// SPDX-License-Identifier: GPL-2.0-only
/*
 * Interface for exporting the OPAL ELF core.
 * Heavily inspired from fs/proc/vmcore.c
 *
 * Copyright 2019, Hari Bathini, IBM Corporation.
 */

#define pr_fmt(fmt) "opal core: " fmt

#include <linux/memblock.h>
#include <linux/uaccess.h>
#include <linux/proc_fs.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/kobject.h>
#include <linux/sysfs.h>
#include <linux/slab.h>
#include <linux/crash_core.h>
#include <linux/of.h>

#include <asm/page.h>
#include <asm/opal.h>
#include <asm/fadump-internal.h>

#include "opal-fadump.h"

#define MAX_PT_LOAD_CNT         8

/* NT_AUXV note related info */
#define AUXV_CNT                1
#define AUXV_DESC_SZ            (((2 * AUXV_CNT) + 1) * sizeof(Elf64_Off))

struct opalcore_config {
        u32                     num_cpus;
        /* PIR value of crashing CPU */
        u32                     crashing_cpu;

        /* CPU state data info from F/W */
        u64                     cpu_state_destination_vaddr;
        u64                     cpu_state_data_size;
        u64                     cpu_state_entry_size;

        /* OPAL memory to be exported as PT_LOAD segments */
        u64                     ptload_addr[MAX_PT_LOAD_CNT];
        u64                     ptload_size[MAX_PT_LOAD_CNT];
        u64                     ptload_cnt;

        /* Pointer to the first PT_LOAD in the ELF core file */
        Elf64_Phdr              *ptload_phdr;

        /* Total size of opalcore file. */
        size_t                  opalcore_size;

        /* Buffer for all the ELF core headers and the PT_NOTE */
        size_t                  opalcorebuf_sz;
        char                    *opalcorebuf;

        /* NT_AUXV buffer */
        char                    auxv_buf[AUXV_DESC_SZ];
};

struct opalcore {
        struct list_head        list;
        u64                     paddr;
        size_t                  size;
        loff_t                  offset;
};

static LIST_HEAD(opalcore_list);
static struct opalcore_config *oc_conf;
static const struct opal_mpipl_fadump *opalc_metadata;
static const struct opal_mpipl_fadump *opalc_cpu_metadata;
static struct kobject *mpipl_kobj;

/*
 * Set crashing CPU's signal to SIGUSR1. if the kernel is triggered
 * by kernel, SIGTERM otherwise.
 */
bool kernel_initiated;

static struct opalcore * __init get_new_element(void)
{
        return kzalloc(sizeof(struct opalcore), GFP_KERNEL);
}

static inline int is_opalcore_usable(void)
{
        return (oc_conf && oc_conf->opalcorebuf != NULL) ? 1 : 0;
}

static Elf64_Word *append_elf64_note(Elf64_Word *buf, char *name,
                                     u32 type, void *data,
                                     size_t data_len)
{
        Elf64_Nhdr *note = (Elf64_Nhdr *)buf;
        Elf64_Word namesz = strlen(name) + 1;

        note->n_namesz = cpu_to_be32(namesz);
        note->n_descsz = cpu_to_be32(data_len);
        note->n_type   = cpu_to_be32(type);
        buf += DIV_ROUND_UP(sizeof(*note), sizeof(Elf64_Word));
        memcpy(buf, name, namesz);
        buf += DIV_ROUND_UP(namesz, sizeof(Elf64_Word));
        memcpy(buf, data, data_len);
        buf += DIV_ROUND_UP(data_len, sizeof(Elf64_Word));

        return buf;
}

static void fill_prstatus(struct elf_prstatus *prstatus, int pir,
                          struct pt_regs *regs)
{
        memset(prstatus, 0, sizeof(struct elf_prstatus));
        elf_core_copy_kernel_regs(&(prstatus->pr_reg), regs);

        /*
         * Overload PID with PIR value.
         * As a PIR value could also be '0', add an offset of '100'
         * to every PIR to avoid misinterpretations in GDB.
         */
        prstatus->common.pr_pid  = cpu_to_be32(100 + pir);
        prstatus->common.pr_ppid = cpu_to_be32(1);

