RE: [PATCH 6/9] x86/bpf: Fix JIT frame pointer usage

[David Laight]

On Thu, Jun 13, 2019 at 08:21:03AM -0500, Josh Poimboeuf wrote:
> The BPF JIT code clobbers RBP.  This breaks frame pointer convention and
> thus prevents the FP unwinder from unwinding through JIT generated code.
>
> RBP is currently used as the BPF stack frame pointer register.  The
> actual register used is opaque to the user, as long as it's a
> callee-saved register.  Change it to use R12 instead.

Could you maintain the system %rbp chain through the BPF stack?
It might even be possible to put something relevant in the %rip
location.

	David

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