// SPDX-License-Identifier: GPL-2.0
/*
 * S390 kdump implementation
 *
 * Copyright IBM Corp. 2011
 * Author(s): Michael Holzheu <holzheu@linux.vnet.ibm.com>
 */

#include <linux/crash_dump.h>
#include <asm/lowcore.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/memblock.h>
#include <linux/elf.h>
#include <asm/asm-offsets.h>
#include <asm/os_info.h>
#include <asm/elf.h>
#include <asm/ipl.h>
#include <asm/sclp.h>

#define PTR_ADD(x, y) (((char *) (x)) + ((unsigned long) (y)))
#define PTR_SUB(x, y) (((char *) (x)) - ((unsigned long) (y)))
#define PTR_DIFF(x, y) ((unsigned long)(((char *) (x)) - ((unsigned long) (y))))

static struct memblock_region oldmem_region;

static struct memblock_type oldmem_type = {
        .cnt = 1,
        .max = 1,
        .total_size = 0,
        .regions = &oldmem_region,
        .name = "oldmem",
};

struct save_area {
        struct list_head list;
        u64 psw[2];
        u64 ctrs[16];
        u64 gprs[16];
        u32 acrs[16];
        u64 fprs[16];
        u32 fpc;
        u32 prefix;
        u64 todpreg;
        u64 timer;
        u64 todcmp;
        u64 vxrs_low[16];
        __vector128 vxrs_high[16];
};

static LIST_HEAD(dump_save_areas);

/*
 * Allocate a save area
 */
struct save_area * __init save_area_alloc(bool is_boot_cpu)
{
        struct save_area *sa;

        sa = (void *) memblock_phys_alloc(sizeof(*sa), 8);
        if (!sa)
                panic("Failed to allocate save area\n");

        if (is_boot_cpu)
                list_add(&sa->list, &dump_save_areas);
        else
                list_add_tail(&sa->list, &dump_save_areas);
        return sa;
}

/*
 * Return the address of the save area for the boot CPU
 */
struct save_area * __init save_area_boot_cpu(void)
{
        return list_first_entry_or_null(&dump_save_areas, struct save_area, list);
}

/*
 * Copy CPU registers into the save area
 */
void __init save_area_add_regs(struct save_area *sa, void *regs)
{
        struct lowcore *lc;

        lc = (struct lowcore *)(regs - __LC_FPREGS_SAVE_AREA);
        memcpy(&sa->psw, &lc->psw_save_area, sizeof(sa->psw));
        memcpy(&sa->ctrs, &lc->cregs_save_area, sizeof(sa->ctrs));
        memcpy(&sa->gprs, &lc->gpregs_save_area, sizeof(sa->gprs));
        memcpy(&sa->acrs, &lc->access_regs_save_area, sizeof(sa->acrs));
        memcpy(&sa->fprs, &lc->floating_pt_save_area, sizeof(sa->fprs));
        memcpy(&sa->fpc, &lc->fpt_creg_save_area, sizeof(sa->fpc));
        memcpy(&sa->prefix, &lc->prefixreg_save_area, sizeof(sa->prefix));
        memcpy(&sa->todpreg, &lc->tod_progreg_save_area, sizeof(sa->todpreg));
        memcpy(&sa->timer, &lc->cpu_timer_save_area, sizeof(sa->timer));
        memcpy(&sa->todcmp, &lc->clock_comp_save_area, sizeof(sa->todcmp));
}

/*
 * Copy vector registers into the save area
 */
void __init save_area_add_vxrs(struct save_area *sa, __vector128 *vxrs)
{
        int i;

        /* Copy lower halves of vector registers 0-15 */
        for (i = 0; i < 16; i++)
                memcpy(&sa->vxrs_low[i], &vxrs[i].u[2], 8);
        /* Copy vector registers 16-31 */
        memcpy(sa->vxrs_high, vxrs + 16, 16 * sizeof(__vector128));
}

/*
 * Return physical address for virtual address
 */
static inline void *load_real_addr(void *addr)
{
        unsigned long real_addr;

        asm volatile(
                   "    lra     %0,0(%1)\n"
                   "    jz      0f\n"
                   "    la      %0,0\n"
                   "0:"
                   : "=a" (real_addr) : "a" (addr) : "cc");
        return (void *)real_addr;
}

