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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 <pmladek@suse.com>
Cc: Guo Ren <guoren@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Jisheng Zhang <jszhang@kernel.org>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: Miroslav Benes <mbenes@suse.cz>
Reported-by: Abaci <abaci@linux.alibaba.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
[ Removed extra line in comment - SDR ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The division is a slow operation. If the divisor is a power of 2, use a
shift instead.
Results were obtained using Android's version of perf (simpleperf[1]) as
described below:
1. hist_field_div() is modified to call 2 test functions:
test_hist_field_div_[not]_optimized(); passing them the
same args. Use noinline and volatile to ensure these are
not optimized out by the compiler.
2. Create a hist event trigger that uses division:
events/kmem/rss_stat$ echo 'hist:keys=common_pid:x=size/<divisor>'
>> trigger
events/kmem/rss_stat$ echo 'hist:keys=common_pid:vals=$x'
>> trigger
3. Run Android's lmkd_test[2] to generate rss_stat events, and
record CPU samples with Android's simpleperf:
simpleperf record -a --exclude-perf --post-unwind=yes -m 16384 -g
-f 2000 -o perf.data
== Results ==
Divisor is a power of 2 (divisor == 32):
test_hist_field_div_not_optimized | 8,717,091 cpu-cycles
test_hist_field_div_optimized | 1,643,137 cpu-cycles
If the divisor is a power of 2, the optimized version is ~5.3x faster.
Divisor is not a power of 2 (divisor == 33):
test_hist_field_div_not_optimized | 4,444,324 cpu-cycles
test_hist_field_div_optimized | 5,497,958 cpu-cycles
If the divisor is not a power of 2, as expected, the optimized version is
slightly slower (~24% slower).
[1] https://android.googlesource.com/platform/system/extras/+/master/simpleperf/doc/README.md
[2] https://cs.android.com/android/platform/superproject/+/master:system/memory/lmkd/tests/lmkd_test.cpp
Link: https://lkml.kernel.org/r/20211025200852.3002369-7-kaleshsingh@google.com
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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If both operands of a hist trigger expression are constants, convert the
expression to a constant. This optimization avoids having to perform the
same calculation multiple times and also saves on memory since the
merged constants are represented by a single struct hist_field instead
or multiple.
Link: https://lkml.kernel.org/r/20211025200852.3002369-6-kaleshsingh@google.com
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The '-' in .sym-offset can confuse the hist trigger arithmetic
expression parsing. Simplify the handling of this by replacing the
'sym-offset' with 'symXoffset'. This allows us to correctly evaluate
expressions where the user may have inadvertently added a .sym-offset
modifier to one of the operands in an expression, instead of bailing
out. In this case the .sym-offset has no effect on the evaluation of the
expression. The only valid use of the .sym-offset is as a hist key
modifier.
Link: https://lkml.kernel.org/r/20211025200852.3002369-5-kaleshsingh@google.com
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The current histogram expression evaluation logic evaluates the
expression from right to left. This can lead to incorrect results
if the operations are not associative (as is the case for subtraction
and, the now added, division operators).
e.g. 16-8-4-2 should be 2 not 10 --> 16-8-4-2 = ((16-8)-4)-2
64/8/4/2 should be 1 not 16 --> 64/8/4/2 = ((64/8)/4)/2
Division and multiplication are currently limited to single operation
expression due to operator precedence support not yet implemented.
Rework the expression parsing to support the correct evaluation of
expressions containing operators of different precedences; and fix
the associativity error by evaluating expressions with operators of
the same precedence from left to right.
Examples:
(1) echo 'hist:keys=common_pid:a=8,b=4,c=2,d=1,w=$a-$b-$c-$d' \
>> event/trigger
(2) echo 'hist:keys=common_pid:x=$a/$b/3/2' >> event/trigger
(3) echo 'hist:keys=common_pid:y=$a+10/$c*1024' >> event/trigger
(4) echo 'hist:keys=common_pid:z=$a/$b+$c*$d' >> event/trigger
Link: https://lkml.kernel.org/r/20211025200852.3002369-4-kaleshsingh@google.com
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Adds basic support for division and multiplication operations for
hist trigger variable expressions.
