x86/headers: Replace #include <asm/export.h> with #include <linux/export.h>

The following commit:

ddb5cdbafaaa ("kbuild: generate KSYMTAB entries by modpost")

deprecated <asm/export.h>, which is now a wrapper of <linux/export.h>.

Use <linux/export.h> in *.S as well as in *.c files.

After all the <asm/export.h> lines are replaced, <asm/export.h> and
<asm-generic/export.h> will be removed.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230806145958.380314-2-masahiroy@kernel.org

x86/ftrace: Enable HAVE_FUNCTION_GRAPH_RETVAL

The previous patch ("function_graph: Support recording and printing
the return value of function") has laid the groundwork for the for
the funcgraph-retval, and this modification makes it available on
the x86 platform.

We introduce a new structure called fgraph_ret_regs for the x86
platform to hold return registers and the frame pointer. We then
fill its content in the return_to_handler and pass its address
to the function ftrace_return_to_handler to record the return
value.

Link: https://lkml.kernel.org/r/53a506f0f18ff4b7aeb0feb762f1c9a5e9b83ee9.1680954589.git.pengdonglin@sangfor.com.cn

Signed-off-by: Donglin Peng <pengdonglin@sangfor.com.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

x86,objtool: Split UNWIND_HINT_EMPTY in two

Mark reported that the ORC unwinder incorrectly marks an unwind as
reliable when the unwind terminates prematurely in the dark corners of
return_to_handler() due to lack of information about the next frame.

The problem is UNWIND_HINT_EMPTY is used in two different situations:

1) The end of the kernel stack unwind before hitting user entry, boot
code, or fork entry

2) A blind spot in ORC coverage where the unwinder has to bail due to
lack of information about the next frame

The ORC unwinder has no way to tell the difference between the two.
When it encounters an undefined stack state with 'end=1', it blindly
marks the stack reliable, which can break the livepatch consistency
model.

Fix it by splitting UNWIND_HINT_EMPTY into UNWIND_HINT_UNDEFINED and
UNWIND_HINT_END_OF_STACK.

Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/fd6212c8b450d3564b855e1cb48404d6277b4d9f.1677683419.git.jpoimboe@kernel.org

ftrace: selftest: remove broken trace_direct_tramp

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 <mark.rutland@arm.com>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Florent Revest <revest@chromium.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

ftrace,kcfi: Define ftrace_stub_graph conditionally

When CONFIG_FUNCTION_GRAPH_TRACER is disabled, __kcfi_typeid_ftrace_stub_graph
is missing, causing a link failure:

ld.lld: error: undefined symbol: __kcfi_typeid_ftrace_stub_graph
referenced by arch/x86/kernel/ftrace_64.o:(__cfi_ftrace_stub_graph) in archive vmlinux.a

Mark the reference to it as conditional on the same symbol, as
is done on arm64.

Link: https://lore.kernel.org/linux-trace-kernel/20230131093643.3850272-1-arnd@kernel.org

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Fixes: 883bbbffa5a4 ("ftrace,kcfi: Separate ftrace_stub() and ftrace_stub_graph()")
See-also: 2598ac6ec493 ("arm64: ftrace: Define ftrace_stub_graph only with FUNCTION_GRAPH_TRACER")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

x86/ftrace: Make it call depth tracking aware

Since ftrace has trampolines, don't use thunks for the __fentry__ site
but instead require that every function called from there includes
accounting. This very much includes all the direct-call functions.

Additionally, ftrace uses ROP tricks in two places:

- return_to_handler(), and
- ftrace_regs_caller() when pt_regs->orig_ax is set by a direct-call.

return_to_handler() already uses a retpoline to replace an
indirect-jump to defeat IBT, since this is a jump-type retpoline, make
sure there is no accounting done and ALTERNATIVE the RET into a ret.

ftrace_regs_caller() does much the same and gets the same treatment.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111148.927545073@infradead.org

x86/ftrace: Rebalance RSB

ftrace_regs_caller() uses a PUSH;RET pattern to tail-call into a
direct-call function, this unbalances the RSB, fix that.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111148.823216933@infradead.org

x86/ftrace: Remove ftrace_epilogue()

Remove the weird jumps to RET and simply use RET.