        /*
         * Indicate SIGUSR1 for crash initiated from kernel.
         * SIGTERM otherwise.
         */
        if (pir == oc_conf->crashing_cpu) {
                short sig;

                sig = kernel_initiated ? SIGUSR1 : SIGTERM;
                prstatus->common.pr_cursig = cpu_to_be16(sig);
        }
}

static Elf64_Word *auxv_to_elf64_notes(Elf64_Word *buf,
                                       u64 opal_boot_entry)
{
        Elf64_Off *bufp = (Elf64_Off *)oc_conf->auxv_buf;
        int idx = 0;

        memset(bufp, 0, AUXV_DESC_SZ);

        /* Entry point of OPAL */
        bufp[idx++] = cpu_to_be64(AT_ENTRY);
        bufp[idx++] = cpu_to_be64(opal_boot_entry);

        /* end of vector */
        bufp[idx++] = cpu_to_be64(AT_NULL);

        buf = append_elf64_note(buf, CRASH_CORE_NOTE_NAME, NT_AUXV,
                                oc_conf->auxv_buf, AUXV_DESC_SZ);
        return buf;
}

/*
 * Read from the ELF header and then the crash dump.
 * Returns number of bytes read on success, -errno on failure.
 */
static ssize_t read_opalcore(struct file *file, struct kobject *kobj,
                             struct bin_attribute *bin_attr, char *to,
                             loff_t pos, size_t count)
{
        struct opalcore *m;
        ssize_t tsz, avail;
        loff_t tpos = pos;

        if (pos >= oc_conf->opalcore_size)
                return 0;

        /* Adjust count if it goes beyond opalcore size */
        avail = oc_conf->opalcore_size - pos;
        if (count > avail)
                count = avail;

        if (count == 0)
                return 0;

        /* Read ELF core header and/or PT_NOTE segment */
        if (tpos < oc_conf->opalcorebuf_sz) {
                tsz = min_t(size_t, oc_conf->opalcorebuf_sz - tpos, count);
                memcpy(to, oc_conf->opalcorebuf + tpos, tsz);
                to += tsz;
                tpos += tsz;
                count -= tsz;
        }

        list_for_each_entry(m, &opalcore_list, list) {
                /* nothing more to read here */
                if (count == 0)
                        break;

                if (tpos < m->offset + m->size) {
                        void *addr;

                        tsz = min_t(size_t, m->offset + m->size - tpos, count);
                        addr = (void *)(m->paddr + tpos - m->offset);
                        memcpy(to, __va(addr), tsz);
                        to += tsz;
                        tpos += tsz;
                        count -= tsz;
                }
        }

        return (tpos - pos);
}

static struct bin_attribute opal_core_attr = {
        .attr = {.name = "core", .mode = 0400},
        .read = read_opalcore
};

/*
 * Read CPU state dump data and convert it into ELF notes.
 *
 * Each register entry is of 16 bytes, A numerical identifier along with
 * a GPR/SPR flag in the first 8 bytes and the register value in the next
 * 8 bytes. For more details refer to F/W documentation.
 */
static Elf64_Word * __init opalcore_append_cpu_notes(Elf64_Word *buf)
{
        u32 thread_pir, size_per_thread, regs_offset, regs_cnt, reg_esize;
        struct hdat_fadump_thread_hdr *thdr;
        struct elf_prstatus prstatus;
        Elf64_Word *first_cpu_note;
        struct pt_regs regs;
        char *bufp;
        int i;

        size_per_thread = oc_conf->cpu_state_entry_size;
        bufp = __va(oc_conf->cpu_state_destination_vaddr);

        /*
         * Offset for register entries, entry size and registers count is
         * duplicated in every thread header in keeping with HDAT format.
         * Use these values from the first thread header.
         */
        thdr = (struct hdat_fadump_thread_hdr *)bufp;
        regs_offset = (offsetof(struct hdat_fadump_thread_hdr, offset) +
                       be32_to_cpu(thdr->offset));
        reg_esize = be32_to_cpu(thdr->esize);
        regs_cnt  = be32_to_cpu(thdr->ecnt);

        pr_debug("--------CPU State Data------------\n");
        pr_debug("NumCpus     : %u\n", oc_conf->num_cpus);
        pr_debug("\tOffset: %u, Entry size: %u, Cnt: %u\n",
                 regs_offset, reg_esize, regs_cnt);

