/*
 * 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/module.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/bootmem.h>
#include <linux/elf.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))))


/*
 * 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 real to virtual or real memory
 */
static int copy_from_realmem(void *dest, void *src, size_t count)
{
        unsigned long size;
        int rc;

        if (!count)
                return 0;
        if (!is_vmalloc_or_module_addr(dest))
                return memcpy_real(dest, src, count);
        do {
                size = min(count, PAGE_SIZE - (__pa(dest) & ~PAGE_MASK));
                if (memcpy_real(load_real_addr(dest), src, size))
                        return -EFAULT;
                count -= size;
                dest += size;
                src += size;
        } while (count);
        return 0;
}

/*
 * Pointer to ELF header in new kernel
 */
static void *elfcorehdr_newmem;

/*
 * Copy one page from zfcpdump "oldmem"
 *
 * For pages below ZFCPDUMP_HSA_SIZE memory from the HSA is copied. Otherwise
 * real memory copy is used.
 */
static ssize_t copy_oldmem_page_zfcpdump(char *buf, size_t csize,
                                         unsigned long src, int userbuf)
{
        int rc;

        if (src < ZFCPDUMP_HSA_SIZE) {
                rc = memcpy_hsa(buf, src, csize, userbuf);
        } else {
                if (userbuf)
                        rc = copy_to_user_real((void __force __user *) buf,
                                               (void *) src, csize);
                else
                        rc = memcpy_real(buf, (void *) src, csize);
        }
        return rc ? rc : csize;
}

/*
 * Copy one page from kdump "oldmem"
 *
 * For the kdump reserved memory this functions performs a swap operation:
 *  - [OLDMEM_BASE - OLDMEM_BASE + OLDMEM_SIZE] is mapped to [0 - OLDMEM_SIZE].
 *  - [0 - OLDMEM_SIZE] is mapped to [OLDMEM_BASE - OLDMEM_BASE + OLDMEM_SIZE]
 */
static ssize_t copy_oldmem_page_kdump(char *buf, size_t csize,
                                      unsigned long src, int userbuf)

{
        int rc;

        if (src < OLDMEM_SIZE)
                src += OLDMEM_BASE;
        else if (src > OLDMEM_BASE &&
                 src < OLDMEM_BASE + OLDMEM_SIZE)
                src -= OLDMEM_BASE;
        if (userbuf)
                rc = copy_to_user_real((void __force __user *) buf,
                                       (void *) src, csize);
        else
                rc = copy_from_realmem(buf, (void *) src, csize);
        return (rc == 0) ? rc : csize;
}

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

        if (!csize)
                return 0;
        src = (pfn << PAGE_SHIFT) + offset;
        if (OLDMEM_BASE)
                return copy_oldmem_page_kdump(buf, csize, src, userbuf);
        else
                return copy_oldmem_page_zfcpdump(buf, csize, src, userbuf);
}

/*
 * 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 zfcpdump
 *
 * We only map available memory above ZFCPDUMP_HSA_SIZE. Memory below
 * ZFCPDUMP_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 size_hsa;

        if (pfn < ZFCPDUMP_HSA_SIZE >> PAGE_SHIFT) {
                size_hsa = min(size, ZFCPDUMP_HSA_SIZE - (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 zfcpdump
 */
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);
}

/*
 * Copy memory from old kernel
 */
int copy_from_oldmem(void *dest, void *src, size_t count)
{
        unsigned long copied = 0;
        int rc;

        if (OLDMEM_BASE) {
                if ((unsigned long) src < OLDMEM_SIZE) {
                        copied = min(count, OLDMEM_SIZE - (unsigned long) src);
                        rc = copy_from_realmem(dest, src + OLDMEM_BASE, copied);
                        if (rc)
                                return rc;
                }
        } else {
                if ((unsigned long) src < ZFCPDUMP_HSA_SIZE) {
                        copied = min(count,
                                     ZFCPDUMP_HSA_SIZE - (unsigned long) src);
                        rc = memcpy_hsa(dest, (unsigned long) src, copied, 0);
                        if (rc)
                                return rc;
                }
        }
        return copy_from_realmem(dest + copied, src + copied, count - copied);
}

/*
 * Alloc memory and panic in case of ENOMEM
 */
static void *kzalloc_panic(int len)
{
        void *rc;

        rc = kzalloc(len, GFP_KERNEL);
        if (!rc)
                panic("s390 kdump kzalloc (%d) failed", len);
        return rc;
}