This then promotes ftrace_stub() to a real function; which becomes
important for kcfi.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111148.719080593@infradead.org

ftrace,kcfi: Separate ftrace_stub() and ftrace_stub_graph()

Different function signatures means they needs to be different
functions; otherwise CFI gets upset.

As triggered by the ftrace boot tests:

[] CFI failure at ftrace_return_to_handler+0xac/0x16c (target: ftrace_stub+0x0/0x14; expected type: 0x0a5d5347)

Fixes: 3c516f89e17e ("x86: Add support for CONFIG_CFI_CLANG")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lkml.kernel.org/r/Y06dg4e1xF6JTdQq@hirez.programming.kicks-ass.net

x86/ftrace: Remove ftrace_epilogue()

Remove the weird jumps to RET and simply use RET.

This then promotes ftrace_stub() to a real function; which becomes
important for kcfi.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111148.719080593@infradead.org
Signed-off-by: Peter Zijlstra <peterz@infradead.org>

x86/ftrace: Remove OBJECT_FILES_NON_STANDARD usage

The file-wide OBJECT_FILES_NON_STANDARD annotation is used with
CONFIG_FRAME_POINTER to tell objtool to skip the entire file when frame
pointers are enabled. However that annotation is now deprecated because
it doesn't work with IBT, where objtool runs on vmlinux.o instead of
individual translation units.

Instead, use more fine-grained function-specific annotations:

- The 'save_mcount_regs' macro does funny things with the frame pointer.
Use STACK_FRAME_NON_STANDARD_FP to tell objtool to ignore the
functions using it.

- The return_to_handler() "function" isn't actually a callable function.
Instead of being called, it's returned to. The real return address
isn't on the stack, so unwinding is already doomed no matter which
unwinder is used. So just remove the STT_FUNC annotation, telling
objtool to ignore it. That also removes the implicit
ANNOTATE_NOENDBR, which now needs to be made explicit.

Fixes the following warning:

vmlinux.o: warning: objtool: __fentry__+0x16: return with modified stack frame

Fixes: ed53a0d97192 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/b7a7a42fe306aca37826043dac89e113a1acdbac.1654268610.git.jpoimboe@kernel.org

x86/ibt,ftrace: Annotate ftrace code patching

These are code patching sites, not indirect targets.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.936599479@infradead.org

x86/ibt,ftrace: Make function-graph play nice

Return trampoline must not use indirect branch to return; while this
preserves the RSB, it is fundamentally incompatible with IBT. Instead
use a retpoline like ROP gadget that defeats IBT while not unbalancing
the RSB.

And since ftrace_stub is no longer a plain RET, don't use it to copy
from. Since RET is a trivial instruction, poke it directly.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.347296408@infradead.org

x86: Prepare asm files for straight-line-speculation

Replace all ret/retq instructions with RET in preparation of making
RET a macro. Since AS is case insensitive it's a big no-op without
RET defined.

find arch/x86/ -name \*.S | while read file
do
sed -i 's/\<ret[q]*\>/RET/' $file
done

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211204134907.905503893@infradead.org

x86/ftrace: Make function graph use ftrace directly

We don't need special hook for graph tracer entry point,
but instead we can use graph_ops::func function to install
the return_hooker.

This moves the graph tracing setup _before_ the direct
trampoline prepares the stack, so the return_hooker will
be called when the direct trampoline is finished.

This simplifies the code, because we don't need to take into
account the direct trampoline setup when preparing the graph
tracer hooker and we can allow function graph tracer on entries
registered with direct trampoline.

Link: https://lkml.kernel.org/r/20211008091336.33616-4-jolsa@kernel.org

[fixed compile error reported by kernel test robot <lkp@intel.com>]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

x86/ftrace: Remove extra orig rax move

There's identical move 2 lines earlier.

Link: https://lkml.kernel.org/r/20211008091336.33616-2-jolsa@kernel.org

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

x86/ftrace: Support objtool vmlinux.o validation in ftrace_64.S

With objtool vmlinux.o validation of return_to_handler(), now that
objtool has visibility inside the retpoline, jumping from EMPTY state to
a proper function state results in a stack state mismatch.

return_to_handler() is actually quite normal despite the underlying
magic. Just annotate it as a normal function.

