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2f0e8aae26
Function memcpy_real() is an univeral data mover that does not require DAT mode to be able reading from a physical address. Its advantage is an ability to read from any address, even those for which no kernel virtual mapping exists. Although memcpy_real() is interrupt-safe, there are no handlers that make use of this function. The compiler instrumentation have to be disabled and separate no-DAT stack used to allow execution of the function once DAT mode is disabled. Rework memcpy_real() to overcome these shortcomings. As result, data copying (which is primarily reading out a crashed system memory by a user process) is executed on a regular stack with enabled interrupts. Also, use of memcpy_real_buf swap buffer becomes unnecessary and the swapping is eliminated. The above is achieved by using a fixed virtual address range that spans a single page and remaps that page repeatedly when memcpy_real() is called for a particular physical address. Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
331 lines
7.8 KiB
C
331 lines
7.8 KiB
C
// SPDX-License-Identifier: GPL-1.0+
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/*
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* zcore module to export memory content and register sets for creating system
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* dumps on SCSI/NVMe disks (zfcp/nvme dump).
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*
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* For more information please refer to Documentation/s390/zfcpdump.rst
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*
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* Copyright IBM Corp. 2003, 2008
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* Author(s): Michael Holzheu
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*/
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#define KMSG_COMPONENT "zdump"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/debugfs.h>
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#include <linux/panic_notifier.h>
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#include <linux/reboot.h>
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#include <linux/uio.h>
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#include <asm/asm-offsets.h>
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#include <asm/ipl.h>
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#include <asm/sclp.h>
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#include <asm/setup.h>
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#include <linux/uaccess.h>
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#include <asm/debug.h>
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#include <asm/processor.h>
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#include <asm/irqflags.h>
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#include <asm/checksum.h>
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#include <asm/os_info.h>
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#include <asm/switch_to.h>
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#include <asm/maccess.h>
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#include "sclp.h"
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#define TRACE(x...) debug_sprintf_event(zcore_dbf, 1, x)
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enum arch_id {
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ARCH_S390 = 0,
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ARCH_S390X = 1,
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};
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struct ipib_info {
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unsigned long ipib;
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u32 checksum;
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} __attribute__((packed));
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static struct debug_info *zcore_dbf;
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static int hsa_available;
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static struct dentry *zcore_dir;
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static struct dentry *zcore_reipl_file;
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static struct dentry *zcore_hsa_file;
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static struct ipl_parameter_block *zcore_ipl_block;
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static DEFINE_MUTEX(hsa_buf_mutex);
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static char hsa_buf[PAGE_SIZE] __aligned(PAGE_SIZE);
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/*
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* Copy memory from HSA to iterator (not reentrant):
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*
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* @iter: Iterator where memory should be copied to
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* @src: Start address within HSA where data should be copied
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* @count: Size of buffer, which should be copied
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*/
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size_t memcpy_hsa_iter(struct iov_iter *iter, unsigned long src, size_t count)
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{
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size_t bytes, copied, res = 0;
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unsigned long offset;
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if (!hsa_available)
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return 0;
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mutex_lock(&hsa_buf_mutex);
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while (count) {
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if (sclp_sdias_copy(hsa_buf, src / PAGE_SIZE + 2, 1)) {
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TRACE("sclp_sdias_copy() failed\n");
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break;
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}
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offset = src % PAGE_SIZE;
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bytes = min(PAGE_SIZE - offset, count);
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copied = copy_to_iter(hsa_buf + offset, bytes, iter);
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count -= copied;
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src += copied;
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res += copied;
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if (copied < bytes)
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break;
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}
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mutex_unlock(&hsa_buf_mutex);
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return res;
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}
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/*
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* Copy memory from HSA to kernel memory (not reentrant):
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*
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* @dest: Kernel or user buffer where memory should be copied to
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* @src: Start address within HSA where data should be copied
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* @count: Size of buffer, which should be copied
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*/
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static inline int memcpy_hsa_kernel(void *dst, unsigned long src, size_t count)
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{
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struct iov_iter iter;
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struct kvec kvec;
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kvec.iov_base = dst;
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kvec.iov_len = count;
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iov_iter_kvec(&iter, WRITE, &kvec, 1, count);
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if (memcpy_hsa_iter(&iter, src, count) < count)
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return -EIO;
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return 0;
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}
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static int __init init_cpu_info(void)
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{
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struct save_area *sa;
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/* get info for boot cpu from lowcore, stored in the HSA */
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sa = save_area_boot_cpu();
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if (!sa)
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return -ENOMEM;
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if (memcpy_hsa_kernel(hsa_buf, __LC_FPREGS_SAVE_AREA, 512) < 0) {
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TRACE("could not copy from HSA\n");
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return -EIO;
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}
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save_area_add_regs(sa, hsa_buf); /* vx registers are saved in smp.c */
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return 0;
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}
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/*
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* Release the HSA
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*/
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static void release_hsa(void)
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{
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diag308(DIAG308_REL_HSA, NULL);
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hsa_available = 0;
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}
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static ssize_t zcore_reipl_write(struct file *filp, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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if (zcore_ipl_block) {
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diag308(DIAG308_SET, zcore_ipl_block);
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diag308(DIAG308_LOAD_CLEAR, NULL);
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}
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return count;
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}
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static int zcore_reipl_open(struct inode *inode, struct file *filp)
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{
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return stream_open(inode, filp);
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}
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static int zcore_reipl_release(struct inode *inode, struct file *filp)
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{
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return 0;
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}
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static const struct file_operations zcore_reipl_fops = {
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.owner = THIS_MODULE,
