kernel.git/arch/s390/kernel/mcount.S, branch linux-6.4.y

Merge tag 's390-6.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2023-04-30T18:43:31Z

Pull s390 updates from Vasily Gorbik: - Add support for stackleak feature. Also allow specifying architecture-specific stackleak poison function to enable faster implementation. On s390, the mvc-based implementation helps decrease typical overhead from a factor of 3 to just 25% - Convert all assembler files to use SYM* style macros, deprecating the ENTRY() macro and other annotations. Select ARCH_USE_SYM_ANNOTATIONS - Improve KASLR to also randomize module and special amode31 code base load addresses - Rework decompressor memory tracking to support memory holes and improve error handling - Add support for protected virtualization AP binding - Add support for set_direct_map() calls - Implement set_memory_rox() and noexec module_alloc() - Remove obsolete overriding of mem*() functions for KASAN - Rework kexec/kdump to avoid using nodat_stack to call purgatory - Convert the rest of the s390 code to use flexible-array member instead of a zero-length array - Clean up uaccess inline asm - Enable ARCH_HAS_MEMBARRIER_SYNC_CORE - Convert to using CONFIG_FUNCTION_ALIGNMENT and enable DEBUG_FORCE_FUNCTION_ALIGN_64B - Resolve last_break in userspace fault reports - Simplify one-level sysctl registration - Clean up branch prediction handling - Rework CPU counter facility to retrieve available counter sets just once - Other various small fixes and improvements all over the code * tag 's390-6.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (118 commits) s390/stackleak: provide fast __stackleak_poison() implementation stackleak: allow to specify arch specific stackleak poison function s390: select ARCH_USE_SYM_ANNOTATIONS s390/mm: use VM_FLUSH_RESET_PERMS in module_alloc() s390: wire up memfd_secret system call s390/mm: enable ARCH_HAS_SET_DIRECT_MAP s390/mm: use BIT macro to generate SET_MEMORY bit masks s390/relocate_kernel: adjust indentation s390/relocate_kernel: use SYM* macros instead of ENTRY(), etc. s390/entry: use SYM* macros instead of ENTRY(), etc. s390/purgatory: use SYM* macros instead of ENTRY(), etc. s390/kprobes: use SYM* macros instead of ENTRY(), etc. s390/reipl: use SYM* macros instead of ENTRY(), etc. s390/head64: use SYM* macros instead of ENTRY(), etc. s390/earlypgm: use SYM* macros instead of ENTRY(), etc. s390/mcount: use SYM* macros instead of ENTRY(), etc. s390/crc32le: use SYM* macros instead of ENTRY(), etc. s390/crc32be: use SYM* macros instead of ENTRY(), etc. s390/crypto,chacha: use SYM* macros instead of ENTRY(), etc. s390/amode31: use SYM* macros instead of ENTRY(), etc. ...

s390/mcount: use SYM* macros instead of ENTRY(), etc.

2023-04-19T15:24:17Z

Consistently use the SYM* family of macros instead of the deprecated ENTRY(), ENDPROC(), etc. family of macros. Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

ftrace: selftest: remove broken trace_direct_tramp

2023-03-21T17:59:29Z

The ftrace selftest code has a trace_direct_tramp() function which it uses as a direct call trampoline. This happens to work on x86, since the direct call's return address is in the usual place, and can be returned to via a RET, but in general the calling convention for direct calls is different from regular function calls, and requires a trampoline written in assembly. On s390, regular function calls place the return address in %r14, and an ftrace patch-site in an instrumented function places the trampoline's return address (which is within the instrumented function) in %r0, preserving the original %r14 value in-place. As a regular C function will return to the address in %r14, using a C function as the trampoline results in the trampoline returning to the caller of the instrumented function, skipping the body of the instrumented function. Note that the s390 issue is not detcted by the ftrace selftest code, as the instrumented function is trivial, and returning back into the caller happens to be equivalent. On arm64, regular function calls place the return address in x30, and an ftrace patch-site in an instrumented function saves this into r9 and places the trampoline's return address (within the instrumented function) in x30. A regular C function will return to the address in x30, but will not restore x9 into x30. Consequently, using a C function as the trampoline results in returning to the trampoline's return address having corrupted x30, such that when the instrumented function returns, it will return back into itself. To avoid future issues in this area, remove the trace_direct_tramp() function, and require that each architecture with direct calls provides a stub trampoline, named ftrace_stub_direct_tramp. This can be written to handle the architecture's trampoline calling convention, and in future could be used elsewhere (e.g. in the ftrace ops sample, to measure the overhead of direct calls), so we may as well always build it in. Link: https://lkml.kernel.org/r/20230321140424.345218-8-revest@chromium.org Signed-off-by: Mark Rutland Cc: Li Huafei Cc: Xu Kuohai Signed-off-by: Florent Revest Acked-by: Jiri Olsa Signed-off-by: Steven Rostedt (Google)