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/14f48e623f61dbdcd84cf27a56ed8ccae73199ef.1611263462.git.jpoimboe@redhat.com

objtool: Combine UNWIND_HINT_RET_OFFSET and UNWIND_HINT_FUNC

The ORC metadata generated for UNWIND_HINT_FUNC isn't actually very
func-like. With certain usages it can cause stack state mismatches
because it doesn't set the return address (CFI_RA).

Also, users of UNWIND_HINT_RET_OFFSET no longer need to set a custom
return stack offset. Instead they just need to specify a func-like
situation, so the current ret_offset code is hacky for no good reason.

Solve both problems by simplifying the RET_OFFSET handling and
converting it into a more useful UNWIND_HINT_FUNC.

If we end up needing the old 'ret_offset' functionality again in the
future, we should be able to support it pretty easily with the addition
of a custom 'sp_offset' in UNWIND_HINT_FUNC.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/db9d1f5d79dddfbb3725ef6d8ec3477ad199948d.1611263462.git.jpoimboe@redhat.com

x86/ftrace: Add UNWIND_HINT_FUNC annotation for ftrace_stub

Prevent an unreachable objtool warning after the sibling call detection
gets improved. ftrace_stub() is basically a function, annotate it as
such.

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/6845e1b2fb0723a95740c6674e548ba38c5ea489.1611263461.git.jpoimboe@redhat.com

livepatch: Use the default ftrace_ops instead of REGS when ARGS is available

When CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS is available, the ftrace call
will be able to set the ip of the calling function. This will improve the
performance of live kernel patching where it does not need all the regs to
be stored just to change the instruction pointer.

If all archs that support live kernel patching also support
HAVE_DYNAMIC_FTRACE_WITH_ARGS, then the architecture specific function
klp_arch_set_pc() could be made generic.

It is possible that an arch can support HAVE_DYNAMIC_FTRACE_WITH_ARGS but
not HAVE_DYNAMIC_FTRACE_WITH_REGS and then have access to live patching.

Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: live-patching@vger.kernel.org
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

ftrace/x86: Allow for arguments to be passed in to ftrace_regs by default

Currently, the only way to get access to the registers of a function via a
ftrace callback is to set the "FL_SAVE_REGS" bit in the ftrace_ops. But as this
saves all regs as if a breakpoint were to trigger (for use with kprobes), it
is expensive.

The regs are already saved on the stack for the default ftrace callbacks, as
that is required otherwise a function being traced will get the wrong
arguments and possibly crash. And on x86, the arguments are already stored
where they would be on a pt_regs structure to use that code for both the
regs version of a callback, it makes sense to pass that information always
to all functions.

If an architecture does this (as x86_64 now does), it is to set
HAVE_DYNAMIC_FTRACE_WITH_ARGS, and this will let the generic code that it
could have access to arguments without having to set the flags.

This also includes having the stack pointer being saved, which could be used
for accessing arguments on the stack, as well as having the function graph
tracer not require its own trampoline!

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

x86/ftrace: Do not jump to direct code in created trampolines

When creating a trampoline based on the ftrace_regs_caller code, nop out the
jnz test that would jmup to the code that would return to a direct caller
(stored in the ORIG_RAX field) and not back to the function that called it.

Link: http://lkml.kernel.org/r/20200422162750.638839749@goodmis.org

Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

x86/ftrace: Only have the builtin ftrace_regs_caller call direct hooks

If a direct hook is attached to a function that ftrace also has a function
attached to it, then it is required that the ftrace_ops_list_func() is used
to iterate over the registered ftrace callbacks. This will also include the
direct ftrace_ops helper, that tells ftrace_regs_caller where to return to
(the direct callback and not the function that called it).

As this direct helper is only to handle the case of ftrace callbacks
attached to the same function as the direct callback, the ftrace callback
allocated trampolines (used to only call them), should never be used to
return back to a direct callback.

Only copy the portion of the ftrace_regs_caller that will return back to
what called it, and not the portion that returns back to the direct caller.

The direct ftrace_ops must then pick the ftrace_regs_caller builtin function
as its own trampoline to ensure that it will never have one allocated for
it (which would not include the handling of direct callbacks).