/*
 * Copy memory of the old, dumped system to a kernel space virtual address
 */
int copy_oldmem_kernel(void *dst, void *src, size_t count)
{
        unsigned long from, len;
        void *ra;
        int rc;

        while (count) {
                from = __pa(src);
                if (!OLDMEM_BASE && from < sclp.hsa_size) {
                        /* Copy from zfcp/nvme dump HSA area */
                        len = min(count, sclp.hsa_size - from);
                        rc = memcpy_hsa_kernel(dst, from, len);
                        if (rc)
                                return rc;
                } else {
                        /* Check for swapped kdump oldmem areas */
                        if (OLDMEM_BASE && from - OLDMEM_BASE < OLDMEM_SIZE) {
                                from -= OLDMEM_BASE;
                                len = min(count, OLDMEM_SIZE - from);
                        } else if (OLDMEM_BASE && from < OLDMEM_SIZE) {
                                len = min(count, OLDMEM_SIZE - from);
                                from += OLDMEM_BASE;
                        } else {
                                len = count;
                        }
                        if (is_vmalloc_or_module_addr(dst)) {
                                ra = load_real_addr(dst);
                                len = min(PAGE_SIZE - offset_in_page(ra), len);
                        } else {
                                ra = dst;
                        }
                        if (memcpy_real(ra, (void *) from, len))
                                return -EFAULT;
                }
                dst += len;
                src += len;
                count -= len;
        }
        return 0;
}

/*
 * Copy memory of the old, dumped system to a user space virtual address
 */
static int copy_oldmem_user(void __user *dst, void *src, size_t count)
{
        unsigned long from, len;
        int rc;

        while (count) {
                from = __pa(src);
                if (!OLDMEM_BASE && from < sclp.hsa_size) {
                        /* Copy from zfcp/nvme dump HSA area */
                        len = min(count, sclp.hsa_size - from);
                        rc = memcpy_hsa_user(dst, from, len);
                        if (rc)
                                return rc;
                } else {
                        /* Check for swapped kdump oldmem areas */
                        if (OLDMEM_BASE && from - OLDMEM_BASE < OLDMEM_SIZE) {
                                from -= OLDMEM_BASE;
                                len = min(count, OLDMEM_SIZE - from);
                        } else if (OLDMEM_BASE && from < OLDMEM_SIZE) {
                                len = min(count, OLDMEM_SIZE - from);
                                from += OLDMEM_BASE;
                        } else {
                                len = count;
                        }
                        rc = copy_to_user_real(dst, (void *) from, count);
                        if (rc)
                                return rc;
                }
                dst += len;
                src += len;
                count -= len;
        }
        return 0;
}

/*
 * Copy one page from "oldmem"
 */
ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
                         unsigned long offset, int userbuf)
{
        void *src;
        int rc;

        if (!csize)
                return 0;
        src = (void *) (pfn << PAGE_SHIFT) + offset;
        if (userbuf)
                rc = copy_oldmem_user((void __force __user *) buf, src, csize);
        else
                rc = copy_oldmem_kernel((void *) buf, src, csize);
        return rc;
}

/*
 * Remap "oldmem" for kdump
 *
 * For the kdump reserved memory this functions performs a swap operation:
 * [0 - OLDMEM_SIZE] is mapped to [OLDMEM_BASE - OLDMEM_BASE + OLDMEM_SIZE]
 */
static int remap_oldmem_pfn_range_kdump(struct vm_area_struct *vma,
                                        unsigned long from, unsigned long pfn,
                                        unsigned long size, pgprot_t prot)
{
        unsigned long size_old;
        int rc;

        if (pfn < OLDMEM_SIZE >> PAGE_SHIFT) {
                size_old = min(size, OLDMEM_SIZE - (pfn << PAGE_SHIFT));
                rc = remap_pfn_range(vma, from,
                                     pfn + (OLDMEM_BASE >> PAGE_SHIFT),
                                     size_old, prot);
                if (rc || size == size_old)
                        return rc;
                size -= size_old;
                from += size_old;
                pfn += size_old >> PAGE_SHIFT;
        }
        return remap_pfn_range(vma, from, pfn, size, prot);
}