/*
 * Get memory layout and create hole for oldmem
 */
static struct mem_chunk *get_memory_layout(void)
{
        struct mem_chunk *chunk_array;

        chunk_array = kzalloc_panic(MEMORY_CHUNKS * sizeof(struct mem_chunk));
        detect_memory_layout(chunk_array, 0);
        create_mem_hole(chunk_array, OLDMEM_BASE, OLDMEM_SIZE);
        return chunk_array;
}

/*
 * Initialize ELF note
 */
static void *nt_init(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);
}

/*
 * Initialize prstatus note
 */
static void *nt_prstatus(void *ptr, struct save_area *sa)
{
        struct elf_prstatus nt_prstatus;
        static int cpu_nr = 1;

        memset(&nt_prstatus, 0, sizeof(nt_prstatus));
        memcpy(&nt_prstatus.pr_reg.gprs, sa->gp_regs, sizeof(sa->gp_regs));
        memcpy(&nt_prstatus.pr_reg.psw, sa->psw, sizeof(sa->psw));
        memcpy(&nt_prstatus.pr_reg.acrs, sa->acc_regs, sizeof(sa->acc_regs));
        nt_prstatus.pr_pid = cpu_nr;
        cpu_nr++;

        return nt_init(ptr, NT_PRSTATUS, &nt_prstatus, sizeof(nt_prstatus),
                         "CORE");
}

/*
 * Initialize fpregset (floating point) note
 */
static void *nt_fpregset(void *ptr, struct save_area *sa)
{
        elf_fpregset_t nt_fpregset;

        memset(&nt_fpregset, 0, sizeof(nt_fpregset));
        memcpy(&nt_fpregset.fpc, &sa->fp_ctrl_reg, sizeof(sa->fp_ctrl_reg));
        memcpy(&nt_fpregset.fprs, &sa->fp_regs, sizeof(sa->fp_regs));

        return nt_init(ptr, NT_PRFPREG, &nt_fpregset, sizeof(nt_fpregset),
                       "CORE");
}

/*
 * Initialize timer note
 */
static void *nt_s390_timer(void *ptr, struct save_area *sa)
{
        return nt_init(ptr, NT_S390_TIMER, &sa->timer, sizeof(sa->timer),
                         KEXEC_CORE_NOTE_NAME);
}

/*
 * Initialize TOD clock comparator note
 */
static void *nt_s390_tod_cmp(void *ptr, struct save_area *sa)
{
        return nt_init(ptr, NT_S390_TODCMP, &sa->clk_cmp,
                       sizeof(sa->clk_cmp), KEXEC_CORE_NOTE_NAME);
}

/*
 * Initialize TOD programmable register note
 */
static void *nt_s390_tod_preg(void *ptr, struct save_area *sa)
{
        return nt_init(ptr, NT_S390_TODPREG, &sa->tod_reg,
                       sizeof(sa->tod_reg), KEXEC_CORE_NOTE_NAME);
}

/*
 * Initialize control register note
 */
static void *nt_s390_ctrs(void *ptr, struct save_area *sa)
{
        return nt_init(ptr, NT_S390_CTRS, &sa->ctrl_regs,
                       sizeof(sa->ctrl_regs), KEXEC_CORE_NOTE_NAME);
}

/*
 * Initialize prefix register note
 */
static void *nt_s390_prefix(void *ptr, struct save_area *sa)
{
        return nt_init(ptr, NT_S390_PREFIX, &sa->pref_reg,
                         sizeof(sa->pref_reg), KEXEC_CORE_NOTE_NAME);
}

/*
 * Fill ELF notes for one CPU with save area registers
 */
void *fill_cpu_elf_notes(void *ptr, struct save_area *sa)
{
        ptr = nt_prstatus(ptr, sa);
        ptr = nt_fpregset(ptr, sa);
        ptr = nt_s390_timer(ptr, sa);
        ptr = nt_s390_tod_cmp(ptr, sa);
        ptr = nt_s390_tod_preg(ptr, sa);
        ptr = nt_s390_ctrs(ptr, sa);
        ptr = nt_s390_prefix(ptr, sa);
        return ptr;
}

/*
 * 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),
                       KEXEC_CORE_NOTE_NAME);
}

