Messages in this thread | | | Date | Wed, 24 Jul 2019 16:39:14 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH v2 2/4] arm64: unwind: Prohibit probing on return_address() |
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On Tue, 23 Jul 2019 17:04:21 +0100 James Morse <james.morse@arm.com> wrote:
> 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")
Thanks!
> > > > 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!
Oops, that's my mistake. Then it should be NOKPROBE_SYMBOL.
> > This would be needed for on_accessible_stack(). > Should we cover ftrace_graph_get_ret_stack()?, or is that already in hand?
No, that is OK. It just covers that the functions which are involved in the kprobe execution path. ftrace_graph_ret_stack() is out of the debug exception handler.
Thank you,
> > { > > 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
-- Masami Hiramatsu <mhiramat@kernel.org>
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