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linux-sg2042/arch/x86/kernel/crash.c

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/*
* Architecture specific (i386/x86_64) functions for kexec based crash dumps.
*
* 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>
#include <linux/reboot.h>
#include <linux/kexec.h>
#include <linux/delay.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <asm/processor.h>
#include <asm/hardirq.h>
#include <asm/nmi.h>
#include <asm/hw_irq.h>
#include <asm/apic.h>
#include <asm/e820/types.h>
#include <asm/io_apic.h>
#include <asm/hpet.h>
#include <linux/kdebug.h>
#include <asm/cpu.h>
#include <asm/reboot.h>
#include <asm/virtext.h>
#include <asm/intel_pt.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
* crash reserved region, etc.
*/
unsigned int max_nr_ranges;
/* 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;
};
/*
* This is used to VMCLEAR all VMCSs loaded on the
* processor. And when loading kvm_intel module, the
* callback function pointer will be assigned.
*
* protected by rcu.
*/
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)
{
crash_vmclear_fn *do_vmclear_operation = NULL;
rcu_read_lock();
do_vmclear_operation = rcu_dereference(crash_vmclear_loaded_vmcss);
if (do_vmclear_operation)
do_vmclear_operation();
rcu_read_unlock();
}
#if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
{
#ifdef CONFIG_X86_32
struct pt_regs fixed_regs;
if (!user_mode(regs)) {
crash_fixup_ss_esp(&fixed_regs, regs);
regs = &fixed_regs;
}
#endif
crash_save_cpu(regs, cpu);
/*
* VMCLEAR VMCSs loaded on all cpus if needed.
*/
cpu_crash_vmclear_loaded_vmcss();
/* Disable VMX or SVM if needed.
*
* We need to disable virtualization on all CPUs.
* Having VMX or SVM enabled on any CPU may break rebooting
* after the kdump kernel has finished its task.
*/
cpu_emergency_vmxoff();
cpu_emergency_svm_disable();
/*
* Disable Intel PT to stop its logging
*/
cpu_emergency_stop_pt();
disable_local_APIC();
}
void kdump_nmi_shootdown_cpus(void)
{
nmi_shootdown_cpus(kdump_nmi_callback);
disable_local_APIC();
}
/* Override the weak function in kernel/panic.c */
void crash_smp_send_stop(void)
{
static int cpus_stopped;
if (cpus_stopped)
return;
if (smp_ops.crash_stop_other_cpus)
smp_ops.crash_stop_other_cpus();
else
smp_send_stop();
cpus_stopped = 1;
}
#else
void crash_smp_send_stop(void)
{
/* There are no cpus to shootdown */
}
#endif
void native_machine_crash_shutdown(struct pt_regs *regs)
{
/* This function is only called after the system
* has panicked or is otherwise in a critical state.
* The minimum amount of code to allow a kexec'd kernel
* to run successfully needs to happen here.
*
* In practice this means shooting down the other cpus in
* an SMP system.
*/
/* The kernel is broken so disable interrupts */
local_irq_disable();
crash_smp_send_stop();
/*
* VMCLEAR VMCSs loaded on this cpu if needed.
*/
cpu_crash_vmclear_loaded_vmcss();
/* Booting kdump kernel with VMX or SVM enabled won't work,
* because (among other limitations) we can't disable paging
* with the virt flags.
*/
cpu_emergency_vmxoff();
cpu_emergency_svm_disable();
/*
* Disable Intel PT to stop its logging
*/
cpu_emergency_stop_pt();
#ifdef CONFIG_X86_IO_APIC
/* Prevent crash_kexec() from deadlocking on ioapic_lock. */
ioapic_zap_locks();
disable_IO_APIC();
#endif
lapic_shutdown();
#ifdef CONFIG_HPET_TIMER
hpet_disable();
#endif
crash_save_cpu(regs, safe_smp_processor_id());
}
#ifdef CONFIG_KEXEC_FILE
static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
{
unsigned int *nr_ranges = arg;
(*nr_ranges)++;
return 0;
}
/* 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_res(0, -1, &nr_ranges,
get_nr_ram_ranges_callback);
ced->max_nr_ranges = 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)
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;
if (crashk_low_res.end) {
ret = exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
if (ret)
return ret;
}
return ret;
}
static int prepare_elf64_ram_headers_callback(struct resource *res, 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, res->start, res->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 = VMCOREINFO_NOTE_SIZE;
(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 e820_entry *entry)
{
unsigned int nr_e820_entries;
nr_e820_entries = params->e820_entries;
if (nr_e820_entries >= E820_MAX_ENTRIES_ZEROPAGE)
return 1;
memcpy(&params->e820_table[nr_e820_entries], entry,
sizeof(struct e820_entry));
params->e820_entries++;
return 0;
}
static int memmap_entry_callback(struct resource *res, void *arg)
{
struct crash_memmap_data *cmd = arg;
struct boot_params *params = cmd->params;
struct e820_entry ei;
ei.addr = res->start;
ei.size = resource_size(res);
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 e820_entry 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_TYPE_RAM;
add_e820_entry(params, &ei);
/* Add ACPI tables */
cmd.type = E820_TYPE_ACPI;
flags = IORESOURCE_MEM | IORESOURCE_BUSY;
walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1, &cmd,
memmap_entry_callback);
/* Add ACPI Non-volatile Storage */
cmd.type = E820_TYPE_NVS;
walk_iomem_res_desc(IORES_DESC_ACPI_NV_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_TYPE_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_TYPE_RAM;
add_e820_entry(params, &ei);
}
out:
vfree(cmem);
return ret;
}
static int determine_backup_region(struct resource *res, void *arg)
{
struct kimage *image = arg;
image->arch.backup_src_start = res->start;
image->arch.backup_src_sz = resource_size(res);
/* Expecting only one range for backup region */
return 1;
}
int crash_load_segments(struct kimage *image)
{
int ret;
struct kexec_buf kbuf = { .image = image, .buf_min = 0,
.buf_max = ULONG_MAX, .top_down = false };
/*
* 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;
/* Add backup segment. */
if (image->arch.backup_src_sz) {
kbuf.buffer = &crash_zero_bytes;
kbuf.bufsz = sizeof(crash_zero_bytes);
kbuf.memsz = image->arch.backup_src_sz;
kbuf.buf_align = PAGE_SIZE;
/*
* Ideally there is no source for backup segment. This is
* copied in purgatory after crash. Just add a zero filled
* segment for now to make sure checksum logic works fine.
*/
ret = kexec_add_buffer(&kbuf);
if (ret)
return ret;
image->arch.backup_load_addr = kbuf.mem;
pr_debug("Loaded backup region at 0x%lx backup_start=0x%lx memsz=0x%lx\n",
image->arch.backup_load_addr,
image->arch.backup_src_start, kbuf.memsz);
}
/* Prepare elf headers and add a segment */
ret = prepare_elf_headers(image, &kbuf.buffer, &kbuf.bufsz);
if (ret)
return ret;
image->arch.elf_headers = kbuf.buffer;
image->arch.elf_headers_sz = kbuf.bufsz;
kbuf.memsz = kbuf.bufsz;
kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
ret = kexec_add_buffer(&kbuf);
if (ret) {
vfree((void *)image->arch.elf_headers);
return ret;
}
image->arch.elf_load_addr = kbuf.mem;
pr_debug("Loaded ELF headers at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
image->arch.elf_load_addr, kbuf.bufsz, kbuf.bufsz);
return ret;
}
#endif /* CONFIG_KEXEC_FILE */
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