| Message ID | 173344373580.50709.5332611753907139634.stgit@devnote2 (mailing list archive) |
|---|---|
| Headers | show |
| Series | tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph | expand |
Hi,
Sorry, I found a problem on arm64 on qemu. Let me recheck it.
[ 592.422044] # test_fprobe_entry: EXPECTATION FAILED at lib/test_fprobe.c:38
[ 592.422044] Expected (preempt_count() == 0 && !({ unsigned long _flags; do { ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); _flags = arch_local_save_flags(); } while (0); ({ ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); arch_irqs_disabled_flags(_flags); }); })) to be false, but is true
[ 592.427029] # test_fprobe_entry: EXPECTATION FAILED at lib/test_fprobe.c:38
[ 592.427029] Expected (preempt_count() == 0 && !({ unsigned long _flags; do { ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); _flags = arch_local_save_flags(); } while (0); ({ ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); arch_irqs_disabled_flags(_flags); }); })) to be false, but is true
[ 592.461632] not ok 1 test_fprobe_entry
[ 592.564126] # test_fprobe: EXPECTATION FAILED at lib/test_fprobe.c:38
[ 592.564126] Expected (preempt_count() == 0 && !({ unsigned long _flags; do { ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); _flags = arch_local_save_flags(); } while (0); ({ ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); arch_irqs_disabled_flags(_flags); }); })) to be false, but is true
[ 592.568100] # test_fprobe: EXPECTATION FAILED at lib/test_fprobe.c:38
[ 592.568100] Expected (preempt_count() == 0 && !({ unsigned long _flags; do { ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); _flags = arch_local_save_flags(); } while (0); ({ ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); arch_irqs_disabled_flags(_flags); }); })) to be false, but is true
[ 592.603844] not ok 2 test_fprobe
[ 592.650501] # test_fprobe_syms: EXPECTATION FAILED at lib/test_fprobe.c:38
[ 592.650501] Expected (preempt_count() == 0 && !({ unsigned long _flags; do { ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); _flags = arch_local_save_flags(); } while (0); ({ ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); arch_irqs_disabled_flags(_flags); }); })) to be false, but is true
[ 592.654706] # test_fprobe_syms: EXPECTATION FAILED at lib/test_fprobe.c:38
[ 592.654706] Expected (preempt_count() == 0 && !({ unsigned long _flags; do { ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); _flags = arch_local_save_flags(); } while (0); ({ ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); arch_irqs_disabled_flags(_flags); }); })) to be false, but is true
[ 592.699596] not ok 3 test_fprobe_syms
[ 592.802046] # test_fprobe_data: EXPECTATION FAILED at lib/test_fprobe.c:38
[ 592.802046] Expected (preempt_count() == 0 && !({ unsigned long _flags; do { ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); _flags = arch_local_save_flags(); } while (0); ({ ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); arch_irqs_disabled_flags(_flags); }); })) to be false, but is true
[ 592.839950] not ok 4 test_fprobe_data
[ 592.945481] # test_fprobe_skip: EXPECTATION FAILED at lib/test_fprobe.c:38
[ 592.945481] Expected (preempt_count() == 0 && !({ unsigned long _flags; do { ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); _flags = arch_local_save_flags(); } while (0); ({ ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); arch_irqs_disabled_flags(_flags); }); })) to be false, but is true
[ 592.979938] not ok 5 test_fprobe_skip
[ 592.980046] # fprobe_test: pass:0 fail:5 skip:0 total:5
[ 592.980388] # Totals: pass:0 fail:5 skip:0 total:5
Thanks,
On Fri, 6 Dec 2024 09:08:56 +0900
"Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote:
> Hi,
>
> Here is the 20th version of the series to re-implement the fprobe on
> function-graph tracer. The previous version is;
>
> https://lore.kernel.org/all/173125372214.172790.6929368952404083802.stgit@devnote2/
>
> This version is rebased on v6.13-rc1 and fixes to make CONFIG_FPROBE
> "n" by default, so that it does not enable function graph tracer by
> default.
