Currently there are some variables in the purgatory (e.g. kernel_entry)
which are defined twice, once in assembler- and once in c-code. The reason
for this is that these variables are set during purgatory load, where
sanity checks on the corresponding Elf_Sym's are made, while they are used
in assembler-code. Thus adding a second definition in c-code is a handy
workaround to guarantee correct Elf_Sym's are created.
When the purgatory is compiled with -fcommon (default for gcc on s390) this
is no problem because both symbols are merged by the linker. However this
is not required by ISO C and when the purgatory is built with -fno-common
the linker fails with errors like
arch/s390/purgatory/purgatory.o:(.bss+0x18): multiple definition of `kernel_entry'
arch/s390/purgatory/head.o:/.../arch/s390/purgatory/head.S:230: first defined here
Thus remove the duplicate definitions and add the required size and type
information to the assembler definition. Also add -fno-common to the
command line options to prevent similar hacks in the future.
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Without FORCE make does not detect changes only made to the command line
options. So object files might not be re-built even when they should be.
Fix this by adding FORCE where it is missing.
Fixes: 840798a1f5 ("s390/kexec_file: Add purgatory")
Cc: <stable@vger.kernel.org> # 4.17
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
When the kernel is built with CONFIG_EXPOLINE=y and a compiler with
indirect branch mitigation enabled the purgatory crashes. The reason for
that is that the macros defined for expoline are used in mem.S. These
macros define new sections (.text.__s390x_indirect_*) which are marked
executable. Due to the missing linker script those sections are linked to
address 0, just as the .text section. In combination with the entry point
also being at address 0 this causes the purgatory load code
(kernel/kexec_file.c: kexec_purgatory_setup_sechdrs) to update the entry
point twice. Thus the old kernel jumps to some 'random' address causing the
crash.
To fix this turn off expolines for the purgatory. There is no problem with
this in this case due to the fact that the purgatory only runs once and the
tlb is purged (diag 308) in the end.
Fixes: 840798a1f5 ("s390/kexec_file: Add purgatory")
Cc: <stable@vger.kernel.org> # 4.17
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
New compilers use the floating-point registers as spill registers when
there is high register pressure. In the purgatory however, the afp control
bit is not set. This leads to an exception whenever a floating-point
instruction is used, which again causes an interrupt loop.
Forbid the compiler to use floating-point instructions by adding
-msoft-float to KBUILD_CFLAGS.
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Fixes: 840798a1f5 (s390/kexec_file: Add purgatory)
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Add support to load a crash kernel to the image loader. This requires
extending the purgatory.
Signed-off-by: Philipp Rudo <prudo@linux.vnet.ibm.com>
Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The common code expects the architecture to have a purgatory that runs
between the two kernels. Add it now. For simplicity first skip crash
support.
Signed-off-by: Philipp Rudo <prudo@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
