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Commit 92aa63a5a1bf2e7b0c79e6716d24b76dbbdcf951

Authored by Vivek Goyal
Committed by Linus Torvalds
1 parent d58831e416
Exists in master and in 39 other branches 8mp-imx_5.4.70_2.3.0, 8qm-imx_5.4.70_2.3.0, emb_imx_lf-5.15.y, emb_lf-6.1.y, imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, imx_4.1.15_1.0.0_ga, pitx_8mp_lf-5.10.y, rt-smarc-imx_4.1.15_1.0.0_ga, rt_linux_5.15.71, smarc-8m-android-11.0.0_2.0.0, smarc-imx6_4.14.98_2.0.0_ga, smarc-imx6_4.9.88_2.0.0_ga, smarc-imx7_4.14.98_2.0.0_ga, smarc-imx7_4.9.11_1.0.0_ga, smarc-imx7_4.9.88_2.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-imx_4.1.15_1.0.0_ga, smarc-imx_4.9.11_1.0.0_ga, smarc-imx_4.9.51_imx8m_ga, smarc-imx_4.9.88_2.0.0_ga, smarc-m6.0.1_2.1.0-ga, smarc-n7.1.2_2.0.0-ga, smarc-rel_imx_4.1.15_1.2.0_ga, smarc_8m_00d0_imx_4.14.98_2.0.0_ga, smarc_8m_imx_4.14.78_1.0.0_ga, smarc_8m_imx_4.14.98_2.0.0_ga, smarc_8m_imx_4.19.35_1.1.0, smarc_8mm_imx_4.14.78_1.0.0_ga, smarc_8mm_imx_4.14.98_2.0.0_ga, smarc_8mm_imx_4.19.35_1.1.0, smarc_8mm_imx_5.4.24_2.1.0, smarc_8mp_lf-5.10.y, smarc_8mq_imx_5.4.24_2.1.0, smarc_8mq_lf-5.10.y, smarc_imx_lf-5.15.y

[PATCH] kdump: Retrieve saved max pfn 

This patch retrieves the max_pfn being used by previous kernel and stores it
in a safe location (saved_max_pfn) before it is overwritten due to user
defined memory map.  This pfn is used to make sure that user does not try to
read the physical memory beyond saved_max_pfn.

Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Showing 3 changed files with 24 additions and 0 deletions Side-by-side Diff

arch/i386/kernel/setup.c
Diff comments   View file @ 92aa63a
... ... @@ -59,6 +59,9 @@
59 59 #include "setup_arch_pre.h"
60 60 #include <bios_ebda.h>
61 61  
  62 +/* Forward Declaration. */
  63 +void __init find_max_pfn(void);
  64 +
62 65 /* This value is set up by the early boot code to point to the value
63 66 immediately after the boot time page tables. It contains a *physical*
64 67 address, and must not be in the .bss segment! */
... ... @@ -736,6 +739,15 @@
736 739 if (to != command_line)
737 740 to--;
738 741 if (!memcmp(from+7, "exactmap", 8)) {
  742 +#ifdef CONFIG_CRASH_DUMP
  743 + /* If we are doing a crash dump, we
  744 + * still need to know the real mem
  745 + * size before original memory map is
  746 + * reset.
  747 + */
  748 + find_max_pfn();
  749 + saved_max_pfn = max_pfn;
  750 +#endif
739 751 from += 8+7;
740 752 e820.nr_map = 0;
741 753 userdef = 1;
include/linux/bootmem.h
Diff comments   View file @ 92aa63a
... ... @@ -22,6 +22,10 @@
22 22 */
23 23 extern unsigned long max_pfn;
24 24  
  25 +#ifdef CONFIG_CRASH_DUMP
  26 +extern unsigned long saved_max_pfn;
  27 +#endif
  28 +
25 29 /*
26 30 * node_bootmem_map is a map pointer - the bits represent all physical
27 31 * memory pages (including holes) on the node.
... ... @@ -33,6 +33,14 @@
33 33 * dma_get_required_mask(), which uses
34 34 * it, can be an inline function */
35 35  
  36 +#ifdef CONFIG_CRASH_DUMP
  37 +/*
  38 + * If we have booted due to a crash, max_pfn will be a very low value. We need
  39 + * to know the amount of memory that the previous kernel used.
  40 + */
  41 +unsigned long saved_max_pfn;
  42 +#endif
  43 +
36 44 /* return the number of _pages_ that will be allocated for the boot bitmap */
37 45 unsigned long __init bootmem_bootmap_pages (unsigned long pages)
38 46 {