Re: [PATCH 4.14 v2 1/4] bpf: Do not use ax register in interpreter on div/mod

Greg KH
2023-02-23T09:01:50Z

On Wed, Feb 22, 2023 at 07:29:21PM +0000, Edward Liaw wrote:
> From: Daniel Borkmann <daniel@iogearbox.net>
>
> Partially undo old commit 144cd91c4c2b ("bpf: move tmp variable into ax
> register in interpreter"). The reason we need this here is because ax
> register will be used for holding temporary state for div/mod instruction
> which otherwise interpreter would corrupt. This will cause a small +8 byte
> stack increase for interpreter, but with the gain that we can use it from
> verifier rewrites as scratch register.
>
> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
> Reviewed-by: John Fastabend <john.fastabend@gmail.com>
> [cascardo: This partial revert is needed in order to support using AX for
> the following two commits, as there is no JMP32 on 4.19.y]
> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
> [edliaw: Removed redeclaration of tmp]
> Signed-off-by: Edward Liaw <edliaw@google.com>
> ---
> kernel/bpf/core.c | 31 ++++++++++++++-----------------
> 1 file changed, 14 insertions(+), 17 deletions(-)

What is the git commit id in Linus's tree of this commit?

thanks,

greg k-h