On Thu, Jul 09, 2020 at 07:18:01AM +0000,Peng Hao(Richard) wrote: > On Thu, 9 Jul 2020 at 09:50, Peng Hao(Richard) <[email protected]> wrote: > >> >Apparently, you are hitting a R_AARCH64_JUMP26 or R_AARCH64_CALL26 > >> >relocation that operates on a b or bl instruction that is more than > >> >128 megabytes away from its target. > >> > > >> My understanding is that a module that calls functions that are not part > >> of the module will use PLT. > >> Plt_max_entries =0 May occur if a module does not depend on other module > >> functions. > >> > > > >A PLT slot is allocated for each b or bl instruction that refers to a > >symbol that lives in a different section, either of the same module > > (e.g., bl in .init calling into .text), of another module, or of the > >core kernel. > > > >I don't see how you end up with plt_max_entries in this case, though. > if a module does not depend on other module functions, PLT entries in the > module is equal to 0.
>This brings me back to my earlier question: if there are no PLT entries in >the module, then count_plts() will not find any R_AARCH64_JUMP26 or >R_AARCH64_CALL26 relocations that require PLTs and will therefore return 0. >The absence of these relocations means that module_emit_plt_entry() will not >be called by apply_relocate_add(), and so your patch should have no effect. 1.The module in question is the calling function from core kernel.( Ib_core.ko triggered the warning multiple times). 2. There are multiple threads loading IB_core.ko [ 73.388931] ###cpu=33, name=ib_core, core_plts=0, init_plts=0 [ 73.402102] #### cpu=33,pid=2297,name=ib_core, module_emit_plt_entry:plt_num_entries=1, plt_max_entries=0 (warning) [ 73.439391] ###cpu=24, name=ib_core, core_plts=0, init_plts=0 [ 73.448617] ###cpu=4, name=ib_core, core_plts=0, init_plts=0 [ 73.547535] ###cpu=221, name=ib_core, core_plts=0, init_plts=0 [ 75.198075] #### cpu=24,pid=2336,name=ib_core, module_emit_plt_entry:plt_num_entries=1, plt_max_entries=0 (warning) [ 75.489496] #### cpu=4,pid=2344,name=ib_core, module_emit_plt_entry:plt_num_entries=1, plt_max_entries=0(warning) I don't understand why count_plts returns 0 when CONFIG_RANDOMIZE_BASE=n for R_AARCH64_JUMP26 and R_AARCH64_CALL26. 3. Set CONFIG_ARM64_MODULE_PLTS=y and restart the server several times without triggering this warning.
