xtensa: Ensure xtensa_elf_relocate() never produces bad code #96210
Description
Summary
On Xtensa platforms, xtensa_elf_relocate() is used to patch L32R (and CALLn?) instructions at runtime when linking loadable LLEXT modules. The L32R instruction loads a literal value into a register. L32R requires the literal address to be within the range -262141 to -4 relative to the instruction address.
The current version of xtensa_elf_relocate() does not perform any check to verify that the literal address satisfies the -262141 to -4 range requirement. If xtensa_elf_relocate() is called with a bad literal address — for example, as a result of a bug in linking an LLEXT loadable module, such as a bad linker script (literals section placed after the section with L32R or positioned very far away) or linking with bad section addresses supplied via the command line — xtensa_elf_relocate() silently patches L32R with the wrong address, resulting in weird behavior and hard-to-debug problems.
Describe the solution you'd like
It would be beneficial to extend the xtensa_elf_relocate() implementation to check if the supplied literal address is within the -262141 to -4 range. If it is not, the function should report an error and fail without producing bad code.
Alternatives
No response
Additional Context
No response