s390/ftrace: move hotpatch trampolines to mcount.S

2023-03-20T10:12:46Z

Move the ftrace hotpatch trampolines to mcount.S. This allows to make use of the standard SYM_CODE macros which again makes sure that the hotpatch trampolines follow the function alignment rules of the rest of the kernel. Signed-off-by: Heiko Carstens Acked-by: Ilya Leoshkevich Signed-off-by: Heiko Carstens

s390/kprobes: replace kretprobe with rethook

2023-01-22T17:42:35Z

That's an adaptation of commit f3a112c0c40d ("x86,rethook,kprobes: Replace kretprobe with rethook on x86") to s390. Replaces the kretprobe code with rethook on s390. With this patch, kretprobe on s390 uses the rethook instead of kretprobe specific trampoline code. Tested-by: Ilya Leoshkevich Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens

s390/kprobes: Avoid additional kprobe in kretprobe handling

2022-03-10T14:58:17Z

So far, s390 registered a krobe on __kretprobe_trampoline which is called everytime a kretprobe fires. This kprobe would then determine the correct return address and adjust the psw accordingly, such that the kretprobe would branch to the appropriate address after completion. Some other archs handle kretprobes without such an additional kprobe. This approach is adopted to s390 with this patch. Furthermore, the __kretprobe_trampoline now uses an assembler function to correctly gather the register and psw content to be passed to the registered kretprobe handler as struct pt_regs. After completion, the register content and the psw are set based on the contents of said pt_regs struct. Note that a change to the psw address in struct pt_regs will not have an impact, as the probe will still return to the original return address of the probed function. The return address is now recovered by using the appropriate function arch_kretprobe_fixup_return. The no longer needed kprobe is removed. Reviewed-by: Vasily Gorbik Signed-off-by: Tobias Huschle Signed-off-by: Vasily Gorbik

s390: raise minimum supported machine generation to z10

2022-03-10T14:58:17Z

Machine generations up to z9 (released in May 2006) have been officially out of service for several years now (z9 end of service - January 31, 2019). No distributions build kernels supporting those old machine generations anymore, except Debian, which seems to pick the oldest supported generation. The team supporting Debian on s390 has been notified about the change. Raising minimum supported machine generation to z10 helps to reduce maintenance cost and effectively remove code, which is not getting enough testing coverage due to lack of older hardware and distributions support. Besides that this unblocks some optimization opportunities and allows to use wider instruction set in asm files for future features implementation. Due to this change spectre mitigation and usercopy implementations could be drastically simplified and many newer instructions could be converted from ".insn" encoding to instruction names. Acked-by: Ilya Leoshkevich Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/ftrace: make use of epsw to get psw mask

2022-03-01T20:05:10Z

Finally use epsw to create a complete psw mask within pt_regs. Without this only some bits are correct, while other bits are (incorrectly) always zero. The epsw instruction is quite heavy weight, however given that this only effects ftrace_regs_caller this seems to be the right thing, so we finally get a complete psw mask for ftrace kprobed functions. Reviewed-by: Sven Schnelle Acked-by: Ilya Leoshkevich Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: always use the packed stack layout

2022-03-01T20:05:09Z

-mpacked-stack option has been supported by both minimum gcc and clang versions for a while. With commit e2bc3e91d91e ("scripts/min-tool-version.sh: Raise minimum clang version to 13.0.0 for s390") minimum clang version now also supports a combination of flags -mpacked-stack -mbackchain -pg -mfentry and fulfills all requirements to always enable the packed stack layout. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

Merge branch 'fixes' into features

2022-03-01T20:02:48Z

This helps to avoid several merge conflicts later. * fixes: s390/extable: fix exception table sorting s390/ftrace: fix arch_ftrace_get_regs implementation s390/ftrace: fix ftrace_caller/ftrace_regs_caller generation s390/setup: preserve memory at OLDMEM_BASE and OLDMEM_SIZE s390/cio: verify the driver availability for path_event call s390/module: fix building test_modules_helpers.o with clang MAINTAINERS: downgrade myself to Reviewer for s390 MAINTAINERS: add Alexander Gordeev as maintainer for s390 Signed-off-by: Vasily Gorbik