        /*
         * Skip past the first CPU note. Fill this note with the
         * crashing CPU's prstatus.
         */
        first_cpu_note = buf;
        buf = append_elf64_note(buf, CRASH_CORE_NOTE_NAME, NT_PRSTATUS,
                                &prstatus, sizeof(prstatus));

        for (i = 0; i < oc_conf->num_cpus; i++, bufp += size_per_thread) {
                thdr = (struct hdat_fadump_thread_hdr *)bufp;
                thread_pir = be32_to_cpu(thdr->pir);

                pr_debug("[%04d] PIR: 0x%x, core state: 0x%02x\n",
                         i, thread_pir, thdr->core_state);

                /*
                 * Register state data of MAX cores is provided by firmware,
                 * but some of this cores may not be active. So, while
                 * processing register state data, check core state and
                 * skip threads that belong to inactive cores.
                 */
                if (thdr->core_state == HDAT_FADUMP_CORE_INACTIVE)
                        continue;

                opal_fadump_read_regs((bufp + regs_offset), regs_cnt,
                                      reg_esize, false, &regs);

                pr_debug("PIR 0x%x - R1 : 0x%llx, NIP : 0x%llx\n", thread_pir,
                         be64_to_cpu(regs.gpr[1]), be64_to_cpu(regs.nip));
                fill_prstatus(&prstatus, thread_pir, &regs);

                if (thread_pir != oc_conf->crashing_cpu) {
                        buf = append_elf64_note(buf, CRASH_CORE_NOTE_NAME,
                                                NT_PRSTATUS, &prstatus,
                                                sizeof(prstatus));
                } else {
                        /*
                         * Add crashing CPU as the first NT_PRSTATUS note for
                         * GDB to process the core file appropriately.
                         */
                        append_elf64_note(first_cpu_note, CRASH_CORE_NOTE_NAME,
                                          NT_PRSTATUS, &prstatus,
                                          sizeof(prstatus));
                }
        }

        return buf;
}

static int __init create_opalcore(void)
{
        u64 opal_boot_entry, opal_base_addr, paddr;
        u32 hdr_size, cpu_notes_size, count;
        struct device_node *dn;
        struct opalcore *new;
        loff_t opalcore_off;
        struct page *page;
        Elf64_Phdr *phdr;
        Elf64_Ehdr *elf;
        int i, ret;
        char *bufp;

        /* Get size of header & CPU notes for OPAL core */
        hdr_size = (sizeof(Elf64_Ehdr) +
                    ((oc_conf->ptload_cnt + 1) * sizeof(Elf64_Phdr)));
        cpu_notes_size = ((oc_conf->num_cpus * (CRASH_CORE_NOTE_HEAD_BYTES +
                          CRASH_CORE_NOTE_NAME_BYTES +
                          CRASH_CORE_NOTE_DESC_BYTES)) +
                          (CRASH_CORE_NOTE_HEAD_BYTES +
                          CRASH_CORE_NOTE_NAME_BYTES + AUXV_DESC_SZ));

        /* Allocate buffer to setup OPAL core */
        oc_conf->opalcorebuf_sz = PAGE_ALIGN(hdr_size + cpu_notes_size);
        oc_conf->opalcorebuf = alloc_pages_exact(oc_conf->opalcorebuf_sz,
                                                 GFP_KERNEL | __GFP_ZERO);
        if (!oc_conf->opalcorebuf) {
                pr_err("Not enough memory to setup OPAL core (size: %lu)\n",
                       oc_conf->opalcorebuf_sz);
                oc_conf->opalcorebuf_sz = 0;
                return -ENOMEM;
        }
        count = oc_conf->opalcorebuf_sz / PAGE_SIZE;
        page = virt_to_page(oc_conf->opalcorebuf);
        for (i = 0; i < count; i++)
                mark_page_reserved(page + i);

        pr_debug("opalcorebuf = 0x%llx\n", (u64)oc_conf->opalcorebuf);

