Messages in this thread | | | Date | Mon, 26 Sep 2022 14:37:23 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH] kprobes: Mark ftrace mcount handler functions nokprobe |
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On Mon, 19 Sep 2022 16:45:33 +0800 Liao Chang <liaochang1@huawei.com> wrote:
> Mark ftrace mcount handler functions nokprobe since probing on these > functions probably reaches mcount recursivly during kprobe breakpoint > handler for some architecture(tested for riscv, arm64), and reenter > kprobe is treated as a fatal error, causes kernel panic.
This looks to me that the affected archs should be made more robust for this case than to add this to the generic code.
-- Steve
> > Pesudo code below demonstrate this problem: > > mcount > function_trace_call (probed) > arch_breakpoint_handler > arch_setup_singlestep [mcount] > function_trace_call (probed) > arch_breakpoint_handler > reenter_kprobe > BUG > > Signed-off-by: Liao Chang <liaochang1@huawei.com> > --- > kernel/trace/trace_functions.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c > index 9f1bfbe105e8..440a678a8c7c 100644 > --- a/kernel/trace/trace_functions.c > +++ b/kernel/trace/trace_functions.c > @@ -16,6 +16,7 @@ > #include <linux/ftrace.h> > #include <linux/slab.h> > #include <linux/fs.h> > +#include <linux/kprobes.h> > > #include "trace.h" > > @@ -194,6 +195,7 @@ function_trace_call(unsigned long ip, unsigned long parent_ip, > > ftrace_test_recursion_unlock(bit); > } > +NOKPROBE_SYMBOL(function_trace_call); > > #ifdef CONFIG_UNWINDER_ORC > /* > @@ -245,6 +247,7 @@ function_stack_trace_call(unsigned long ip, unsigned long parent_ip, > atomic_dec(&data->disabled); > local_irq_restore(flags); > } > +NOKPROBE_SYMBOL(function_stack_trace_call); > > static inline bool is_repeat_check(struct trace_array *tr, > struct trace_func_repeats *last_info, > @@ -321,6 +324,7 @@ function_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip, > out: > ftrace_test_recursion_unlock(bit); > } > +NOKPROBE_SYMBOL(function_no_repeats_trace_call); > > static void > function_stack_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip, > @@ -363,6 +367,7 @@ function_stack_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip, > atomic_dec(&data->disabled); > local_irq_restore(flags); > } > +NOKPROBE_SYMBOL(function_stack_no_repeats_trace_call); > > static struct tracer_opt func_opts[] = { > #ifdef CONFIG_STACKTRACE
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