commit db23a25ad41e56ebfbeab3a1e1deb31477663cde
author Alexander Potapenko <glider@google.com> Mon Nov 27 17:46:34 2023 +0100
committer Alexander Potapenko <glider@google.com> Tue Jan 16 18:23:03 2024 +0100
tree e491e17ea77a46e1016eb44e9ee1e2a3e45485e5
parent 75626e6dbd01be349da09766c768ec121927b3cd

pkg/cover/backend: adjust module base address by .text offset

Modules' .text sections are not necessarily loaded at the address shown
in /proc/modules. If there are other non-init code sections preceding them
in the ELF binary, .text is loaded at non-zero address.

For example, for a module with the following sections:

Idx Name          Size      VMA               LMA               File off  Algn
...
  5 .plt          00000001  0000000000000000  0000000000000000  00000500  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  6 .init.ddplt     00000001  0000000000000000  0000000000000000  00000501  2**0
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  7 .text.ftrace_trampoline 00000001  0000000000000000  0000000000000000  00000502  2**0
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  8 .hyp.text     00002000  0000000000000000  0000000000000000  00001000  2**12
                  CONTENTS, ALLOC, LOAD, RELOC, READONLY, CODE
...
 13 .text         00001aac  0000000000000000  0000000000000000  00005048  2**2
                  CONTENTS, ALLOC, LOAD, RELOC, READONLY, CODE

the base address displayed in /proc/modules points to the beginning of
.plt, and other sections have the following offsets:
 .init.plt - ignored
 .text.ftrace_trampoline - 0x1
 .hyp.text - 0x1000
 .text - 0x3000

This patch calculates the offset of the .text section and uses it to
adjust the address obtained from /proc/modules.