Commit dd5f7260 authored by Vivek Goyal's avatar Vivek Goyal Committed by Linus Torvalds
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kexec: support for kexec on panic using new system call



This patch adds support for loading a kexec on panic (kdump) kernel usning
new system call.

It prepares ELF headers for memory areas to be dumped and for saved cpu
registers.  Also prepares the memory map for second kernel and limits its
boot to reserved areas only.
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: WANG Chao <chaowang@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 27f48d3e
#ifndef _ASM_X86_CRASH_H
#define _ASM_X86_CRASH_H
int crash_load_segments(struct kimage *image);
int crash_copy_backup_region(struct kimage *image);
int crash_setup_memmap_entries(struct kimage *image,
struct boot_params *params);
#endif /* _ASM_X86_CRASH_H */
......@@ -25,6 +25,8 @@
#include <asm/ptrace.h>
#include <asm/bootparam.h>
struct kimage;
/*
* KEXEC_SOURCE_MEMORY_LIMIT maximum page get_free_page can return.
* I.e. Maximum page that is mapped directly into kernel memory,
......@@ -62,6 +64,10 @@
# define KEXEC_ARCH KEXEC_ARCH_X86_64
#endif
/* Memory to backup during crash kdump */
#define KEXEC_BACKUP_SRC_START (0UL)
#define KEXEC_BACKUP_SRC_END (640 * 1024UL) /* 640K */
/*
* CPU does not save ss and sp on stack if execution is already
* running in kernel mode at the time of NMI occurrence. This code
......@@ -161,17 +167,35 @@ struct kimage_arch {
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
/* Details of backup region */
unsigned long backup_src_start;
unsigned long backup_src_sz;
/* Physical address of backup segment */
unsigned long backup_load_addr;
/* Core ELF header buffer */
void *elf_headers;
unsigned long elf_headers_sz;
unsigned long elf_load_addr;
};
#endif /* CONFIG_X86_32 */
#ifdef CONFIG_X86_64
/*
* Number of elements and order of elements in this structure should match
* with the ones in arch/x86/purgatory/entry64.S. If you make a change here
* make an appropriate change in purgatory too.
*/
struct kexec_entry64_regs {
uint64_t rax;
uint64_t rbx;
uint64_t rcx;
uint64_t rdx;
uint64_t rsi;
uint64_t rdi;
uint64_t rbx;
uint64_t rsp;
uint64_t rbp;
uint64_t rsi;
uint64_t rdi;
uint64_t r8;
uint64_t r9;
uint64_t r10;
......
......@@ -4,9 +4,14 @@
* Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
*
* Copyright (C) IBM Corporation, 2004. All rights reserved.
* Copyright (C) Red Hat Inc., 2014. All rights reserved.
* Authors:
* Vivek Goyal <vgoyal@redhat.com>
*
*/
#define pr_fmt(fmt) "kexec: " fmt
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/smp.h>
......@@ -16,6 +21,7 @@
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <asm/processor.h>
#include <asm/hardirq.h>
......@@ -28,6 +34,45 @@
#include <asm/reboot.h>
#include <asm/virtext.h>
/* Alignment required for elf header segment */
#define ELF_CORE_HEADER_ALIGN 4096
/* This primarily represents number of split ranges due to exclusion */
#define CRASH_MAX_RANGES 16
struct crash_mem_range {
u64 start, end;
};
struct crash_mem {
unsigned int nr_ranges;
struct crash_mem_range ranges[CRASH_MAX_RANGES];
};
/* Misc data about ram ranges needed to prepare elf headers */
struct crash_elf_data {
struct kimage *image;
/*
* Total number of ram ranges we have after various adjustments for
* GART, crash reserved region etc.
