by kernel test robot

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Subject: Re: [PATCH 6/7] kallsyms: add /proc/kallmodsyms

Hi Nick,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on kbuild/for-next]
[also build test WARNING on linus/master v5.13]
[cannot apply to kbuild/kconfig next-20210709]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url: https://github.com/0day-ci/linux/commits/Nick-Alcock/kbuild-bring-back-tristate-conf/20210710-072558
base: https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git for-next
config: s390-randconfig-r012-20210709 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 8d69635ed9ecf36fd0ca85906bfde17949671cbe)
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 s390 cross compiling tool for clang build
# apt-get install binutils-s390x-linux-gnu
# https://github.com/0day-ci/linux/commit/af04f89ab6ea4f6ffbd83ee71afe1e8a0df26ee1
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Nick-Alcock/kbuild-bring-back-tristate-conf/20210710-072558
git checkout af04f89ab6ea4f6ffbd83ee71afe1e8a0df26ee1
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=s390

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>

All warnings (new ones prefixed by >>):

In file included from kernel/kallsyms.c:25:
In file included from include/linux/filter.h:13:
In file included from include/linux/skbuff.h:31:
In file included from include/linux/dma-mapping.h:10:
In file included from include/linux/scatterlist.h:9:
In file included from arch/s390/include/asm/io.h:75:
include/asm-generic/io.h:464:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
val = __raw_readb(PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:477:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
~~~~~~~~~~ ^
include/uapi/linux/byteorder/big_endian.h:36:59: note: expanded from macro '__le16_to_cpu'
#define __le16_to_cpu(x) __swab16((__force __u16)(__le16)(x))
^
include/uapi/linux/swab.h:102:54: note: expanded from macro '__swab16'
#define __swab16(x) (__u16)__builtin_bswap16((__u16)(x))
^
In file included from kernel/kallsyms.c:25:
In file included from include/linux/filter.h:13:
In file included from include/linux/skbuff.h:31:
In file included from include/linux/dma-mapping.h:10:
In file included from include/linux/scatterlist.h:9:
In file included from arch/s390/include/asm/io.h:75:
include/asm-generic/io.h:490:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
~~~~~~~~~~ ^
include/uapi/linux/byteorder/big_endian.h:34:59: note: expanded from macro '__le32_to_cpu'
#define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
^
include/uapi/linux/swab.h:115:54: note: expanded from macro '__swab32'
#define __swab32(x) (__u32)__builtin_bswap32((__u32)(x))
^
In file included from kernel/kallsyms.c:25:
In file included from include/linux/filter.h:13:
In file included from include/linux/skbuff.h:31:
In file included from include/linux/dma-mapping.h:10:
In file included from include/linux/scatterlist.h:9:
In file included from arch/s390/include/asm/io.h:75:
include/asm-generic/io.h:501:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
__raw_writeb(value, PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:511:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
__raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:521:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
__raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:609:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
readsb(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:617:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
readsw(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:625:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
readsl(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:634:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
writesb(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:643:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
writesw(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
include/asm-generic/io.h:652:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
writesl(PCI_IOBASE + addr, buffer, count);
~~~~~~~~~~ ^
kernel/kallsyms.c:581:12: warning: no previous prototype for function 'arch_get_kallsym' [-Wmissing-prototypes]
int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,
^
kernel/kallsyms.c:581:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,
^
static