>
> Overview
> --------
> This series rewrites the fprobe on this function-graph.
> The purposes of this change are;
>
> 1) Remove dependency of the rethook from fprobe so that we can reduce
> the return hook code and shadow stack.
>
> 2) Make 'ftrace_regs' the common trace interface for the function
> boundary.
>
> 1) Currently we have 2(or 3) different function return hook codes,
> the function-graph tracer and rethook (and legacy kretprobe).
> But since this is redundant and needs double maintenance cost,
> I would like to unify those. From the user's viewpoint, function-
> graph tracer is very useful to grasp the execution path. For this
> purpose, it is hard to use the rethook in the function-graph
> tracer, but the opposite is possible. (Strictly speaking, kretprobe
> can not use it because it requires 'pt_regs' for historical reasons.)
>
> 2) Now the fprobe provides the 'pt_regs' for its handler, but that is
> wrong for the function entry and exit. Moreover, depending on the
> architecture, there is no way to accurately reproduce 'pt_regs'
> outside of interrupt or exception handlers. This means fprobe should
> not use 'pt_regs' because it does not use such exceptions.
> (Conversely, kprobe should use 'pt_regs' because it is an abstract
> interface of the software breakpoint exception.)
>
> This series changes fprobe to use function-graph tracer for tracing
> function entry and exit, instead of mixture of ftrace and rethook.
> Unlike the rethook which is a per-task list of system-wide allocated
> nodes, the function graph's ret_stack is a per-task shadow stack.
> Thus it does not need to set 'nr_maxactive' (which is the number of
> pre-allocated nodes).
> Also the handlers will get the 'ftrace_regs' instead of 'pt_regs'.
> Since eBPF mulit_kprobe/multi_kretprobe events still use 'pt_regs' as
> their register interface, this changes it to convert 'ftrace_regs' to
> 'pt_regs'. Of course this conversion makes an incomplete 'pt_regs',
> so users must access only registers for function parameters or
> return value.
>
> Design
> ------
> Instead of using ftrace's function entry hook directly, the new fprobe
> is built on top of the function-graph's entry and return callbacks
> with 'ftrace_regs'.
>
> Since the fprobe requires access to 'ftrace_regs', the architecture
> must support CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS and
> CONFIG_HAVE_FTRACE_GRAPH_FUNC, which enables to call function-graph
> entry callback with 'ftrace_regs', and also
> CONFIG_HAVE_FUNCTION_GRAPH_FREGS, which passes the ftrace_regs to
> return_to_handler.
>
> All fprobes share a single function-graph ops (means shares a common
> ftrace filter) similar to the kprobe-on-ftrace. This needs another
> layer to find corresponding fprobe in the common function-graph
> callbacks, but has much better scalability, since the number of
> registered function-graph ops is limited.
>
> In the entry callback, the fprobe runs its entry_handler and saves the
> address of 'fprobe' on the function-graph's shadow stack as data. The
> return callback decodes the data to get the 'fprobe' address, and runs
> the exit_handler.
>
> The fprobe introduces two hash-tables, one is for entry callback which
> searches fprobes related to the given function address passed by entry
> callback. The other is for a return callback which checks if the given
> 'fprobe' data structure pointer is still valid. Note that it is
> possible to unregister fprobe before the return callback runs. Thus
> the address validation must be done before using it in the return
> callback.
>
> Download
> --------
> This series can be applied against the ftrace/for-next branch in
> linux-trace tree.
>
> This series can also be found below branch.
