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![Xunlei Pang](/assets/img/avatar_default.png)
Currently vmcoreinfo data is updated at boot time subsys_initcall(), it has the risk of being modified by some wrong code during system is running. As a result, vmcore dumped may contain the wrong vmcoreinfo. Later on, when using "crash", "makedumpfile", etc utility to parse this vmcore, we probably will get "Segmentation fault" or other unexpected errors. E.g. 1) wrong code overwrites vmcoreinfo_data; 2) further crashes the system; 3) trigger kdump, then we obviously will fail to recognize the crash context correctly due to the corrupted vmcoreinfo. Now except for vmcoreinfo, all the crash data is well protected(including the cpu note which is fully updated in the crash path, thus its correctness is guaranteed). Given that vmcoreinfo data is a large chunk prepared for kdump, we better protect it as well. To solve this, we relocate and copy vmcoreinfo_data to the crash memory when kdump is loading via kexec syscalls. Because the whole crash memory will be protected by existing arch_kexec_protect_crashkres() mechanism, we naturally protect vmcoreinfo_data from write(even read) access under kernel direct mapping after kdump is loaded. Since kdump is usually loaded at the very early stage after boot, we can trust the correctness of the vmcoreinfo data copied. On the other hand, we still need to operate the vmcoreinfo safe copy when crash happens to generate vmcoreinfo_note again, we rely on vmap() to map out a new kernel virtual address and update to use this new one instead in the following crash_save_vmcoreinfo(). BTW, we do not touch vmcoreinfo_note, because it will be fully updated using the protected vmcoreinfo_data after crash which is surely correct just like the cpu crash note. Link: http://lkml.kernel.org/r/1493281021-20737-3-git-send-email-xlpang@redhat.com Signed-off-by: Xunlei Pang <xlpang@redhat.com> Tested-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Young <dyoung@redhat.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Hari Bathini <hbathini@linux.vnet.ibm.com> Cc: Juergen Gross <jgross@suse.com> Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
471 lines
11 KiB
C
471 lines
11 KiB
C
/*
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* crash.c - kernel crash support code.
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* Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com>
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*
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* This source code is licensed under the GNU General Public License,
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* Version 2. See the file COPYING for more details.
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*/
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#include <linux/crash_core.h>
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#include <linux/utsname.h>
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#include <linux/vmalloc.h>
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#include <asm/page.h>
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#include <asm/sections.h>
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/* vmcoreinfo stuff */
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static unsigned char *vmcoreinfo_data;
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static size_t vmcoreinfo_size;
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u32 *vmcoreinfo_note;
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/* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */
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static unsigned char *vmcoreinfo_data_safecopy;
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/*
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* parsing the "crashkernel" commandline
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*
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* this code is intended to be called from architecture specific code
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*/
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/*
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* This function parses command lines in the format
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*
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* crashkernel=ramsize-range:size[,...][@offset]
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*
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* The function returns 0 on success and -EINVAL on failure.
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*/
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static int __init parse_crashkernel_mem(char *cmdline,
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unsigned long long system_ram,
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unsigned long long *crash_size,
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unsigned long long *crash_base)
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{
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char *cur = cmdline, *tmp;
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/* for each entry of the comma-separated list */
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do {
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unsigned long long start, end = ULLONG_MAX, size;
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/* get the start of the range */
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start = memparse(cur, &tmp);
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if (cur == tmp) {
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pr_warn("crashkernel: Memory value expected\n");
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return -EINVAL;
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}
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cur = tmp;
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if (*cur != '-') {
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pr_warn("crashkernel: '-' expected\n");
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return -EINVAL;
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}
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cur++;
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/* if no ':' is here, than we read the end */
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if (*cur != ':') {
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end = memparse(cur, &tmp);
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if (cur == tmp) {
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pr_warn("crashkernel: Memory value expected\n");
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return -EINVAL;
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}
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cur = tmp;
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if (end <= start) {
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pr_warn("crashkernel: end <= start\n");
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return -EINVAL;
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}
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}
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if (*cur != ':') {
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pr_warn("crashkernel: ':' expected\n");
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return -EINVAL;
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}
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cur++;
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size = memparse(cur, &tmp);
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if (cur == tmp) {
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pr_warn("Memory value expected\n");
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return -EINVAL;
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}
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cur = tmp;
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if (size >= system_ram) {
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pr_warn("crashkernel: invalid size\n");
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return -EINVAL;
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}
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/* match ? */
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if (system_ram >= start && system_ram < end) {
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*crash_size = size;
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break;
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}
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} while (*cur++ == ',');
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if (*crash_size > 0) {
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while (*cur && *cur != ' ' && *cur != '@')
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cur++;
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if (*cur == '@') {
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cur++;
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*crash_base = memparse(cur, &tmp);
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if (cur == tmp) {
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pr_warn("Memory value expected after '@'\n");
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return -EINVAL;
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}
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}
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}
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return 0;
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}
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/*
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* That function parses "simple" (old) crashkernel command lines like
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*
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* crashkernel=size[@offset]
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*
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* It returns 0 on success and -EINVAL on failure.