>> kernel/kallsyms.c:688:7: warning: variable 'mod_idx' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if (kallsyms_module_offsets)
^~~~~~~~~~~~~~~~~~~~~~~
kernel/kallsyms.c:708:35: note: uninitialized use occurs here
iter->hint_builtin_module_idx = mod_idx;
^~~~~~~
kernel/kallsyms.c:688:3: note: remove the 'if' if its condition is always true
if (kallsyms_module_offsets)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/kallsyms.c:675:23: note: initialize the variable 'mod_idx' to silence this warning
unsigned long mod_idx;
^
= 0
14 warnings generated.

vim +688 kernel/kallsyms.c

580
> 581 int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,
582 char *type, char *name)
583 {
584 return -EINVAL;
585 }
586
587 static int get_ksymbol_arch(struct kallsym_iter *iter)
588 {
589 int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms,
590 &iter->value, &iter->type,
591 iter->name);
592
593 if (ret < 0) {
594 iter->pos_arch_end = iter->pos;
595 return 0;
596 }
597
598 return 1;
599 }
600
601 static int get_ksymbol_mod(struct kallsym_iter *iter)
602 {
603 int ret = module_get_kallsym(iter->pos - iter->pos_arch_end,
604 &iter->value, &iter->type,
605 iter->name, iter->module_name,
606 &iter->exported);
607 iter->builtin_module_names = NULL;
608
609 if (ret < 0) {
610 iter->pos_mod_end = iter->pos;
611 return 0;
612 }
613
614 return 1;
615 }
616
617 /*
618 * ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace
619 * purposes. In that case "__builtin__ftrace" is used as a module name, even
620 * though "__builtin__ftrace" is not a module.
621 */
622 static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
623 {
624 int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
625 &iter->value, &iter->type,
626 iter->name, iter->module_name,
627 &iter->exported);
628 iter->builtin_module_names = NULL;
629
630 if (ret < 0) {
631 iter->pos_ftrace_mod_end = iter->pos;
632 return 0;
633 }
634
635 return 1;
636 }
637
638 static int get_ksymbol_bpf(struct kallsym_iter *iter)
639 {
640 int ret;
641
642 strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN);
643 iter->exported = 0;
644 iter->builtin_module_names = NULL;
645 ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
646 &iter->value, &iter->type,
647 iter->name);
648 if (ret < 0) {
649 iter->pos_bpf_end = iter->pos;
650 return 0;
651 }
652
653 return 1;
654 }
655
656 /*
657 * This uses "__builtin__kprobes" as a module name for symbols for pages
658 * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a
659 * module.
660 */
661 static int get_ksymbol_kprobe(struct kallsym_iter *iter)
662 {
663 strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
664 iter->exported = 0;
665 iter->builtin_module_names = NULL;
666 return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
667 &iter->value, &iter->type,
668 iter->name) < 0 ? 0 : 1;
669 }
670
671 /* Returns space to next name. */
672 static unsigned long get_ksymbol_core(struct kallsym_iter *iter, int kallmodsyms)
673 {
674 unsigned off = iter->nameoff;
675 unsigned long mod_idx;
676
677 iter->exported = 0;
678 iter->value = kallsyms_sym_address(iter->pos);
679
680 iter->type = kallsyms_get_symbol_type(off);
681
682 iter->module_name[0] = '\0';
683 iter->builtin_module_names = NULL;
684
685 off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
686 #ifdef CONFIG_KALLMODSYMS
687 if (kallmodsyms) {
> 688 if (kallsyms_module_offsets)
689 mod_idx =
690 get_builtin_module_idx(iter->value,
691 iter->hint_builtin_module_idx);
692
693 /*
694 * This is a built-in module iff the tables of built-in modules
695 * (address->module name mappings) and module names are known,
696 * and if the address was found there, and if the corresponding
697 * module index is nonzero. All other cases mean off the end of
698 * the binary or in a non-modular range in between one or more
699 * modules. (Also guard against a corrupt kallsyms_objfiles
700 * array pointing off the end of kallsyms_modules.)
701 */
702 if (kallsyms_modules != NULL && kallsyms_module_names != NULL &&
703 mod_idx != (unsigned long) -1 &&
704 kallsyms_modules[mod_idx] != 0 &&
705 kallsyms_modules[mod_idx] < kallsyms_module_names_len)
706 iter->builtin_module_names =
707 &kallsyms_module_names[kallsyms_modules[mod_idx]];
708 iter->hint_builtin_module_idx = mod_idx;
709 }
710 #endif
711 return off - iter->nameoff;
712 }
713

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]

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