linux-kernel - Re: [PATCH v3 07/29] x86: bpf

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Date:   Mon, 24 Apr 2017 17:41:06 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     David Miller <davem@...emloft.net>
Cc:     alexei.starovoitov@...il.com, mingo@...hat.com, tglx@...utronix.de,
        hpa@...or.com, x86@...nel.org, jpoimboe@...hat.com,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        daniel@...earbox.net, edumazet@...gle.com
Subject: Re: [PATCH v3 07/29] x86: bpf_jit, use ENTRY+ENDPROC

On 04/24/2017, 05:08 PM, David Miller wrote:
> If you align the entry points, then the code sequence as a whole is
> are no longer densely packed.

Sure.

> Or do I misunderstand how your macros work?

Perhaps. So the suggested macros for the code are:
#define BPF_FUNC_START_LOCAL(name) \
		SYM_START(name, SYM_V_LOCAL, SYM_A_NONE)
#define BPF_FUNC_START(name) \
		SYM_START(name, SYM_V_GLOBAL, SYM_A_NONE)

and they differ from the standard ones:
#define SYM_FUNC_START_LOCAL(name)                      \
        SYM_START(name, SYM_V_LOCAL, SYM_A_ALIGN)
#define SYM_FUNC_START(name)                            \
        SYM_START(name, SYM_V_GLOBAL, SYM_A_ALIGN)


The difference is SYM_A_NONE vs. SYM_A_ALIGN, which means:
#define SYM_A_ALIGN                             ALIGN
#define SYM_A_NONE                              /* nothing */

Does it look OK now?

thanks,
-- 
js
suse labs