On Tue, Oct 6, 2020 at 1:10 PM Alexei Starovoitov
<alexei.starovoi...@gmail.com> wrote:
>
> From: Yonghong Song <y...@fb.com>
>
> Under register pressure the llvm may spill registers with bounds into the 
> stack.
> The verifier has to track them through spill/fill otherwise many kinds of 
> bound
> errors will be seen. The spill/fill of induction variables was already
> happening. This patch extends this logic from tracking spill/fill of a 
> constant
> into any bounded register. There is no need to track spill/fill of unbounded,
> since no new information will be retrieved from the stack during register 
> fill.
>
> Though extra stack difference could cause state pruning to be less effective, 
> no
> adverse affects were seen from this patch on selftests and on cilium programs.
>
> Signed-off-by: Yonghong Song <y...@fb.com>
> Signed-off-by: Alexei Starovoitov <a...@kernel.org>
> ---

Acked-by: Andrii Nakryiko <and...@kernel.org>

>  kernel/bpf/verifier.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
>

[...]

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