linux.git/kernel/livepatch/patch.c, branch v6.6.132

ftrace: rename ftrace_instruction_pointer_set() -> ftrace_regs_set_instruction_pointer()

2022-11-18T13:56:41+00:00

In subsequent patches we'll add a sew of ftrace_regs_{get,set}_*()
helpers. In preparation, this patch renames
ftrace_instruction_pointer_set() to
ftrace_regs_set_instruction_pointer().

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland 
Cc: Florent Revest 
Cc: Masami Hiramatsu 
Cc: Steven Rostedt 
Reviewed-by: Masami Hiramatsu (Google) 
Reviewed-by: Steven Rostedt (Google) 
Link: https://lore.kernel.org/r/20221103170520.931305-3-mark.rutland@arm.com
Signed-off-by: Will Deacon

livepatch: Remove klp_arch_set_pc() and asm/livepatch.h

2022-05-24T06:46:37+00:00

All three versions of klp_arch_set_pc() do exactly the same: they
call ftrace_instruction_pointer_set().

Call ftrace_instruction_pointer_set() directly and remove
klp_arch_set_pc().

As klp_arch_set_pc() was the only thing remaining in asm/livepatch.h
on x86 and s390, remove asm/livepatch.h

livepatch.h remains on powerpc but its content is exclusively used
by powerpc specific code.

Signed-off-by: Christophe Leroy 
Acked-by: Petr Mladek 
Acked-by: Peter Zijlstra (Intel) 
Acked-by: Miroslav Benes 
Signed-off-by: Petr Mladek

x86/livepatch: Validate fentry location

2022-03-15T09:32:37+00:00

Currently livepatch assumes __fentry__ lives at func+0, which is most
likely untrue with IBT on. Instead make it use ftrace_location() by
default which both validates and finds the actual ip if there is any
in the same symbol.

Suggested-by: Josh Poimboeuf 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/20220308154318.285971256@infradead.org

ftrace: disable preemption when recursion locked

2021-10-27T15:21:49+00:00

As the documentation explained, ftrace_test_recursion_trylock()
and ftrace_test_recursion_unlock() were supposed to disable and
enable preemption properly, however currently this work is done
outside of the function, which could be missing by mistake.

And since the internal using of trace_test_and_set_recursion()
and trace_clear_recursion() also require preemption disabled, we
can just merge the logical.

This patch will make sure the preemption has been disabled when
trace_test_and_set_recursion() return bit >= 0, and
trace_clear_recursion() will enable the preemption if previously
enabled.

Link: https://lkml.kernel.org/r/13bde807-779c-aa4c-0672-20515ae365ea@linux.alibaba.com

CC: Petr Mladek 
Cc: Guo Ren 
Cc: Ingo Molnar 
Cc: "James E.J. Bottomley" 
Cc: Helge Deller 
Cc: Michael Ellerman 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Paul Walmsley 
Cc: Palmer Dabbelt 
Cc: Albert Ou 
Cc: Thomas Gleixner 
Cc: Borislav Petkov 
Cc: "H. Peter Anvin" 
Cc: Josh Poimboeuf 
Cc: Jiri Kosina 
Cc: Joe Lawrence 
Cc: Masami Hiramatsu 
Cc: Nicholas Piggin 
Cc: Jisheng Zhang 
CC: Steven Rostedt 
CC: Miroslav Benes 
Reported-by: Abaci 
Suggested-by: Peter Zijlstra 
Signed-off-by: Michael Wang 
[ Removed extra line in comment - SDR ]
Signed-off-by: Steven Rostedt (VMware)

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

2020-11-13T17:15:28+00:00

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 
Cc: Jiri Kosina 
Cc: live-patching@vger.kernel.org
Acked-by: Peter Zijlstra (Intel) 
Acked-by: Miroslav Benes 
Signed-off-by: Steven Rostedt (VMware)

ftrace: Have the callbacks receive a struct ftrace_regs instead of pt_regs

2020-11-13T17:14:55+00:00

In preparation to have arguments of a function passed to callbacks attached
to functions as default, change the default callback prototype to receive a
struct ftrace_regs as the forth parameter instead of a pt_regs.

For callbacks that set the FL_SAVE_REGS flag in their ftrace_ops flags, they
will now need to get the pt_regs via a ftrace_get_regs() helper call. If
this is called by a callback that their ftrace_ops did not have a
FL_SAVE_REGS flag set, it that helper function will return NULL.

