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Marchesi" , , "Martin KaFai Lau" , "Puranjay Mohan" Subject: Re: [PATCH bpf-next v2 21/23] bpf, arm64: Map BPF_REG_0 to x8 instead of x7 X-Mailer: aerc References: <20260507212942.1122000-1-yonghong.song@linux.dev> <20260507213156.1139442-1-yonghong.song@linux.dev> In-Reply-To: <20260507213156.1139442-1-yonghong.song@linux.dev> On Thu May 7, 2026 at 2:31 PM PDT, Yonghong Song wrote: > From: Puranjay Mohan > > Move the BPF return value register from x7 to x8, freeing x7 for use > as an argument register. AAPCS64 designates x8 as the indirect result > location register; it is caller-saved and not used for argument > passing, making it a suitable home for BPF_REG_0. > > This is a prerequisite for stack argument support, which needs x5-x7 > to pass arguments 6-8 to native kfuncs following the AAPCS64 calling > convention. > > Signed-off-by: Yonghong Song > Signed-off-by: Yonghong Song That's not right. It should probably be: Signed-off-by: Puranjay Mohan Signed-off-by: Yonghong Song