add s390 support to kexec-tools-1.101

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Hi Milton,

first of all thanks for looking at the patches.

> 1) When patching the command line, you read the string from the
> optarg.  While you clear the area in the kernel looking at
> COMMAND_LINE_SIZE, you do not limit the length that you copy into
> the kernel by this amount.  This would seem like a buffer-overflow
> situation that could easily be trapped.

Yes, you're right. The kernel image could be damaged. Fixed.

> 2) I noticed your ramdisk code is quite similar in function to
> slurp_file in kexec/kexec.c.   I realize this is probably a new
> function.

Fixed as well :)

> 3) Your elf-rel loading seem to not be implemented, but your probe
> returns 0 just like the image loader.

I think you're talking about the function machine_verify_elf_rel().
Unlike the probe functions this one should return 0 on error,
shouldn't it?

> 4) You seem to have several addresses hard-coded into the kexec-s390.h
> file.  This would seem to limit the image you are loading, including
> any panic crash kernel options using the current scheme.  I don't
> know your abi to know what other issues you might have with a more
> generic kexec to image interface.  (It appears you setup your image
> to load as if it were from 0 but skipping IMAGE_READ_OFFSET bytes.

The hard coded addresses are part of the kernel abi. Nothing needs to
be changed here. Skipping the first 64k of the kernel image is ok too,
since you usually would only find a loader routine there which would
load the rest of the kernel image into ram and then start it.
If you are really interested you might have a look at
arch/s390/kernel/head.S in the kernel sources :)
Also we do not plan to use the kdump feature. It doesn't make too
much sense for the s390 architecture since we have already other
mechanisms which allow to reliably dump complete memory and register
contents at any given state of the system.

The patch below should be better (still against 1.101). Guess I will
come up with an improved kernel patch too.

Thanks,
Heiko

diffstat:
 configure                              |    5 -
 kexec/arch/s390/Makefile               |    6 +
 kexec/arch/s390/include/arch/options.h |   11 ++
 kexec/arch/s390/kexec-elf-rel-s390.c   |   23 +++++
 kexec/arch/s390/kexec-image.c          |  137 +++++++++++++++++++++++++++++++++
 kexec/arch/s390/kexec-s390.c           |  104 +++++++++++++++++++++++++
 kexec/arch/s390/kexec-s390.h           |   25 ++++++
 kexec/kexec-syscall.h                  |    7 +
 purgatory/arch/s390/Makefile           |    7 +
 purgatory/arch/s390/include/limits.h   |   54 +++++++++++++
 purgatory/arch/s390/include/stdint.h   |   24 +++++
 11 files changed, 402 insertions(+), 1 deletion(-)

1 files changed, 7 insertions, 0 deletions

diff --git a/kexec/kexec-syscall.h b/kexec/kexec-syscall.h
index 7b2670c..3de05eb 100644
--- a/kexec/kexec-syscall.h
+++ b/kexec/kexec-syscall.h
@@ -37,6 +37,12 @@
 #ifdef __x86_64__
 #define __NR_kexec_load		246
 #endif
+#ifdef __s390x__
+#define __NR_kexec_load		277
+#endif
+#ifdef __s390__
+#define __NR_kexec_load		277
+#endif
 #ifndef __NR_kexec_load
 #error Unknown processor architecture.  Needs a kexec_load syscall number.
 #endif
@@ -67,6 +73,7 @@ static inline long kexec_reboot(void)
 #define KEXEC_ARCH_PPC     (20 << 16)
 #define KEXEC_ARCH_PPC64   (21 << 16)
 #define KEXEC_ARCH_IA_64   (50 << 16)
+#define KEXEC_ARCH_S390    (22 << 16)
 
 #define KEXEC_MAX_SEGMENTS 8