linux-dev/arch/s390/lib/Makefile, branch master

s390/nospec: build expoline.o for modules_prepare target

2022-07-13T13:21:55Z

When CONFIG_EXPOLINE_EXTERN is used expoline thunks are generated from arch/s390/lib/expoline.S and postlinked into every module. This is also true for external modules. Add expoline.o build to the modules_prepare target. Fixes: 1d2ad084800e ("s390/nospec: add an option to use thunk-extern") Reported-by: Joe Lawrence Tested-by: Sumanth Korikkar Acked-by: Sumanth Korikkar Tested-by: C. Erastus Toe Tested-by: Joe Lawrence Link: https://lore.kernel.org/r/patch-1.thread-d13b6c.git-a2387a74dc49.your-ad-here.call-01656331067-ext-4899@work.hours Signed-off-by: Vasily Gorbik Signed-off-by: Alexander Gordeev

s390/nospec: add an option to use thunk-extern

2022-03-10T14:58:17Z

Currently with -mindirect-branch=thunk and -mfunction-return=thunk compiler options expoline thunks are put into individual COMDAT group sections. s390 is the only architecture which has group sections and it has implications for kpatch and objtool tools support. Using -mindirect-branch=thunk-extern and -mfunction-return=thunk-extern is an alternative, which comes with a need to generate all required expoline thunks manually. Unfortunately modules area is too far away from the kernel image, and expolines from the kernel image cannon be used. But since all new distributions (except Debian) build kernels for machine generations newer than z10, where "exrl" instruction is available, that leaves only 16 expolines thunks possible. Provide an option to build the kernel with -mindirect-branch=thunk-extern and -mfunction-return=thunk-extern for z10 or newer. This also requires to postlink expoline thunks into all modules explicitly. Currently modules already contain most expolines anyhow. Unfortunately -mindirect-branch=thunk-extern and -mfunction-return=thunk-extern options support is broken in gcc <= 11.2. Additional compile test is required to verify proper gcc support. Acked-by: Ilya Leoshkevich Co-developed-by: Sumanth Korikkar Signed-off-by: Sumanth Korikkar Signed-off-by: Vasily Gorbik

s390/module: test loading modules with a lot of relocations

2022-01-24T08:10:59Z

Add a test in order to prevent regressions. Signed-off-by: Ilya Leoshkevich Reviewed-by: Heiko Carstens Cc: Vasily Gorbik Cc: Christian Borntraeger Signed-off-by: Heiko Carstens

kprobes: add testcases for s390

2021-10-04T07:49:37Z

Add a few testcases to make sure that it's not possible to place a kprobe in the mid of an instruction on s390. Signed-off-by: Sven Schnelle Acked-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: enable HAVE_FUNCTION_ERROR_INJECTION

2020-07-27T08:33:28Z

This kernel feature is required for enabling BPF_KPROBE_OVERRIDE. Define override_function_with_return() and regs_set_return_value() functions, and fix compile errors in syscall_wrapper.h. Signed-off-by: Ilya Leoshkevich Signed-off-by: Heiko Carstens

s390/unwind: add a test for the internal API

2019-11-30T09:52:46Z

unwind_for_each_frame can take at least 8 different sets of parameters. Add a test to make sure they all are handled in a sane way. Reviewed-by: Heiko Carstens Signed-off-by: Ilya Leoshkevich Co-developed-by: Vasily Gorbik Signed-off-by: Vasily Gorbik

s390: clean .bss before running uncompressed kernel

2019-08-21T10:58:52Z

Clean uncompressed kernel .bss section in the startup code before the uncompressed kernel is executed. At this point of time initrd and certificates have been already rescued. Uncompressed kernel .bss size is known from vmlinux_info. It is also taken into consideration during uncompressed kernel positioning by kaslr (so it is safe to clean it). With that uncompressed kernel is starting with .bss section zeroed and no .bss section usage restrictions apply. Which makes chkbss checks for uncompressed kernel objects obsolete and they can be removed. early_nobss.c is also not needed anymore. Parts of it which are still relevant are moved to early.c. Kasan initialization code is now called directly from head64 (early.c is instrumented and should not be executed before kasan shadow memory is set up). Reviewed-by: Philipp Rudo Signed-off-by: Vasily Gorbik

s390: enforce CONFIG_SMP

2019-06-07T08:09:37Z

There never have been distributions that shiped with CONFIG_SMP=n for s390. In addition the kernel currently doesn't even compile with CONFIG_SMP=n for s390. Most likely it wouldn't even work, even if we fix the compile error, since nobody tests it, since there is no use case that I can think of. Therefore simply enforce CONFIG_SMP and get rid of some more or less unused code. Reviewed-by: Christian Borntraeger Signed-off-by: Heiko Carstens

s390/kasan: avoid user access code instrumentation

2018-10-09T09:21:21Z

Kasan instrumentation adds "store" check for variables marked as modified by inline assembly. With user pointers containing addresses from another address space this produces false positives. static inline unsigned long clear_user_xc(void __user *to, ...) { asm volatile( ... : "+a" (to) ... User space access functions are wrapped by manually instrumented functions in kasan common code, which should be sufficient to catch errors. So, we just disable uaccess.o instrumentation altogether. Reviewed-by: Martin Schwidefsky Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390: introduce compile time check for empty .bss section

2018-05-09T08:55:01Z

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