[PATCH v2 0/2] fix & prevent the missing preemption disabling
From: 王贇 <hidden>
Date: 2021-10-13 03:17:07
Also in:
linux-riscv, live-patching, lkml
The testing show that perf_ftrace_function_call() are using smp_processor_id() with preemption enabled, all the checking on CPU could be wrong after preemption. As Peter point out, the section between ftrace_test_recursion_trylock/unlock() pair require the preemption to be disabled as 'Documentation/trace/ftrace-uses.rst' explained, but currently the work is done outside of the helpers. Patch 1/2 will make sure preemption disabled after trylock() succeed, patch 2/2 will do smp_processor_id() checking after trylock to address the issue. Michael Wang (2): ftrace: disable preemption between ftrace_test_recursion_trylock/unlock() ftrace: do CPU checking after preemption disabled arch/csky/kernel/probes/ftrace.c | 2 -- arch/parisc/kernel/ftrace.c | 2 -- arch/powerpc/kernel/kprobes-ftrace.c | 2 -- arch/riscv/kernel/probes/ftrace.c | 2 -- arch/x86/kernel/kprobes/ftrace.c | 2 -- include/linux/trace_recursion.h | 22 +++++++++++++++++++++- kernel/livepatch/patch.c | 6 ------ kernel/trace/trace_event_perf.c | 6 +++--- kernel/trace/trace_functions.c | 5 ----- 9 files changed, 24 insertions(+), 25 deletions(-) -- 1.8.3.1