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*/
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static int __init parse_crashkernel_simple(char *cmdline,
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unsigned long long *crash_size,
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unsigned long long *crash_base)
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{
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char *cur = cmdline;
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*crash_size = memparse(cmdline, &cur);
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if (cmdline == cur) {
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pr_warn("crashkernel: memory value expected\n");
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return -EINVAL;
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}
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if (*cur == '@')
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*crash_base = memparse(cur+1, &cur);
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else if (*cur != ' ' && *cur != '\0') {
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pr_warn("crashkernel: unrecognized char: %c\n", *cur);
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return -EINVAL;
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}
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return 0;
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}
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#define SUFFIX_HIGH 0
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#define SUFFIX_LOW 1
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#define SUFFIX_NULL 2
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static __initdata char *suffix_tbl[] = {
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[SUFFIX_HIGH] = ",high",
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[SUFFIX_LOW] = ",low",
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[SUFFIX_NULL] = NULL,
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};
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/*
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* That function parses "suffix" crashkernel command lines like
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*
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* crashkernel=size,[high|low]
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*
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* It returns 0 on success and -EINVAL on failure.
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*/
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static int __init parse_crashkernel_suffix(char *cmdline,
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unsigned long long *crash_size,
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const char *suffix)
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{
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char *cur = cmdline;
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*crash_size = memparse(cmdline, &cur);
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if (cmdline == cur) {
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pr_warn("crashkernel: memory value expected\n");
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return -EINVAL;
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}
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/* check with suffix */
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if (strncmp(cur, suffix, strlen(suffix))) {
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pr_warn("crashkernel: unrecognized char: %c\n", *cur);
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return -EINVAL;
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}
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cur += strlen(suffix);
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if (*cur != ' ' && *cur != '\0') {
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pr_warn("crashkernel: unrecognized char: %c\n", *cur);
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return -EINVAL;
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}
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return 0;
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}
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static __init char *get_last_crashkernel(char *cmdline,
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const char *name,
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const char *suffix)
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{
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char *p = cmdline, *ck_cmdline = NULL;
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/* find crashkernel and use the last one if there are more */
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p = strstr(p, name);
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while (p) {
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char *end_p = strchr(p, ' ');
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char *q;
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if (!end_p)
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end_p = p + strlen(p);
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if (!suffix) {
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int i;
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/* skip the one with any known suffix */
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for (i = 0; suffix_tbl[i]; i++) {
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q = end_p - strlen(suffix_tbl[i]);
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if (!strncmp(q, suffix_tbl[i],
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strlen(suffix_tbl[i])))
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goto next;
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}
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ck_cmdline = p;
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} else {
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q = end_p - strlen(suffix);
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if (!strncmp(q, suffix, strlen(suffix)))
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ck_cmdline = p;
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}
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next:
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p = strstr(p+1, name);
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}
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if (!ck_cmdline)
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return NULL;
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return ck_cmdline;
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}
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static int __init __parse_crashkernel(char *cmdline,
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unsigned long long system_ram,
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unsigned long long *crash_size,
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unsigned long long *crash_base,
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const char *name,
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const char *suffix)
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{
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char *first_colon, *first_space;
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char *ck_cmdline;
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BUG_ON(!crash_size || !crash_base);
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*crash_size = 0;
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*crash_base = 0;
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ck_cmdline = get_last_crashkernel(cmdline, name, suffix);
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if (!ck_cmdline)
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return -EINVAL;
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ck_cmdline += strlen(name);
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if (suffix)
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return parse_crashkernel_suffix(ck_cmdline, crash_size,
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suffix);
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/*
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* if the commandline contains a ':', then that's the extended
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* syntax -- if not, it must be the classic syntax
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*/
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first_colon = strchr(ck_cmdline, ':');
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first_space = strchr(ck_cmdline, ' ');
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if (first_colon && (!first_space || first_colon < first_space))
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return parse_crashkernel_mem(ck_cmdline, system_ram,
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crash_size, crash_base);
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return parse_crashkernel_simple(ck_cmdline, crash_size, crash_base);
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}
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/*
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* That function is the entry point for command line parsing and should be
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* called from the arch-specific code.