/*
 * Remap "oldmem" for zfcp/nvme dump
 *
 * We only map available memory above HSA size. Memory below HSA size
 * is read on demand using the copy_oldmem_page() function.
 */
static int remap_oldmem_pfn_range_zfcpdump(struct vm_area_struct *vma,
                                           unsigned long from,
                                           unsigned long pfn,
                                           unsigned long size, pgprot_t prot)
{
        unsigned long hsa_end = sclp.hsa_size;
        unsigned long size_hsa;

        if (pfn < hsa_end >> PAGE_SHIFT) {
                size_hsa = min(size, hsa_end - (pfn << PAGE_SHIFT));
                if (size == size_hsa)
                        return 0;
                size -= size_hsa;
                from += size_hsa;
                pfn += size_hsa >> PAGE_SHIFT;
        }
        return remap_pfn_range(vma, from, pfn, size, prot);
}

/*
 * Remap "oldmem" for kdump or zfcp/nvme dump
 */
int remap_oldmem_pfn_range(struct vm_area_struct *vma, unsigned long from,
                           unsigned long pfn, unsigned long size, pgprot_t prot)
{
        if (OLDMEM_BASE)
                return remap_oldmem_pfn_range_kdump(vma, from, pfn, size, prot);
        else
                return remap_oldmem_pfn_range_zfcpdump(vma, from, pfn, size,
                                                       prot);
}

static const char *nt_name(Elf64_Word type)
{
        const char *name = "LINUX";

        if (type == NT_PRPSINFO || type == NT_PRSTATUS || type == NT_PRFPREG)
                name = KEXEC_CORE_NOTE_NAME;
        return name;
}

/*
 * Initialize ELF note
 */
static void *nt_init_name(void *buf, Elf64_Word type, void *desc, int d_len,
                          const char *name)
{
        Elf64_Nhdr *note;
        u64 len;

        note = (Elf64_Nhdr *)buf;
        note->n_namesz = strlen(name) + 1;
        note->n_descsz = d_len;
        note->n_type = type;
        len = sizeof(Elf64_Nhdr);

        memcpy(buf + len, name, note->n_namesz);
        len = roundup(len + note->n_namesz, 4);

        memcpy(buf + len, desc, note->n_descsz);
        len = roundup(len + note->n_descsz, 4);

        return PTR_ADD(buf, len);
}

static inline void *nt_init(void *buf, Elf64_Word type, void *desc, int d_len)
{
        return nt_init_name(buf, type, desc, d_len, nt_name(type));
}

/*
 * Calculate the size of ELF note
 */
static size_t nt_size_name(int d_len, const char *name)
{
        size_t size;

        size = sizeof(Elf64_Nhdr);
        size += roundup(strlen(name) + 1, 4);
        size += roundup(d_len, 4);

        return size;
}

static inline size_t nt_size(Elf64_Word type, int d_len)
{
        return nt_size_name(d_len, nt_name(type));
}

/*
 * Fill ELF notes for one CPU with save area registers
 */
static void *fill_cpu_elf_notes(void *ptr, int cpu, struct save_area *sa)
{
        struct elf_prstatus nt_prstatus;
        elf_fpregset_t nt_fpregset;