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.write = zcore_reipl_write,
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.open = zcore_reipl_open,
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.release = zcore_reipl_release,
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.llseek = no_llseek,
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};
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static ssize_t zcore_hsa_read(struct file *filp, char __user *buf,
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size_t count, loff_t *ppos)
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{
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static char str[18];
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if (hsa_available)
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snprintf(str, sizeof(str), "%lx\n", sclp.hsa_size);
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else
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snprintf(str, sizeof(str), "0\n");
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return simple_read_from_buffer(buf, count, ppos, str, strlen(str));
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}
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static ssize_t zcore_hsa_write(struct file *filp, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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char value;
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if (*ppos != 0)
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return -EPIPE;
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if (copy_from_user(&value, buf, 1))
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return -EFAULT;
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if (value != '0')
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return -EINVAL;
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release_hsa();
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return count;
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}
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static const struct file_operations zcore_hsa_fops = {
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.owner = THIS_MODULE,
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.write = zcore_hsa_write,
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.read = zcore_hsa_read,
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.open = nonseekable_open,
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.llseek = no_llseek,
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};
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static int __init check_sdias(void)
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{
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if (!sclp.hsa_size) {
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TRACE("Could not determine HSA size\n");
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return -ENODEV;
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}
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return 0;
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}
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/*
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* Provide IPL parameter information block from either HSA or memory
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* for future reipl
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*/
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static int __init zcore_reipl_init(void)
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{
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struct ipib_info ipib_info;
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int rc;
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rc = memcpy_hsa_kernel(&ipib_info, __LC_DUMP_REIPL, sizeof(ipib_info));
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if (rc)
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return rc;
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if (ipib_info.ipib == 0)
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return 0;
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zcore_ipl_block = (void *) __get_free_page(GFP_KERNEL);
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if (!zcore_ipl_block)
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return -ENOMEM;
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if (ipib_info.ipib < sclp.hsa_size)
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rc = memcpy_hsa_kernel(zcore_ipl_block, ipib_info.ipib,
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PAGE_SIZE);
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else
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rc = memcpy_real(zcore_ipl_block, ipib_info.ipib, PAGE_SIZE);
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if (rc || (__force u32)csum_partial(zcore_ipl_block, zcore_ipl_block->hdr.len, 0) !=
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ipib_info.checksum) {
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TRACE("Checksum does not match\n");
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free_page((unsigned long) zcore_ipl_block);
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zcore_ipl_block = NULL;
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}
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return 0;
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}
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static int zcore_reboot_and_on_panic_handler(struct notifier_block *self,
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unsigned long event,
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void *data)
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{
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if (hsa_available)
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release_hsa();
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return NOTIFY_OK;
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}
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static struct notifier_block zcore_reboot_notifier = {
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.notifier_call = zcore_reboot_and_on_panic_handler,
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/* we need to be notified before reipl and kdump */
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.priority = INT_MAX,
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};
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static struct notifier_block zcore_on_panic_notifier = {
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.notifier_call = zcore_reboot_and_on_panic_handler,
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/* we need to be notified before reipl and kdump */
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.priority = INT_MAX,
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};
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static int __init zcore_init(void)
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{
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unsigned char arch;
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int rc;
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if (!is_ipl_type_dump())
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return -ENODATA;
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if (oldmem_data.start)
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return -ENODATA;
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zcore_dbf = debug_register("zcore", 4, 1, 4 * sizeof(long));
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debug_register_view(zcore_dbf, &debug_sprintf_view);
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debug_set_level(zcore_dbf, 6);
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if (ipl_info.type == IPL_TYPE_FCP_DUMP) {
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TRACE("type: fcp\n");
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TRACE("devno: %x\n", ipl_info.data.fcp.dev_id.devno);
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TRACE("wwpn: %llx\n", (unsigned long long) ipl_info.data.fcp.wwpn);
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TRACE("lun: %llx\n", (unsigned long long) ipl_info.data.fcp.lun);
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} else if (ipl_info.type == IPL_TYPE_NVME_DUMP) {
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TRACE("type: nvme\n");
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TRACE("fid: %x\n", ipl_info.data.nvme.fid);
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TRACE("nsid: %x\n", ipl_info.data.nvme.nsid);
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}
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rc = sclp_sdias_init();
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if (rc)
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goto fail;
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rc = check_sdias();
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if (rc)
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goto fail;
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hsa_available = 1;
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rc = memcpy_hsa_kernel(&arch, __LC_AR_MODE_ID, 1);
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if (rc)
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goto fail;
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if (arch == ARCH_S390) {
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pr_alert("The 64-bit dump tool cannot be used for a "
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"32-bit system\n");
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rc = -EINVAL;
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goto fail;
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}
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pr_alert("The dump process started for a 64-bit operating system\n");
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rc = init_cpu_info();
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if (rc)
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goto fail;
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rc = zcore_reipl_init();
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if (rc)
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goto fail;
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zcore_dir = debugfs_create_dir("zcore" , NULL);
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zcore_reipl_file = debugfs_create_file("reipl", S_IRUSR, zcore_dir,
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NULL, &zcore_reipl_fops);
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zcore_hsa_file = debugfs_create_file("hsa", S_IRUSR|S_IWUSR, zcore_dir,
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NULL, &zcore_hsa_fops);
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register_reboot_notifier(&zcore_reboot_notifier);
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atomic_notifier_chain_register(&panic_notifier_list, &zcore_on_panic_notifier);
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return 0;
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fail:
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diag308(DIAG308_REL_HSA, NULL);
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return rc;
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}
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subsys_initcall(zcore_init);
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