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*/
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int __init parse_crashkernel(char *cmdline,
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unsigned long long system_ram,
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unsigned long long *crash_size,
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unsigned long long *crash_base)
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{
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return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
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"crashkernel=", NULL);
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}
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int __init parse_crashkernel_high(char *cmdline,
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unsigned long long system_ram,
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unsigned long long *crash_size,
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unsigned long long *crash_base)
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{
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return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
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"crashkernel=", suffix_tbl[SUFFIX_HIGH]);
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}
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int __init parse_crashkernel_low(char *cmdline,
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unsigned long long system_ram,
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unsigned long long *crash_size,
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unsigned long long *crash_base)
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{
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return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
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"crashkernel=", suffix_tbl[SUFFIX_LOW]);
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}
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Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
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void *data, size_t data_len)
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{
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struct elf_note *note = (struct elf_note *)buf;
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note->n_namesz = strlen(name) + 1;
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note->n_descsz = data_len;
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note->n_type = type;
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buf += DIV_ROUND_UP(sizeof(*note), sizeof(Elf_Word));
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memcpy(buf, name, note->n_namesz);
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buf += DIV_ROUND_UP(note->n_namesz, sizeof(Elf_Word));
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memcpy(buf, data, data_len);
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buf += DIV_ROUND_UP(data_len, sizeof(Elf_Word));
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return buf;
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}
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void final_note(Elf_Word *buf)
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{
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memset(buf, 0, sizeof(struct elf_note));
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}
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static void update_vmcoreinfo_note(void)
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{
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u32 *buf = vmcoreinfo_note;
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if (!vmcoreinfo_size)
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return;
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buf = append_elf_note(buf, VMCOREINFO_NOTE_NAME, 0, vmcoreinfo_data,
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vmcoreinfo_size);
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final_note(buf);
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}
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void crash_update_vmcoreinfo_safecopy(void *ptr)
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{
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if (ptr)
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memcpy(ptr, vmcoreinfo_data, vmcoreinfo_size);
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vmcoreinfo_data_safecopy = ptr;
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}
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void crash_save_vmcoreinfo(void)
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{
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if (!vmcoreinfo_note)
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return;
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/* Use the safe copy to generate vmcoreinfo note if have */
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if (vmcoreinfo_data_safecopy)
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vmcoreinfo_data = vmcoreinfo_data_safecopy;
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vmcoreinfo_append_str("CRASHTIME=%ld\n", get_seconds());
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update_vmcoreinfo_note();
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}
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void vmcoreinfo_append_str(const char *fmt, ...)