For simplicity this patch only supports, division and multiplication
for a single operation expression (e.g. x=$a/$b), as currently
expressions are always evaluated right to left. This can lead to some
incorrect results:
e.g. echo 'hist:keys=common_pid:x=8-4-2' >> event/trigger
8-4-2 should evaluate to 2 i.e. (8-4)-2
but currently x evaluate to 6 i.e. 8-(4-2)
Multiplication and division in sub-expressions will work correctly, once
correct operator precedence support is added (See next patch in this
series).
For the undefined case of division by 0, the histogram expression
evaluates to (u64)(-1). Since this cannot be detected when the
expression is created, it is the responsibility of the user to be
aware and account for this possibility.
Examples:
echo 'hist:keys=common_pid:a=8,b=4,x=$a/$b' \
>> event/trigger
echo 'hist:keys=common_pid:y=5*$b' \
>> event/trigger
Link: https://lkml.kernel.org/r/20211025200852.3002369-3-kaleshsingh@google.com
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Currently hist trigger expressions don't support the use of numeric
literals:
e.g. echo 'hist:keys=common_pid:x=$y-1234'
--> is not valid expression syntax
Having the ability to use numeric constants in hist triggers supports
a wider range of expressions for creating variables.
Add support for creating trace event histogram variables from numeric
literals.
e.g. echo 'hist:keys=common_pid:x=1234,y=size-1024' >> event/trigger
A negative numeric constant is created, using unary minus operator
(parentheses are required).
e.g. echo 'hist:keys=common_pid:z=-(2)' >> event/trigger
Constants can be used with division/multiplication (added in the
next patch in this series) to implement granularity filters for frequent
trace events. For instance we can limit emitting the rss_stat
trace event to when there is a 512KB cross over in the rss size:
# Create a synthetic event to monitor instead of the high frequency
# rss_stat event
echo 'rss_stat_throttled unsigned int mm_id; unsigned int curr;
int member; long size' >> tracing/synthetic_events
# Create a hist trigger that emits the synthetic rss_stat_throttled
# event only when the rss size crosses a 512KB boundary.
echo 'hist:keys=keys=mm_id,member:bucket=size/0x80000:onchange($bucket)
.rss_stat_throttled(mm_id,curr,member,size)'
>> events/kmem/rss_stat/trigger
A use case for using constants with addition/subtraction is not yet
known, but for completeness the use of constants are supported for all
operators.
Link: https://lkml.kernel.org/r/20211025200852.3002369-2-kaleshsingh@google.com
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Since config KPROBES_SANITY_TEST is in lib/Kconfig.debug, it is better to
let test_kprobes.c in lib/, just like other similar tests found in lib/.
Link: https://lkml.kernel.org/r/1635213091-24387-4-git-send-email-yangtiezhu@loongson.cn
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Add a test case for stacktrace from kretprobe handler and
nested kretprobe handlers.
This test checks both of stack trace inside kretprobe handler
and stack trace from pt_regs. Those stack trace must include
actual function return address instead of kretprobe trampoline.
The nested kretprobe stacktrace test checks whether the unwinder
can correctly unwind the call frame on the stack which has been
modified by the kretprobe.
Since the stacktrace on kretprobe is correctly fixed only on x86,
this introduces a meta kconfig ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
which tells user that the stacktrace on kretprobe is correct or not.
The test results will be shown like below;
TAP version 14
1..1
# Subtest: kprobes_test
1..6
ok 1 - test_kprobe
ok 2 - test_kprobes
ok 3 - test_kretprobe
ok 4 - test_kretprobes
ok 5 - test_stacktrace_on_kretprobe
ok 6 - test_stacktrace_on_nested_kretprobe
# kprobes_test: pass:6 fail:0 skip:0 total:6
# Totals: pass:6 fail:0 skip:0 total:6
ok 1 - kprobes_test
Link: https://lkml.kernel.org/r/163516211244.604541.18350507860972214415.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The sparse tool complains as follows:
kernel/trace/trace_hwlat.c:82:27: warning: symbol 'hwlat_single_cpu_data' was not declared. Should it be static?
kernel/trace/trace_hwlat.c:83:1: warning: symbol '__pcpu_scope_hwlat_per_cpu_data' was not declared. Should it be static?