        /* Prepare prstatus note */
        memset(&nt_prstatus, 0, sizeof(nt_prstatus));
        memcpy(&nt_prstatus.pr_reg.gprs, sa->gprs, sizeof(sa->gprs));
        memcpy(&nt_prstatus.pr_reg.psw, sa->psw, sizeof(sa->psw));
        memcpy(&nt_prstatus.pr_reg.acrs, sa->acrs, sizeof(sa->acrs));
        nt_prstatus.common.pr_pid = cpu;
        /* Prepare fpregset (floating point) note */
        memset(&nt_fpregset, 0, sizeof(nt_fpregset));
        memcpy(&nt_fpregset.fpc, &sa->fpc, sizeof(sa->fpc));
        memcpy(&nt_fpregset.fprs, &sa->fprs, sizeof(sa->fprs));
        /* Create ELF notes for the CPU */
        ptr = nt_init(ptr, NT_PRSTATUS, &nt_prstatus, sizeof(nt_prstatus));
        ptr = nt_init(ptr, NT_PRFPREG, &nt_fpregset, sizeof(nt_fpregset));
        ptr = nt_init(ptr, NT_S390_TIMER, &sa->timer, sizeof(sa->timer));
        ptr = nt_init(ptr, NT_S390_TODCMP, &sa->todcmp, sizeof(sa->todcmp));
        ptr = nt_init(ptr, NT_S390_TODPREG, &sa->todpreg, sizeof(sa->todpreg));
        ptr = nt_init(ptr, NT_S390_CTRS, &sa->ctrs, sizeof(sa->ctrs));
        ptr = nt_init(ptr, NT_S390_PREFIX, &sa->prefix, sizeof(sa->prefix));
        if (MACHINE_HAS_VX) {
                ptr = nt_init(ptr, NT_S390_VXRS_HIGH,
                              &sa->vxrs_high, sizeof(sa->vxrs_high));
                ptr = nt_init(ptr, NT_S390_VXRS_LOW,
                              &sa->vxrs_low, sizeof(sa->vxrs_low));
        }
        return ptr;
}

/*
 * Calculate size of ELF notes per cpu
 */
static size_t get_cpu_elf_notes_size(void)
{
        struct save_area *sa = NULL;
        size_t size;

        size =  nt_size(NT_PRSTATUS, sizeof(struct elf_prstatus));
        size +=  nt_size(NT_PRFPREG, sizeof(elf_fpregset_t));
        size +=  nt_size(NT_S390_TIMER, sizeof(sa->timer));
        size +=  nt_size(NT_S390_TODCMP, sizeof(sa->todcmp));
        size +=  nt_size(NT_S390_TODPREG, sizeof(sa->todpreg));
        size +=  nt_size(NT_S390_CTRS, sizeof(sa->ctrs));
        size +=  nt_size(NT_S390_PREFIX, sizeof(sa->prefix));
        if (MACHINE_HAS_VX) {
                size += nt_size(NT_S390_VXRS_HIGH, sizeof(sa->vxrs_high));
                size += nt_size(NT_S390_VXRS_LOW, sizeof(sa->vxrs_low));
        }

        return size;
}

/*
 * Initialize prpsinfo note (new kernel)
 */
static void *nt_prpsinfo(void *ptr)
{
        struct elf_prpsinfo prpsinfo;

        memset(&prpsinfo, 0, sizeof(prpsinfo));
        prpsinfo.pr_sname = 'R';
        strcpy(prpsinfo.pr_fname, "vmlinux");
        return nt_init(ptr, NT_PRPSINFO, &prpsinfo, sizeof(prpsinfo));
}

/*
 * Get vmcoreinfo using lowcore->vmcore_info (new kernel)
 */
static void *get_vmcoreinfo_old(unsigned long *size)
{
        char nt_name[11], *vmcoreinfo;
        Elf64_Nhdr note;
        void *addr;

        if (copy_oldmem_kernel(&addr, &S390_lowcore.vmcore_info, sizeof(addr)))
                return NULL;
        memset(nt_name, 0, sizeof(nt_name));
        if (copy_oldmem_kernel(&note, addr, sizeof(note)))
                return NULL;
        if (copy_oldmem_kernel(nt_name, addr + sizeof(note),
                               sizeof(nt_name) - 1))
                return NULL;
        if (strcmp(nt_name, VMCOREINFO_NOTE_NAME) != 0)
                return NULL;
        vmcoreinfo = kzalloc(note.n_descsz, GFP_KERNEL);
        if (!vmcoreinfo)
                return NULL;
        if (copy_oldmem_kernel(vmcoreinfo, addr + 24, note.n_descsz)) {
                kfree(vmcoreinfo);
                return NULL;
        }
        *size = note.n_descsz;
        return vmcoreinfo;
}

