[PATCH v2] ARM: module: fix unwind section relocation out of range error

[Ard Biesheuvel]

Hi,



On Mon, 23 Feb 2026, at 03:30, William Zhang wrote:
> Hi,
>
> On Mon, Sep 22, 2025 at 1:24 PM William Zhang
> <william.zhang at broadcom.com> wrote:
>>
>> In an armv7 system that uses non-3G/1G split and with more than 512MB
>> physical memory, driver load may fail with following error:
>>    section 29 reloc 0 sym '': relocation 42 out of range (0xc2ab9be8 ->
>> 0x7fad5998)
>>
>> This happens when relocation R_ARM_PREL31 from the unwind section
>> .ARM.extab and .ARM.exidx are allocated from the VMALLOC space while
>> .text section is from MODULES_VADDR space. It exceeds the +/-1GB
>> relocation requirement of R_ARM_PREL31 hence triggers the error.
>>
>> The fix is to mark .ARM.extab and .ARM.exidx sections as executable so
>> they can be allocated along with .text section and always meet range
>> requirement.
>>
>> Fixes: ac3b43283923 ("module: replace module_layout with module_memory")
>>
>> Co-developed-by: Ard Biesheuvel <ardb at kernel.org>
>> Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
>> Signed-off-by: William Zhang <william.zhang at broadcom.com>
>>
>> ---
>>
>> Changes in v2:
>> - Fix the comment in code and commit message regarding the unwind
>> section location
>> - Add fix tag for more visibility
>>
>>  arch/arm/kernel/module-plts.c | 12 ++++++++++++
>>  1 file changed, 12 insertions(+)
>>
>> diff --git a/arch/arm/kernel/module-plts.c b/arch/arm/kernel/module-plts.c
>> index 354ce16d83cb..b5338fe59706 100644
>> --- a/arch/arm/kernel/module-plts.c
>> +++ b/arch/arm/kernel/module-plts.c
>> @@ -225,6 +225,18 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
>>                         mod->arch.init.plt = s;
>>                 else if (s->sh_type == SHT_SYMTAB)
>>                         syms = (Elf32_Sym *)s->sh_addr;
>> +#if defined(CONFIG_ARM_UNWIND) && !defined(CONFIG_VMSPLIT_3G)
>> +               else if (s->sh_type == ELF_SECTION_UNWIND ||
>> +                        (strncmp(".ARM.extab", secstrings + s->sh_name, 10) == 0)) {
>> +                       /*
>> +                        * To avoid the possible relocation out of range issue for
>> +                        * R_ARM_PREL31, mark unwind section .ARM.extab and .ARM.exidx as
>> +                        * executable so they will be allocated along with .text section to
>> +                        * meet +/-1GB range requirement of the R_ARM_PREL31 relocation
>> +                        */
>> +                       s->sh_flags |= SHF_EXECINSTR;
>> +               }
>> +#endif
>>         }
>>
>>         if (!mod->arch.core.plt || !mod->arch.init.plt) {
>> --
>> 2.43.7
>>
>
> Is this version okay to be accepted?
>

Please put it in Russell's patch tracker.

https://www.arm.linux.org.uk/developer/patches/