I found that having the ftrace infrastructure use its own trampoline to
handle recursion and RCU by defaulte unless the ftrace_ops set the
appropriate flags, was an issue that nobody set those flags. But then their
callbacks would suffer from an unnecessary overhead instead of simply
handling the recursion itself.
This series makes it mandatory that ftrace callbacks handle recursion or set
a flag asking ftrace to do it for it. It also creates helper functions to
help these callbacks to have recursion protection.
Changes since v2:
- Move get_kprobe() into preempt disabled sections for various archs
- Use trace_recursion flags in current for protecting recursion of recursion
recording
- Make the recursion logic a little cleaner
- Export GPL the recursion recording
Steven Rostedt (VMware) (11):
ftrace: Move the recursion testing into global headers
ftrace: Add ftrace_test_recursion_trylock() helper function
ftrace: Optimize testing what context current is in
pstore/ftrace: Add recursion protection to the ftrace callback
kprobes/ftrace: Add recursion protection to the ftrace callback
livepatch/ftrace: Add recursion protection to the ftrace callback
livepatch: Trigger WARNING if livepatch function fails due to recursion
perf/ftrace: Add recursion protection to the ftrace callback
perf/ftrace: Check for rcu_is_watching() in callback function
ftrace: Reverse what the RECURSION flag means in the ftrace_ops
ftrace: Add recording of functions that caused recursion
----
Documentation/trace/ftrace-uses.rst | 84 ++++++++----
arch/csky/kernel/probes/ftrace.c | 12 +-
arch/parisc/kernel/ftrace.c | 16 ++-
arch/powerpc/kernel/kprobes-ftrace.c | 11 +-
arch/s390/kernel/ftrace.c | 16 ++-
arch/x86/kernel/kprobes/ftrace.c | 12 +-
fs/pstore/ftrace.c | 6 +
include/linux/ftrace.h | 13 +-
include/linux/trace_recursion.h | 240 ++++++++++++++++++++++++++++++++++
kernel/livepatch/patch.c | 5 +
kernel/trace/Kconfig | 25 ++++
kernel/trace/Makefile | 1 +
kernel/trace/fgraph.c | 3 +-
kernel/trace/ftrace.c | 24 ++--
kernel/trace/trace.h | 177 -------------------------
kernel/trace/trace_event_perf.c | 13 +-
kernel/trace/trace_events.c | 1 -
kernel/trace/trace_functions.c | 14 +-
kernel/trace/trace_output.c | 6 +-
kernel/trace/trace_output.h | 1 +
kernel/trace/trace_recursion_record.c | 236 +++++++++++++++++++++++++++++++++
kernel/trace/trace_selftest.c | 7 +-
kernel/trace/trace_stack.c | 1 -
23 files changed, 673 insertions(+), 251 deletions(-)
create mode 100644 include/linux/trace_recursion.h
create mode 100644 kernel/trace/trace_recursion_record.c
