* Re: arch/mips/boot/compressed/decompress.c:undefined reference to `__ashldi3' [not found] <202609301826.MFaFMsmd-lkp@intel.com> @ 2026-09-30 19:01 ` Andrew Morton 2026-09-30 19:11 ` Bradley Morgan 2026-10-01 10:30 ` Pedro Falcato 0 siblings, 2 replies; 5+ messages in thread From: Andrew Morton @ 2026-09-30 19:01 UTC (permalink / raw) To: kernel test robot Cc: Josh Law, oe-kbuild-all, linux-kernel, Linux Memory Management List, linux-mips, Bradley Morgan On Wed, 30 Sep 2026 18:36:50 +0200 kernel test robot <lkp@intel.com> wrote: > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > head: 551c722f40809618230001baccf219193e22fc5a > commit: d4dba3b9c03a326cfa73833d6b166aeb442f82b5 lib: decompress_bunzip2: fix 32-bit shift undefined behavior > date: 6 months ago > config: mips-randconfig-r2300-20260930 (https://download.01.org/0day-ci/archive/20260930/202609301826.MFaFMsmd-lkp@intel.com/config) > compiler: mips-linux-gcc (GCC) 15.2.0 > sparse: v0.6.5-rc1 > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260930/202609301826.MFaFMsmd-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 > | Fixes: d4dba3b9c03a ("lib: decompress_bunzip2: fix 32-bit shift undefined behavior") > | Reported-by: kernel test robot <lkp@intel.com> > | Closes: https://lore.kernel.org/oe-kbuild-all/202609301826.MFaFMsmd-lkp@intel.com/ > > All errors (new ones prefixed by >>): > > mips-linux-ld: arch/mips/boot/compressed/decompress.o: in function `get_bits': > >> arch/mips/boot/compressed/decompress.c:(.text+0xf4): undefined reference to `__ashldi3' > >> mips-linux-ld: arch/mips/boot/compressed/decompress.c:(.text+0x168): undefined reference to `__ashldi3' I dunno, I'd be suspecting a toolchain issue here? --- a/lib/decompress_bunzip2.c +++ b/lib/decompress_bunzip2.c @@ -135,7 +135,7 @@ static unsigned int INIT get_bits(struct bunzip_data *bd, char bits_wanted) } /* Avoid 32-bit overflow (dump bit buffer to top of output) */ if (bd->inbufBitCount >= 24) { - bits = bd->inbufBits&((1 << bd->inbufBitCount)-1); + bits = bd->inbufBits & ((1ULL << bd->inbufBitCount) - 1); bits_wanted -= bd->inbufBitCount; bits <<= bits_wanted; bd->inbufBitCount = 0; @@ -146,7 +146,7 @@ static unsigned int INIT get_bits(struct bunzip_data *bd, char bits_wanted) } /* Calculate result */ bd->inbufBitCount -= bits_wanted; - bits |= (bd->inbufBits >> bd->inbufBitCount)&((1 << bits_wanted)-1); + bits |= (bd->inbufBits >> bd->inbufBitCount) & ((1ULL << bits_wanted) - 1); return bits; } 32-bit MIPS should be able to do this? ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: arch/mips/boot/compressed/decompress.c:undefined reference to `__ashldi3' 2026-09-30 19:01 ` arch/mips/boot/compressed/decompress.c:undefined reference to `__ashldi3' Andrew Morton @ 2026-09-30 19:11 ` Bradley Morgan 2026-10-01 10:30 ` Pedro Falcato 1 sibling, 0 replies; 5+ messages in thread From: Bradley Morgan @ 2026-09-30 19:11 UTC (permalink / raw) To: Andrew Morton, kernel test robot Cc: Josh Law, oe-kbuild-all, linux-kernel, Linux Memory Management List, linux-mips On 30 September 2026 20:01:59 BST, Andrew Morton <akpm@linux-foundation.org> wrote: >On Wed, 30 Sep 2026 18:36:50 +0200 kernel test robot <lkp@intel.com> >wrote: > >> tree: >https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master >> head: 551c722f40809618230001baccf219193e22fc5a >> commit: d4dba3b9c03a326cfa73833d6b166aeb442f82b5 lib: >decompress_bunzip2: fix 32-bit shift undefined behavior >> date: 6 months ago >> config: mips-randconfig-r2300-20260930 >(https://download.01.org/0day-ci/archive/20260930/202609301826.MFaFMsmd-lkp@intel.com/config) >> compiler: mips-linux-gcc (GCC) 15.2.0 >> sparse: v0.6.5-rc1 >> reproduce (this is a W=1 build): >(https://download.01.org/0day-ci/archive/20260930/202609301826.MFaFMsmd-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 >> | Fixes: d4dba3b9c03a ("lib: decompress_bunzip2: fix 32-bit shift >undefined behavior") >> | Reported-by: kernel test robot <lkp@intel.com> >> | Closes: >https://lore.kernel.org/oe-kbuild-all/202609301826.MFaFMsmd-lkp@intel.com/ >> >> All errors (new ones prefixed by >>): >> >> mips-linux-ld: arch/mips/boot/compressed/decompress.o: in function >`get_bits': >> >> arch/mips/boot/compressed/decompress.c:(.text+0xf4): undefined >reference to `__ashldi3' >> >> mips-linux-ld: arch/mips/boot/compressed/decompress.c:(.text+0x168): >undefined reference to `__ashldi3' > >I dunno, I'd be suspecting a toolchain issue here? > >--- a/lib/decompress_bunzip2.c >+++ b/lib/decompress_bunzip2.c >@@ -135,7 +135,7 @@ static unsigned int INIT get_bits(struct bunzip_data *bd, char bits_wanted) > } > /* Avoid 32-bit overflow (dump bit buffer to top of output) */ > if (bd->inbufBitCount >= 24) { >- bits = bd->inbufBits&((1 << bd->inbufBitCount)-1); >+ bits = bd->inbufBits & ((1ULL << bd->inbufBitCount) - 1); > bits_wanted -= bd->inbufBitCount; > bits <<= bits_wanted; > bd->inbufBitCount = 0; >@@ -146,7 +146,7 @@ static unsigned int INIT get_bits(struct bunzip_data *bd, char bits_wanted) > } > /* Calculate result */ > bd->inbufBitCount -= bits_wanted; >- bits |= (bd->inbufBits >> bd->inbufBitCount)&((1 << bits_wanted)-1); >+ bits |= (bd->inbufBits >> bd->inbufBitCount) & ((1ULL << bits_wanted) - 1); > > return bits; > } > >32-bit MIPS should be able to do this? May I ask why I got CCed in this..?? --- Thanks! "I'm not a very positive person" - Linus torvalds ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: arch/mips/boot/compressed/decompress.c:undefined reference to `__ashldi3' 2026-09-30 19:01 ` arch/mips/boot/compressed/decompress.c:undefined reference to `__ashldi3' Andrew Morton 2026-09-30 19:11 ` Bradley Morgan @ 2026-10-01 10:30 ` Pedro Falcato 2026-10-02 1:07 ` Andrew Morton 2026-10-02 9:53 ` David Laight 1 sibling, 2 replies; 5+ messages in thread From: Pedro Falcato @ 2026-10-01 10:30 UTC (permalink / raw) To: Andrew Morton Cc: kernel test robot, Josh Law, oe-kbuild-all, linux-kernel, Linux Memory Management List, linux-mips, Bradley Morgan On Wed, Sep 30, 2026 at 12:01:59PM -0700, Andrew Morton wrote: > On Wed, 30 Sep 2026 18:36:50 +0200 kernel test robot <lkp@intel.com> wrote: > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > > head: 551c722f40809618230001baccf219193e22fc5a > > commit: d4dba3b9c03a326cfa73833d6b166aeb442f82b5 lib: decompress_bunzip2: fix 32-bit shift undefined behavior > > date: 6 months ago > > config: mips-randconfig-r2300-20260930 (https://download.01.org/0day-ci/archive/20260930/202609301826.MFaFMsmd-lkp@intel.com/config) > > compiler: mips-linux-gcc (GCC) 15.2.0 > > sparse: v0.6.5-rc1 > > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260930/202609301826.MFaFMsmd-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 > > | Fixes: d4dba3b9c03a ("lib: decompress_bunzip2: fix 32-bit shift undefined behavior") > > | Reported-by: kernel test robot <lkp@intel.com> > > | Closes: https://lore.kernel.org/oe-kbuild-all/202609301826.MFaFMsmd-lkp@intel.com/ > > > > All errors (new ones prefixed by >>): > > > > mips-linux-ld: arch/mips/boot/compressed/decompress.o: in function `get_bits': > > >> arch/mips/boot/compressed/decompress.c:(.text+0xf4): undefined reference to `__ashldi3' > > >> mips-linux-ld: arch/mips/boot/compressed/decompress.c:(.text+0x168): undefined