8:49 a.m.
Hello Wenjian,
First -- please send patches as email attachments. Even if I cut-and-paste your
patch from the crash-utility archives (which normally works), there are
still no tabs in your patch.
Now, with respect to the patch, it's not clear to me what would happen if you
make no changes to check_dumpfile_size()?
It seems to me that a read error would occur regardless whether you change
the PT_LOAD-related contents or not.
If no changes are made:
If a readmem() of a truncated page is attempted, read_netdump() would
calculate an offset based upon the original PT_LOAD contents, but then
the subsequent read() would fail, and would return a READ_ERROR.
If your patch is applied:
If a readmem() of a truncated page is attempted, read_netdump() would not
be able to calculate an offset, and would return a READ_ERROR.
What's the difference? Why even bother making the changes?
I also don't understand what the difference between "truncated" and
"incomplete"
is? Why did you separate the messages into two?
Anyway, I had already created a patch in preparation for the changes to
makedumpfile for ELF and compressed kdump vmcores. The patch will apply
to the current github master branch. Please apply it alone, and tell me
what happens.
Thanks,
Dave
----- Original Message -----
Since the incomplete dump file generated by ENOSPC error can't be
analysed
by crash utility, but sometimes this file may contain important information
and the panic problem won't be reproduced, then we came up with an idea to
modify the exist data of the incomplete dump file to make it analysable by
crash utility.
However, we found it will be more suitable to check the incomplete data than
modifying it in make dump file.
So, we change the p_filesz of PT_LOAD header, zero_fill and phys_end of
PT_LOAD
segments, to make crash can analyse incomplete ELF dump file, when incomplete
flag exists.
the issue was discussed at
http://lists.infradead.org/pipermail/kexec/2014-October/012669.html
--- a/netdump.c
+++ b/netdump.c
@@ -52,6 +52,7 @@ static char *vmcoreinfo_read_string(const char *);
#define MIN_PAGE_SIZE (4096)
+#define DUMP_ELF_INCOMPLETE 0x1
/*
* Architectures that have configurable page sizes,
* can differ from the host machine's page size.
@@ -488,6 +489,10 @@ check_dumpfile_size(char *file)
if (stat64(file, &stat) < 0)
return;
+ Elf64_Phdr *load64 = nd->load64;
+ Elf32_Phdr *load32 = nd->load32;
+ unsigned int e_flag = (NULL == nd->elf64) ? (nd->elf32)->e_flags :
(nd->elf64)->e_flags;
+ int status = e_flag & DUMP_ELF_INCOMPLETE;
for (i = 0; i < nd->num_pt_load_segments; i++) {
pls = &nd->pt_load_segments[i];
@@ -495,7 +500,19 @@ check_dumpfile_size(char *file)
(pls->phys_end - pls->phys_start);
if (segment_end > stat.st_size) {
- error(WARNING, "%s: may be truncated or incomplete\n"
+ if (!status){
+ error(WARNING, "%s: may be truncated\n"
+ " PT_LOAD p_offset: %lld\n"
+ " p_filesz: %lld\n"
+ " bytes required: %lld\n"
+ " dumpfile size:
%lld\n\n",
+ file, pls->file_offset,
+ pls->phys_end - pls->phys_start,
+ segment_end, stat.st_size);
+ return;
+ }
+ else{
+ error(WARNING, "%s: may be incomplete\n"
" PT_LOAD p_offset: %lld\n"
" p_filesz: %lld\n"
" bytes required: %lld\n"
@@ -503,8 +520,25 @@ check_dumpfile_size(char *file)
file, pls->file_offset,
pls->phys_end - pls->phys_start,
segment_end, stat.st_size);
- return;
+ }
+ if (pls->file_offset > stat.st_size){
+ pls->file_offset = 0;
+ pls->phys_start = 0;
+ pls->phys_end = 0;
+ }
+ else {
+ if (NULL == load32)
+ load64->p_filesz = stat.st_size -
pls->file_offset;
+ else
+ load32->p_filesz = stat.st_size -
pls->file_offset;
+ pls->zero_fill = pls->phys_end;
+ pls->phys_end = stat.st_size -
pls->file_offset + pls->phys_start;
+ }
}
+ if (NULL == load32)
+ load64++;
+ else
+ load32++;
}
}
--
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