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{
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va_list args;
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char buf[0x50];
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size_t r;
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va_start(args, fmt);
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r = vscnprintf(buf, sizeof(buf), fmt, args);
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va_end(args);
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r = min(r, (size_t)VMCOREINFO_BYTES - vmcoreinfo_size);
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memcpy(&vmcoreinfo_data[vmcoreinfo_size], buf, r);
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vmcoreinfo_size += r;
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}
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/*
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* provide an empty default implementation here -- architecture
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* code may override this
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*/
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void __weak arch_crash_save_vmcoreinfo(void)
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{}
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phys_addr_t __weak paddr_vmcoreinfo_note(void)
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{
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return __pa(vmcoreinfo_note);
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}
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static int __init crash_save_vmcoreinfo_init(void)
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{
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vmcoreinfo_data = (unsigned char *)get_zeroed_page(GFP_KERNEL);
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if (!vmcoreinfo_data) {
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pr_warn("Memory allocation for vmcoreinfo_data failed\n");
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return -ENOMEM;
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}
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vmcoreinfo_note = alloc_pages_exact(VMCOREINFO_NOTE_SIZE,
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GFP_KERNEL | __GFP_ZERO);
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if (!vmcoreinfo_note) {
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free_page((unsigned long)vmcoreinfo_data);
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vmcoreinfo_data = NULL;
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pr_warn("Memory allocation for vmcoreinfo_note failed\n");
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return -ENOMEM;
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}
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VMCOREINFO_OSRELEASE(init_uts_ns.name.release);
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VMCOREINFO_PAGESIZE(PAGE_SIZE);
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VMCOREINFO_SYMBOL(init_uts_ns);
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VMCOREINFO_SYMBOL(node_online_map);
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#ifdef CONFIG_MMU
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VMCOREINFO_SYMBOL(swapper_pg_dir);
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#endif
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VMCOREINFO_SYMBOL(_stext);
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VMCOREINFO_SYMBOL(vmap_area_list);
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#ifndef CONFIG_NEED_MULTIPLE_NODES
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VMCOREINFO_SYMBOL(mem_map);
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VMCOREINFO_SYMBOL(contig_page_data);
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#endif
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#ifdef CONFIG_SPARSEMEM
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VMCOREINFO_SYMBOL(mem_section);
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VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS);
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VMCOREINFO_STRUCT_SIZE(mem_section);
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VMCOREINFO_OFFSET(mem_section, section_mem_map);
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#endif
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VMCOREINFO_STRUCT_SIZE(page);
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VMCOREINFO_STRUCT_SIZE(pglist_data);
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VMCOREINFO_STRUCT_SIZE(zone);
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VMCOREINFO_STRUCT_SIZE(free_area);
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VMCOREINFO_STRUCT_SIZE(list_head);
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VMCOREINFO_SIZE(nodemask_t);
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VMCOREINFO_OFFSET(page, flags);
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VMCOREINFO_OFFSET(page, _refcount);
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VMCOREINFO_OFFSET(page, mapping);
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VMCOREINFO_OFFSET(page, lru);
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VMCOREINFO_OFFSET(page, _mapcount);
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VMCOREINFO_OFFSET(page, private);
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VMCOREINFO_OFFSET(page, compound_dtor);
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VMCOREINFO_OFFSET(page, compound_order);
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VMCOREINFO_OFFSET(page, compound_head);
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VMCOREINFO_OFFSET(pglist_data, node_zones);
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VMCOREINFO_OFFSET(pglist_data, nr_zones);
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#ifdef CONFIG_FLAT_NODE_MEM_MAP
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VMCOREINFO_OFFSET(pglist_data, node_mem_map);
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#endif
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VMCOREINFO_OFFSET(pglist_data, node_start_pfn);
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VMCOREINFO_OFFSET(pglist_data, node_spanned_pages);
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VMCOREINFO_OFFSET(pglist_data, node_id);
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VMCOREINFO_OFFSET(zone, free_area);
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VMCOREINFO_OFFSET(zone, vm_stat);
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VMCOREINFO_OFFSET(zone, spanned_pages);
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VMCOREINFO_OFFSET(free_area, free_list);
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VMCOREINFO_OFFSET(list_head, next);
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VMCOREINFO_OFFSET(list_head, prev);
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VMCOREINFO_OFFSET(vmap_area, va_start);
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VMCOREINFO_OFFSET(vmap_area, list);
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VMCOREINFO_LENGTH(zone.free_area, MAX_ORDER);
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log_buf_vmcoreinfo_setup();
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VMCOREINFO_LENGTH(free_area.free_list, MIGRATE_TYPES);
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VMCOREINFO_NUMBER(NR_FREE_PAGES);
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VMCOREINFO_NUMBER(PG_lru);
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VMCOREINFO_NUMBER(PG_private);
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VMCOREINFO_NUMBER(PG_swapcache);
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VMCOREINFO_NUMBER(PG_slab);
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#ifdef CONFIG_MEMORY_FAILURE
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VMCOREINFO_NUMBER(PG_hwpoison);
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#endif
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VMCOREINFO_NUMBER(PG_head_mask);
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VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE);
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#ifdef CONFIG_HUGETLB_PAGE
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VMCOREINFO_NUMBER(HUGETLB_PAGE_DTOR);
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#endif
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arch_crash_save_vmcoreinfo();
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update_vmcoreinfo_note();
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return 0;
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}
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subsys_initcall(crash_save_vmcoreinfo_init);
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