/*
 * 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_from_oldmem(&addr, &S390_lowcore.vmcore_info, sizeof(addr)))
                return NULL;
        memset(nt_name, 0, sizeof(nt_name));
        if (copy_from_oldmem(&note, addr, sizeof(note)))
                return NULL;
        if (copy_from_oldmem(nt_name, addr + sizeof(note), sizeof(nt_name) - 1))
                return NULL;
        if (strcmp(nt_name, "VMCOREINFO") != 0)
                return NULL;
        vmcoreinfo = kzalloc_panic(note.n_descsz);
        if (copy_from_oldmem(vmcoreinfo, addr + 24, note.n_descsz))
                return NULL;
        *size = note.n_descsz;
        return vmcoreinfo;
}

/*
 * Initialize vmcoreinfo note (new kernel)
 */
static void *nt_vmcoreinfo(void *ptr)
{
        unsigned long size;
        void *vmcoreinfo;

        vmcoreinfo = os_info_old_entry(OS_INFO_VMCOREINFO, &size);
        if (!vmcoreinfo)
                vmcoreinfo = get_vmcoreinfo_old(&size);
        if (!vmcoreinfo)
                return ptr;
        return nt_init(ptr, 0, vmcoreinfo, size, "VMCOREINFO");
}

/*
 * 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)
{
        int i, cpus = 0;

        for (i = 0; zfcpdump_save_areas[i]; i++) {
                if (zfcpdump_save_areas[i]->pref_reg == 0)
                        continue;
                cpus++;
        }
        return cpus;
}

/*
 * Return memory chunk count for ELF header (new kernel)
 */
static int get_mem_chunk_cnt(void)
{
        struct mem_chunk *chunk_array, *mem_chunk;
        int i, cnt = 0;

        chunk_array = get_memory_layout();
        for (i = 0; i < MEMORY_CHUNKS; i++) {
                mem_chunk = &chunk_array[i];
                if (chunk_array[i].type != CHUNK_READ_WRITE &&
                    chunk_array[i].type != CHUNK_READ_ONLY)
                        continue;
                if (mem_chunk->size == 0)
                        continue;
                cnt++;
        }
        kfree(chunk_array);
        return cnt;
}

/*
 * Initialize ELF loads (new kernel)
 */
static int loads_init(Elf64_Phdr *phdr, u64 loads_offset)
{
        struct mem_chunk *chunk_array, *mem_chunk;
        int i;

        chunk_array = get_memory_layout();
        for (i = 0; i < MEMORY_CHUNKS; i++) {
                mem_chunk = &chunk_array[i];
                if (mem_chunk->size == 0)
                        continue;
                if (chunk_array[i].type != CHUNK_READ_WRITE &&
                    chunk_array[i].type != CHUNK_READ_ONLY)
                        continue;
                else
                        phdr->p_filesz = mem_chunk->size;
                phdr->p_type = PT_LOAD;
                phdr->p_offset = mem_chunk->addr;
                phdr->p_vaddr = mem_chunk->addr;
                phdr->p_paddr = mem_chunk->addr;
                phdr->p_memsz = mem_chunk->size;
                phdr->p_flags = PF_R | PF_W | PF_X;
                phdr->p_align = PAGE_SIZE;
                phdr++;
        }
        kfree(chunk_array);
        return i;
}

/*
 * 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 i;

        ptr = nt_prpsinfo(ptr);

        for (i = 0; zfcpdump_save_areas[i]; i++) {
                sa = zfcpdump_save_areas[i];
                if (sa->pref_reg == 0)
                        continue;
                ptr = fill_cpu_elf_notes(ptr, sa);
        }
        ptr = nt_vmcoreinfo(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;
}

/*
 * 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 zfcpdump mode return */
        if (!OLDMEM_BASE && ipl_info.type != IPL_TYPE_FCP_DUMP)
                return 0;
        /* If elfcorehdr= has been passed via cmdline, we use that one */
        if (elfcorehdr_addr != ELFCORE_ADDR_MAX)
                return 0;
        mem_chunk_cnt = get_mem_chunk_cnt();

        alloc_size = 0x1000 + get_cpu_cnt() * 0x300 +
                mem_chunk_cnt * sizeof(Elf64_Phdr);
        hdr = kzalloc_panic(alloc_size);
        /* 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;
        elfcorehdr_newmem = 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)
{
        if (!elfcorehdr_newmem)
                return;
        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;

        src = elfcorehdr_newmem ? src : src - OLDMEM_BASE;
        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;
        int rc;

        if (elfcorehdr_newmem) {
                memcpy(buf, src, count);
        } else {
                rc = copy_from_oldmem(buf, src, count);
                if (rc)
                        return rc;
        }
        *ppos += count;
        return count;
}