Messages in this thread | | | Subject | Re: [PATCH v2 2/4] arm64: unwind: Prohibit probing on return_address() | From | James Morse <> | Date | Tue, 23 Jul 2019 17:04:21 +0100 |
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Hi,
On 22/07/2019 08:48, Masami Hiramatsu wrote: > Prohibit probing on return_address() and subroutines which > is called from return_address(), since the it is invoked from > trace_hardirqs_off() which is also kprobe blacklisted.
(Nits: "which are called" and "since it is")
> diff --git a/arch/arm64/kernel/return_address.c b/arch/arm64/kernel/return_address.c > index b21cba90f82d..7f8a143268b0 100644 > --- a/arch/arm64/kernel/return_address.c > +++ b/arch/arm64/kernel/return_address.c > @@ -8,6 +8,7 @@ > > #include <linux/export.h> > #include <linux/ftrace.h> > +#include <linux/kprobes.h> > > #include <asm/stack_pointer.h> > #include <asm/stacktrace.h> > @@ -17,7 +18,7 @@ struct return_address_data { > void *addr; > }; > > -static int save_return_addr(struct stackframe *frame, void *d) > +static nokprobe_inline int save_return_addr(struct stackframe *frame, void *d)
This nokprobe_inline ends up as __always_inline if kprobes is enabled. What do we expect the compiler to do with this? save_return_addr is passed as a function-pointer to walk_stackframe()... I don't see how the compiler can inline it!
This would be needed for on_accessible_stack(). Should we cover ftrace_graph_get_ret_stack()?, or is that already in hand?
> { > struct return_address_data *data = d; > > @@ -52,3 +53,4 @@ void *return_address(unsigned int level) > return NULL; > } > EXPORT_SYMBOL_GPL(return_address); > +NOKPROBE_SYMBOL(return_address);
Thanks,
James
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