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    SubjectRe: [PATCH 2/2] kprobe: fix: Add ftrace_ops_assist_func to kprobe blacklist
    On Wed, 11 Jul 2018 15:34:30 -0400
    Francis Deslauriers <francis.deslauriers@efficios.com> wrote:

    > Hi Steven,
    > I tested it and it prevents the kernel crash I am witnessing.
    > As for the side-effect that Masami mentioned regarding not being able to probe
    > function inside the trace_kprobe.c file, I suggest we move the target
    > function in
    > its own separate compile unit so it can be compiled with the ftrace cflags.
    > See patch below.
    >

    The patch below looks fine and so does Masami's. But there's too many
    patches within emails (not separated out). I have no idea what to
    apply. I'm not going to apply anything that is not sent as a proper
    patch (ie. any patch within a separate thread, like the patch below).

    -- Steve


    > Thanks
    > Francis
    >
    > >From d5a3645bd0046f28275d6b60207958f2751c1f47 Mon Sep 17 00:00:00 2001
    > From: Francis Deslauriers <francis.deslauriers@efficios.com>
    > Date: Wed, 11 Jul 2018 12:34:22 -0400
    > Subject: [PATCH] selftest/ftrace: Move kprobe selftest function to separate
    > compile unit
    >
    > Move selftest function to its own compile unit so it can be compiled
    > with the ftrace cflags (CC_FLAGS_FTRACE) allowing it to be probed
    > during the ftrace startup tests.
    >
    > Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
    > ---
    > kernel/trace/Makefile | 5 +++++
    > kernel/trace/trace_kprobe.c | 12 +-----------
    > kernel/trace/trace_kprobe_selftest.c | 10 ++++++++++
    > kernel/trace/trace_kprobe_selftest.h | 7 +++++++
    > 4 files changed, 23 insertions(+), 11 deletions(-)
    > create mode 100644 kernel/trace/trace_kprobe_selftest.c
    > create mode 100644 kernel/trace/trace_kprobe_selftest.h
    >
    > diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
    > index e2538c7..e38771e 100644
    > --- a/kernel/trace/Makefile
    > +++ b/kernel/trace/Makefile
    > @@ -13,6 +13,11 @@ obj-y += trace_selftest_dynamic.o
    > endif
    > endif
    >
    > +ifdef CONFIG_FTRACE_STARTUP_TEST
    > +CFLAGS_trace_kprobe_selftest.o = $(CC_FLAGS_FTRACE)
    > +obj-$(CONFIG_KPROBE_EVENTS) += trace_kprobe_selftest.o
    > +endif
    > +
    > # If unlikely tracing is enabled, do not trace these files
    > ifdef CONFIG_TRACING_BRANCHES
    > KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
    > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
    > index 952dc2a..3fe966f 100644
    > --- a/kernel/trace/trace_kprobe.c
    > +++ b/kernel/trace/trace_kprobe.c
    > @@ -24,6 +24,7 @@
    > #include <linux/error-injection.h>
    >
    > #include "trace_probe.h"
    > +#include "trace_kprobe_selftest.h"
    >
    > #define KPROBE_EVENT_SYSTEM "kprobes"
    > #define KRETPROBE_MAXACTIVE_MAX 4096
    > @@ -1560,17 +1561,6 @@ fs_initcall(init_kprobe_trace);
    >
    >
    > #ifdef CONFIG_FTRACE_STARTUP_TEST
    > -/*
    > - * The "__used" keeps gcc from removing the function symbol
    > - * from the kallsyms table. 'noinline' makes sure that there
    > - * isn't an inlined version used by the test method below
    > - */
    > -static __used __init noinline int
    > -kprobe_trace_selftest_target(int a1, int a2, int a3, int a4, int a5, int a6)
    > -{
    > - return a1 + a2 + a3 + a4 + a5 + a6;
    > -}
    > -
    > static __init struct trace_event_file *
    > find_trace_probe_file(struct trace_kprobe *tk, struct trace_array *tr)
    > {
    > diff --git a/kernel/trace/trace_kprobe_selftest.c
    > b/kernel/trace/trace_kprobe_selftest.c
    > new file mode 100644
    > index 0000000..a3d2090
    > --- /dev/null
    > +++ b/kernel/trace/trace_kprobe_selftest.c
    > @@ -0,0 +1,10 @@
    > +// SPDX-License-Identifier: GPL-2.0
    > +/*
    > + * Function used during the kprobe self test. This function is in a seperate
    > + * compile unit so it can be compile with CC_FLAGS_FTRACE to ensure that it
    > + * can be probed by the selftests.
    > + */
    > +int kprobe_trace_selftest_target(int a1, int a2, int a3, int a4, int
    > a5, int a6)
    > +{
    > + return a1 + a2 + a3 + a4 + a5 + a6;
    > +}
    > diff --git a/kernel/trace/trace_kprobe_selftest.h
    > b/kernel/trace/trace_kprobe_selftest.h
    > new file mode 100644
    > index 0000000..9243d4e
    > --- /dev/null
    > +++ b/kernel/trace/trace_kprobe_selftest.h
    > @@ -0,0 +1,7 @@
    > +// SPDX-License-Identifier: GPL-2.0
    > +/*
    > + * Function used during the kprobe self test. This function is in a seperate
    > + * compile unit so it can be compile with CC_FLAGS_FTRACE to ensure that it
    > + * can be probed by the selftests.
    > + */
    > +int kprobe_trace_selftest_target(int a1, int a2, int a3, int a4, int
    > a5, int a6);

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