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From d015e6df8bd320fbabcd98cc157acf655fc0851b Mon Sep 17 00:00:00 2001
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From: "Hatayama, Daisuke" <d.hatayama@jp.fujitsu.com>
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Date: Tue, 30 Oct 2018 02:47:22 +0000
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Subject: [PATCH] makedumpfile: sadump: fix failure of reading 640 KB backup
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region if at over 4GB location
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Currently, in function sadump_kdump_backup_region_init(), variable mem
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holding physical memory to read as a candidate of the ELF core header
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is of type unsigned int with just 4 byte length:
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for (i = 0; i < ARRAY_LENGTH(kimage.segment); ++i) {
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char e_ident[EI_NIDENT];
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unsigned mem;
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mem=ULONG(buf+i*SIZE(kexec_segment)+OFFSET(kexec_segment.mem));
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if (!mem)
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continue;
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if (!readmem(PADDR, mem, e_ident, SELFMAG)) {
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DEBUG_MSG("sadump: failed to read elfcorehdr buffer\n");
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return;
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}
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Thus, if backup region for the first 640KB physical memory is located
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at over 4GB location thanks to crashkernel=size,high like:
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# grep crashkernel /proc/cmdline
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BOOT_IMAGE=(hd0,gpt2)/vmlinuz-4.18 root=/dev/mapper/rhel-root ro crashkernel=512M,high
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# grep Crash /proc/iomem
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06000000-15ffffff : Crash kernel
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107f000000-109effffff : Crash kernel
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crash> rd -p 0x109ef5d000
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109ef5d000: 00010102464c457f .ELF....
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the upper 32-bit of the physical address in mem variable is dropped
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and readmem() fails while outputting the following debug message:
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# LANG=C ./makedumpfile --message-level 8 -f -l -d 31 -x ./vmlinux /dev/sdc vmcore-ld31
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sadump: read dump device as single partition
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sadump: single partition configuration
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page_size : 4096
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sadump: timezone information is missing
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sadump: idtr=fffffe0000000000
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sadump: cr3=86b42e000
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sadump: idtr(phys)=4c35cc000
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sadump: devide_error(vmlinux)=ffffffff81a00c50
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sadump: devide_error(vmcore)=ffffffffa0c00c50
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sadump: cmdline vaddr: ffffffffa1bcf008
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sadump: cmdline paddr: 4c35cf008
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sadump: cmdline buf vaddr: ffff8ae89ffceec0
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sadump: cmdline buf paddr: 109ffceec0
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sadump: kaslr_offset=1f200000
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sadump: phys_base=4a1a00000
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sadump: online cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 [...]
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sadump: nr_cpus: 60
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sadump: failed to read elfcorehdr buffer <--- This is the debug message indicating
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reading ELF core header fails
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Then, the generated vmcore has invalid data in its first 640KB part.
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The variable mem needs to have type of 64-bit length.
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With this patch, kdump backup region is successfully found as follows:
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# LANG=C ./makedumpfile --message-level 31 -f -l -d 31 -x ./vmlinux /dev/sdc vmcore-ld31
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sadump: read dump device as single partition
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sadump: single partition configuration
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page_size : 4096
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sadump: timezone information is missing
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sadump: idtr=fffffe0000000000
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sadump: cr3=86b42e000
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sadump: idtr(phys)=4c35cc000
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sadump: devide_error(vmlinux)=ffffffff81a00c50
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sadump: devide_error(vmcore)=ffffffffa0c00c50
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sadump: cmdline vaddr: ffffffffa1bcf008
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sadump: cmdline paddr: 4c35cf008
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sadump: cmdline buf vaddr: ffff8ae89ffceec0
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sadump: cmdline buf paddr: 109ffceec0
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sadump: kaslr_offset=1f200000
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sadump: phys_base=4a1a00000
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sadump: online cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 [...]
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sadump: nr_cpus: 60
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The kernel version is not supported.
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The makedumpfile operation may be incomplete.
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sadump: SRC_START: 0x00000000001000 SRC_SIZE: 0x0000000009f000 SRC_OFFSET: 0x0000109ef61000
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sadump: kdump backup region used
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...<snip>...
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By the way, before crashkernel=size,high was introduced, there was
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limitation that ELF core header resides at under 4GB location, so
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defining it as unsigned int was not entirely wrong at that time.
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Signed-off-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
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---
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sadump_info.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/makedumpfile-1.6.4/sadump_info.c b/makedumpfile-1.6.4/sadump_info.c
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index 34b568c..46867ce 100644
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--- a/makedumpfile-1.6.4/sadump_info.c
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+++ b/makedumpfile-1.6.4/sadump_info.c
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@@ -2395,7 +2395,7 @@ sadump_kdump_backup_region_init(void)
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elfcorehdr_p = 0;
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for (i = 0; i < ARRAY_LENGTH(kimage.segment); ++i) {
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char e_ident[EI_NIDENT];
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- unsigned mem;
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+ unsigned long mem;
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mem=ULONG(buf+i*SIZE(kexec_segment)+OFFSET(kexec_segment.mem));
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if (!mem)
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--
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2.17.1
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