Hello all, This is what I see when I search “KERNEL_RWX” during “make menuconfig” for arm64 kernel(5-10.0-rc5). The Kconfig file says CONFIG_STRICT_KERNEL_RWX is for setting text and rodata read-only. Symbol: ARCH_OPTIONAL_KERNEL_RWX [=n] Type : bool Defined at arch/Kconfig:928 Symbol: ARCH_OPTIONAL_KERNEL_RWX_DEFAULT [=n] Type : bool Defined at arch/Kconfig:931 Symbol: STRICT_KERNEL_RWX [=y] Type : bool Defined at arch/Kconfig:937 Prompt: Make kernel text and rodata read-only Depends on: ARCH_HAS_STRICT_KERNEL_RWX [=y] Visible if: ARCH_HAS_STRICT_KERNEL_RWX [=y] && ARCH_OPTIONAL_KERNEL_RWX [=n] Location: (1) -> General architecture-dependent options I wanted to try setting STRICT_KERNEL_RWX to =n. It says this option is visible when ARCH_OPTIONAL_KERNEL_RWX is =y which is now =n. So I modified to ARCH_OPTIONAL_KERNEL_RWX=y in arch/Kconfig line 928. (BTW, is it correct to modify this Kconfig file directly? I’m not sure at the moment) Then I could see the STRICT_KERNEL_RWX menu in the menuconfig and I set it to =n as I wanted. But when I build the kernel, I see this errors. ckim@ckim-ubuntu:~/ProjX/LinuxDevDrv/kernel-release-RD-INFRA-2020.11.30$ makeit CALL scripts/atomic/check-atomics.sh CALL scripts/checksyscalls.sh CHK include/generated/compile.h CC arch/arm64/mm/mmu.o arch/arm64/mm/mmu.c: In function 'parse_rodata': arch/arm64/mm/mmu.c:595:28: error: 'rodata_enabled' undeclared (first use in this function) 595 | int ret = strtobool(arg, &rodata_enabled); | ^~~~~~~~~~~~~~ arch/arm64/mm/mmu.c:595:28: note: each undeclared identifier is reported only once for each function it appears in arch/arm64/mm/mmu.c: In function 'map_entry_trampoline': arch/arm64/mm/mmu.c:614:18: error: 'rodata_enabled' undeclared (first use in this function) 614 | pgprot_t prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC; | ^~~~~~~~~~~~~~ arch/arm64/mm/mmu.c: In function 'map_kernel': arch/arm64/mm/mmu.c:669:23: error: 'rodata_enabled' undeclared (first use in this function) 669 | pgprot_t text_prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC; | ^~~~~~~~~~~~~~ make[2]: *** [scripts/Makefile.build:283: arch/arm64/mm/mmu.o] Error 1 make[1]: *** [scripts/Makefile.build:500: arch/arm64/mm] Error 2 make: *** [Makefile:1799: arch/arm64] Error 2 variable “rodata_enabled” is defined in init/main.c as below. #if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX) bool rodata_enabled __ro_after_init = true; static int __init set_debug_rodata(char *str) { return strtobool(str, &rodata_enabled); } __setup("rodata=", set_debug_rodata); #endif But now since CONFIG_STRICT_KERNEL_RWX=n, it is not defined here(CONFIG_STRICT_MODULE_RWX=n too). and arch/arm64/mm/mmu.c code is still using `rodata_enabled`. Is this a bug of the code? Or am I missing something? I can modify init/main.c and include/linux/init.h so that this rodata_enabled and related functions be defined regardless of these CONFIG values and make the errors go away, but I’m curious if this a kind of kernel bug raising compiler error. Any comment will be really appreciated. Thank you! Chan Kim |
_______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
