ELF section not represented in symbol table

ELF section not represented in symbol table

[Oleh Matiusha]

Hello GCC,
I am stuck debugging the compilation of my kernel module.

The files and copy-pasted description of this problem can be viewed here:
github.com/omatiusha/cdevmod .

My dir structure is following:


..
  |-linux       (here resides the source code for linux kernel
5.14.0-09718-g4b93c544e90e,
  |              built with GCC Ubuntu 9.3.0-17ubuntu1~20.04 + binutils 2.34)
  |-linux-cross (here resides the source code for linux kernel
5.14.0-09718-g4b93c544e90e,
  |              built with x86_64-linux-gcc 8.5.0 + binutils 2.36.1
  |              from https://mirrors.edge.kernel.org/pub/tools/crosstool/).
  |              Tried also versions 9.4 and 11.1 from there.
  |-extmodules - repo mentioned above.

I am trying to get my module working with kpatch (github.com/dynup/kpatch)
and get stuck debugging the compiler. To spot the place when everything
gets wrong, I compile this module independently four times, with host or
cross compiler, and patched or unpatched.

make KCFLAGS="-ffunction-sections -fdata-sections"

for host-compiler, and

CROSS_COMPILE=x86_64-linux- suffix=-cross make KCFLAGS="-ffunction-sections
-fdata-sections"

for cross-compiler. Then I dump symbols with objdump -t cdevmod.o and full
text with objdump -s cdevmod.o | grep PATCHED -C5. And notice that for a
host compiler, both sections .rodata.cdev_read.str1.1 and
.rodata.cdev_read.str1.8 are present in symbol table of patched version,
while for a cross compiler section .rodata.cdev_read.str1.1 is present as a
section, but absent in the symbol table. This causes kpatch utilities not
to work properly and crash.

I want the cross compiler to behave like host one. Please someone suggest
why it behaves differently.

Best regards,

Oleh Matiusha