linux/samples/ftrace, branch v6.3

samples: ftrace: Make some global variables static

2023-02-07T17:48:00Z

smatch reports this representative issue samples/ftrace/ftrace-ops.c:15:14: warning: symbol 'nr_function_calls' was not declared. Should it be static? The nr_functions_calls and several other global variables are only used in ftrace-ops.c, so they should be static. Remove the instances of initializing static int to 0. Link: https://lore.kernel.org/linux-trace-kernel/20230130193708.1378108-1-trix@redhat.com Signed-off-by: Tom Rix Acked-by: Mark Rutland Signed-off-by: Steven Rostedt (Google)

ftrace: sample: avoid open-coded 64-bit division

2023-02-07T17:45:18Z

Calculating the average period requires a 64-bit division that leads to a link failure on 32-bit architectures: x86_64-linux-ld: samples/ftrace/ftrace-ops.o: in function `ftrace_ops_sample_init': ftrace-ops.c:(.init.text+0x23b): undefined reference to `__udivdi3' Use the div_u64() helper to do this instead. Since this is an init function that is not called frequently, the runtime overhead is going to be acceptable. Link: https://lore.kernel.org/linux-trace-kernel/20230130130246.247537-1-arnd@kernel.org Cc: Masami Hiramatsu Fixes: b56c68f705ca ("ftrace: Add sample with custom ops") Signed-off-by: Arnd Bergmann Acked-by: Mark Rutland Signed-off-by: Steven Rostedt (Google)

samples: ftrace: Include the nospec-branch.h only for x86

2023-02-07T17:44:39Z

When other architectures without the nospec functionality write their direct-call functions of samples/ftrace/*.c, the including of asm/nospec-branch.h must be taken care to fix the no header file found error in building process. This commit (ee3e2469b346 "x86/ftrace: Make it call depth tracking aware") file-globally includes asm/nospec-branch.h providing CALL_DEPTH_ACCOUNT for only x86 direct-call functions. It seems better to move the including to `#ifdef CONFIG_X86_64`. Link: https://lore.kernel.org/linux-trace-kernel/20230130085954.647845-1-suagrfillet@gmail.com Signed-off-by: Song Shuai Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google)

ftrace: Add sample with custom ops

2023-01-25T15:31:23Z

When reworking core ftrace code or architectural ftrace code, it's often necessary to test/analyse/benchmark a number of ftrace_ops configurations. This patch adds a module which can be used to explore some of those configurations. I'm using this to benchmark various options for changing the way trampolines and handling of ftrace_ops work on arm64, and ensuring other architectures aren't adversely affected. For example, in a QEMU+KVM VM running on a 2GHz Xeon E5-2660 workstation, loading the module in various configurations produces: | # insmod ftrace-ops.ko | ftrace_ops: registering: | relevant ops: 1 | tracee: tracee_relevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | irrelevant ops: 0 | tracee: tracee_irrelevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | saving registers: NO | assist recursion: NO | assist RCU: NO | ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 1681558ns (16ns / call) | # insmod ftrace-ops.ko nr_ops_irrelevant=5 | ftrace_ops: registering: | relevant ops: 1 | tracee: tracee_relevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | irrelevant ops: 5 | tracee: tracee_irrelevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | saving registers: NO | assist recursion: NO | assist RCU: NO | ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 1693042ns (16ns / call) | # insmod ftrace-ops.ko nr_ops_relevant=2 | ftrace_ops: registering: | relevant ops: 2 | tracee: tracee_relevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | irrelevant ops: 0 | tracee: tracee_irrelevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | saving registers: NO | assist recursion: NO | assist RCU: NO | ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 11965582ns (119ns / call) | # insmod ftrace-ops.ko save_regs=true | ftrace_ops: registering: | relevant ops: 1 | tracee: tracee_relevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | irrelevant ops: 0 | tracee: tracee_irrelevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | saving registers: YES | assist recursion: NO | assist RCU: NO | ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 4459624ns (44ns / call) Link: https://lkml.kernel.org/r/20230103124912.2948963-4-mark.rutland@arm.com Cc: Florent Revest Acked-by: Masami Hiramatsu (Google) Signed-off-by: Mark Rutland Signed-off-by: Steven Rostedt (Google)

