linux.git/arch/s390/kernel/Makefile, branch v4.18

s390: introduce compile time check for empty .bss section

2018-05-09T08:55:01+00:00

Introduce compile time check for files which should avoid using .bss
section, because of the following reasons:
- .bss section has not been zeroed yet,
- initrd has not been moved to a safe location and could be overlapping
with .bss section.

Reviewed-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Martin Schwidefsky

s390/early: move functions which may not access bss section to extra file

2018-05-09T08:55:01+00:00

Move functions which may not access bss section to extra file. This
makes it easier to verify that all early functions which may not rely
on an initialized bss section are not accessing it.

Reviewed-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390: move spectre sysfs attribute code

2018-05-07T19:12:41+00:00

The nospec-branch.c file is compiled without the gcc options to
generate expoline thunks. The return branch of the sysfs show
functions cpu_show_spectre_v1 and cpu_show_spectre_v2 is an indirect
branch as well. These need to be compiled with expolines.

Move the sysfs functions for spectre reporting to a separate file
and loose an '.' for one of the messages.

Cc: stable@vger.kernel.org # 4.16
Fixes: d424986f1d ("s390: add sysfs attributes for spectre")
Signed-off-by: Martin Schwidefsky

s390/kexec_file: Add ELF loader

2018-04-16T07:10:23+00:00

Add an ELF loader for kexec_file. The main task here is to do proper sanity
checks on the ELF file. Basically all other functionality was already
implemented for the image loader.

Signed-off-by: Philipp Rudo 
Signed-off-by: Martin Schwidefsky

s390/kexec_file: Add image loader

2018-04-16T07:10:22+00:00

Add an image loader for kexec_file_load. For simplicity first skip crash
support. The functions defined in machine_kexec_file will later be shared
with the ELF loader.

Signed-off-by: Philipp Rudo 
Reviewed-by: Martin Schwidefsky 
Signed-off-by: Martin Schwidefsky

s390/kexec_file: Add kexec_file_load system call

2018-04-16T07:10:22+00:00

This patch adds the kexec_file_load system call to s390 as well as the arch
specific functions common code requires to work. Loaders for the different
file types will be added later.

Signed-off-by: Philipp Rudo 
Signed-off-by: Martin Schwidefsky

s390: move nobp parameter functions to nospec-branch.c

2018-03-28T06:38:23+00:00

Keep the code for the nobp parameter handling with the code for
expolines. Both are related to the spectre v2 mitigation.

Signed-off-by: Martin Schwidefsky

s390: introduce execute-trampolines for branches

2018-02-07T14:57:02+00:00

Add CONFIG_EXPOLINE to enable the use of the new -mindirect-branch= and
-mfunction_return= compiler options to create a kernel fortified against
the specte v2 attack.

With CONFIG_EXPOLINE=y all indirect branches will be issued with an
execute type instruction. For z10 or newer the EXRL instruction will
be used, for older machines the EX instruction. The typical indirect
call

	basr	%r14,%r1

is replaced with a PC relative call to a new thunk

	brasl	%r14,__s390x_indirect_jump_r1

The thunk contains the EXRL/EX instruction to the indirect branch

__s390x_indirect_jump_r1:
	exrl	0,0f
	j	.
0:	br	%r1

The detour via the execute type instruction has a performance impact.
To get rid of the detour the new kernel parameter "nospectre_v2" and
"spectre_v2=[on,off,auto]" can be used. If the parameter is specified
the kernel and module code will be patched at runtime.

Signed-off-by: Martin Schwidefsky

s390/perf: add perf_regs support and user stack dump

2017-11-16T14:06:11+00:00

Add s390 support to dump user stack to user space for DWARF
stack unwinding.

Signed-off-by: Heiko Carstens 
Reviewed-by: Hendrik Brueckner 
Reviewed-and-tested-by: Thomas Richter 
Signed-off-by: Martin Schwidefsky

s390: enable CPU alternatives unconditionally

2017-11-14T21:08:12+00:00

Remove the CPU_ALTERNATIVES config option and enable the code
unconditionally. The config option was only added to avoid a conflict
with the named saved segment support. Since that code is gone there is
no reason to keep the CPU_ALTERNATIVES config option.

Just enable it unconditionally to also reduce the number of config
options and make it less likely that something breaks.

Signed-off-by: Heiko Carstens