This symbol is not used outside of trace_hwlat.c, so this commit
marks it static.
Link: https://lkml.kernel.org/r/20211021035225.1050685-1-bobo.shaobowang@huawei.com
Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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trace_boot_init_histograms misses NULL pointer checks for kstrdup
failure.
Link: https://lkml.kernel.org/r/20211015195550.22742-1-mathieu.desnoyers@efficios.com
Fixes: 64dc7f6958ef5 ("tracing/boot: Show correct histogram error command")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Since "54357f0c9149 tracing: Add migrate-disabled counter to tracing
output," the migrate disabled field is also printed in the !PREEMPR_RT
kernel config. While this information was added to the vast majority of
tracers, osnoise and timerlat were not updated (because they are new
tracers).
Fix timerlat header by adding the information about migrate disabled.
Link: https://lkml.kernel.org/r/bc0c234ab49946cdd63effa6584e1d5e8662cb44.1634308385.git.bristot@kernel.org
Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: x86@kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Fixes: 54357f0c9149 ("tracing: Add migrate-disabled counter to tracing output.")
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Since "54357f0c9149 tracing: Add migrate-disabled counter to tracing
output," the migrate disabled field is also printed in the !PREEMPR_RT
kernel config. While this information was added to the vast majority of
tracers, osnoise and timerlat were not updated (because they are new
tracers).
Fix osnoise header by adding the information about migrate disabled.
Link: https://lkml.kernel.org/r/9cb3d54e29e0588dbba12e81486bd8a09adcd8ca.1634308385.git.bristot@kernel.org
Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: x86@kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Fixes: 54357f0c9149 ("tracing: Add migrate-disabled counter to tracing output.")
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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It is useful to trace functions in kernel/event/core.c. Allow ftrace for
them by removing $(CC_FLAGS_FTRACE) from Makefile.
Link: https://lkml.kernel.org/r/20211006210732.2826289-1-songliubraving@fb.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: KP Singh <kpsingh@kernel.org>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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This symbol is not used outside of ftrace.c, so marks it static.
Fixes the following sparse warning:
kernel/trace/ftrace.c:579:5: warning: symbol 'ftrace_profile_pages_init'
was not declared. Should it be static?
Link: https://lkml.kernel.org/r/1634640534-18280-1-git-send-email-jiapeng.chong@linux.alibaba.com
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Fixes: cafb168a1c92 ("tracing: make the function profiler per cpu")
Signed-off-by: chongjiapeng <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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This converts the kprobes testcases to use the kunit framework.
It adds a dependency on CONFIG_KUNIT, and the output will change
to TAP:
TAP version 14
1..1
# Subtest: kprobes_test
1..4
random: crng init done
ok 1 - test_kprobe
ok 2 - test_kprobes
ok 3 - test_kretprobe
ok 4 - test_kretprobes
ok 1 - kprobes_test
Note that the kprobes testcases are no longer run immediately after
kprobes initialization, but as a late initcall when kunit is
initialized. kprobes itself is initialized with an early initcall,
so the order is still correct.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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clang started warning about excessive stack usage in
hist_trigger_print_key()
kernel/trace/trace_events_hist.c:4723:13: error: stack frame size (1336) exceeds limit (1024) in function 'hist_trigger_print_key' [-Werror,-Wframe-larger-than]
The problem is that there are two 512-byte arrays on the stack if
hist_trigger_stacktrace_print() gets inlined. I don't think this has
changed in the past five years, but something probably changed the
inlining decisions made by the compiler, so the problem is now made
more obvious.
Rather than printing the symbol names into separate buffers, it
seems we can simply use the special %ps format string modifier
to print the pointers symbolically and get rid of both buffers.
Marking hist_trigger_stacktrace_print() would be a simpler
way of avoiding the warning, but that would not address the
excessive stack usage.
