[PATCH V3 2/2] arm64: bpf: make BPF prologue and epilogue align with ARM64 AAPCS
zlim.lnx at gmail.com
Fri Nov 13 18:39:33 PST 2015
Yang, I noticed another thing...
On Fri, Nov 13, 2015 at 10:09 AM, Yang Shi <yang.shi at linaro.org> wrote:
> Save and restore FP/LR in BPF prog prologue and epilogue, save SP to FP
> in prologue in order to get the correct stack backtrace.
> However, ARM64 JIT used FP (x29) as eBPF fp register, FP is subjected to
> change during function call so it may cause the BPF prog stack base address
> change too.
> Use x25 to replace FP as BPF stack base register (fp). Since x25 is callee
> saved register, so it will keep intact during function call.
Can you please add save/restore for x25 also? :)
> It is initialized in BPF prog prologue when BPF prog is started to run
> everytime. When BPF prog exits, it could be just tossed.
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