>
> https://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git/log/?h=topic/fprobe-on-fgraph
>
> Thank you,
>
> ---
>
> Masami Hiramatsu (Google) (18):
> fgraph: Pass ftrace_regs to entryfunc
> fgraph: Replace fgraph_ret_regs with ftrace_regs
> fgraph: Pass ftrace_regs to retfunc
> fprobe: Use ftrace_regs in fprobe entry handler
> fprobe: Use ftrace_regs in fprobe exit handler
> tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs
> tracing: Add ftrace_fill_perf_regs() for perf event
> tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS
> bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled
> ftrace: Add CONFIG_HAVE_FTRACE_GRAPH_FUNC
> fprobe: Rewrite fprobe on function-graph tracer
> fprobe: Add fprobe_header encoding feature
> tracing/fprobe: Remove nr_maxactive from fprobe
> selftests: ftrace: Remove obsolate maxactive syntax check
> selftests/ftrace: Add a test case for repeating register/unregister fprobe
> Documentation: probes: Update fprobe on function-graph tracer
> ftrace: Add ftrace_get_symaddr to convert fentry_ip to symaddr
> bpf: Use ftrace_get_symaddr() in get_entry_ip()
>
> Sven Schnelle (1):
> s390/tracing: Enable HAVE_FTRACE_GRAPH_FUNC
>
>
> Documentation/trace/fprobe.rst | 42 +
> arch/arm64/Kconfig | 2
> arch/arm64/include/asm/Kbuild | 1
> arch/arm64/include/asm/ftrace.h | 51 +-
> arch/arm64/kernel/asm-offsets.c | 12
> arch/arm64/kernel/entry-ftrace.S | 32 +
> arch/arm64/kernel/ftrace.c | 78 ++
> arch/loongarch/Kconfig | 4
> arch/loongarch/include/asm/fprobe.h | 12
> arch/loongarch/include/asm/ftrace.h | 32 -
> arch/loongarch/kernel/asm-offsets.c | 12
> arch/loongarch/kernel/ftrace_dyn.c | 10
> arch/loongarch/kernel/mcount.S | 17 -
> arch/loongarch/kernel/mcount_dyn.S | 14
> arch/powerpc/Kconfig | 1
> arch/powerpc/include/asm/ftrace.h | 13
> arch/powerpc/kernel/trace/ftrace.c | 2
> arch/powerpc/kernel/trace/ftrace_64_pg.c | 10
> arch/riscv/Kconfig | 3
> arch/riscv/include/asm/Kbuild | 1
> arch/riscv/include/asm/ftrace.h | 45 +
> arch/riscv/kernel/ftrace.c | 17 -
> arch/riscv/kernel/mcount.S | 24 -
> arch/s390/Kconfig | 4
> arch/s390/include/asm/fprobe.h | 10
> arch/s390/include/asm/ftrace.h | 37 +
> arch/s390/kernel/asm-offsets.c | 6
> arch/s390/kernel/entry.h | 1
> arch/s390/kernel/ftrace.c | 48 -
> arch/s390/kernel/mcount.S | 23 -
> arch/x86/Kconfig | 4
> arch/x86/include/asm/Kbuild | 1
> arch/x86/include/asm/ftrace.h | 54 +-
> arch/x86/kernel/ftrace.c | 50 +-
> arch/x86/kernel/ftrace_32.S | 13
> arch/x86/kernel/ftrace_64.S | 17 -
> include/asm-generic/fprobe.h | 46 +
> include/linux/fprobe.h | 62 +-
> include/linux/ftrace.h | 116 +++
> include/linux/ftrace_regs.h | 2
> kernel/trace/Kconfig | 22 -
> kernel/trace/bpf_trace.c | 38 -
> kernel/trace/fgraph.c | 57 +-
> kernel/trace/fprobe.c | 664 +++++++++++++++-----
> kernel/trace/ftrace.c | 6
> kernel/trace/trace.h | 6
> kernel/trace/trace_fprobe.c | 146 ++--
> kernel/trace/trace_functions_graph.c | 10
> kernel/trace/trace_irqsoff.c | 6
> kernel/trace/trace_probe_tmpl.h | 2
> kernel/trace/trace_sched_wakeup.c | 6
> kernel/trace/trace_selftest.c | 11
> lib/test_fprobe.c | 51 --
> samples/fprobe/fprobe_example.c | 4
> .../test.d/dynevent/add_remove_fprobe_repeat.tc | 19 +
> .../ftrace/test.d/dynevent/fprobe_syntax_errors.tc | 4
> 56 files changed, 1312 insertions(+), 669 deletions(-)
> create mode 100644 arch/loongarch/include/asm/fprobe.h
> create mode 100644 arch/s390/include/asm/fprobe.h
> create mode 100644 include/asm-generic/fprobe.h
> create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_repeat.tc