Link: https://lkml.kernel.org/r/20211019153337.294790-1-arnd@kernel.org
Fixes: 69a0200c2e25 ("tracing: Add hist trigger support for stacktraces as keys")
Link: https://lore.kernel.org/all/20211015095704.49a99859@gandalf.local.home/
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Tested-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Currently to switch a set of "multi" direct trampolines from one
trampoline to another, a full shutdown of the current set needs to be
done, followed by an update to what trampoline the direct callers would
call, and then re-enabling the callers. This leaves a time when the
functions will not be calling anything, and events may be missed.
Instead, use a trick to allow all the functions with direct trampolines
attached will always call either the new or old trampoline while the
switch is happening. To do this, first attach a "dummy" callback via
ftrace to all the functions that the current direct trampoline is attached
to. This will cause the functions to call the "list func" instead of the
direct trampoline. The list function will call the direct trampoline
"helper" that will set the function it should call as it returns back to
the ftrace trampoline.
At this moment, the direct caller descriptor can safely update the direct
call trampoline. The list function will pick either the new or old
function (depending on the memory coherency model of the architecture).
Now removing the dummy function from each of the locations of the direct
trampoline caller, will put back the direct call, but now to the new
trampoline.
A better visual is:
[ Changing direct call from my_direct_1 to my_direct_2 ]
<traced_func>:
call my_direct_1
||||||||||||||||||||
vvvvvvvvvvvvvvvvvvvv
<traced_func>:
call ftrace_caller
<ftrace_caller>:
[..]
call ftrace_ops_list_func
ftrace_ops_list_func()
{
ops->func() -> direct_helper -> set rax to my_direct_1 or my_direct_2
}
call rax (to either my_direct_1 or my_direct_2
||||||||||||||||||||
vvvvvvvvvvvvvvvvvvvv
<traced_func>:
call my_direct_2
Link: https://lore.kernel.org/all/20211014162819.5c85618b@gandalf.local.home/
Acked-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Adding interface to modify registered direct function
for ftrace_ops. Adding following function:
modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
The function changes the currently registered direct
function for all attached functions.
Link: https://lkml.kernel.org/r/20211008091336.33616-8-jolsa@kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Adding interface to register multiple direct functions
within single call. Adding following functions:
register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
The register_ftrace_direct_multi registers direct function (addr)
with all functions in ops filter. The ops filter can be updated
before with ftrace_set_filter_ip calls.
All requested functions must not have direct function currently
registered, otherwise register_ftrace_direct_multi will fail.
The unregister_ftrace_direct_multi unregisters ops related direct
functions.
Link: https://lkml.kernel.org/r/20211008091336.33616-7-jolsa@kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Factor out the code that adds (ip, addr) tuple to direct_functions
hash in new ftrace_add_rec_direct function. It will be used in
following patches.
Link: https://lkml.kernel.org/r/20211008091336.33616-6-jolsa@kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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There's a new test in trace_selftest_startup_function_graph() that
requires the use of ftrace args being supported as well does some tricks
with dynamic tracing. Although this code checks HAVE_DYNAMIC_FTRACE_WITH_ARGS
it fails to check DYNAMIC_FTRACE, and the kernel fails to build due to
that dependency.
Also only define the prototype of trace_direct_tramp() if it is used.
Link: https://lkml.kernel.org/r/20211021134357.7f48e173@gandalf.local.home
Acked-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Adding selftest for checking that direct trampoline can
co-exist together with graph tracer on same function.
This is supported for CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
config option, which is defined only for x86_64 for now.
Link: https://lkml.kernel.org/r/20211008091336.33616-5-jolsa@kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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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>
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Now that there are three different instances of doing the addition trick
to the preempt_count() and NMI_MASK, HARDIRQ_MASK and SOFTIRQ_OFFSET
macros, it deserves a helper function defined in the preempt.h header.
Add the interrupt_context_level() helper and replace the three instances
that do that logic with it.
Link: https://lore.kernel.org/all/20211015142541.4badd8a9@gandalf.local.home/
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Instead of having branches that adds noise to the branch prediction, use
the addition logic to set the bit for the level of interrupt context that
the state is currently in. This copies the logic from perf's
get_recursion_context() function.