reference to `__ashldi3' > > I dunno, I'd be suspecting a toolchain issue here? > > --- a/lib/decompress_bunzip2.c > +++ b/lib/decompress_bunzip2.c > @@ -135,7 +135,7 @@ static unsigned int INIT get_bits(struct bunzip_data *bd, char bits_wanted) > } > /* Avoid 32-bit overflow (dump bit buffer to top of output) */ > if (bd->inbufBitCount >= 24) { > - bits = bd->inbufBits&((1 << bd->inbufBitCount)-1); > + bits = bd->inbufBits & ((1ULL << bd->inbufBitCount) - 1); > bits_wanted -= bd->inbufBitCount; > bits <<= bits_wanted; > bd->inbufBitCount = 0; > @@ -146,7 +146,7 @@ static unsigned int INIT get_bits(struct bunzip_data *bd, char bits_wanted) > } > /* Calculate result */ > bd->inbufBitCount -= bits_wanted; > - bits |= (bd->inbufBits >> bd->inbufBitCount)&((1 << bits_wanted)-1); > + bits |= (bd->inbufBits >> bd->inbufBitCount) & ((1ULL << bits_wanted) - 1); > > return bits; > } > > 32-bit MIPS should be able to do this? FWIW the patch seems entirely bogus. I don't think you can have inbufBitCount >= 32. If you could, then the patch would still not fix anything, because bd->inbufBits is an (32-bit) unsigned int. As per MIPS itself, MIPS does not link ashldi3.o into the decompressor for BZ2. It only does so for XZ and ZSTD. Changing arch/mips/boot/compressed/Makefile would work, but since the change is entirely wrong I would suggest perhaps reverting? -- Pedro ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: arch/mips/boot/compressed/decompress.c:undefined reference to `__ashldi3' 2026-10-01 10:30 ` Pedro Falcato @ 2026-10-02 1:07 ` Andrew Morton 2026-10-02 9:53 ` David Laight 1 sibling, 0 replies; 5+ messages in thread From: Andrew Morton @ 2026-10-02 1:07 UTC (permalink / raw) To: Pedro Falcato Cc: kernel test robot, Josh Law, oe-kbuild-all, linux-kernel, Linux Memory Management List, linux-mips, Bradley Morgan On Thu, 1 Oct 2026 11:30:09 +0100 Pedro Falcato <pfalcato@suse.de> wrote: > > - bits |= (bd->inbufBits >> bd->inbufBitCount)&((1 << bits_wanted)-1); > > + bits |= (bd->inbufBits >> bd->inbufBitCount) & ((1ULL << bits_wanted) - 1); > > > > return bits; > > } > > > > 32-bit MIPS should be able to do this? > > FWIW the patch seems entirely bogus. I don't think you can have inbufBitCount >= > 32. If you could, then the patch would still not fix anything, because > bd->inbufBits is an (32-bit) unsigned int. > > As per MIPS itself, MIPS does not link ashldi3.o into the decompressor for BZ2. > It only does so for XZ and ZSTD. > > Changing arch/mips/boot/compressed/Makefile would work, but since the change is > entirely wrong I would suggest perhaps reverting? Sure, thanks. Do you have time to send a formal patch? ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: arch/mips/boot/compressed/decompress.c:undefined reference to `__ashldi3' 2026-10-01 10:30 ` Pedro Falcato 2026-10-02 1:07 ` Andrew Morton @ 2026-10-02 9:53 ` David Laight 1 sibling, 0 replies; 5+ messages in thread From: David Laight @ 2026-10-02 9:53 UTC (permalink / raw) To: Pedro Falcato Cc: Andrew Morton, kernel test robot, Josh Law, oe-kbuild-all, linux-kernel, Linux Memory Management List, linux-mips, Bradley Morgan On Thu, 1 Oct 2026 11:30:09 +0100 Pedro Falcato <pfalcato@suse.de> wrote: > On Wed, Sep 30, 2026 at 12:01:59PM -0700, Andrew Morton wrote: > > On Wed, 30 Sep 2026 18:36:50 +0200 kernel test robot <lkp@intel.com> wrote: > > > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > > > head: 551c722f40809618230001baccf219193e22fc5a > > > commit: d4dba3b9c03a326cfa73833d6b166aeb442f82b5 lib: decompress_bunzip2: fix 32-bit shift undefined behavior > > > date: 6 months ago > > > config: mips-randconfig-r2300-20260930 (https://download.01.org/0day-ci/archive/20260930/202609301826.MFaFMsmd-lkp@intel.com/config) > > > compiler: mips-linux-gcc (GCC) 15.2.0 > > > sparse: v0.6.5-rc1 > > > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260930/202609301826.MFaFMsmd-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 > > > | Fixes: d4dba3b9c03a ("lib: decompress_bunzip2: fix 32-bit shift undefined behavior") > > > | Reported-by: kernel test robot <lkp@intel.com> > > > | Closes: https://lore.kernel.org/oe-kbuild-all/202609301826.MFaFMsmd-lkp@intel.com/ > > > > > > All errors (new ones prefixed by >>): > > > > > > mips-linux-ld: arch/mips/boot/compressed/decompress.o: in function `get_bits': > > > >> arch/mips/boot/compressed/decompress.c:(.text+0xf4): undefined reference to `__ashldi3' > > > >> mips-linux-ld: arch/mips/boot/compressed/decompress.c:(.text+0x168): undefined reference to `__ashldi3' > > > > I dunno, I'd be suspecting a toolchain issue here? > > > > --- a/lib/decompress_bunzip2.c > > +++ b/lib/decompress_bunzip2.c > > @@ -135,7 +135,7 @@ static unsigned int INIT get_bits(struct bunzip_data *bd, char bits_wanted) > > } > > /* Avoid 32-bit overflow (dump bit buffer to top of output) */ > > if (bd->inbufBitCount >= 24) { > > - bits = bd->inbufBits&((1 << bd->inbufBitCount)-1); > > + bits = bd->inbufBits & ((1ULL << bd->inbufBitCount) - 1); > > bits_wanted -= bd->inbufBitCount; > > bits <<= bits_wanted; > > bd->inbufBitCount = 0; > > @@ -146,7 +146,7 @@ static unsigned int INIT get_bits(struct bunzip_data *bd, char bits_wanted) > > } > > /* Calculate result */ > > bd->inbufBitCount -= bits_wanted; > > - bits |= (bd->inbufBits >> bd->inbufBitCount)&((1 << bits_wanted)-1); > > + bits |= (bd->inbufBits >> bd->inbufBitCount) & ((1ULL << bits_wanted) - 1); > > > > return bits; > > } > > > > 32-bit MIPS should be able to do this? > > FWIW the patch seems entirely bogus. I don't think you can have inbufBitCount >= > 32. If you could, then the patch would still not fix anything, because > bd->inbufBits is an (32-bit) unsigned int. The 1 should probably be 1U (or possibly 1UL is 64bit values can happen on 64bit) rather than 1ULL. Wasn't the problem being solved '1 << 31' being undefined (or UB) and one of the static checkers deciding that should never shift a signed value left? That is entirely bogus anyway. It is only non-portable because C allows 1's compliment and sign overpunch for negative integers, gcc supports neither (and I think the next C standard mandates 2's compliment). That is separate from shift right of negative values being UB to allow for cpu that don't have a sign replicating shift (all modern ones do). Think about it, for a shift/rotate left you need one of 0/carry/high-bit and for shift right 0/carry/low-bit so two instruction bits can select one of 0/carry/low-bit/high-bit (giving the often implemented but undocumented shift left that replicates the low bit). David > > As per MIPS itself, MIPS does not link ashldi3.o into the decompressor for BZ2. > It only does so for XZ and ZSTD. > > Changing arch/mips/boot/compressed/Makefile would work, but since the change is > entirely wrong I would suggest perhaps reverting? > > ^ permalink raw reply [flat|nested] 5+ messages in thread
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2026-09-30 19:01 ` arch/mips/boot/compressed/decompress.c:undefined reference to `__ashldi3' Andrew Morton
2026-09-30 19:11 ` Bradley Morgan
2026-10-01 10:30 ` Pedro Falcato
2026-10-02 1:07 ` Andrew Morton
2026-10-02 9:53 ` David Laight
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