// SPDX-License-Identifier: GPL-2.0
#include <linux/string.h>
#include <linux/elf.h>
#include <asm/boot_data.h>
#include <asm/sections.h>
#include <asm/cpu_mf.h>
#include <asm/setup.h>
#include <asm/kexec.h>
#include <asm/sclp.h>
#include <asm/diag.h>
#include <asm/uv.h>
#include "compressed/decompressor.h"
#include "boot.h"

extern char __boot_data_start[], __boot_data_end[];
extern char __boot_data_preserved_start[], __boot_data_preserved_end[];
unsigned long __bootdata_preserved(__kaslr_offset);
unsigned long __bootdata(ident_map_size);

/*
 * Some code and data needs to stay below 2 GB, even when the kernel would be
 * relocated above 2 GB, because it has to use 31 bit addresses.
 * Such code and data is part of the .dma section, and its location is passed
 * over to the decompressed / relocated kernel via the .boot.preserved.data
 * section.
 */
extern char _sdma[], _edma[];
extern char _stext_dma[], _etext_dma[];
extern struct exception_table_entry _start_dma_ex_table[];
extern struct exception_table_entry _stop_dma_ex_table[];
unsigned long __bootdata_preserved(__sdma) = __pa(&_sdma);
unsigned long __bootdata_preserved(__edma) = __pa(&_edma);
unsigned long __bootdata_preserved(__stext_dma) = __pa(&_stext_dma);
unsigned long __bootdata_preserved(__etext_dma) = __pa(&_etext_dma);
struct exception_table_entry *
        __bootdata_preserved(__start_dma_ex_table) = _start_dma_ex_table;
struct exception_table_entry *
        __bootdata_preserved(__stop_dma_ex_table) = _stop_dma_ex_table;

int _diag210_dma(struct diag210 *addr);
int _diag26c_dma(void *req, void *resp, enum diag26c_sc subcode);
int _diag14_dma(unsigned long rx, unsigned long ry1, unsigned long subcode);
void _diag0c_dma(struct hypfs_diag0c_entry *entry);
void _diag308_reset_dma(void);
struct diag_ops __bootdata_preserved(diag_dma_ops) = {
        .diag210 = _diag210_dma,
        .diag26c = _diag26c_dma,
        .diag14 = _diag14_dma,
        .diag0c = _diag0c_dma,
        .diag308_reset = _diag308_reset_dma
};
static struct diag210 _diag210_tmp_dma __section(".dma.data");
struct diag210 *__bootdata_preserved(__diag210_tmp_dma) = &_diag210_tmp_dma;

void error(char *x)
{
        sclp_early_printk("\n\n");
        sclp_early_printk(x);
        sclp_early_printk("\n\n -- System halted");

        disabled_wait();
}

static void setup_lpp(void)
{
        S390_lowcore.current_pid = 0;
        S390_lowcore.lpp = LPP_MAGIC;
        if (test_facility(40))
                lpp(&S390_lowcore.lpp);
}

#ifdef CONFIG_KERNEL_UNCOMPRESSED
unsigned long mem_safe_offset(void)
{
        return vmlinux.default_lma + vmlinux.image_size + vmlinux.bss_size;
}
#endif

static void rescue_initrd(unsigned long addr)
{
        if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD))
                return;
        if (!INITRD_START || !INITRD_SIZE)
                return;
        if (addr <= INITRD_START)
                return;
        memmove((void *)addr, (void *)INITRD_START, INITRD_SIZE);
        INITRD_START = addr;
}

static void copy_bootdata(void)
{
        if (__boot_data_end - __boot_data_start != vmlinux.bootdata_size)
                error(".boot.data section size mismatch");
        memcpy((void *)vmlinux.bootdata_off, __boot_data_start, vmlinux.bootdata_size);
        if (__boot_data_preserved_end - __boot_data_preserved_start != vmlinux.bootdata_preserved_size)
                error(".boot.preserved.data section size mismatch");
        memcpy((void *)vmlinux.bootdata_preserved_off, __boot_data_preserved_start, vmlinux.bootdata_preserved_size);
}

static void handle_relocs(unsigned long offset)
{
        Elf64_Rela *rela_start, *rela_end, *rela;
        int r_type, r_sym, rc;
        Elf64_Addr loc, val;
        Elf64_Sym *dynsym;

        rela_start = (Elf64_Rela *) vmlinux.rela_dyn_start;
        rela_end = (Elf64_Rela *) vmlinux.rela_dyn_end;
        dynsym = (Elf64_Sym *) vmlinux.dynsym_start;
        for (rela = rela_start; rela < rela_end; rela++) {
                loc = rela->r_offset + offset;
                val = rela->r_addend;
                r_sym = ELF64_R_SYM(rela->r_info);
                if (r_sym) {
                        if (dynsym[r_sym].st_shndx != SHN_UNDEF)
                                val += dynsym[r_sym].st_value + offset;
                } else {
                        /*
                         * 0 == undefined symbol table index (STN_UNDEF),
                         * used for R_390_RELATIVE, only add KASLR offset
                         */
                        val += offset;
                }
                r_type = ELF64_R_TYPE(rela->r_info);
                rc = arch_kexec_do_relocs(r_type, (void *) loc, val, 0);
                if (rc)
                        error("Unknown relocation type");
        }
}

