linux-toradex.git/arch/s390/kernel/crash_dump.c, branch v4.9.60

s390/kdump: Add final note

2017-05-25T13:44:35+00:00

commit dcc00b79fc3d076832f7240de8870f492629b171 upstream.

Since linux v3.14 with commit 38dfac843cb6d7be1 ("vmcore: prevent PT_NOTE
p_memsz overflow during header update") on s390 we get the following
message in the kdump kernel:

  Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x6b6b6b6b,
  n_descsz=0x6b6b6b6b

The reason for this is that we don't create a final zero note in
the ELF header which the proc/vmcore code uses to find out the end
of the notes section (see also kernel/kexec_core.c:final_note()).

It still worked on s390 by chance because we (most of the time?) have the
byte pattern 0x6b6b6b6b after the notes section which also makes the notes
parsing code stop in update_note_header_size_elf64() because 0x6b6b6b6b is
interpreded as note size:

  if ((real_sz + sz) > max_sz) {
          pr_warn("Warning: Exceeded p_memsz, dropping P ...);
          break;
  }

So fix this and add the missing final note to the ELF header.
We don't have to adjust the memory size for ELF header ("alloc_size")
because the new ELF note still fits into the 0x1000 base memory.

Signed-off-by: Michael Holzheu 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman

s390/kdump: Use "LINUX" ELF note name instead of "CORE"

2017-03-15T02:02:41+00:00

commit a4a81d8eebdc1d209d034f62a082a5131e4242b5 upstream.

In binutils/libbfd (bfd/elf.c) it is enforced that all s390 specific ELF
notes like e.g. NT_S390_PREFIX or NT_S390_CTRS have "LINUX" specified
as note name. Otherwise the notes are ignored.

For /proc/vmcore we currently use "CORE" for these notes.

Up to now this has not been a real problem because the dump analysis tool
"crash" does not check the note name. But it will break all programs that
use libbfd for processing ELF notes.

So fix this and use "LINUX" for all s390 specific notes to comply with
libbfd.

Reported-by: Philipp Rudo 
Reviewed-by: Philipp Rudo 
Signed-off-by: Michael Holzheu 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman

s390/crashdump: use list_first_entry_or_null

2016-09-20T12:26:04+00:00

The combo of list_empty() check and return list_first_entry()
can be replaced with list_first_entry_or_null().

Signed-off-by: Masahiro Yamada 
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390: make couple of variables and functions static

2016-05-10T11:24:50+00:00

copy_oldmem_user() and ap_jumptable are private to the files they are
being used in. Therefore make them static.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390: remove superfluous memblock_alloc() return value checks

2016-01-19T11:14:02+00:00

memblock_alloc() and memblock_alloc_base() will panic on their own if
they can't find free memory. Therefore remove some pointless checks.

Signed-off-by: Heiko Carstens 
Acked-by: Michael Holzheu 
Signed-off-by: Martin Schwidefsky

s390: rename struct _lowcore to struct lowcore

2016-01-11T11:27:15+00:00

Finally get rid of the leading underscore. I tried this already two or
three years ago, however Michael Holzheu objected since this would
break the crash utility (again).

However Michael integrated support for the new name into the crash
utility back then, so it doesn't break if the name will be changed
now.  So finally get rid of the ever confusing leading underscore.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390/dump: cleanup CPU save area handling

2015-11-27T08:24:14+00:00

Introduce save_area_alloc(), save_area_boot_cpu(), save_area_add_regs()
and save_area_add_vxrs to deal with storing the CPU state in case of a
system dump. Remove struct save_area and save_area_ext, and create a new
struct save_area as a local definition to arch/s390/kernel/crash_dump.c.
Copy each individual field from the hardware status area to the save area,
storing the minimum of required data.

Signed-off-by: Martin Schwidefsky

s390/dump: streamline oldmem copy functions

2015-11-27T08:24:12+00:00

Introduce two copy functions for the memory of the dumped system,
copy_oldmem_kernel() to copy to the virtual kernel address space
and copy_oldmem_user() to copy to user space.

Acked-by: Michael Holzheu 
Signed-off-by: Martin Schwidefsky

s390/kdump: remove code to create ELF notes in the crashed system

2015-11-27T08:24:12+00:00

The s390 architecture can store the CPU registers of the crashed system
after the kdump kernel has been started and this is the preferred way.
Remove the remaining code fragments that deal with storing CPU registers
while the crashed system is still active.

Acked-by: Michael Holzheu 
Signed-off-by: Martin Schwidefsky

s390/crash_dump: use for_each_mem_range

2015-10-14T12:32:01+00:00

The  already provides for_each_mem_range() macro that
iterates through memblock areas from type_a and not included in type_b.
We can remove custom for_each_dump_mem_range() macro and use the
for_each_mem_range() instead.

Signed-off-by: Alexander Kuleshov 
Signed-off-by: Heiko Carstens