*/
unsigned int max_nr_ranges;
unsigned long gart_start, gart_end;
/* Pointer to elf header */
void *ehdr;
/* Pointer to next phdr */
void *bufp;
struct crash_mem mem;
};
/* Used while preparing memory map entries for second kernel */
struct crash_memmap_data {
struct boot_params *params;
/* Type of memory */
unsigned int type;
};
int in_crash_kexec;
/*
......@@ -39,6 +84,7 @@ int in_crash_kexec;
*/
crash_vmclear_fn __rcu *crash_vmclear_loaded_vmcss = NULL;
EXPORT_SYMBOL_GPL(crash_vmclear_loaded_vmcss);
unsigned long crash_zero_bytes;
static inline void cpu_crash_vmclear_loaded_vmcss(void)
{
......@@ -135,3 +181,520 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
#endif
crash_save_cpu(regs, safe_smp_processor_id());
}
#ifdef CONFIG_X86_64
static int get_nr_ram_ranges_callback(unsigned long start_pfn,
unsigned long nr_pfn, void *arg)
{
int *nr_ranges = arg;
(*nr_ranges)++;
return 0;
}
static int get_gart_ranges_callback(u64 start, u64 end, void *arg)
{
struct crash_elf_data *ced = arg;
ced->gart_start = start;
ced->gart_end = end;
/* Not expecting more than 1 gart aperture */
return 1;
}
/* Gather all the required information to prepare elf headers for ram regions */
static void fill_up_crash_elf_data(struct crash_elf_data *ced,
struct kimage *image)
{
unsigned int nr_ranges = 0;
ced->image = image;
walk_system_ram_range(0, -1, &nr_ranges,
get_nr_ram_ranges_callback);
ced->max_nr_ranges = nr_ranges;
/*
* We don't create ELF headers for GART aperture as an attempt
* to dump this memory in second kernel leads to hang/crash.
* If gart aperture is present, one needs to exclude that region
* and that could lead to need of extra phdr.
*/
walk_iomem_res("GART", IORESOURCE_MEM, 0, -1,
ced, get_gart_ranges_callback);
/*
* If we have gart region, excluding that could potentially split
* a memory range, resulting in extra header. Account for that.
*/
if (ced->gart_end)
ced->max_nr_ranges++;
/* Exclusion of crash region could split memory ranges */
ced->max_nr_ranges++;
/* If crashk_low_res is not 0, another range split possible */
if (crashk_low_res.end != 0)
ced->max_nr_ranges++;
}
static int exclude_mem_range(struct crash_mem *mem,
unsigned long long mstart, unsigned long long mend)
{
int i, j;
unsigned long long start, end;
struct crash_mem_range temp_range = {0, 0};
for (i = 0; i < mem->nr_ranges; i++) {
start = mem->ranges[i].start;
end = mem->ranges[i].end;
if (mstart > end || mend < start)
continue;
/* Truncate any area outside of range */
if (mstart < start)
mstart = start;
if (mend > end)
mend = end;
/* Found completely overlapping range */
if (mstart == start && mend == end) {
mem->ranges[i].start = 0;
mem->ranges[i].end = 0;
if (i < mem->nr_ranges - 1) {
/* Shift rest of the ranges to left */
for (j = i; j < mem->nr_ranges - 1; j++) {
mem->ranges[j].start =
mem->ranges[j+1].start;
mem->ranges[j].end =
mem->ranges[j+1].end;
}
}
mem->nr_ranges--;
return 0;
}
if (mstart > start && mend < end) {
/* Split original range */
mem->ranges[i].end = mstart - 1;
temp_range.start = mend + 1;
temp_range.end = end;
} else if (mstart != start)
mem->ranges[i].end = mstart - 1;
else
mem->ranges[i].start = mend + 1;
break;
}
/* If a split happend, add the split to array */
if (!temp_range.end)
return 0;
/* Split happened */
if (i == CRASH_MAX_RANGES - 1) {
pr_err("Too many crash ranges after split\n");
return -ENOMEM;
}
/* Location where new range should go */
j = i + 1;
if (j < mem->nr_ranges) {
/* Move over all ranges one slot towards the end */
for (i = mem->nr_ranges - 1; i >= j; i--)
mem->ranges[i + 1] = mem->ranges[i];
}
mem->ranges[j].start = temp_range.start;
mem->ranges[j].end = temp_range.end;
mem->nr_ranges++;
return 0;
}
/*
* Look for any unwanted ranges between mstart, mend and remove them. This
* might lead to split and split ranges are put in ced->mem.ranges[] array
*/
static int elf_header_exclude_ranges(struct crash_elf_data *ced,
unsigned long long mstart, unsigned long long mend)
{
struct crash_mem *cmem = &ced->mem;
int ret = 0;
memset(cmem->ranges, 0, sizeof(cmem->ranges));
cmem->ranges[0].start = mstart;
cmem->ranges[0].end = mend;
cmem->nr_ranges = 1;
/* Exclude crashkernel region */
ret = exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
if (ret)
return ret;
ret = exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
if (ret)
return ret;
/* Exclude GART region */
if (ced->gart_end) {
ret = exclude_mem_range(cmem, ced->gart_start, ced->gart_end);
if (ret)
return ret;
}
return ret;
}
static int prepare_elf64_ram_headers_callback(u64 start, u64 end, void *arg)
{
struct crash_elf_data *ced = arg;
Elf64_Ehdr *ehdr;
Elf64_Phdr *phdr;
unsigned long mstart, mend;
struct kimage *image = ced->image;
struct crash_mem *cmem;
int ret, i;
ehdr = ced->ehdr;
/* Exclude unwanted mem ranges */
ret = elf_header_exclude_ranges(ced, start, end);
if (ret)
return ret;
/* Go through all the ranges in ced->mem.ranges[] and prepare phdr */
cmem = &ced->mem;
for (i = 0; i < cmem->nr_ranges; i++) {
mstart = cmem->ranges[i].start;
mend = cmem->ranges[i].end;
phdr = ced->bufp;
ced->bufp += sizeof(Elf64_Phdr);
phdr->p_type = PT_LOAD;
phdr->p_flags = PF_R|PF_W|PF_X;
phdr->p_offset = mstart;
/*
* If a range matches backup region, adjust offset to backup
* segment.
