Re: ppc64le STRICT_MODULE_RWX and livepatch apply_relocate_add() crashes
From: Joe Lawrence <joe.lawrence@redhat.com>
Date: 2021-12-13 14:48:35
Also in:
live-patching
On 12/13/21 2:42 AM, Christophe Leroy wrote:
Hello Joe, I'm implementing LIVEPATCH on PPC32 and I wanted to test with STRICT_MODULE_RWX enabled so I took your branch as suggested, but I'm getting the following errors on build. What shall I do ? CALL scripts/checksyscalls.sh CALL scripts/atomic/check-atomics.sh CHK include/generated/compile.h KLP lib/livepatch/test_klp_convert1.ko klp-convert: section .rela.klp.module_relocs.test_klp_convert_mod length beyond nr_entries klp-convert: Unable to load user-provided sympos make[2]: *** [scripts/Makefile.modfinal:79: lib/livepatch/test_klp_convert1.ko] Error 255 KLP lib/livepatch/test_klp_convert2.ko klp-convert: section .rela.klp.module_relocs.test_klp_convert_mod length beyond nr_entries klp-convert: Unable to load user-provided sympos make[2]: *** [scripts/Makefile.modfinal:79: lib/livepatch/test_klp_convert2.ko] Error 255 KLP lib/livepatch/test_klp_convert_sections.ko klp-convert: section .rela.klp.module_relocs.test_klp_convert_mod length beyond nr_entries klp-convert: Unable to load user-provided sympos make[2]: *** [scripts/Makefile.modfinal:79: lib/livepatch/test_klp_convert_sections.ko] Error 255 make[2]: Target '__modfinal' not remade because of errors. make[1]: *** [scripts/Makefile.modpost:145: __modpost] Error 2 make: *** [Makefile:1770: modules] Error 2
Hi Christophe, Interesting failure mode. That's klp-convert complaining that it found more relocations in a .klp.module_relocs.<objname> section than expected, i.e. nr_entries = sec->size / sizeof(struct klp_module_reloc). A few possibilities: the ELF sec->size was incorrectly set/read by build/libelf (I doubt that). Or maybe the layout/size of struct klp_module_reloc is not consistent between kernel and userspace (I'm more suspicious of this). Can you post a copy of the build's symbols.klp and lib/livepatch/test_klp_convert1.tmp.ko somewhere? I should be able to start debug with those files. Thanks, -- Joe