[kbuild-all] Re: arch/powerpc/kernel/optprobes.c:34:1: error: unused function 'is_kprobe_ppc_optinsn_slot'

On Wed, 12 May 2021 21:50:57 +0900 Masami Hiramatsu <mhiramat(a)kernel.org&gt; wrote: > On Wed, 12 May 2021 11:52:30 +0200 > Christophe Leroy <christophe.leroy(a)csgroup.eu&gt; wrote: >> >> Le 12/05/2021 à 11:36, Christophe Leroy a écrit : >>> >>> >>> Le 11/05/2021 à 20:46, Nathan Chancellor a écrit : >>>> On 5/11/2021 9:47 AM, Christophe Leroy wrote: >>>>> Hi All, >>>>> >>>>> Le 11/05/2021 à 18:30, kernel test robot a écrit : >>>>>> Hi Christophe, >>>>>> >>>>>> First bad commit (maybe != root cause): >>>>>> >>>>>> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master >>>>>> head:   1140ab592e2ebf8153d2b322604031a8868ce7a5 >>>>>> commit: eacf4c0202654adfa94bbb17b5c5c77c0be14af8 powerpc: Enable OPTPROBES on PPC32 >>> >>> Ok, the problem appears on PPC32 with that patch, but it must have been there on PPC64 since the >>> implementation of optprobes with commit 51c9c0843993 ("powerpc/kprobes: Implement Optprobes") >>> >>> >>>>>> date:   3 weeks ago >>>>>> config: powerpc-randconfig-r033-20210511 (attached as .config) >>>>>> compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project >>>>>> a0fed635fe1701470062495a6ffee1c608f3f1bc) >>>>> >>>>> A clang issue ? >>>>> >>>>> >>>>>> reproduce (this is a W=1 build): >>>>>>          wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O >>>>>> ~/bin/make.cross >>>>>>          chmod +x ~/bin/make.cross >>>>>>          # install powerpc cross compiling tool for clang build >>>>>>          # apt-get install binutils-powerpc-linux-gnu >>>>>>          # >>>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit... >>>>>> >>>>>>          git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git >>>>>>          git fetch --no-tags linus master >>>>>>          git checkout eacf4c0202654adfa94bbb17b5c5c77c0be14af8 >>>>>>          # save the attached .config to linux build tree >>>>>>          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=powerpc >>>>>> >>>>>> If you fix the issue, kindly add following tag as appropriate >>>>>> Reported-by: kernel test robot <lkp(a)intel.com&gt; >>>>>> >>>>>> All errors (new ones prefixed by >>): >>>>>> >>>>>>>> arch/powerpc/kernel/optprobes.c:34:1: error: unused function 'is_kprobe_ppc_optinsn_slot' >>>>>>>> [-Werror,-Wunused-function] >>>>>>     DEFINE_INSN_CACHE_OPS(ppc_optinsn); >>>>>>     ^ >>>>>>     include/linux/kprobes.h:306:20: note: expanded from macro 'DEFINE_INSN_CACHE_OPS' >>>>>>     static inline bool is_kprobe_##__name##_slot(unsigned long addr)        \ >>>>> >>>>> That's a 'static inline', shouldn't generate an 'unused function' warning. >>>> This is a W=1 build, which means that "inline" does not silence unused function warnings with >>>> clang because of commit 6863f5643dd7 ("kbuild: allow Clang to find unused static inline functions >>>> for W=1 build"). >>> >>> Ok, I didn't know that. >> >> After looking at it in more details, I don't really know what should be done to avoid that. > > Ah, thanks for reporting! > >> >> This unused function is defined as part of DEFINE_INSN_CACHE_OPS(ppc_optinsn). >> >> The code uses other items defined by macro DEFINE_INSN_CACHE_OPS, so it cannot be removed. >> >> Solution could be to hide that in a .h, but is that worth it ? > > The best solution is to remove ppc_optinsn, but that is defined in kernel/kprobes.c > just because page allocation is different. > I think the easiest fix is to add weak alloc_optinsn_page() and override it > in arch/powerpc/kernel/optprobe.c. Please try this patch. Thank you,

From 7782fa154349923ed52baa8843cc1d5eed26e82d Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu <mhiramat(a)kernel.org&gt; Date: Wed, 12 May 2021 23:33:10 +0900 Subject: [PATCH] powerpc/kprobes: Define arch specific optinsn memory allocation

@@ -203,14 +193,14 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p) unsigned long nip, size; int rc, i; - kprobe_ppc_optinsn_slots.insn_size = MAX_OPTINSN_SIZE; + kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;

nip = can_optimize(p); if (!nip) return -EILSEQ; /* Allocate instruction slot for detour buffer */ - buff = get_ppc_optinsn_slot(); + buff = get_optinsn_slot(); if (!buff) return -ENOMEM;