>
> --
> Masami Hiramatsu (Google) <mhiramat@kernel.org>
>
On Fri, Dec 06, 2024 at 09:08:56AM +0900, Masami Hiramatsu (Google) wrote: > Hi, > > Here is the 20th version of the series to re-implement the fprobe on > function-graph tracer. The previous version is; > > https://lore.kernel.org/all/173125372214.172790.6929368952404083802.stgit@devnote2/ > > This version is rebased on v6.13-rc1 and fixes to make CONFIG_FPROBE > "n" by default, so that it does not enable function graph tracer by > default. Is there a reason why you didn't add the ACKs I provided for s390 related patches for v19 of this series?
On Fri, 6 Dec 2024 10:35:56 +0100 Heiko Carstens <hca@linux.ibm.com> wrote: > On Fri, Dec 06, 2024 at 09:08:56AM +0900, Masami Hiramatsu (Google) wrote: > > Hi, > > > > Here is the 20th version of the series to re-implement the fprobe on > > function-graph tracer. The previous version is; > > > > https://lore.kernel.org/all/173125372214.172790.6929368952404083802.stgit@devnote2/ > > > > This version is rebased on v6.13-rc1 and fixes to make CONFIG_FPROBE > > "n" by default, so that it does not enable function graph tracer by > > default. > > Is there a reason why you didn't add the ACKs I provided for s390 > related patches for v19 of this series? Probably just missed it. Masami, One thing I usually do when I rebase to a new series is to take my older patch series from Patchwork and reapply them. Because patchwork will pick up any acks, reviewed-bys or tested-bys. I then only drop the tags if the patch needs significant changes. You can also use b4 to do the same. -- Steve
On Fri, 6 Dec 2024 17:20:03 +0900 Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote: > Hi, > > Sorry, I found a problem on arm64 on qemu. Let me recheck it. > > [ 592.422044] # test_fprobe_entry: EXPECTATION FAILED at lib/test_fprobe.c:38 > [ 592.422044] Expected (preempt_count() == 0 && !({ unsigned long _flags; do { ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); _flags = arch_local_save_flags(); } while (0); ({ ({ unsigned long __dummy; typeof(_flags) __dummy2; (void)(&__dummy == &__dummy2); 1; }); arch_irqs_disabled_flags(_flags); }); })) to be false, but is true This checks the handler is called with preempt off. On x86_64, the ftrace_graph_func calls function_graph_enter_regs() with ftrace_test_recursion_trylock() as below; void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, struct ftrace_regs *fregs) { struct pt_regs *regs = &arch_ftrace_regs(fregs)->regs; unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs); unsigned long return_hooker = (unsigned long)&return_to_handler; unsigned long *parent = (unsigned long *)stack; int bit; if (unlikely(skip_ftrace_return())) return; bit = ftrace_test_recursion_trylock(ip, *parent); if (bit < 0) return; if (!function_graph_enter_regs(*parent, ip, 0, parent, fregs)) *parent = return_hooker; ftrace_test_recursion_unlock(bit); } However, arm64 version does not; void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, struct ftrace_regs *fregs) { unsigned long return_hooker = (unsigned long)&return_to_handler; unsigned long frame_pointer = arch_ftrace_regs(fregs)->fp; unsigned long *parent = &arch_ftrace_regs(fregs)->lr; unsigned long old; if (unlikely(atomic_read(¤t->tracing_graph_pause))) return; old = *parent; if (!function_graph_enter_regs(old, ip, frame_pointer, (void *)frame_pointer, fregs)) { *parent = return_hooker; } } Is it a bug or intended? Thank you,
