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SubjectRe: [PATCH] export.h: reduce __ksymtab_strings string duplication by using "MS" section flags
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cc += binutils ML

[on @progbits v %progbits in generic (data only) assembly code]

On 22/11/2019 12.44, Masahiro Yamada wrote:
> On Fri, Nov 22, 2019 at 1:09 AM Jessica Yu <jeyu@kernel.org> wrote:
>>

>> I think this would work, and it feels like the more correct solution
>> especially if arm isn't the only one with the odd progbits char. It
>> might be overkill if it's just arm that's affected though. I leave it
>> to Masahiro to see what he prefers.
>>
>
>
> BTW, is there any reason why
> not use %progbits all the time?
>
>
> include/linux/init.h hard-codes %progbits
>
> #define __INITDATA .section ".init.data","aw",%progbits
> #define __INITRODATA .section ".init.rodata","a",%progbits
>
>
> So, my understanding is '%' works for all architectures,
> but it is better to ask 0-day bot to test it.

It seems that you're absolutely right. The binutils source has code like

+ if (*input_line_pointer == '@' || *input_line_pointer == '%')
+ {
+ ++input_line_pointer;
+ if (strncmp (input_line_pointer, "progbits",
+ sizeof "progbits" - 1) == 0)
+ {
+ type = SHT_PROGBITS;
+ input_line_pointer += sizeof "progbits" - 1;
+ }
+ else if (strncmp (input_line_pointer, "nobits",
+ sizeof "nobits" - 1) == 0)
+ {
+ type = SHT_NOBITS;
+ input_line_pointer += sizeof "nobits" - 1;
+ }


all the way back from

commit 252b5132c753830d5fd56823373aed85f2a0db63 (tag: binu_ss_19990502)
Author: Richard Henderson <rth@redhat.com>
Date: Mon May 3 07:29:11 1999 +0000

19990502 sourceware import

So yes, let's just try unconditionally using %progbits, that makes
everything much simpler.

The only reason I thought one needed to do it differently on ARM is this
from the gas docs:

===
The optional TYPE argument may contain one of the following
constants:

'@progbits'
section contains data
...
Note on targets where the '@' character is the start of a comment (eg
ARM) then another character is used instead. For example the ARM port
uses the '%' character.
===

That doesn't suggest the possibility that % or some other character
might work on all architectures.

Jessica, can you resend using just %progbits to let kbuild chew on that?
Please include a comment about the misleading gas documentation.

Rasmus

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