Messages in this thread | | | From | Matthias Schiffer <> | Subject | [PATCH modules v2 0/2] Fix handling of exit unwinding sections (on ARM) | Date | Fri, 7 Jun 2019 12:49:10 +0200 |
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For some time (050d18d1c651 "ARM: 8650/1: module: handle negative R_ARM_PREL31 addends correctly", v4.11+), building a kernel without CONFIG_MODULE_UNLOAD would lead to module loads failing on ARM systems with certain memory layouts, with messages like:
imx_sdma: section 16 reloc 0 sym '': relocation 42 out of range (0x7f015260 -> 0xc0f5a5e8)
(0x7f015260 is in the module load area, 0xc0f5a5e8 a regular vmalloc address; relocation 42 is R_ARM_PREL31)
This is caused by relocatiosn in the .ARM.extab.exit.text and .ARM.exidx.exit.text sections referencing the .exit.text section. As the module loader will omit loading .exit.text without CONFIG_MODULE_UNLOAD, there will be relocations from loaded to unloaded sections; the resulting huge offsets trigger the sanity checks added in 050d18d1c651.
IA64 might be affected by a similar issue - sections with names like .IA_64.unwind.exit.text and .IA_64.unwind_info.exit.text appear in the ld script - but I don't know much about that arch.
Also, I'm not sure if this is stable-worthy - just enabling CONFIG_MODULE_UNLOAD should be a viable workaround on affected kernels.
v2: Use __weak function as suggested by Jessica
Matthias Schiffer (2): module: allow arch overrides for .exit section names ARM: module: recognize unwind exit sections
arch/arm/kernel/module.c | 7 +++++++ include/linux/moduleloader.h | 5 +++++ kernel/module.c | 7 ++++++- 3 files changed, 18 insertions(+), 1 deletion(-)
-- 2.17.1
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