linux-toradex.git/arch/s390/kernel/mcount.S, branch v6.8

s390: remove unneeded #include

2023-08-09T13:20:50+00:00

There is no EXPORT_SYMBOL line there, hence #include 
is unneeded.

Signed-off-by: Masahiro Yamada 
Link: https://lore.kernel.org/r/20230806151641.394720-1-masahiroy@kernel.org
Signed-off-by: Heiko Carstens

s390/ftrace: use la instead of aghik in return_to_handler()

2023-07-27T11:11:35+00:00

Nathan Chancellor reported the following build error when compiling the
kernel with CONFIG_MARCH_Z10=y:

  arch/s390/kernel/mcount.S: Assembler messages:
  arch/s390/kernel/mcount.S:140: Error: Unrecognized opcode: `aghik'

The aghik instruction is only available since z196. Use the la instruction
instead which is available for all machines.

Reported-by: Nathan Chancellor 
Closes: https://lore.kernel.org/all/20230725211105.GA224840@dev-arch.thelio-3990X
Fixes: 1256e70a082a ("s390/ftrace: enable HAVE_FUNCTION_GRAPH_RETVAL")
Reviewed-by: Sven Schnelle 
Tested-by: Nathan Chancellor  # build
Link: https://lore.kernel.org/r/20230726061834.1300984-1-hca@linux.ibm.com
Signed-off-by: Heiko Carstens

s390/tracing: pass struct ftrace_regs to ftrace_trace_function

2023-07-24T10:12:24+00:00

ftrace_trace_function expects a struct ftrace_regs, but the s390
architecure code passes struct pt_regs. This isn't a problem with the
current code because struct ftrace_regs contains only one member:
struct pt_regs. To avoid issues in the future this should be fixed.

Signed-off-by: Sven Schnelle 
Reviewed-by: Heiko Carstens 
Signed-off-by: Heiko Carstens

s390/ftrace: enable HAVE_FUNCTION_GRAPH_RETVAL

2023-07-24T10:12:22+00:00

Add support for tracing return values in the function graph tracer.
This requires return_to_handler() to record gpr2 and the frame pointer

Signed-off-by: Sven Schnelle 
Reviewed-by: Heiko Carstens 
Signed-off-by: Heiko Carstens

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

2023-04-30T18:43:31+00:00

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.

2023-04-19T15:24:17+00:00

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

2023-03-21T17:59:29+00:00

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

2023-03-20T10:12:46+00:00

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

2023-01-22T17:42:35+00:00

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

2022-03-10T14:58:17+00:00

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