machine_kexec.c

Go to the documentation of this file.

/*
 * Copyright 2010 Tilera Corporation. All Rights Reserved.
 *
 *   This program is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU General Public License
 *   as published by the Free Software Foundation, version 2.
 *
 *   This program is distributed in the hope that it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 *   NON INFRINGEMENT.  See the GNU General Public License for
 *   more details.
 *
 * based on machine_kexec.c from other architectures in linux-2.6.18
 */

#include <linux/mm.h>
#include <linux/kexec.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/errno.h>
#include <linux/vmalloc.h>
#include <linux/cpumask.h>
#include <linux/kernel.h>
#include <linux/elf.h>
#include <linux/highmem.h>
#include <linux/mmu_context.h>
#include <linux/io.h>
#include <linux/timex.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/cacheflush.h>
#include <asm/checksum.h>
#include <asm/tlbflush.h>
#include <asm/homecache.h>
#include <hv/hypervisor.h>


/*
 * This stuff is not in elf.h and is not in any other kernel include.
 * This stuff is needed below in the little boot notes parser to
 * extract the command line so we can pass it to the hypervisor.
 */
struct Elf32_Bhdr {
    Elf32_Word b_signature;
    Elf32_Word b_size;
    Elf32_Half b_checksum;
    Elf32_Half b_records;
};
#define ELF_BOOT_MAGIC      0x0E1FB007
#define EBN_COMMAND_LINE    0x00000004
#define roundupsz(X) (((X) + 3) & ~3)

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */


void machine_shutdown(void)
{
    /*
     * Normally we would stop all the other processors here, but
     * the check in machine_kexec_prepare below ensures we'll only
     * get this far if we've been booted with "nosmp" on the
     * command line or without CONFIG_SMP so there's nothing to do
     * here (for now).
     */
}

void machine_crash_shutdown(struct pt_regs *regs)
{
    /*
     * Cannot happen.  This type of kexec is disabled on this
     * architecture (and enforced in machine_kexec_prepare below).
     */
}


int machine_kexec_prepare(struct kimage *image)
{
    if (num_online_cpus() > 1) {
        pr_warning("%s: detected attempt to kexec "
               "with num_online_cpus() > 1\n",
               __func__);
        return -ENOSYS;
    }
    if (image->type != KEXEC_TYPE_DEFAULT) {
        pr_warning("%s: detected attempt to kexec "
               "with unsupported type: %d\n",
               __func__,
               image->type);
        return -ENOSYS;
    }
    return 0;
}

void machine_kexec_cleanup(struct kimage *image)
{
    /*
     * We did nothing in machine_kexec_prepare,
     * so we have nothing to do here.
     */
}

/*
 * If we can find elf boot notes on this page, return the command
 * line.  Otherwise, silently return null.  Somewhat kludgy, but no
 * good way to do this without significantly rearchitecting the
 * architecture-independent kexec code.
 */

static unsigned char *kexec_bn2cl(void *pg)
{
    struct Elf32_Bhdr *bhdrp;
    Elf32_Nhdr *nhdrp;
    unsigned char *desc;
    unsigned char *command_line;
    __sum16 csum;

    bhdrp = (struct Elf32_Bhdr *) pg;

    /*
     * This routine is invoked for every source page, so make
     * sure to quietly ignore every impossible page.
     */
    if (bhdrp->b_signature != ELF_BOOT_MAGIC ||
        bhdrp->b_size > PAGE_SIZE)
        return 0;

    /*
     * If we get a checksum mismatch, warn with the checksum
     * so we can diagnose better.
     */
    csum = ip_compute_csum(pg, bhdrp->b_size);
    if (csum != 0) {
        pr_warning("%s: bad checksum %#x (size %d)\n",
               __func__, csum, bhdrp->b_size);
        return 0;
    }

    nhdrp = (Elf32_Nhdr *) (bhdrp + 1);

    while (nhdrp->n_type != EBN_COMMAND_LINE) {

        desc = (unsigned char *) (nhdrp + 1);
        desc += roundupsz(nhdrp->n_descsz);

        nhdrp = (Elf32_Nhdr *) desc;

