linux-kernel - Re: [PATCH v2 2/6] powerpc64/bpf: Support tailcalls with subprogs

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Message-ID: <4728530f-41c8-4a26-aa8a-30f53f1fe629@linux.ibm.com>
Date: Sat, 17 Jan 2026 15:53:10 +0530
From: Hari Bathini <hbathini@...ux.ibm.com>
To: adubey@...ux.ibm.com, bpf@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: sachinpb@...ux.ibm.com, venkat88@...ux.ibm.com, andrii@...nel.org,
        eddyz87@...il.com, mykolal@...com, ast@...nel.org,
        daniel@...earbox.net, martin.lau@...ux.dev, song@...nel.org,
        yonghong.song@...ux.dev, john.fastabend@...il.com, kpsingh@...nel.org,
        sdf@...ichev.me, haoluo@...gle.com, jolsa@...nel.org,
        christophe.leroy@...roup.eu, naveen@...nel.org, maddy@...ux.ibm.com,
        mpe@...erman.id.au, npiggin@...il.com, memxor@...il.com,
        iii@...ux.ibm.com, shuah@...nel.org
Subject: Re: [PATCH v2 2/6] powerpc64/bpf: Support tailcalls with subprogs



On 14/01/26 5:14 pm, adubey@...ux.ibm.com wrote:
> From: Abhishek Dubey<adubey@...ux.ibm.com>
> 
> Enabling tailcalls with subprog combinations by referencing
> method. The actual tailcall count is always maintained in the
> tail_call_info variable present in the frame of main function
> (also called entry function). The tail_call_info variables in
> the frames of all other subprog contains reference to the
> tail_call_info present in frame of main function.

I would rephrase:

"The tail_call_info variables in the frames of all other subprog
contains reference to the tail_call_info present in frame of
main function."

to:

"The tail_call_info field in the stack frame of subprogs contains
reference to the tail_call_info field in the stack frame of main
BPF program."

- Hari