
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const char *uname, int depth, void *data);
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extern int fadump_reserve_mem(void);
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extern int setup_fadump(void);
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extern int is_fadump_active(void);
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extern int should_fadump_crash(void);
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extern void crash_fadump(struct pt_regs *, const char *);
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extern void fadump_cleanup(void);
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#else /* CONFIG_FA_DUMP */
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static inline int is_fadump_active(void) { return 0; }
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static inline int should_fadump_crash(void) { return 0; }
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static inline void crash_fadump(struct pt_regs *regs, const char *str) { }
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#endif
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#endif
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