Link: http://lkml.kernel.org/r/20200422162750.495903799@goodmis.org

Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

x86/ftrace: Make non direct case the default in ftrace_regs_caller

If a direct function is hooked along with one of the ftrace registered
functions, then the ftrace_regs_caller is attached to the function that
shares the direct hook as well as the ftrace hook. The ftrace_regs_caller
will call ftrace_ops_list_func() that iterates through all the registered
ftrace callbacks, and if there's a direct callback attached to that
function, the direct ftrace_ops callback is called to notify that
ftrace_regs_caller to return to the direct caller instead of going back to
the function that called it.

But this is a very uncommon case. Currently, the code has it as the default
case. Modify ftrace_regs_caller to make the default case (the non jump) to
just return normally, and have the jump to the handling of the direct
caller.

Link: http://lkml.kernel.org/r/20200422162750.350373278@goodmis.org

Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

x86/entry/64: Move non entry code into .text section

All ASM code which is not part of the entry functionality can move out into
the .text section. No reason to keep it in the non-instrumentable entry
section.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134340.227579223@linutronix.de

x86: Change {JMP,CALL}_NOSPEC argument

In order to change the {JMP,CALL}_NOSPEC macros to call out-of-line
versions of the retpoline magic, we need to remove the '%' from the
argument, such that we can paste it onto symbol names.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200428191700.151623523@infradead.org

x86,ftrace: Shrink ftrace_regs_caller() by one byte

'Optimize' ftrace_regs_caller. Instead of comparing against an
immediate, the more natural way to test for zero on x86 is: 'test
%r,%r'.

48 83 f8 00 cmp $0x0,%rax
74 49 je 226 <ftrace_regs_call+0xa3>

48 85 c0 test %rax,%rax
74 49 je 225 <ftrace_regs_call+0xa2>

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.867411350@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

x86,ftrace: Use SIZEOF_PTREGS

There's a convenient macro for 'SS+8' called FRAME_SIZE. Use it to
clarify things.

(entry/calling.h calls this SIZEOF_PTREGS but we're using
asm/ptrace-abi.h)

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.808485515@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

x86,ftrace: Fix ftrace_regs_caller() unwind

The ftrace_regs_caller() trampoline does something 'funny' when there
is a direct-caller present. In that case it stuffs the 'direct-caller'
address on the return stack and then exits the function. This then
results in 'returning' to the direct-caller with the exact registers
we came in with -- an indirect tail-call without using a register.

This however (rightfully) confuses objtool because the function shares
a few instruction in order to have a single exit path, but the stack
layout is different for them, depending through which path we came
there.

This is currently cludged by forcing the stack state to the non-direct
case, but this generates actively wrong (ORC) unwind information for
the direct case, leading to potential broken unwinds.

Fix this issue by fully separating the exit paths. This results in
having to poke a second RET into the trampoline copy, see
ftrace_regs_caller_ret.

This brings us to a second objtool problem, in order for it to
perceive the 'jmp ftrace_epilogue' as a function exit, it needs to be
recognised as a tail call. In order to make that happen,
ftrace_epilogue needs to be the start of an STT_FUNC, so re-arrange
code to make this so.

Finally, a third issue is that objtool requires functions to exit with
the same stack layout they started with, which is obviously violated
in the direct case, employ the new HINT_RET_OFFSET to tell objtool
this is an expected exception.

Together, this results in generating correct ORC unwind information
for the ftrace_regs_caller() function and it's trampoline copies.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.749606694@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

ftrace/x86: Tell objtool to ignore nondeterministic ftrace stack layout

Objtool complains about the new ftrace direct trampoline code:

arch/x86/kernel/ftrace_64.o: warning: objtool: ftrace_regs_caller()+0x190: stack state mismatch: cfa1=7+16 cfa2=7+24

Typically, code has a deterministic stack layout, such that at a given
instruction address, the stack frame size is always the same.

That's not the case for the new ftrace_regs_caller() code after it
adjusts the stack for the direct case. Just plead ignorance and assume
it's always the non-direct path. Note this creates a tiny window for
ORC to get confused.