On Sat, 7 Dec 2024 15:51:36 +0900 Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote: > This checks the handler is called with preempt off. > > On x86_64, the ftrace_graph_func calls function_graph_enter_regs() with > ftrace_test_recursion_trylock() as below; > > void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, > struct ftrace_ops *op, struct ftrace_regs *fregs) > { > struct pt_regs *regs = &arch_ftrace_regs(fregs)->regs; > unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs); > unsigned long return_hooker = (unsigned long)&return_to_handler; > unsigned long *parent = (unsigned long *)stack; > int bit; > > if (unlikely(skip_ftrace_return())) > return; > > bit = ftrace_test_recursion_trylock(ip, *parent); > if (bit < 0) > return; > > if (!function_graph_enter_regs(*parent, ip, 0, parent, fregs)) > *parent = return_hooker; > > ftrace_test_recursion_unlock(bit); > } > > However, arm64 version does not; Hmm, I think we can move that recursion check out of the arch/x86 code and into ftrace_graph_enter_regs(). -- Steve
On Fri, 6 Dec 2024 09:52:47 -0500 Steven Rostedt <rostedt@goodmis.org> wrote: > On Fri, 6 Dec 2024 10:35:56 +0100 > Heiko Carstens <hca@linux.ibm.com> wrote: > > > On Fri, Dec 06, 2024 at 09:08:56AM +0900, Masami Hiramatsu (Google) wrote: > > > Hi, > > > > > > Here is the 20th version of the series to re-implement the fprobe on > > > function-graph tracer. The previous version is; > > > > > > https://lore.kernel.org/all/173125372214.172790.6929368952404083802.stgit@devnote2/ > > > > > > This version is rebased on v6.13-rc1 and fixes to make CONFIG_FPROBE > > > "n" by default, so that it does not enable function graph tracer by > > > default. > > > > Is there a reason why you didn't add the ACKs I provided for s390 > > related patches for v19 of this series? > > Probably just missed it. > > Masami, > > One thing I usually do when I rebase to a new series is to take my older > patch series from Patchwork and reapply them. Because patchwork will pick > up any acks, reviewed-bys or tested-bys. I then only drop the tags if the > patch needs significant changes. Oops, sorry, I missed those tags on v19. Let me fix that. Thanks. > > You can also use b4 to do the same. > > -- Steve
On Sat, 7 Dec 2024 09:47:10 -0500 Steven Rostedt <rostedt@goodmis.org> wrote: > On Sat, 7 Dec 2024 15:51:36 +0900 > Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote: > > > This checks the handler is called with preempt off. > > > > On x86_64, the ftrace_graph_func calls function_graph_enter_regs() with > > ftrace_test_recursion_trylock() as below; > > > > void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, > > struct ftrace_ops *op, struct ftrace_regs *fregs) > > { > > struct pt_regs *regs = &arch_ftrace_regs(fregs)->regs; > > unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs); > > unsigned long return_hooker = (unsigned long)&return_to_handler; > > unsigned long *parent = (unsigned long *)stack; > > int bit; > > > > if (unlikely(skip_ftrace_return())) > > return; > > > > bit = ftrace_test_recursion_trylock(ip, *parent); > > if (bit < 0) > > return; > > > > if (!function_graph_enter_regs(*parent, ip, 0, parent, fregs)) > > *parent = return_hooker; > > > > ftrace_test_recursion_unlock(bit); > > } > > > > However, arm64 version does not; > > Hmm, I think we can move that recursion check out of the arch/x86 code > and into ftrace_graph_enter_regs(). OK, that's reasonable. Thanks, > > -- Steve