        /* Read OPAL related device-tree entries */
        dn = of_find_node_by_name(NULL, "ibm,opal");
        if (dn) {
                ret = of_property_read_u64(dn, "opal-base-address",
                                           &opal_base_addr);
                pr_debug("opal-base-address: %llx\n", opal_base_addr);
                ret |= of_property_read_u64(dn, "opal-boot-address",
                                            &opal_boot_entry);
                pr_debug("opal-boot-address: %llx\n", opal_boot_entry);
        }
        if (!dn || ret)
                pr_warn("WARNING: Failed to read OPAL base & entry values\n");

        /* Use count to keep track of the program headers */
        count = 0;

        bufp = oc_conf->opalcorebuf;
        elf = (Elf64_Ehdr *)bufp;
        bufp += sizeof(Elf64_Ehdr);
        memcpy(elf->e_ident, ELFMAG, SELFMAG);
        elf->e_ident[EI_CLASS] = ELF_CLASS;
        elf->e_ident[EI_DATA] = ELFDATA2MSB;
        elf->e_ident[EI_VERSION] = EV_CURRENT;
        elf->e_ident[EI_OSABI] = ELF_OSABI;
        memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
        elf->e_type = cpu_to_be16(ET_CORE);
        elf->e_machine = cpu_to_be16(ELF_ARCH);
        elf->e_version = cpu_to_be32(EV_CURRENT);
        elf->e_entry = 0;
        elf->e_phoff = cpu_to_be64(sizeof(Elf64_Ehdr));
        elf->e_shoff = 0;
        elf->e_flags = 0;

        elf->e_ehsize = cpu_to_be16(sizeof(Elf64_Ehdr));
        elf->e_phentsize = cpu_to_be16(sizeof(Elf64_Phdr));
        elf->e_phnum = 0;
        elf->e_shentsize = 0;
        elf->e_shnum = 0;
        elf->e_shstrndx = 0;

        phdr = (Elf64_Phdr *)bufp;
        bufp += sizeof(Elf64_Phdr);
        phdr->p_type    = cpu_to_be32(PT_NOTE);
        phdr->p_flags   = 0;
        phdr->p_align   = 0;
        phdr->p_paddr   = phdr->p_vaddr = 0;
        phdr->p_offset  = cpu_to_be64(hdr_size);
        phdr->p_filesz  = phdr->p_memsz = cpu_to_be64(cpu_notes_size);
        count++;

        opalcore_off = oc_conf->opalcorebuf_sz;
        oc_conf->ptload_phdr  = (Elf64_Phdr *)bufp;
        paddr = 0;
        for (i = 0; i < oc_conf->ptload_cnt; i++) {
                phdr = (Elf64_Phdr *)bufp;
                bufp += sizeof(Elf64_Phdr);
                phdr->p_type    = cpu_to_be32(PT_LOAD);
                phdr->p_flags   = cpu_to_be32(PF_R|PF_W|PF_X);
                phdr->p_align   = 0;

                new = get_new_element();
                if (!new)
                        return -ENOMEM;
                new->paddr  = oc_conf->ptload_addr[i];
                new->size   = oc_conf->ptload_size[i];
                new->offset = opalcore_off;
                list_add_tail(&new->list, &opalcore_list);

                phdr->p_paddr   = cpu_to_be64(paddr);
                phdr->p_vaddr   = cpu_to_be64(opal_base_addr + paddr);
                phdr->p_filesz  = phdr->p_memsz  =
                        cpu_to_be64(oc_conf->ptload_size[i]);
                phdr->p_offset  = cpu_to_be64(opalcore_off);

                count++;
                opalcore_off += oc_conf->ptload_size[i];
                paddr += oc_conf->ptload_size[i];
        }

        elf->e_phnum = cpu_to_be16(count);

        bufp = (char *)opalcore_append_cpu_notes((Elf64_Word *)bufp);
        bufp = (char *)auxv_to_elf64_notes((Elf64_Word *)bufp, opal_boot_entry);

        oc_conf->opalcore_size = opalcore_off;
        return 0;
}

static void opalcore_cleanup(void)
{
        if (oc_conf == NULL)
                return;