*/
if (mstart == image->arch.backup_src_start &&
(mend - mstart + 1) == image->arch.backup_src_sz)
phdr->p_offset = image->arch.backup_load_addr;
phdr->p_paddr = mstart;
phdr->p_vaddr = (unsigned long long) __va(mstart);
phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
phdr->p_align = 0;
ehdr->e_phnum++;
pr_debug("Crash PT_LOAD elf header. phdr=%p vaddr=0x%llx, paddr=0x%llx, sz=0x%llx e_phnum=%d p_offset=0x%llx\n",
phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz,
ehdr->e_phnum, phdr->p_offset);
}
return ret;
}
static int prepare_elf64_headers(struct crash_elf_data *ced,
void **addr, unsigned long *sz)
{
Elf64_Ehdr *ehdr;
Elf64_Phdr *phdr;
unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;
unsigned char *buf, *bufp;
unsigned int cpu;
unsigned long long notes_addr;
int ret;
/* extra phdr for vmcoreinfo elf note */
nr_phdr = nr_cpus + 1;
nr_phdr += ced->max_nr_ranges;
/*
* kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
* area on x86_64 (ffffffff80000000 - ffffffffa0000000).
* I think this is required by tools like gdb. So same physical
* memory will be mapped in two elf headers. One will contain kernel
* text virtual addresses and other will have __va(physical) addresses.
*/
nr_phdr++;
elf_sz = sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr);
elf_sz = ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN);
buf = vzalloc(elf_sz);
if (!buf)
return -ENOMEM;
bufp = buf;
ehdr = (Elf64_Ehdr *)bufp;
bufp += sizeof(Elf64_Ehdr);
memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
ehdr->e_ident[EI_CLASS] = ELFCLASS64;
ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
ehdr->e_ident[EI_VERSION] = EV_CURRENT;
ehdr->e_ident[EI_OSABI] = ELF_OSABI;
memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
ehdr->e_type = ET_CORE;
ehdr->e_machine = ELF_ARCH;
ehdr->e_version = EV_CURRENT;
ehdr->e_phoff = sizeof(Elf64_Ehdr);
ehdr->e_ehsize = sizeof(Elf64_Ehdr);
ehdr->e_phentsize = sizeof(Elf64_Phdr);
/* Prepare one phdr of type PT_NOTE for each present cpu */
for_each_present_cpu(cpu) {
phdr = (Elf64_Phdr *)bufp;
bufp += sizeof(Elf64_Phdr);
phdr->p_type = PT_NOTE;
notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
phdr->p_offset = phdr->p_paddr = notes_addr;
phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);
(ehdr->e_phnum)++;
}
/* Prepare one PT_NOTE header for vmcoreinfo */
phdr = (Elf64_Phdr *)bufp;
bufp += sizeof(Elf64_Phdr);
phdr->p_type = PT_NOTE;
phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
phdr->p_filesz = phdr->p_memsz = sizeof(vmcoreinfo_note);
(ehdr->e_phnum)++;
#ifdef CONFIG_X86_64
/* Prepare PT_LOAD type program header for kernel text region */
phdr = (Elf64_Phdr *)bufp;
bufp += sizeof(Elf64_Phdr);
phdr->p_type = PT_LOAD;
phdr->p_flags = PF_R|PF_W|PF_X;
phdr->p_vaddr = (Elf64_Addr)_text;
phdr->p_filesz = phdr->p_memsz = _end - _text;
phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
(ehdr->e_phnum)++;
#endif
/* Prepare PT_LOAD headers for system ram chunks. */
ced->ehdr = ehdr;
ced->bufp = bufp;
ret = walk_system_ram_res(0, -1, ced,
prepare_elf64_ram_headers_callback);
if (ret < 0)
return ret;
*addr = buf;
*sz = elf_sz;
return 0;
}
/* Prepare elf headers. Return addr and size */
static int prepare_elf_headers(struct kimage *image, void **addr,
unsigned long *sz)
{
struct crash_elf_data *ced;
int ret;
ced = kzalloc(sizeof(*ced), GFP_KERNEL);
if (!ced)
return -ENOMEM;
