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Message-ID: <87bk0nqbhb.fsf@mail.lhotse>
Date: Tue, 17 Sep 2024 12:07:28 +1000
From: Michael Ellerman <mpe@...erman.id.au>
To: kernel test robot <lkp@...el.com>, Naveen N Rao <naveen@...nel.org>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org, Christophe
Leroy <christophe.leroy@...roup.eu>
Subject: Re: arch/powerpc/kernel/trace/ftrace.c:752:46: sparse: sparse: cast
truncates bits from constant value (200000000 becomes 0)
kernel test robot <lkp@...el.com> writes:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: a430d95c5efa2b545d26a094eb5f624e36732af0
> commit: f3993a0330e2d11e42c095810c6c33084024df46 powerpc/ftrace: Extend ftrace support for large kernels to ppc32
> date: 1 year, 1 month ago
> config: powerpc-randconfig-r132-20240916 (https://download.01.org/0day-ci/archive/20240917/202409170855.Lb8k7eyz-lkp@intel.com/config)
CONFIG_PPC32=y
# CONFIG_PPC64 is not set
32-bit build.
> compiler: powerpc-linux-gcc (GCC) 14.1.0
> reproduce: (https://download.01.org/0day-ci/archive/20240917/202409170855.Lb8k7eyz-lkp@intel.com/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@...el.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202409170855.Lb8k7eyz-lkp@intel.com/
>
> sparse warnings: (new ones prefixed by >>)
> arch/powerpc/kernel/trace/ftrace.c: note: in included file (through include/linux/mmzone.h, include/linux/topology.h, include/linux/irq.h, ...):
> include/linux/page-flags.h:240:46: sparse: sparse: self-comparison always evaluates to false
>>> arch/powerpc/kernel/trace/ftrace.c:752:46: sparse: sparse: cast truncates bits from constant value (200000000 becomes 0)
> arch/powerpc/kernel/trace/ftrace.c:752:72: sparse: sparse: cast truncates bits from constant value (200000000 becomes 0)
>
> vim +752 arch/powerpc/kernel/trace/ftrace.c
>
> 84ade0a6655bee arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2022-05-16 720
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 721 int __init ftrace_dyn_arch_init(void)
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 722 {
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 723 unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init };
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 724 unsigned long addr = FTRACE_REGS_ADDR;
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 725 long reladdr;
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 726 int i;
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 727 u32 stub_insns[] = {
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 728 #ifdef CONFIG_PPC_KERNEL_PCREL
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 729 /* pla r12,addr */
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 730 PPC_PREFIX_MLS | __PPC_PRFX_R(1),
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 731 PPC_INST_PADDI | ___PPC_RT(_R12),
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 732 PPC_RAW_MTCTR(_R12),
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 733 PPC_RAW_BCTR()
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 734 #elif defined(CONFIG_PPC64)
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 735 PPC_RAW_LD(_R12, _R13, offsetof(struct paca_struct, kernel_toc)),
> e89aa642be21b1 arch/powerpc/kernel/trace/ftrace.c Christophe Leroy 2022-05-09 736 PPC_RAW_ADDIS(_R12, _R12, 0),
> e89aa642be21b1 arch/powerpc/kernel/trace/ftrace.c Christophe Leroy 2022-05-09 737 PPC_RAW_ADDI(_R12, _R12, 0),
> e89aa642be21b1 arch/powerpc/kernel/trace/ftrace.c Christophe Leroy 2022-05-09 738 PPC_RAW_MTCTR(_R12),
> e89aa642be21b1 arch/powerpc/kernel/trace/ftrace.c Christophe Leroy 2022-05-09 739 PPC_RAW_BCTR()
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 740 #else
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 741 PPC_RAW_LIS(_R12, 0),
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 742 PPC_RAW_ADDI(_R12, _R12, 0),
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 743 PPC_RAW_MTCTR(_R12),
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 744 PPC_RAW_BCTR()
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 745 #endif
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 746 };
> af8b9f352ffd43 arch/powerpc/kernel/trace/ftrace.c Christophe Leroy 2022-05-09 747
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 748 if (IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) {
In practice this is 64-bit only code, but I guess sparse doesn't know that.
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 749 for (i = 0; i < 2; i++) {
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 750 reladdr = addr - (unsigned long)tramp[i];
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 751
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 @752 if (reladdr >= (long)SZ_8G || reladdr < -(long)SZ_8G) {
We could use s64 for these casts?
cheers
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 753 pr_err("Address of %ps out of range of pcrel address.\n",
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 754 (void *)addr);
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 755 return -1;
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 756 }
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 757
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 758 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 759 tramp[i][0] |= IMM_H18(reladdr);
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 760 tramp[i][1] |= IMM_L(reladdr);
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 761 add_ftrace_tramp((unsigned long)tramp[i]);
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 762 }
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 763 } else if (IS_ENABLED(CONFIG_PPC64)) {
> af8b9f352ffd43 arch/powerpc/kernel/trace/ftrace.c Christophe Leroy 2022-05-09 764 reladdr = addr - kernel_toc_addr();
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 765
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 766 if (reladdr >= (long)SZ_2G || reladdr < -(long long)SZ_2G) {
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 767 pr_err("Address of %ps out of range of kernel_toc.\n",
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 768 (void *)addr);
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 769 return -1;
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 770 }
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 771
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 772 for (i = 0; i < 2; i++) {
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 773 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 774 tramp[i][1] |= PPC_HA(reladdr);
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 775 tramp[i][2] |= PPC_LO(reladdr);
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 776 add_ftrace_tramp((unsigned long)tramp[i]);
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 777 }
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 778 } else {
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 779 for (i = 0; i < 2; i++) {
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 780 memcpy(tramp[i], stub_insns, sizeof(stub_insns));
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 781 tramp[i][0] |= PPC_HA(addr);
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 782 tramp[i][1] |= PPC_LO(addr);
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 783 add_ftrace_tramp((unsigned long)tramp[i]);
> f3993a0330e2d1 arch/powerpc/kernel/trace/ftrace.c Naveen N Rao 2023-06-19 784 }
> 7e3a68be42e10f arch/powerpc/kernel/trace/ftrace.c Nicholas Piggin 2023-04-08 785 }
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 786
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 787 return 0;
> 67361cf8071286 arch/powerpc/kernel/trace/ftrace.c Naveen N. Rao 2018-10-17 788 }
> 6794c78243bfda arch/powerpc/kernel/ftrace.c Steven Rostedt 2009-02-09 789
>
> :::::: The code at line 752 was first introduced by commit
> :::::: 7e3a68be42e10f5fa5890e97afc0afd992355bc3 powerpc/64: vmlinux support building with PCREL addresing
>
> :::::: TO: Nicholas Piggin <npiggin@...il.com>
> :::::: CC: Michael Ellerman <mpe@...erman.id.au>
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
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