        /* still in bounds? */
        if ((unsigned char *) (nhdrp + 1) >
            ((unsigned char *) pg) + bhdrp->b_size) {

            pr_info("%s: out of bounds\n", __func__);
            return 0;
        }
    }

    command_line = (unsigned char *) (nhdrp + 1);
    desc = command_line;

    while (*desc != '\0') {
        desc++;
        if (((unsigned long)desc & PAGE_MASK) != (unsigned long)pg) {
            pr_info("%s: ran off end of page\n",
                   __func__);
            return 0;
        }
    }

    return command_line;
}

static void kexec_find_and_set_command_line(struct kimage *image)
{
    kimage_entry_t *ptr, entry;

    unsigned char *command_line = 0;
    unsigned char *r;
    HV_Errno hverr;

    for (ptr = &image->head;
         (entry = *ptr) && !(entry & IND_DONE);
         ptr = (entry & IND_INDIRECTION) ?
             phys_to_virt((entry & PAGE_MASK)) : ptr + 1) {

        if ((entry & IND_SOURCE)) {
            void *va =
                kmap_atomic_pfn(entry >> PAGE_SHIFT);
            r = kexec_bn2cl(va);
            if (r) {
                command_line = r;
                break;
            }
            kunmap_atomic(va);
        }
    }

    if (command_line != 0) {
        pr_info("setting new command line to \"%s\"\n",
               command_line);

        hverr = hv_set_command_line(
            (HV_VirtAddr) command_line, strlen(command_line));
        kunmap_atomic(command_line);
    } else {
        pr_info("%s: no command line found; making empty\n",
               __func__);
        hverr = hv_set_command_line((HV_VirtAddr) command_line, 0);
    }
    if (hverr)
        pr_warning("%s: hv_set_command_line returned error: %d\n",
               __func__, hverr);
}

/*
 * The kexec code range-checks all its PAs, so to avoid having it run
 * amok and allocate memory and then sequester it from every other
 * controller, we force it to come from controller zero.  We also
 * disable the oom-killer since if we do end up running out of memory,
 * that almost certainly won't help.
 */
struct page *kimage_alloc_pages_arch(gfp_t gfp_mask, unsigned int order)
{
    gfp_mask |= __GFP_THISNODE | __GFP_NORETRY;
    return alloc_pages_node(0, gfp_mask, order);
}

/*
 * Address range in which pa=va mapping is set in setup_quasi_va_is_pa().
 * For tilepro, PAGE_OFFSET is used since this is the largest possbile value
 * for tilepro, while for tilegx, we limit it to entire middle level page
 * table which we assume has been allocated and is undoubtedly large enough.
 */
#ifndef __tilegx__
#define QUASI_VA_IS_PA_ADDR_RANGE PAGE_OFFSET
#else
#define QUASI_VA_IS_PA_ADDR_RANGE PGDIR_SIZE
#endif

static void setup_quasi_va_is_pa(void)
{
    HV_PTE pte;
    unsigned long i;

    /*
     * Flush our TLB to prevent conflicts between the previous contents
     * and the new stuff we're about to add.
     */
    local_flush_tlb_all();

    /*
     * setup VA is PA, at least up to QUASI_VA_IS_PA_ADDR_RANGE.
     * Note here we assume that level-1 page table is defined by
     * HPAGE_SIZE.
     */
    pte = hv_pte(_PAGE_KERNEL | _PAGE_HUGE_PAGE);
    pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3);
    for (i = 0; i < (QUASI_VA_IS_PA_ADDR_RANGE >> HPAGE_SHIFT); i++) {
        unsigned long vaddr = i << HPAGE_SHIFT;
        pgd_t *pgd = pgd_offset(current->mm, vaddr);
        pud_t *pud = pud_offset(pgd, vaddr);
        pte_t *ptep = (pte_t *) pmd_offset(pud, vaddr);
        unsigned long pfn = i << (HPAGE_SHIFT - PAGE_SHIFT);

        if (pfn_valid(pfn))
            __set_pte(ptep, pfn_pte(pfn, pte));
    }
}


void machine_kexec(struct kimage *image)
{
    void *reboot_code_buffer;
    pte_t *ptep;
    void (*rnk)(unsigned long, void *, unsigned long)
        __noreturn;

    /* Mask all interrupts before starting to reboot. */
    interrupt_mask_set_mask(~0ULL);

    kexec_find_and_set_command_line(image);

    /*
     * Adjust the home caching of the control page to be cached on
     * this cpu, and copy the assembly helper into the control
     * code page, which we map in the vmalloc area.
     */
    homecache_change_page_home(image->control_code_page, 0,
                   smp_processor_id());
    reboot_code_buffer = page_address(image->control_code_page);
    BUG_ON(reboot_code_buffer == NULL);
    ptep = virt_to_pte(NULL, (unsigned long)reboot_code_buffer);
    __set_pte(ptep, pte_mkexec(*ptep));
    memcpy(reboot_code_buffer, relocate_new_kernel,
           relocate_new_kernel_size);
    __flush_icache_range(
        (unsigned long) reboot_code_buffer,
        (unsigned long) reboot_code_buffer + relocate_new_kernel_size);

    setup_quasi_va_is_pa();

    /* now call it */
    rnk = reboot_code_buffer;
    (*rnk)(image->head, reboot_code_buffer, image->start);
}