ftrace: Export ftrace_free_filter() to modules

2023-01-24T16:20:58Z

Setting filters on an ftrace ops results in some memory being allocated for the filter hashes, which must be freed before the ops can be freed. This can be done by removing every individual element of the hash by calling ftrace_set_filter_ip() or ftrace_set_filter_ips() with `remove` set, but this is somewhat error prone as it's easy to forget to remove an element. Make it easier to clean this up by exporting ftrace_free_filter(), which can be used to clean up all of the filter hashes after an ftrace_ops has been unregistered. Using this, fix the ftrace-direct* samples to free hashes prior to being unloaded. All other code either removes individual filters explicitly or is built-in and already calls ftrace_free_filter(). Link: https://lkml.kernel.org/r/20230103124912.2948963-3-mark.rutland@arm.com Cc: stable@vger.kernel.org Cc: Florent Revest Cc: Masami Hiramatsu Fixes: e1067a07cfbc ("ftrace/samples: Add module to test multi direct modify interface") Fixes: 5fae941b9a6f ("ftrace/samples: Add multi direct interface test module") Reviewed-by: Masami Hiramatsu (Google) Reviewed-by: Steven Rostedt (Google) Signed-off-by: Mark Rutland Signed-off-by: Steven Rostedt (Google)

x86/ftrace: Make it call depth tracking aware

2022-10-17T14:41:19Z

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) Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20220915111148.927545073@infradead.org

x86/ibt,ftrace: Add ENDBR to samples/ftrace

2022-03-15T09:32:38Z

Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://lore.kernel.org/r/20220308154318.523421433@infradead.org

Merge tag 'x86_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2022-01-13T00:31:19Z

Pull x86 core updates from Borislav Petkov: - Get rid of all the .fixup sections because this generates misleading/wrong stacktraces and confuse RELIABLE_STACKTRACE and LIVEPATCH as the backtrace misses the function which is being fixed up. - Add Straight Line Speculation mitigation support which uses a new compiler switch -mharden-sls= which sticks an INT3 after a RET or an indirect branch in order to block speculation after them. Reportedly, CPUs do speculate behind such insns. - The usual set of cleanups and improvements * tag 'x86_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits) x86/entry_32: Fix segment exceptions objtool: Remove .fixup handling x86: Remove .fixup section x86/word-at-a-time: Remove .fixup usage x86/usercopy: Remove .fixup usage x86/usercopy_32: Simplify __copy_user_intel_nocache() x86/sgx: Remove .fixup usage x86/checksum_32: Remove .fixup usage x86/vmx: Remove .fixup usage x86/kvm: Remove .fixup usage x86/segment: Remove .fixup usage x86/fpu: Remove .fixup usage x86/xen: Remove .fixup usage x86/uaccess: Remove .fixup usage x86/futex: Remove .fixup usage x86/msr: Remove .fixup usage x86/extable: Extend extable functionality x86/entry_32: Remove .fixup usage x86/entry_64: Remove .fixup usage x86/copy_mc_64: Remove .fixup usage ...

ftrace/samples: Add missing prototypes direct functions

2022-01-05T23:34:50Z

There's another compilation fail (first here [1]) reported by kernel test robot for W=1 clang build: >> samples/ftrace/ftrace-direct-multi-modify.c:7:6: warning: no previous prototype for function 'my_direct_func1' [-Wmissing-prototypes] void my_direct_func1(unsigned long ip) Direct functions in ftrace direct sample modules need to have prototypes defined. They are already global in order to be visible for the inline assembly, so there's no problem. The kernel test robot reported just error for ftrace-direct-multi-modify, but I got same errors also for the rest of the modules touched by this patch. [1] 67d4f6e3bf5d ftrace/samples: Add missing prototype for my_direct_func Link: https://lkml.kernel.org/r/20211219135317.212430-1-jolsa@kernel.org Reported-by: kernel test robot Fixes: e1067a07cfbc ("ftrace/samples: Add module to test multi direct modify interface") Fixes: ae0cc3b7e7f5 ("ftrace/samples: Add a sample module that implements modify_ftrace_direct()") Fixes: 156473a0ff4f ("ftrace: Add another example of register_ftrace_direct() use case") Fixes: b06457c83af6 ("ftrace: Add sample module that uses register_ftrace_direct()") Signed-off-by: Jiri Olsa Signed-off-by: Steven Rostedt

ftrace/samples: Add module to test multi direct modify interface

2021-12-09T18:02:44Z

Adding ftrace-direct-multi-modify.ko kernel module that uses modify_ftrace_direct_multi API. The core functionality is taken from ftrace-direct-modify.ko kernel module and changed to fit multi direct interface. The init function creates kthread that periodically calls modify_ftrace_direct_multi to change the trampoline address for the direct ftrace_ops. The ftrace trace_pipe then shows trace from both trampolines. Link: https://lkml.kernel.org/r/20211206182032.87248-4-jolsa@kernel.org Cc: Ingo Molnar Reviewed-by: Heiko Carstens Tested-by: Heiko Carstens Signed-off-by: Jiri Olsa Signed-off-by: Steven Rostedt (VMware)