Link: https://lore.kernel.org/all/20211015161702.GF174703@worktop.programming.kicks-ass.net/
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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If CONFIG_CFI_CLANG=y, attempting to read an event histogram will cause
the kernel to panic due to failed CFI check.
1. echo 'hist:keys=common_pid' >> events/sched/sched_switch/trigger
2. cat events/sched/sched_switch/hist
3. kernel panics on attempting to read hist
This happens because the sort() function expects a generic
int (*)(const void *, const void *) pointer for the compare function.
To prevent this CFI failure, change tracing map cmp_entries_* function
signatures to match this.
Also, fix the build error reported by the kernel test robot [1].
[1] https://lore.kernel.org/r/202110141140.zzi4dRh4-lkp@intel.com/
Link: https://lkml.kernel.org/r/20211014045217.3265162-1-kaleshsingh@google.com
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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In an effort to enable -Wcast-function-type in the top-level Makefile to
support Control Flow Integrity builds, all function casts need to be
removed.
This means that ftrace_ops_list_func() can no longer be defined as
ftrace_ops_no_ops(). The reason for ftrace_ops_no_ops() is to use that when
an architecture calls ftrace_ops_list_func() with only two parameters
(called from assembly). And to make sure there's no C side-effects, those
archs call ftrace_ops_no_ops() which only has two parameters, as
ftrace_ops_list_func() has four parameters.
Instead of a typecast, use vmlinux.lds.h to define ftrace_ops_list_func() to
arch_ftrace_ops_list_func() that will define the proper set of parameters.
Link: https://lore.kernel.org/r/20200614070154.6039-1-oscar.carter@gmx.com
Link: https://lkml.kernel.org/r/20200617165616.52241bde@oasis.local.home
Link: https://lore.kernel.org/all/20211005053922.GA702049@embeddedor/
Requested-by: Oscar Carter <oscar.carter@gmx.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Replace the obsolete and ambiguos macro in_irq() with new
macro in_hardirq().
Link: https://lkml.kernel.org/r/20210930000342.6016-1-changbin.du@gmail.com
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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A self test is provided for the trace function removal functionality.
Link: https://lkml.kernel.org/r/20210918153043.318016-2-carles.pey@gmail.com
Signed-off-by: Carles Pey <carles.pey@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Most of ARCHs use empty ftrace_dyn_arch_init(), introduce a weak common
ftrace_dyn_arch_init() to cleanup them.
Link: https://lkml.kernel.org/r/20210909090216.1955240-1-o451686892@gmail.com
Acked-by: Heiko Carstens <hca@linux.ibm.com> (s390)
Acked-by: Helge Deller <deller@gmx.de> (parisc)
Signed-off-by: Weizhao Ouyang <o451686892@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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When building the files in the tracefs file system, do not by default set
any permissions for OTH (other). This will make it easier for admins who
want to define a group for accessing tracefs and not having to first
disable all the permission bits for "other" in the file system.
As tracing can leak sensitive information, it should never by default
allowing all users access. An admin can still set the permission bits for
others to have access, which may be useful for creating a honeypot and
seeing who takes advantage of it and roots the machine.
Link: https://lkml.kernel.org/r/20210818153038.864149276@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The upper and lower variables are set as link lists to add into the sparse
array. If they are NULL, after the needed allocations are done, then there
is nothing to add. But they need to be initialized to NULL for this to
work.
Link: https://lore.kernel.org/all/221bc7ba-a475-1cb9-1bbe-730bb9c2d448@canonical.com/
Fixes: 8d6e90983ade ("tracing: Create a sparse bitmask for pid filtering")
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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When the trace_pid_list was created, the default pid max was 32768.
Creating a bitmask that can hold one bit for all 32768 took up 4096 (one
page). Having a one page bitmask was not much of a problem, and that was
used for mapping pids. But today, systems are bigger and can run more
tasks, and now the default pid_max is usually set to 4194304. Which means
to handle that many pids requires 524288 bytes. Worse yet, the pid_max can
be set to 2^30 (1073741824 or 1G) which would take 134217728 (128M) of
memory to store this array.