Link: http://lkml.kernel.org/r/20191108225100.ea3bhsbdf6oerj6g@treble

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

ftrace/x86: Add register_ftrace_direct() for custom trampolines

Enable x86 to allow for register_ftrace_direct(), where a custom trampoline
may be called directly from an ftrace mcount/fentry location.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

x86/ftrace: Get rid of function_hook

History lesson courtesy of Steve:

"When ftrace first was introduced to the kernel, it used gcc's
mcount profiling mechanism. The mcount mechanism would add a call to
"mcount" at the start of every function but after the stack frame was
set up. Later, in gcc 4.6, gcc introduced -mfentry, that would create a
call to "__fentry__" instead of "mcount", before the stack frame was
set up. In order to handle both cases, ftrace defined a macro
"function_hook" that would be either "mcount" or "__fentry__" depending
on which one was being used.

The Linux kernel no longer supports the "mcount" method, thus there's
no reason to keep the "function_hook" define around. Simply use
"__fentry__", as there is no ambiguity to the name anymore."

Drop it everywhere.

Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20191018124800.0a7006bb@gandalf.local.home

x86/asm: Replace WEAK uses by SYM_INNER_LABEL_ALIGN

Use the new SYM_INNER_LABEL_ALIGN for WEAK entries in the middle of x86
assembly functions.

And make sure WEAK is not defined for x86 anymore as these were the last
users.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: linux-arch@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191011115108.12392-29-jslaby@suse.cz

x86/asm: Change all ENTRY+ENDPROC to SYM_FUNC_*

These are all functions which are invoked from elsewhere, so annotate
them as global using the new SYM_FUNC_START and their ENDPROC's by
SYM_FUNC_END.

Make sure ENTRY/ENDPROC is not defined on X86_64, given these were the
last users.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> [hibernate]
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> [xen bits]
Acked-by: Herbert Xu <herbert@gondor.apana.org.au> [crypto]
Cc: Allison Randal <allison@lohutok.net>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andy Shevchenko <andy@infradead.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Armijn Hemel <armijn@tjaldur.nl>
Cc: Cao jin <caoj.fnst@cn.fujitsu.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Enrico Weigelt <info@metux.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: kvm ML <kvm@vger.kernel.org>
Cc: Len Brown <len.brown@intel.com>
Cc: linux-arch@vger.kernel.org
Cc: linux-crypto@vger.kernel.org
Cc: linux-efi <linux-efi@vger.kernel.org>
Cc: linux-efi@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: platform-driver-x86@vger.kernel.org
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Wei Huang <wei@redhat.com>
Cc: x86-ml <x86@kernel.org>
Cc: xen-devel@lists.xenproject.org
Cc: Xiaoyao Li <xiaoyao.li@linux.intel.com>
Link: https://lkml.kernel.org/r/20191011115108.12392-25-jslaby@suse.cz

x86/asm/64: Change all ENTRY+END to SYM_CODE_*

Change all assembly code which is marked using END (and not ENDPROC).
Switch all these to the appropriate new annotation SYM_CODE_START and
SYM_CODE_END.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> [xen bits]
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Cao jin <caoj.fnst@cn.fujitsu.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: linux-arch@vger.kernel.org
Cc: Maran Wilson <maran.wilson@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Cc: xen-devel@lists.xenproject.org
Link: https://lkml.kernel.org/r/20191011115108.12392-24-jslaby@suse.cz

x86/asm: Use SYM_INNER_LABEL instead of GLOBAL

The GLOBAL macro had several meanings and is going away. Convert all the
inner function labels marked with GLOBAL to use SYM_INNER_LABEL instead.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: linux-arch@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191011115108.12392-18-jslaby@suse.cz

x86/stackframe, x86/ftrace: Add pt_regs frame annotations

When CONFIG_FRAME_POINTER, we should mark pt_regs frames.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

ftrace/x86: Remove mcount support

There's two methods of enabling function tracing in Linux on x86. One is
with just "gcc -pg" and the other is "gcc -pg -mfentry". The former will use
calls to a special function "mcount" after the frame is set up in all C
functions. The latter will add calls to a special function called "fentry"
as the very first instruction of all C functions.

At compile time, there is a check to see if gcc supports, -mfentry, and if
it does, it will use that, because it is more versatile and less error prone
for function tracing.