/*
 * Merge information from several sources into a single ident_map_size value.
 * "ident_map_size" represents the upper limit of physical memory we may ever
 * reach. It might not be all online memory, but also include standby (offline)
 * memory. "ident_map_size" could be lower then actual standby or even online
 * memory present, due to limiting factors. We should never go above this limit.
 * It is the size of our identity mapping.
 *
 * Consider the following factors:
 * 1. max_physmem_end - end of physical memory online or standby.
 *    Always <= end of the last online memory block (get_mem_detect_end()).
 * 2. CONFIG_MAX_PHYSMEM_BITS - the maximum size of physical memory the
 *    kernel is able to support.
 * 3. "mem=" kernel command line option which limits physical memory usage.
 * 4. OLDMEM_BASE which is a kdump memory limit when the kernel is executed as
 *    crash kernel.
 * 5. "hsa" size which is a memory limit when the kernel is executed during
 *    zfcp/nvme dump.
 */
static void setup_ident_map_size(unsigned long max_physmem_end)
{
        unsigned long hsa_size;

        ident_map_size = max_physmem_end;
        if (memory_limit)
                ident_map_size = min(ident_map_size, memory_limit);
        ident_map_size = min(ident_map_size, 1UL << MAX_PHYSMEM_BITS);

#ifdef CONFIG_CRASH_DUMP
        if (OLDMEM_BASE) {
                kaslr_enabled = 0;
                ident_map_size = min(ident_map_size, OLDMEM_SIZE);
        } else if (ipl_block_valid && is_ipl_block_dump()) {
                kaslr_enabled = 0;
                if (!sclp_early_get_hsa_size(&hsa_size) && hsa_size)
                        ident_map_size = min(ident_map_size, hsa_size);
        }
#endif
}

/*
 * This function clears the BSS section of the decompressed Linux kernel and NOT the decompressor's.
 */
static void clear_bss_section(void)
{
        memset((void *)vmlinux.default_lma + vmlinux.image_size, 0, vmlinux.bss_size);
}

/*
 * Set vmalloc area size to an 8th of (potential) physical memory
 * size, unless size has been set by kernel command line parameter.
 */
static void setup_vmalloc_size(void)
{
        unsigned long size;

        if (vmalloc_size_set)
                return;
        size = round_up(ident_map_size / 8, _SEGMENT_SIZE);
        vmalloc_size = max(size, vmalloc_size);
}

void startup_kernel(void)
{
        unsigned long random_lma;
        unsigned long safe_addr;
        void *img;

        setup_lpp();
        store_ipl_parmblock();
        safe_addr = mem_safe_offset();
        safe_addr = read_ipl_report(safe_addr);
        uv_query_info();
        rescue_initrd(safe_addr);
        sclp_early_read_info();
        setup_boot_command_line();
        parse_boot_command_line();
        setup_ident_map_size(detect_memory());
        setup_vmalloc_size();

        random_lma = __kaslr_offset = 0;
        if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && kaslr_enabled) {
                random_lma = get_random_base(safe_addr);
                if (random_lma) {
                        __kaslr_offset = random_lma - vmlinux.default_lma;
                        img = (void *)vmlinux.default_lma;
                        vmlinux.default_lma += __kaslr_offset;
                        vmlinux.entry += __kaslr_offset;
                        vmlinux.bootdata_off += __kaslr_offset;
                        vmlinux.bootdata_preserved_off += __kaslr_offset;
                        vmlinux.rela_dyn_start += __kaslr_offset;
                        vmlinux.rela_dyn_end += __kaslr_offset;
                        vmlinux.dynsym_start += __kaslr_offset;
                }
        }

        if (!IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED)) {
                img = decompress_kernel();
                memmove((void *)vmlinux.default_lma, img, vmlinux.image_size);
        } else if (__kaslr_offset)
                memcpy((void *)vmlinux.default_lma, img, vmlinux.image_size);

        clear_bss_section();
        copy_bootdata();
        if (IS_ENABLED(CONFIG_RELOCATABLE))
                handle_relocs(__kaslr_offset);

        if (__kaslr_offset) {
                /*
                 * Save KASLR offset for early dumps, before vmcore_info is set.
                 * Mark as uneven to distinguish from real vmcore_info pointer.
                 */
                S390_lowcore.vmcore_info = __kaslr_offset | 0x1UL;
                /* Clear non-relocated kernel */
                if (IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED))
                        memset(img, 0, vmlinux.image_size);
        }
        vmlinux.entry();
}