/*
 * Initialize vmcoreinfo note (new kernel)
 */
static void *nt_vmcoreinfo(void *ptr)
{
        const char *name = VMCOREINFO_NOTE_NAME;
        unsigned long size;
        void *vmcoreinfo;

        vmcoreinfo = os_info_old_entry(OS_INFO_VMCOREINFO, &size);
        if (vmcoreinfo)
                return nt_init_name(ptr, 0, vmcoreinfo, size, name);

        vmcoreinfo = get_vmcoreinfo_old(&size);
        if (!vmcoreinfo)
                return ptr;
        ptr = nt_init_name(ptr, 0, vmcoreinfo, size, name);
        kfree(vmcoreinfo);
        return ptr;
}

static size_t nt_vmcoreinfo_size(void)
{
        const char *name = VMCOREINFO_NOTE_NAME;
        unsigned long size;
        void *vmcoreinfo;

        vmcoreinfo = os_info_old_entry(OS_INFO_VMCOREINFO, &size);
        if (vmcoreinfo)
                return nt_size_name(size, name);

        vmcoreinfo = get_vmcoreinfo_old(&size);
        if (!vmcoreinfo)
                return 0;

        kfree(vmcoreinfo);
        return nt_size_name(size, name);
}

/*
 * Initialize final note (needed for /proc/vmcore code)
 */
static void *nt_final(void *ptr)
{
        Elf64_Nhdr *note;

        note = (Elf64_Nhdr *) ptr;
        note->n_namesz = 0;
        note->n_descsz = 0;
        note->n_type = 0;
        return PTR_ADD(ptr, sizeof(Elf64_Nhdr));
}

/*
 * Initialize ELF header (new kernel)
 */
static void *ehdr_init(Elf64_Ehdr *ehdr, int mem_chunk_cnt)
{
        memset(ehdr, 0, sizeof(*ehdr));
        memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
        ehdr->e_ident[EI_CLASS] = ELFCLASS64;
        ehdr->e_ident[EI_DATA] = ELFDATA2MSB;
        ehdr->e_ident[EI_VERSION] = EV_CURRENT;
        memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
        ehdr->e_type = ET_CORE;
        ehdr->e_machine = EM_S390;
        ehdr->e_version = EV_CURRENT;
        ehdr->e_phoff = sizeof(Elf64_Ehdr);
        ehdr->e_ehsize = sizeof(Elf64_Ehdr);
        ehdr->e_phentsize = sizeof(Elf64_Phdr);
        ehdr->e_phnum = mem_chunk_cnt + 1;
        return ehdr + 1;
}

/*
 * Return CPU count for ELF header (new kernel)
 */
static int get_cpu_cnt(void)
{
        struct save_area *sa;
        int cpus = 0;

        list_for_each_entry(sa, &dump_save_areas, list)
                if (sa->prefix != 0)
                        cpus++;
        return cpus;
}

/*
 * Return memory chunk count for ELF header (new kernel)
 */
static int get_mem_chunk_cnt(void)
{
        int cnt = 0;
        u64 idx;

        for_each_physmem_range(idx, &oldmem_type, NULL, NULL)
                cnt++;
        return cnt;
}

/*
 * Initialize ELF loads (new kernel)
 */
static void loads_init(Elf64_Phdr *phdr, u64 loads_offset)
{
        phys_addr_t start, end;
        u64 idx;

        for_each_physmem_range(idx, &oldmem_type, &start, &end) {
                phdr->p_filesz = end - start;
                phdr->p_type = PT_LOAD;
                phdr->p_offset = start;
                phdr->p_vaddr = start;
                phdr->p_paddr = start;
                phdr->p_memsz = end - start;
                phdr->p_flags = PF_R | PF_W | PF_X;
                phdr->p_align = PAGE_SIZE;
                phdr++;
        }
}