Starting with v4.19, the minimum gcc supported to build the Linux kernel,
was raised to version 4.6. That also happens to be the first gcc version to
support -mfentry. Since on x86, using gcc versions from 4.6 and beyond will
unconditionally enable the -mfentry, it will no longer use mcount as the
method for inserting calls into the C functions of the kernel. This means
that there is no point in continuing to maintain mcount in x86.

Remove support for using mcount. This makes the code less complex, and will
also allow it to be simplified in the future.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

x86/ftrace: Do not call function graph from dynamic trampolines

Since commit 79922b8009c07 ("ftrace: Optimize function graph to be
called directly"), dynamic trampolines should not be calling the
function graph tracer at the end. If they do, it could cause the function
graph tracer to trace functions that it filtered out.

Right now it does not cause a problem because there's a test to check if
the function graph tracer is attached to the same function as the
function tracer, which for now is true. But the function graph tracer is
undergoing changes that can make this no longer true which will cause
the function graph tracer to trace other functions.

For example:

# cd /sys/kernel/tracing/
# echo do_IRQ > set_ftrace_filter
# mkdir instances/foo
# echo ip_rcv > instances/foo/set_ftrace_filter
# echo function_graph > current_tracer
# echo function > instances/foo/current_tracer

Would cause the function graph tracer to trace both do_IRQ and ip_rcv,
if the current tests change.

As the current tests prevent this from being a problem, this code does
not need to be backported. But it does make the code cleaner.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

x86/ftrace: Add one more ENDPROC annotation

When ORC support was added for the ftrace_64.S code, an ENDPROC
for function_hook() was missed. This results in the following warning:

arch/x86/kernel/ftrace_64.o: warning: objtool: .entry.text+0x0: unreachable instruction

Fixes: e2ac83d74a4d ("x86/ftrace: Fix ORC unwinding from ftrace handlers")
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/20180128022150.dqierscqmt3uwwsr@treble

x86/ftrace: Fix ORC unwinding from ftrace handlers

Steven Rostedt discovered that the ftrace stack tracer is broken when
it's used with the ORC unwinder. The problem is that objtool is
instructed by the Makefile to ignore the ftrace_64.S code, so it doesn't
generate any ORC data for it.

Fix it by making the asm code objtool-friendly:

- Objtool doesn't like the fact that save_mcount_regs pushes RBP at the
beginning, but it's never restored (directly, at least). So just skip
the original RBP push, which is only needed for frame pointers anyway.

- Annotate some functions as normal callable functions with
ENTRY/ENDPROC.

- Add an empty unwind hint to return_to_handler(). The return address
isn't on the stack, so there's nothing ORC can do there. It will just
punt in the unlikely case it tries to unwind from that code.

With all that fixed, remove the OBJECT_FILES_NON_STANDARD Makefile
annotation so objtool can read the file.

Link: http://lkml.kernel.org/r/20180123040746.ih4ep3tk4pbjvg7c@treble

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

x86/retpoline/ftrace: Convert ftrace assembler indirect jumps

Convert all indirect jumps in ftrace assembler code to use non-speculative
sequences when CONFIG_RETPOLINE is enabled.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: thomas.lendacky@amd.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kees Cook <keescook@google.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: https://lkml.kernel.org/r/1515707194-20531-8-git-send-email-dwmw@amazon.co.uk

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

x86/ftrace: Use Makefile logic instead of #ifdef for compiling ftrace_*.o

Currently ftrace_32.S and ftrace_64.S are compiled even when
CONFIG_FUNCTION_TRACER is not set. This means there's an unnecessary #ifdef
to protect the code. Instead of using preprocessor directives, only compile
those files when FUNCTION_TRACER is defined.

Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20170316210043.peycxdxktwwn6cid@treble
Link: http://lkml.kernel.org/r/20170323143446.217684991@goodmis.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

x86/ftrace: Rename mcount_64.S to ftrace_64.S

With the advent of -mfentry that uses the new "fentry" hook over mcount,
the mcount name is obsolete. Having the code file that ftrace hooks into
called "mcount*.S" is rather misleading. Rename it to ftrace_64.S and
remove the file name reference.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20170323143445.490601451@goodmis.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>