/*
 * 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 <linux/memblock.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,
};

#define for_each_dump_mem_range(i, nid, p_start, p_end, p_nid)		\
	for (i = 0, __next_mem_range(&i, nid, &memblock.physmem,	\
				     &oldmem_type, p_start,		\
				     p_end, p_nid);			\
	     i != (u64)ULLONG_MAX;					\
	     __next_mem_range(&i, nid, &memblock.physmem,		\
			      &oldmem_type,				\
			      p_start, p_end, p_nid))

struct dump_save_areas dump_save_areas;

/*
 * Allocate and add a save area for a CPU
 */
struct save_area *dump_save_area_create(int cpu)
{
	struct save_area **save_areas, *save_area;

	save_area = kmalloc(sizeof(*save_area), GFP_KERNEL);
	if (!save_area)
		return NULL;
	if (cpu + 1 > dump_save_areas.count) {
		dump_save_areas.count = cpu + 1;
		save_areas = krealloc(dump_save_areas.areas,
				      dump_save_areas.count * sizeof(void *),
				      GFP_KERNEL | __GFP_ZERO);
		if (!save_areas) {
			kfree(save_area);
			return NULL;
		}
		dump_save_areas.areas = save_areas;
	}
	dump_save_areas.areas[cpu] = save_area;
	return save_area;
}

/*
 * 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;

	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 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 < sclp_get_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 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_get_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 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 {
		unsigned long hsa_end = sclp_get_hsa_size();
		if ((unsigned long) src < hsa_end) {
			copied = min(count, hsa_end - (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;
}

/*
 * 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; i < dump_save_areas.count; i++) {
		if (dump_save_areas.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)
{
	int cnt = 0;
	u64 idx;

	for_each_dump_mem_range(idx, NUMA_NO_NODE, NULL, 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_dump_mem_range(idx, NUMA_NO_NODE, &start, &end, NULL) {
		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 i;

	ptr = nt_prpsinfo(ptr);

	for (i = 0; i < dump_save_areas.count; i++) {
		sa = dump_save_areas.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;
	/* If we cannot get HSA size for zfcpdump return error */
	if (ipl_info.type == IPL_TYPE_FCP_DUMP && !sclp_get_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 = 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;
}