Hi, Here is the 20th version of the series to re-implement the fprobe on function-graph tracer. The previous version is; https://lore.kernel.org/all/173125372214.172790.6929368952404083802.stgit@devnote2/ This version is rebased on v6.13-rc1 and fixes to make CONFIG_FPROBE "n" by default, so that it does not enable function graph tracer by default. Overview -------- This series rewrites the fprobe on this function-graph. The purposes of this change are; 1) Remove dependency of the rethook from fprobe so that we can reduce the return hook code and shadow stack. 2) Make 'ftrace_regs' the common trace interface for the function boundary. 1) Currently we have 2(or 3) different function return hook codes, the function-graph tracer and rethook (and legacy kretprobe). But since this is redundant and needs double maintenance cost, I would like to unify those. From the user's viewpoint, function- graph tracer is very useful to grasp the execution path. For this purpose, it is hard to use the rethook in the function-graph tracer, but the opposite is possible. (Strictly speaking, kretprobe can not use it because it requires 'pt_regs' for historical reasons.) 2) Now the fprobe provides the 'pt_regs' for its handler, but that is wrong for the function entry and exit. Moreover, depending on the architecture, there is no way to accurately reproduce 'pt_regs' outside of interrupt or exception handlers. This means fprobe should not use 'pt_regs' because it does not use such exceptions. (Conversely, kprobe should use 'pt_regs' because it is an abstract interface of the software breakpoint exception.) This series changes fprobe to use function-graph tracer for tracing function entry and exit, instead of mixture of ftrace and rethook. Unlike the rethook which is a per-task list of system-wide allocated nodes, the function graph's ret_stack is a per-task shadow stack. Thus it does not need to set 'nr_maxactive' (which is the number of pre-allocated nodes). Also the handlers will get the 'ftrace_regs' instead of 'pt_regs'. Since eBPF mulit_kprobe/multi_kretprobe events still use 'pt_regs' as their register interface, this changes it to convert 'ftrace_regs' to 'pt_regs'. Of course this conversion makes an incomplete 'pt_regs', so users must access only registers for function parameters or return value. Design ------ Instead of using ftrace's function entry hook directly, the new fprobe is built on top of the function-graph's entry and return callbacks with 'ftrace_regs'. Since the fprobe requires access to 'ftrace_regs', the architecture must support CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS and CONFIG_HAVE_FTRACE_GRAPH_FUNC, which enables to call function-graph entry callback with 'ftrace_regs', and also CONFIG_HAVE_FUNCTION_GRAPH_FREGS, which passes the ftrace_regs to return_to_handler. All fprobes share a single function-graph ops (means shares a common ftrace filter) similar to the kprobe-on-ftrace. This needs another layer to find corresponding fprobe in the common function-graph callbacks, but has much better scalability, since the number of registered function-graph ops is limited. In the entry callback, the fprobe runs its entry_handler and saves the address of 'fprobe' on the function-graph's shadow stack as data. The return callback decodes the data to get the 'fprobe' address, and runs the exit_handler. The fprobe introduces two hash-tables, one is for entry callback which searches fprobes related to the given function address passed by entry callback. The other is for a return callback which checks if the given 'fprobe' data structure pointer is still valid. Note that it is possible to unregister fprobe before the return callback runs. Thus the address validation must be