linux-kernel - Re: [PATCHv3 0/8] powerpc/mm: refactor vDSO mapping code

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Date:   Tue, 08 Nov 2016 10:57:49 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Dmitry Safonov <0x7f454c46@...il.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>
Cc:     Dmitry Safonov <dsafonov@...tuozzo.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-mm@...ck.org,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv3 0/8] powerpc/mm: refactor vDSO mapping code

Dmitry Safonov <0x7f454c46@...il.com> writes:

> 2016-10-27 20:09 GMT+03:00 Dmitry Safonov <dsafonov@...tuozzo.com>:
>
> ping?

There's another series doing some similar changes:

http://www.spinics.net/lists/linux-mm/msg115860.html


And I don't like all the macro games in 3/8, eg:

+#ifndef BITS
+#define BITS 32
+#endif
+
+#undef Elf_Ehdr
+#undef Elf_Sym
+#undef Elf_Shdr
+
+#define _CONCAT3(a, b, c)	a ## b ## c
+#define CONCAT3(a, b, c)	_CONCAT3(a, b, c)
+#define Elf_Ehdr	CONCAT3(Elf,  BITS, _Ehdr)
+#define Elf_Sym		CONCAT3(Elf,  BITS, _Sym)
+#define Elf_Shdr	CONCAT3(Elf,  BITS, _Shdr)
+#define VDSO_LBASE	CONCAT3(VDSO, BITS, _LBASE)
+#define vdso_kbase	CONCAT3(vdso, BITS, _kbase)
+#define vdso_pages	CONCAT3(vdso, BITS, _pages)
+
+#undef pr_fmt
+#define pr_fmt(fmt)	"vDSO" __stringify(BITS) ": " fmt
+
+#define lib_elfinfo CONCAT3(lib, BITS, _elfinfo)
+
+#define find_section CONCAT3(find_section, BITS,)
+static void * __init find_section(Elf_Ehdr *ehdr, const char *secname,
+		unsigned long *size)


I'd rather we kept the duplication of code than the obfuscation those
macros add.

If we can come up with a way to share more of the code without having to
do all those tricks then I'd be interested.

cheers