Since the pid_list array is very sparsely populated, it is a huge waste of
memory to store all possible bits for each pid when most will not be set.
Instead, use a page table scheme to store the array, and allow this to
handle up to 30 bit pids.
The pid_mask will start out with 256 entries for the first 8 MSB bits.
This will cost 1K for 32 bit architectures and 2K for 64 bit. Each of
these will have a 256 array to store the next 8 bits of the pid (another
1 or 2K). These will hold an 2K byte bitmask (which will cover the LSB
14 bits or 16384 pids).
When the trace_pid_list is allocated, it will have the 1/2K upper bits
allocated, and then it will allocate a cache for the next upper chunks and
the lower chunks (default 6 of each). Then when a bit is "set", these
chunks will be pulled from the free list and added to the array. If the
free list gets down to a lever (default 2), it will trigger an irqwork
that will refill the cache back up.
On clearing a bit, if the clear causes the bitmask to be zero, that chunk
will then be placed back into the free cache for later use, keeping the
need to allocate more down to a minimum.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Instead of having the logic that does trace_pid_list open coded, wrap it in
abstract functions. This will allow a rewrite of the logic that implements
the trace_pid_list without affecting the users.
Note, this causes a change in behavior. Every time a pid is written into
the set_*_pid file, it creates a new list and uses RCU to update it. If
pid_max is lowered, but there was a pid currently in the list that was
higher than pid_max, those pids will now be removed on updating the list.
The old behavior kept that from happening.
The rewrite of the pid_list logic will no longer depend on pid_max,
and will return the old behavior.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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In x86, the fake return address on the stack saved by
__kretprobe_trampoline() will be replaced with the real return
address after returning from trampoline_handler(). Before fixing
the return address, the real return address can be found in the
'current->kretprobe_instances'.
However, since there is a window between updating the
'current->kretprobe_instances' and fixing the address on the stack,
if an interrupt happens at that timing and the interrupt handler
does stacktrace, it may fail to unwind because it can not get
the correct return address from 'current->kretprobe_instances'.
This will eliminate that window by fixing the return address
right before updating 'current->kretprobe_instances'.
Link: https://lkml.kernel.org/r/163163057094.489837.9044470370440745866.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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ftrace shows "[unknown/kretprobe'd]" indicator all addresses in the
kretprobe_trampoline, but the modified address by kretprobe should
be only kretprobe_trampoline+0.
Link: https://lkml.kernel.org/r/163163056044.489837.794883849706638013.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Since the ORC unwinder from pt_regs requires setting up regs->ip
correctly, set the correct return address to the regs->ip before
calling user kretprobe handler.
This allows the kretrprobe handler to trace stack from the
kretprobe's pt_regs by stack_trace_save_regs() (eBPF will do
this), instead of stack tracing from the handler context by
stack_trace_save() (ftrace will do this).
Link: https://lkml.kernel.org/r/163163053237.489837.4272653874525136832.stgit@devnote2
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Introduce kretprobe_find_ret_addr() and is_kretprobe_trampoline().
These APIs will be used by the ORC stack unwinder and ftrace, so that
they can check whether the given address points kretprobe trampoline
code and query the correct return address in that case.
Link: https://lkml.kernel.org/r/163163046461.489837.1044778356430293962.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Since now there is kretprobe_trampoline_addr() for referring the
address of kretprobe trampoline code, we don't need to access
kretprobe_trampoline directly.
Make it harder to refer by renaming it to __kretprobe_trampoline().
Link: https://lkml.kernel.org/r/163163045446.489837.14510577516938803097.stgit@devnote2
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The __kretprobe_trampoline_handler() callback, called from low level
arch kprobes methods, has the 'trampoline_address' parameter, which is
entirely superfluous as it basically just replicates:
dereference_kernel_function_descriptor(kretprobe_trampoline)
In fact we had bugs in arch code where it wasn't replicated correctly.
So remove this superfluous parameter and use kretprobe_trampoline_addr()
instead.
