diff options
| author | Menglong Dong <menglong8.dong@gmail.com> | 2025-11-18 20:36:29 +0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2025-11-24 09:46:24 -0800 |
| commit | 25e4e3565d45f567f78089f38822fa64abee5230 (patch) | |
| tree | 7da2d2ce9e9ad91b86dfa5e4d6df263163a9495d /kernel/trace/Kconfig | |
| parent | fad804002ef3cae8ca0509849d0d9539be069095 (diff) | |
ftrace: Introduce FTRACE_OPS_FL_JMP
For now, the "nop" will be replaced with a "call" instruction when a
function is hooked by the ftrace. However, sometimes the "call" can break
the RSB and introduce extra overhead. Therefore, introduce the flag
FTRACE_OPS_FL_JMP, which indicate that the ftrace_ops should be called
with a "jmp" instead of "call". For now, it is only used by the direct
call case.
When a direct ftrace_ops is marked with FTRACE_OPS_FL_JMP, the last bit of
the ops->direct_call will be set to 1. Therefore, we can tell if we should
use "jmp" for the callback in ftrace_call_replace().
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20251118123639.688444-2-dongml2@chinatelecom.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/trace/Kconfig')
| -rw-r--r-- | kernel/trace/Kconfig | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index d2c79da81e4f..4661b9e606e0 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -80,6 +80,12 @@ config HAVE_DYNAMIC_FTRACE_NO_PATCHABLE If the architecture generates __patchable_function_entries sections but does not want them included in the ftrace locations. +config HAVE_DYNAMIC_FTRACE_WITH_JMP + bool + help + If the architecture supports to replace the __fentry__ with a + "jmp" instruction. + config HAVE_SYSCALL_TRACEPOINTS bool help @@ -330,6 +336,12 @@ config DYNAMIC_FTRACE_WITH_ARGS depends on DYNAMIC_FTRACE depends on HAVE_DYNAMIC_FTRACE_WITH_ARGS +config DYNAMIC_FTRACE_WITH_JMP + def_bool y + depends on DYNAMIC_FTRACE + depends on DYNAMIC_FTRACE_WITH_DIRECT_CALLS + depends on HAVE_DYNAMIC_FTRACE_WITH_JMP + config FPROBE bool "Kernel Function Probe (fprobe)" depends on HAVE_FUNCTION_GRAPH_FREGS && HAVE_FTRACE_GRAPH_FUNC |