/*
 * Initialize notes (new kernel)
 */
static void *notes_init(Elf64_Phdr *phdr, void *ptr, u64 notes_offset)
{
        struct save_area *sa;
        void *ptr_start = ptr;
        int cpu;

        ptr = nt_prpsinfo(ptr);

        cpu = 1;
        list_for_each_entry(sa, &dump_save_areas, list)
                if (sa->prefix != 0)
                        ptr = fill_cpu_elf_notes(ptr, cpu++, sa);
        ptr = nt_vmcoreinfo(ptr);
        ptr = nt_final(ptr);
        memset(phdr, 0, sizeof(*phdr));
        phdr->p_type = PT_NOTE;
        phdr->p_offset = notes_offset;
        phdr->p_filesz = (unsigned long) PTR_SUB(ptr, ptr_start);
        phdr->p_memsz = phdr->p_filesz;
        return ptr;
}

static size_t get_elfcorehdr_size(int mem_chunk_cnt)
{
        size_t size;

        size = sizeof(Elf64_Ehdr);
        /* PT_NOTES */
        size += sizeof(Elf64_Phdr);
        /* nt_prpsinfo */
        size += nt_size(NT_PRPSINFO, sizeof(struct elf_prpsinfo));
        /* regsets */
        size += get_cpu_cnt() * get_cpu_elf_notes_size();
        /* nt_vmcoreinfo */
        size += nt_vmcoreinfo_size();
        /* nt_final */
        size += sizeof(Elf64_Nhdr);
        /* PT_LOADS */
        size += mem_chunk_cnt * sizeof(Elf64_Phdr);

        return size;
}

/*
 * Create ELF core header (new kernel)
 */
int elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size)
{
        Elf64_Phdr *phdr_notes, *phdr_loads;
        int mem_chunk_cnt;
        void *ptr, *hdr;
        u32 alloc_size;
        u64 hdr_off;

        /* If we are not in kdump or zfcp/nvme dump mode return */
        if (!OLDMEM_BASE && !is_ipl_type_dump())
                return 0;
        /* If we cannot get HSA size for zfcp/nvme dump return error */
        if (is_ipl_type_dump() && !sclp.hsa_size)
                return -ENODEV;

        /* For kdump, exclude previous crashkernel memory */
        if (OLDMEM_BASE) {
                oldmem_region.base = OLDMEM_BASE;
                oldmem_region.size = OLDMEM_SIZE;
                oldmem_type.total_size = OLDMEM_SIZE;
        }

        mem_chunk_cnt = get_mem_chunk_cnt();

        alloc_size = get_elfcorehdr_size(mem_chunk_cnt);

        hdr = kzalloc(alloc_size, GFP_KERNEL);

        /* Without elfcorehdr /proc/vmcore cannot be created. Thus creating
         * a dump with this crash kernel will fail. Panic now to allow other
         * dump mechanisms to take over.
         */
        if (!hdr)
                panic("s390 kdump allocating elfcorehdr failed");

        /* Init elf header */
        ptr = ehdr_init(hdr, mem_chunk_cnt);
        /* Init program headers */
        phdr_notes = ptr;
        ptr = PTR_ADD(ptr, sizeof(Elf64_Phdr));
        phdr_loads = ptr;
        ptr = PTR_ADD(ptr, sizeof(Elf64_Phdr) * mem_chunk_cnt);
        /* Init notes */
        hdr_off = PTR_DIFF(ptr, hdr);
        ptr = notes_init(phdr_notes, ptr, ((unsigned long) hdr) + hdr_off);
        /* Init loads */
        hdr_off = PTR_DIFF(ptr, hdr);
        loads_init(phdr_loads, hdr_off);
        *addr = (unsigned long long) hdr;
        *size = (unsigned long long) hdr_off;
        BUG_ON(elfcorehdr_size > alloc_size);
        return 0;
}

/*
 * Free ELF core header (new kernel)
 */
void elfcorehdr_free(unsigned long long addr)
{
        kfree((void *)(unsigned long)addr);
}

/*
 * Read from ELF header
 */
ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
{
        void *src = (void *)(unsigned long)*ppos;

        memcpy(buf, src, count);
        *ppos += count;
        return count;
}

/*
 * Read from ELF notes data
 */
ssize_t elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos)
{
        void *src = (void *)(unsigned long)*ppos;

        memcpy(buf, src, count);
        *ppos += count;
        return count;
}