Link: https://lkml.kernel.org/r/163163044546.489837.13505751885476015002.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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dereference_symbol_descriptor()
~15 years ago kprobes grew the 'arch_deref_entry_point()' __weak function:
3d7e33825d87: ("jprobes: make jprobes a little safer for users")
But this is just open-coded dereference_symbol_descriptor() in essence, and
its obscure nature was causing bugs.
Just use the real thing and remove arch_deref_entry_point().
Link: https://lkml.kernel.org/r/163163043630.489837.7924988885652708696.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Use the 'bool' type instead of 'int' for the functions which
returns a boolean value, because this makes clear that those
functions don't return any error code.
Link: https://lkml.kernel.org/r/163163041649.489837.17311187321419747536.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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get_optimized_kprobe()
Since get_optimized_kprobe() is only used inside kprobes,
it doesn't need to use 'unsigned long' type for 'addr' parameter.
Make it use 'kprobe_opcode_t *' for the 'addr' parameter and
subsequent call of arch_within_optimized_kprobe() also should use
'kprobe_opcode_t *'.
Note that MAX_OPTIMIZED_LENGTH and RELATIVEJUMP_SIZE are defined
by byte-size, but the size of 'kprobe_opcode_t' depends on the
architecture. Therefore, we must be careful when calculating
addresses using those macros.
Link: https://lkml.kernel.org/r/163163040680.489837.12133032364499833736.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Add assertions for required locks instead of comment it
so that the lockdep can inspect locks automatically.
Link: https://lkml.kernel.org/r/163163039572.489837.18011973177537476885.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Fix coding style issues reported by checkpatch.pl and update
comments to quote variable names and add "()" to function
name.
One TODO comment in __disarm_kprobe() is removed because
it has been done by following commit.
Link: https://lkml.kernel.org/r/163163037468.489837.4282347782492003960.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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This clean up the error/notification messages in kprobes related code.
Basically this defines 'pr_fmt()' macros for each files and update
the messages which describes
- what happened,
- what is the kernel going to do or not do,
- is the kernel fine,
- what can the user do about it.
Also, if the message is not needed (e.g. the function returns unique
error code, or other error message is already shown.) remove it,
and replace the message with WARN_*() macros if suitable.
Link: https://lkml.kernel.org/r/163163036568.489837.14085396178727185469.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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arch_check_ftrace_location() was introduced as a weak function in
commit f7f242ff004499 ("kprobes: introduce weak
arch_check_ftrace_location() helper function") to allow architectures
to handle kprobes call site on their own.
Recently, the only architecture (csky) to implement
arch_check_ftrace_location() was migrated to using the common
version.
As a result, further cleanup the code to drop the weak attribute and
rename the function to remove the architecture specific
implementation.
Link: https://lkml.kernel.org/r/163163035673.489837.2367816318195254104.stgit@devnote2
Signed-off-by: Punit Agrawal <punitagrawal@gmail.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The function prepare_kprobe() is called during kprobe registration and
is responsible for ensuring any architecture related preparation for
the kprobe is done before returning.
One of two versions of prepare_kprobe() is chosen depending on the
availability of KPROBE_ON_FTRACE in the kernel configuration.
Simplify the code by dropping the version when KPROBE_ON_FTRACE is not
selected - instead relying on kprobe_ftrace() to return false when
KPROBE_ON_FTRACE is not set.
No functional change.
Link: https://lkml.kernel.org/r/163163033696.489837.9264661820279300788.stgit@devnote2
Signed-off-by: Punit Agrawal <punitagrawal@gmail.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The "enabled" file provides a debugfs interface to arm / disarm
kprobes in the kernel. In order to parse the buffer containing the
values written from userspace, the callback manually parses the user
input to convert it to a boolean value.
As taking a string value from userspace and converting it to boolean
is a common operation, a helper kstrtobool_from_user() is already
available in the kernel. Update the callback to use the common helper
to parse the write buffer from userspace.
Link: https://lkml.kernel.org/r/163163032637.489837.10678039554832855327.stgit@devnote2
Signed-off-by: Punit Agrawal <punitagrawal@gmail.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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