        /* Remove OPAL core sysfs file */
        sysfs_remove_bin_file(mpipl_kobj, &opal_core_attr);
        oc_conf->ptload_phdr = NULL;
        oc_conf->ptload_cnt = 0;

        /* free the buffer used for setting up OPAL core */
        if (oc_conf->opalcorebuf) {
                void *end = (void *)((u64)oc_conf->opalcorebuf +
                                     oc_conf->opalcorebuf_sz);

                free_reserved_area(oc_conf->opalcorebuf, end, -1, NULL);
                oc_conf->opalcorebuf = NULL;
                oc_conf->opalcorebuf_sz = 0;
        }

        kfree(oc_conf);
        oc_conf = NULL;
}
__exitcall(opalcore_cleanup);

static void __init opalcore_config_init(void)
{
        u32 idx, cpu_data_version;
        struct device_node *np;
        const __be32 *prop;
        u64 addr = 0;
        int i, ret;

        np = of_find_node_by_path("/ibm,opal/dump");
        if (np == NULL)
                return;

        if (!of_device_is_compatible(np, "ibm,opal-dump")) {
                pr_warn("Support missing for this f/w version!\n");
                return;
        }

        /* Check if dump has been initiated on last reboot */
        prop = of_get_property(np, "mpipl-boot", NULL);
        if (!prop) {
                of_node_put(np);
                return;
        }

        /* Get OPAL metadata */
        ret = opal_mpipl_query_tag(OPAL_MPIPL_TAG_OPAL, &addr);
        if ((ret != OPAL_SUCCESS) || !addr) {
                pr_err("Failed to get OPAL metadata (%d)\n", ret);
                goto error_out;
        }

        addr = be64_to_cpu(addr);
        pr_debug("OPAL metadata addr: %llx\n", addr);
        opalc_metadata = __va(addr);

        /* Get OPAL CPU metadata */
        ret = opal_mpipl_query_tag(OPAL_MPIPL_TAG_CPU, &addr);
        if ((ret != OPAL_SUCCESS) || !addr) {
                pr_err("Failed to get OPAL CPU metadata (%d)\n", ret);
                goto error_out;
        }

        addr = be64_to_cpu(addr);
        pr_debug("CPU metadata addr: %llx\n", addr);
        opalc_cpu_metadata = __va(addr);

        /* Allocate memory for config buffer */
        oc_conf = kzalloc(sizeof(struct opalcore_config), GFP_KERNEL);
        if (oc_conf == NULL)
                goto error_out;

        /* Parse OPAL metadata */
        if (opalc_metadata->version != OPAL_MPIPL_VERSION) {
                pr_warn("Supported OPAL metadata version: %u, found: %u!\n",
                        OPAL_MPIPL_VERSION, opalc_metadata->version);
                pr_warn("WARNING: F/W using newer OPAL metadata format!!\n");
        }

        oc_conf->ptload_cnt = 0;
        idx = be32_to_cpu(opalc_metadata->region_cnt);
        if (idx > MAX_PT_LOAD_CNT) {
                pr_warn("WARNING: OPAL regions count (%d) adjusted to limit (%d)",
                        idx, MAX_PT_LOAD_CNT);
                idx = MAX_PT_LOAD_CNT;
        }
        for (i = 0; i < idx; i++) {
                oc_conf->ptload_addr[oc_conf->ptload_cnt] =
                                be64_to_cpu(opalc_metadata->region[i].dest);
                oc_conf->ptload_size[oc_conf->ptload_cnt++] =
                                be64_to_cpu(opalc_metadata->region[i].size);
        }
        oc_conf->ptload_cnt = i;
        oc_conf->crashing_cpu = be32_to_cpu(opalc_metadata->crashing_pir);

        if (!oc_conf->ptload_cnt) {
                pr_err("OPAL memory regions not found\n");
                goto error_out;
        }

