/*
 * 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/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(u64 start, u64 end, 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(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_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1, &cmd,
                       memmap_entry_callback);

        /* Add ACPI Non-volatile Storage */
        cmd.type = E820_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_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)
{
        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 */