fill_up_crash_elf_data(ced, image);
/* By default prepare 64bit headers */
ret = prepare_elf64_headers(ced, addr, sz);
kfree(ced);
return ret;
}
static int add_e820_entry(struct boot_params *params, struct e820entry *entry)
{
unsigned int nr_e820_entries;
nr_e820_entries = params->e820_entries;
if (nr_e820_entries >= E820MAX)
return 1;
memcpy(&params->e820_map[nr_e820_entries], entry,
sizeof(struct e820entry));
params->e820_entries++;
return 0;
}
static int memmap_entry_callback(u64 start, u64 end, void *arg)
{
struct crash_memmap_data *cmd = arg;
struct boot_params *params = cmd->params;
struct e820entry ei;
ei.addr = start;
ei.size = end - start + 1;
ei.type = cmd->type;
add_e820_entry(params, &ei);
return 0;
}
static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem,
unsigned long long mstart,
unsigned long long mend)
{
unsigned long start, end;
int ret = 0;
cmem->ranges[0].start = mstart;
cmem->ranges[0].end = mend;
cmem->nr_ranges = 1;
/* Exclude Backup region */
start = image->arch.backup_load_addr;
end = start + image->arch.backup_src_sz - 1;
ret = exclude_mem_range(cmem, start, end);
if (ret)
return ret;
/* Exclude elf header region */
start = image->arch.elf_load_addr;
end = start + image->arch.elf_headers_sz - 1;
return exclude_mem_range(cmem, start, end);
}
/* Prepare memory map for crash dump kernel */
int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
{
int i, ret = 0;
unsigned long flags;
struct e820entry ei;
struct crash_memmap_data cmd;
struct crash_mem *cmem;
cmem = vzalloc(sizeof(struct crash_mem));
if (!cmem)
return -ENOMEM;
memset(&cmd, 0, sizeof(struct crash_memmap_data));
cmd.params = params;
/* Add first 640K segment */
ei.addr = image->arch.backup_src_start;
ei.size = image->arch.backup_src_sz;
ei.type = E820_RAM;
add_e820_entry(params, &ei);
/* Add ACPI tables */
cmd.type = E820_ACPI;
flags = IORESOURCE_MEM | IORESOURCE_BUSY;
walk_iomem_res("ACPI Tables", flags, 0, -1, &cmd,
memmap_entry_callback);
/* Add ACPI Non-volatile Storage */
cmd.type = E820_NVS;
walk_iomem_res("ACPI Non-volatile Storage", flags, 0, -1, &cmd,
memmap_entry_callback);
/* Add crashk_low_res region */
if (crashk_low_res.end) {
ei.addr = crashk_low_res.start;
ei.size = crashk_low_res.end - crashk_low_res.start + 1;
ei.type = E820_RAM;
add_e820_entry(params, &ei);
}
/* Exclude some ranges from crashk_res and add rest to memmap */
ret = memmap_exclude_ranges(image, cmem, crashk_res.start,
crashk_res.end);
if (ret)
goto out;
for (i = 0; i < cmem->nr_ranges; i++) {
ei.size = cmem->ranges[i].end - cmem->ranges[i].start + 1;
/* If entry is less than a page, skip it */
if (ei.size < PAGE_SIZE)
continue;
ei.addr = cmem->ranges[i].start;
ei.type = E820_RAM;
add_e820_entry(params, &ei);
}
out:
vfree(cmem);
return ret;
}
static int determine_backup_region(u64 start, u64 end, void *arg)
{
struct kimage *image = arg;
image->arch.backup_src_start = start;
image->arch.backup_src_sz = end - start + 1;
/* Expecting only one range for backup region */
return 1;
}
int crash_load_segments(struct kimage *image)
{
unsigned long src_start, src_sz, elf_sz;
void *elf_addr;
int ret;
/*
* Determine and load a segment for backup area. First 640K RAM
* region is backup source
*/
ret = walk_system_ram_res(KEXEC_BACKUP_SRC_START, KEXEC_BACKUP_SRC_END,
image, determine_backup_region);
/* Zero or postive return values are ok */
if (ret < 0)
return ret;