        /* Parse OPAL CPU metadata */
        cpu_data_version = be32_to_cpu(opalc_cpu_metadata->cpu_data_version);
        if (cpu_data_version != HDAT_FADUMP_CPU_DATA_VER) {
                pr_warn("Supported CPU data version: %u, found: %u!\n",
                        HDAT_FADUMP_CPU_DATA_VER, cpu_data_version);
                pr_warn("WARNING: F/W using newer CPU state data format!!\n");
        }

        addr = be64_to_cpu(opalc_cpu_metadata->region[0].dest);
        if (!addr) {
                pr_err("CPU state data not found!\n");
                goto error_out;
        }
        oc_conf->cpu_state_destination_vaddr = (u64)__va(addr);

        oc_conf->cpu_state_data_size =
                        be64_to_cpu(opalc_cpu_metadata->region[0].size);
        oc_conf->cpu_state_entry_size =
                        be32_to_cpu(opalc_cpu_metadata->cpu_data_size);

        if ((oc_conf->cpu_state_entry_size == 0) ||
            (oc_conf->cpu_state_entry_size > oc_conf->cpu_state_data_size)) {
                pr_err("CPU state data is invalid.\n");
                goto error_out;
        }
        oc_conf->num_cpus = (oc_conf->cpu_state_data_size /
                             oc_conf->cpu_state_entry_size);

        of_node_put(np);
        return;

error_out:
        pr_err("Could not export /sys/firmware/opal/core\n");
        opalcore_cleanup();
        of_node_put(np);
}

static ssize_t release_core_store(struct kobject *kobj,
                                  struct kobj_attribute *attr,
                                  const char *buf, size_t count)
{
        int input = -1;

        if (kstrtoint(buf, 0, &input))
                return -EINVAL;

        if (input == 1) {
                if (oc_conf == NULL) {
                        pr_err("'/sys/firmware/opal/core' file not accessible!\n");
                        return -EPERM;
                }

                /*
                 * Take away '/sys/firmware/opal/core' and release all memory
                 * used for exporting this file.
                 */
                opalcore_cleanup();
        } else
                return -EINVAL;

        return count;
}

static struct kobj_attribute opalcore_rel_attr = __ATTR_WO(release_core);

static struct attribute *mpipl_attr[] = {
        &opalcore_rel_attr.attr,
        NULL,
};

static struct bin_attribute *mpipl_bin_attr[] = {
        &opal_core_attr,
        NULL,

};

static struct attribute_group mpipl_group = {
        .attrs = mpipl_attr,
        .bin_attrs =  mpipl_bin_attr,
};

static int __init opalcore_init(void)
{
        int rc = -1;

        opalcore_config_init();

        if (oc_conf == NULL)
                return rc;

        create_opalcore();

        /*
         * If oc_conf->opalcorebuf= is set in the 2nd kernel,
         * then capture the dump.
         */
        if (!(is_opalcore_usable())) {
                pr_err("Failed to export /sys/firmware/opal/mpipl/core\n");
                opalcore_cleanup();
                return rc;
        }

        /* Set OPAL core file size */
        opal_core_attr.size = oc_conf->opalcore_size;

        mpipl_kobj = kobject_create_and_add("mpipl", opal_kobj);
        if (!mpipl_kobj) {
                pr_err("unable to create mpipl kobject\n");
                return -ENOMEM;
        }

        /* Export OPAL core sysfs file */
        rc = sysfs_create_group(mpipl_kobj, &mpipl_group);
        if (rc) {
                pr_err("mpipl sysfs group creation failed (%d)", rc);
                opalcore_cleanup();
                return rc;
        }
        /* The /sys/firmware/opal/core is moved to /sys/firmware/opal/mpipl/
         * directory, need to create symlink at old location to maintain
         * backward compatibility.
         */
        rc = compat_only_sysfs_link_entry_to_kobj(opal_kobj, mpipl_kobj,
                                                  "core", NULL);
        if (rc) {
                pr_err("unable to create core symlink (%d)\n", rc);
                return rc;
        }

        return 0;
}
fs_initcall(opalcore_init);