done before using it in the return callback. Download -------- This series can be applied against the ftrace/for-next branch in linux-trace tree. This series can also be found below branch. https://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git/log/?h=topic/fprobe-on-fgraph Thank you, --- Masami Hiramatsu (Google) (18): fgraph: Pass ftrace_regs to entryfunc fgraph: Replace fgraph_ret_regs with ftrace_regs fgraph: Pass ftrace_regs to retfunc fprobe: Use ftrace_regs in fprobe entry handler fprobe: Use ftrace_regs in fprobe exit handler tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs tracing: Add ftrace_fill_perf_regs() for perf event tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled ftrace: Add CONFIG_HAVE_FTRACE_GRAPH_FUNC fprobe: Rewrite fprobe on function-graph tracer fprobe: Add fprobe_header encoding feature tracing/fprobe: Remove nr_maxactive from fprobe selftests: ftrace: Remove obsolate maxactive syntax check selftests/ftrace: Add a test case for repeating register/unregister fprobe Documentation: probes: Update fprobe on function-graph tracer ftrace: Add ftrace_get_symaddr to convert fentry_ip to symaddr bpf: Use ftrace_get_symaddr() in get_entry_ip() Sven Schnelle (1): s390/tracing: Enable HAVE_FTRACE_GRAPH_FUNC Documentation/trace/fprobe.rst | 42 + arch/arm64/Kconfig | 2 arch/arm64/include/asm/Kbuild | 1 arch/arm64/include/asm/ftrace.h | 51 +- arch/arm64/kernel/asm-offsets.c | 12 arch/arm64/kernel/entry-ftrace.S | 32 + arch/arm64/kernel/ftrace.c | 78 ++ arch/loongarch/Kconfig | 4 arch/loongarch/include/asm/fprobe.h | 12 arch/loongarch/include/asm/ftrace.h | 32 - arch/loongarch/kernel/asm-offsets.c | 12 arch/loongarch/kernel/ftrace_dyn.c | 10 arch/loongarch/kernel/mcount.S | 17 - arch/loongarch/kernel/mcount_dyn.S | 14 arch/powerpc/Kconfig | 1 arch/powerpc/include/asm/ftrace.h | 13 arch/powerpc/kernel/trace/ftrace.c | 2 arch/powerpc/kernel/trace/ftrace_64_pg.c | 10 arch/riscv/Kconfig | 3 arch/riscv/include/asm/Kbuild | 1 arch/riscv/include/asm/ftrace.h | 45 + arch/riscv/kernel/ftrace.c | 17 - arch/riscv/kernel/mcount.S | 24 - arch/s390/Kconfig | 4 arch/s390/include/asm/fprobe.h | 10 arch/s390/include/asm/ftrace.h | 37 + arch/s390/kernel/asm-offsets.c | 6 arch/s390/kernel/entry.h | 1 arch/s390/kernel/ftrace.c | 48 - arch/s390/kernel/mcount.S | 23 - arch/x86/Kconfig | 4 arch/x86/include/asm/Kbuild | 1 arch/x86/include/asm/ftrace.h | 54 +- arch/x86/kernel/ftrace.c | 50 +- arch/x86/kernel/ftrace_32.S | 13 arch/x86/kernel/ftrace_64.S | 17 - include/asm-generic/fprobe.h | 46 + include/linux/fprobe.h | 62 +- include/linux/ftrace.h | 116 +++ include/linux/ftrace_regs.h | 2 kernel/trace/Kconfig | 22 - kernel/trace/bpf_trace.c | 38 - kernel/trace/fgraph.c | 57 +- kernel/trace/fprobe.c | 664 +++++++++++++++----- kernel/trace/ftrace.c | 6 kernel/trace/trace.h | 6 kernel/trace/trace_fprobe.c | 146 ++-- kernel/trace/trace_functions_graph.c | 10 kernel/trace/trace_irqsoff.c | 6 kernel/trace/trace_probe_tmpl.h | 2 kernel/trace/trace_sched_wakeup.c | 6 kernel/trace/trace_selftest.c | 11 lib/test_fprobe.c | 51 -- samples/fprobe/fprobe_example.c | 4 .../test.d/dynevent/add_remove_fprobe_repeat.tc | 19 + .../ftrace/test.d/dynevent/fprobe_syntax_errors.tc | 4 56 files changed, 1312 insertions(+), 669 deletions(-) create mode 100644 arch/loongarch/include/asm/fprobe.h create mode 100644 arch/s390/include/asm/fprobe.h create mode 100644 include/asm-generic/fprobe.h create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_repeat.tc -- Masami Hiramatsu (Google) <mhiramat@kernel.org>