This will allow the ftrace_regs to hold enough just to get the parameters
and stack pointer, but without the worry that callbacks may have a pt_regs
that is not completely filled.

Acked-by: Peter Zijlstra (Intel) 
Reviewed-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt (VMware)

ftrace: Add recording of functions that caused recursion

2020-11-06T13:42:26+00:00

This adds CONFIG_FTRACE_RECORD_RECURSION that will record to a file
"recursed_functions" all the functions that caused recursion while a
callback to the function tracer was running.

Link: https://lkml.kernel.org/r/20201106023548.102375687@goodmis.org

Cc: Masami Hiramatsu 
Cc: Andrew Morton 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Jonathan Corbet 
Cc: Guo Ren 
Cc: "James E.J. Bottomley" 
Cc: Helge Deller 
Cc: Michael Ellerman 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Heiko Carstens 
Cc: Vasily Gorbik 
Cc: Christian Borntraeger 
Cc: Thomas Gleixner 
Cc: Borislav Petkov 
Cc: x86@kernel.org
Cc: "H. Peter Anvin" 
Cc: Kees Cook 
Cc: Anton Vorontsov 
Cc: Colin Cross 
Cc: Tony Luck 
Cc: Josh Poimboeuf 
Cc: Jiri Kosina 
Cc: Miroslav Benes 
Cc: Petr Mladek 
Cc: Joe Lawrence 
Cc: Kamalesh Babulal 
Cc: Mauro Carvalho Chehab 
Cc: Sebastian Andrzej Siewior 
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-csky@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: live-patching@vger.kernel.org
Signed-off-by: Steven Rostedt (VMware)

livepatch: Trigger WARNING if livepatch function fails due to recursion

2020-11-06T13:41:47+00:00

If for some reason a function is called that triggers the recursion
detection of live patching, trigger a warning. By not executing the live
patch code, it is possible that the old unpatched function will be called
placing the system into an unknown state.

Link: https://lore.kernel.org/r/20201029145709.GD16774@alley
Link: https://lkml.kernel.org/r/20201106023547.312639435@goodmis.org

Cc: Masami Hiramatsu 
Cc: Andrew Morton 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Josh Poimboeuf 
Cc: Jiri Kosina 
Cc: Joe Lawrence 
Cc: live-patching@vger.kernel.org
Suggested-by: Miroslav Benes 
Reviewed-by: Petr Mladek 
Acked-by: Miroslav Benes 
Signed-off-by: Steven Rostedt (VMware)

livepatch/ftrace: Add recursion protection to the ftrace callback

2020-11-06T13:36:23+00:00

If a ftrace callback does not supply its own recursion protection and
does not set the RECURSION_SAFE flag in its ftrace_ops, then ftrace will
make a helper trampoline to do so before calling the callback instead of
just calling the callback directly.

The default for ftrace_ops is going to change. It will expect that handlers
provide their own recursion protection, unless its ftrace_ops states
otherwise.

Link: https://lkml.kernel.org/r/20201028115613.291169246@goodmis.org
Link: https://lkml.kernel.org/r/20201106023547.122802424@goodmis.org

Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Masami Hiramatsu 
Cc: Andrew Morton 
Cc: Josh Poimboeuf 
Cc: Jiri Kosina 
Cc: Joe Lawrence 
Cc: live-patching@vger.kernel.org
Reviewed-by: Petr Mladek 
Acked-by: Miroslav Benes 
Signed-off-by: Steven Rostedt (VMware)

ftrace: Introduce PERMANENT ftrace_ops flag

2019-11-04T14:33:15+00:00

Livepatch uses ftrace for redirection to new patched functions. It means
that if ftrace is disabled, all live patched functions are disabled as
well. Toggling global 'ftrace_enabled' sysctl thus affect it directly.
It is not a problem per se, because only administrator can set sysctl
values, but it still may be surprising.

Introduce PERMANENT ftrace_ops flag to amend this. If the
FTRACE_OPS_FL_PERMANENT is set on any ftrace ops, the tracing cannot be
disabled by disabling ftrace_enabled. Equally, a callback with the flag
set cannot be registered if ftrace_enabled is disabled.

Link: http://lkml.kernel.org/r/20191016113316.13415-2-mbenes@suse.cz

Reviewed-by: Petr Mladek 
Reviewed-by: Kamalesh Babulal 
Signed-off-by: Miroslav Benes 
Signed-off-by: Steven Rostedt (VMware)