// 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 <linux/export.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 <linux/uio.h>
#include <asm/asm-offsets.h>
#include <asm/os_info.h>
#include <asm/elf.h>
#include <asm/ipl.h>
#include <asm/sclp.h>
#include <asm/maccess.h>
#include <asm/fpu.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;
        u32 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 = memblock_alloc_or_panic(sizeof(*sa), 8);

        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++)
                sa->vxrs_low[i] = vxrs[i].low;
        /* Copy vector registers 16-31 */
        memcpy(sa->vxrs_high, vxrs + 16, 16 * sizeof(__vector128));
}

static size_t copy_oldmem_iter(struct iov_iter *iter, unsigned long src, size_t count)
{
        size_t len, copied, res = 0;

        while (count) {
                if (!oldmem_data.start && src < sclp.hsa_size) {
                        /* Copy from zfcp/nvme dump HSA area */
                        len = min(count, sclp.hsa_size - src);
                        copied = memcpy_hsa_iter(iter, src, len);
                } else {
                        /* Check for swapped kdump oldmem areas */
                        if (oldmem_data.start && src - oldmem_data.start < oldmem_data.size) {
                                src -= oldmem_data.start;
                                len = min(count, oldmem_data.size - src);
                        } else if (oldmem_data.start && src < oldmem_data.size) {
                                len = min(count, oldmem_data.size - src);
                                src += oldmem_data.start;
                        } else {
                                len = count;
                        }
                        copied = memcpy_real_iter(iter, src, len);
                }
                count -= copied;
                src += copied;
                res += copied;
                if (copied < len)
                        break;
        }
        return res;
}

int copy_oldmem_kernel(void *dst, unsigned long src, size_t count)
{
        struct iov_iter iter;
        struct kvec kvec;

        kvec.iov_base = dst;
        kvec.iov_len = count;
        iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);
        if (copy_oldmem_iter(&iter, src, count) < count)
                return -EFAULT;
        return 0;
}

/*
 * Copy one page from "oldmem"
 */
ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize,
                         unsigned long offset)
{
        unsigned long src;

        src = pfn_to_phys(pfn) + offset;
        return copy_oldmem_iter(iter, src, csize);
}

/*
 * 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_data.size >> PAGE_SHIFT) {
                size_old = min(size, oldmem_data.size - (pfn << PAGE_SHIFT));
                rc = remap_pfn_range(vma, from,
                                     pfn + (oldmem_data.start >> 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_data.start)
                return remap_oldmem_pfn_range_kdump(vma, from, pfn, size, prot);
        else
                return remap_oldmem_pfn_range_zfcpdump(vma, from, pfn, size,
                                                       prot);
}

/*
 * Return true only when in a kdump or stand-alone kdump environment.
 * Note that /proc/vmcore might also be available in "standard zfcp/nvme dump"
 * environments, where this function returns false; see dump_available().
 */
bool is_kdump_kernel(void)
{
        return oldmem_data.start;
}
EXPORT_SYMBOL_GPL(is_kdump_kernel);

/*
 * 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);
}

#define nt_init(buf, type, desc) \
        nt_init_name(buf, NT_ ## type, &(desc), sizeof(desc), NN_ ## 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;
}

#define nt_size(type, desc) nt_size_name(sizeof(desc), NN_ ## 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, PRSTATUS, nt_prstatus);
        ptr = nt_init(ptr, PRFPREG, nt_fpregset);
        ptr = nt_init(ptr, S390_TIMER, sa->timer);
        ptr = nt_init(ptr, S390_TODCMP, sa->todcmp);
        ptr = nt_init(ptr, S390_TODPREG, sa->todpreg);
        ptr = nt_init(ptr, S390_CTRS, sa->ctrs);
        ptr = nt_init(ptr, S390_PREFIX, sa->prefix);
        if (cpu_has_vx()) {
                ptr = nt_init(ptr, S390_VXRS_HIGH, sa->vxrs_high);
                ptr = nt_init(ptr, S390_VXRS_LOW, 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(PRSTATUS, struct elf_prstatus);
        size += nt_size(PRFPREG, elf_fpregset_t);
        size += nt_size(S390_TIMER, sa->timer);
        size += nt_size(S390_TODCMP, sa->todcmp);
        size += nt_size(S390_TODPREG, sa->todpreg);
        size += nt_size(S390_CTRS, sa->ctrs);
        size += nt_size(S390_PREFIX, sa->prefix);
        if (cpu_has_vx()) {
                size += nt_size(S390_VXRS_HIGH, sa->vxrs_high);
                size += nt_size(S390_VXRS_LOW, 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';
        strscpy(prpsinfo.pr_fname, "vmlinux");
        return nt_init(ptr, PRPSINFO, prpsinfo);
}

