Messages in this thread | | | Date | Mon, 29 Nov 2021 18:56:43 +0100 | Subject | Re: [PATCH] recordmcount: Support empty section from recent binutils | From | Christophe Leroy <> |
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Le 29/11/2021 à 18:43, Steven Rostedt a écrit : > On Fri, 26 Nov 2021 08:43:23 +0000 > LEROY Christophe <christophe.leroy@csgroup.eu> wrote: > >> Le 24/11/2021 à 15:43, Christophe Leroy a écrit : >>> Looks like recent binutils (2.36 and over ?) may empty some section, >>> leading to failure like: >>> >>> Cannot find symbol for section 11: .text.unlikely. >>> kernel/kexec_file.o: failed >>> make[1]: *** [scripts/Makefile.build:287: kernel/kexec_file.o] Error 1 >>> >>> In order to avoid that, ensure that the section has a content before >>> returning it's name in has_rel_mcount(). >> >> This patch doesn't work, on PPC32 I get the following message with this >> patch applied: >> >> [ 0.000000] ftrace: No functions to be traced? >> >> Without the patch I get: >> >> [ 0.000000] ftrace: allocating 22381 entries in 66 pages >> [ 0.000000] ftrace: allocated 66 pages with 2 groups > > Because of this report, I have not applied this patch (even though I was > about to push it to Linus). > > I'm pulling it from my queue until this gets resolved. >
I have no idea on how to fix that for the moment.
With GCC 10 (binutils 2.36) an objdump -x on kernel/kexec_file.o gives:
0000000000000000 l d .text.unlikely 0000000000000000 .text.unlikely 0000000000000000 w F .text.unlikely 0000000000000038 .arch_kexec_apply_relocations_add 0000000000000038 w F .text.unlikely 0000000000000038 .arch_kexec_apply_relocations
With GCC 11 (binutils 2.37) the same gives:
0000000000000000 w F .text.unlikely 0000000000000038 .arch_kexec_apply_relocations_add 0000000000000038 w F .text.unlikely 0000000000000038 .arch_kexec_apply_relocations
The problem is that recordmcount drops weak symbols, and it doesn't find any non-weak symbol in .text.unlikely
Explication given at https://elixir.bootlin.com/linux/v5.16-rc2/source/scripts/recordmcount.h#L506
I have no idea on what to do.
Thanks Christophe
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