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

        if (copy_oldmem_kernel(&addr, __LC_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 phdr_count)
{
        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);
        /* Number of PT_LOAD program headers plus PT_NOTE program header */
        ehdr->e_phnum = phdr_count + 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;
}

static void fill_ptload(Elf64_Phdr *phdr, unsigned long paddr,
                unsigned long vaddr, unsigned long size)
{
        phdr->p_type = PT_LOAD;
        phdr->p_vaddr = vaddr;
        phdr->p_offset = paddr;
        phdr->p_paddr = paddr;
        phdr->p_filesz = size;
        phdr->p_memsz = size;
        phdr->p_flags = PF_R | PF_W | PF_X;
        phdr->p_align = PAGE_SIZE;
}

/*
 * Initialize ELF loads (new kernel)
 */
static void loads_init(Elf64_Phdr *phdr, bool os_info_has_vm)
{
        unsigned long old_identity_base = 0;
        phys_addr_t start, end;
        u64 idx;

        if (os_info_has_vm)
                old_identity_base = os_info_old_value(OS_INFO_IDENTITY_BASE);
        for_each_physmem_range(idx, &oldmem_type, &start, &end) {
                fill_ptload(phdr, start, old_identity_base + start,
                            end - start);
                phdr++;
        }
}

static bool os_info_has_vm(void)
{
        return os_info_old_value(OS_INFO_KASLR_OFFSET);
}

#ifdef CONFIG_PROC_VMCORE_DEVICE_RAM
/*
 * Fill PT_LOAD for a physical memory range owned by a device and detected by
 * its device driver.
 */
void elfcorehdr_fill_device_ram_ptload_elf64(Elf64_Phdr *phdr,
                unsigned long long paddr, unsigned long long size)
{
        unsigned long old_identity_base = 0;

        if (os_info_has_vm())
                old_identity_base = os_info_old_value(OS_INFO_IDENTITY_BASE);
        fill_ptload(phdr, paddr, old_identity_base + paddr, size);
}
#endif

/*
 * Prepare PT_LOAD type program header for kernel image region
 */
static void text_init(Elf64_Phdr *phdr)
{
        unsigned long start_phys = os_info_old_value(OS_INFO_IMAGE_PHYS);
        unsigned long start = os_info_old_value(OS_INFO_IMAGE_START);
        unsigned long end = os_info_old_value(OS_INFO_IMAGE_END);

        phdr->p_type = PT_LOAD;
        phdr->p_vaddr = start;
        phdr->p_filesz = end - start;
        phdr->p_memsz = end - start;
        phdr->p_offset = start_phys;
        phdr->p_paddr = start_phys;
        phdr->p_flags = PF_R | PF_W | PF_X;
        phdr->p_align = PAGE_SIZE;
}

/*
 * 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 phdr_count)
{
        size_t size;

        size = sizeof(Elf64_Ehdr);
        /* PT_NOTES */
        size += sizeof(Elf64_Phdr);
        /* nt_prpsinfo */
        size += nt_size(PRPSINFO, 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 += phdr_count * 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, *phdr_text;
        int mem_chunk_cnt, phdr_text_cnt;
        size_t alloc_size;
        void *ptr, *hdr;
        u64 hdr_off;

        /* If we are not in kdump or zfcp/nvme dump mode return */
        if (!oldmem_data.start && !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_data.start) {
                oldmem_region.base = oldmem_data.start;
                oldmem_region.size = oldmem_data.size;
                oldmem_type.total_size = oldmem_data.size;
        }

        mem_chunk_cnt = get_mem_chunk_cnt();
        phdr_text_cnt = os_info_has_vm() ? 1 : 0;

        alloc_size = get_elfcorehdr_size(mem_chunk_cnt + phdr_text_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 */
        phdr_notes = ehdr_init(hdr, mem_chunk_cnt + phdr_text_cnt);
        /* Init program headers */
        if (phdr_text_cnt) {
                phdr_text = phdr_notes + 1;
                phdr_loads = phdr_text + 1;
        } else {
                phdr_loads = phdr_notes + 1;
        }
        ptr = PTR_ADD(phdr_loads, 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 kernel text program header */
        if (phdr_text_cnt)
                text_init(phdr_text);
        /* Init loads */
        loads_init(phdr_loads, phdr_text_cnt);
        /* Finalize program headers */
        hdr_off = PTR_DIFF(ptr, hdr);
        *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;
}