* Helge Deller <deller@xxxxxx>: > On 3/2/21 7:07 PM, Nick Desaulniers wrote: > > + Arnd > > > > On Tue, Mar 2, 2021 at 10:03 AM Helge Deller <deller@xxxxxx> wrote: > > > > > > On 3/2/21 6:29 PM, Nick Desaulniers wrote: > > > > + pa-risc folks > > > > > > Thanks for looking into this, Nick! > > > > > > > On Tue, Mar 2, 2021 at 2:59 AM kernel test robot <lkp@xxxxxxxxx> wrote: > > > > > > > > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > > > > > head: 7a7fd0de4a9804299793e564a555a49c1fc924cb > > > > > commit: eff8728fe69880d3f7983bec3fb6cea4c306261f vmlinux.lds.h: Add PGO and AutoFDO input sections > > > > > > > > This commit added sections explicitly to the kernel's linker script. > > > > > > Yes, but even when reverting this patch it does not prevent > > > the linking problems. > > > > > > > > > > > date: 6 months ago > > > > > config: parisc-randconfig-s031-20210228 (attached as .config) > > > > > > > > ^ randconfig (always find something curious) > > > > > > Yes :-) > > > > > > > > > > > compiler: hppa64-linux-gcc (GCC) 9.3.0 > > > > > reproduce: > > > > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > > > > > chmod +x ~/bin/make.cross > > > > > # apt-get install sparse > > > > > # sparse version: v0.6.3-241-geaceeafa-dirty > > > > > # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=eff8728fe69880d3f7983bec3fb6cea4c306261f > > > > > git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git > > > > > git fetch --no-tags linus master > > > > > git checkout eff8728fe69880d3f7983bec3fb6cea4c306261f > > > > > # save the attached .config to linux build tree > > > > > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=parisc > > > > > > > > > > If you fix the issue, kindly add following tag as appropriate > > > > > Reported-by: kernel test robot <lkp@xxxxxxxxx> > > > > > > > > > > All errors (new ones prefixed by >>): > > > > > > > > > > hppa64-linux-ld: init/main.o(.init.text+0x294): cannot reach printk > > > > > init/main.o: in function `do_early_param': > > > > > (.init.text+0x294): relocation truncated to fit: R_PARISC_PCREL22F against symbol `printk' defined in .text.unlikely section in kernel/printk/printk.o > > > > > > > > ^ so we can't encode a jump to printk from do_early_param. > > > > > > Right. > > > > > > > If the linker is warning that printk is in the .text.unlikely > > > > section, I'm curious why printk is marked cold? > > > > > > printk is always marked cold, see include/linux/printk.h: > > > asmlinkage __printf(1, 2) __cold > > > int printk(const char *fmt, ...); > > > > > > > Likely the randconfig produces a large TEXT_MAIN; > > > > > > Yes. > > > > > > > I'm guessing that .init.text is on one side of TEXT_MAIN, and > > > > .text.unlikely is on the other. Though there are many different > > > > instances below. > > > Yes. But even the large TEXT_MAIN by itself can become a problem. > > > > > > > I'm more familiar with ARM; it's common for the linker to insert > > > > trampolines/thunks to bridge jumps too large to encode in a given > > > > instruction. I don't know if BFD has arch agnostic machinery for > > > > that, but might be seeing if there's anything reuseable there. > > > > > > Dave mentioned in another mail, that long branch stub support is > > > still missing in the 64-bit parisc linker. > > > > > > My question still remains: > > > Is there any possibility to detect that we build/configure a > > > 0-day kernel? If so, auto-enabling CONFIG_MLONGCALLS kernel option > > > would solve it (temporarily). > > > > Arnd, is this kind of case what CONFIG_COMPILE_TEST is usually used for? > > Yes, I think that's the right knob! > CONFIG_COMPILE_TEST is enabled on all parisc configs for which 0-day > reported issues. > I've wired it up in Kconfig and it now works around the issue. I've committed the patch below to the parisc for-next tree, which allows to monitor if this fixes the linkage problems... Helge From: Helge Deller <deller@xxxxxx> Date: Tue, 2 Mar 2021 21:07:07 +0100 Subject: [PATCH] parisc: Enable -mlong-calls gcc option with CONFIG_COMPILE_TEST The kernel test robot reported multiple linkage problems like this: hppa64-linux-ld: init/main.o(.init.text+0x56c): cannot reach printk init/main.o: in function `unknown_bootoption': (.init.text+0x56c): relocation truncated to fit: R_PARISC_PCREL22F against symbol `printk' defined in .text.unlikely section in kernel/printk/printk.o There are two ways to solve it: a) Enable the -mlong-call compiler option (CONFIG_MLONGCALLS), b) Add long branch stub support in 64-bit linker. While b) is the long-term solution, this patch works around the issue by automatically enabling the CONFIG_MLONGCALLS option when CONFIG_COMPILE_TEST is set, which indicates that a non-production kernel (e.g. 0-day kernel) is built. Signed-off-by: Helge Deller <deller@xxxxxx> Reported-by: kernel test robot <lkp@xxxxxxxxx> Fixes: 00e35f2b0e8a ("parisc: Enable -mlong-calls gcc option by default when !CONFIG_MODULES") Cc: stable@xxxxxxxxxxxxxxx # v5.6+ diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig index 4e53ac46e857..afc3b8d03572 100644 --- a/arch/parisc/Kconfig +++ b/arch/parisc/Kconfig @@ -203,9 +203,12 @@ config PREFETCH def_bool y depends on PA8X00 || PA7200 +config PARISC_HUGE_KERNEL + def_bool y if !MODULES || UBSAN || FTRACE || COMPILE_TEST + config MLONGCALLS - def_bool y if !MODULES || UBSAN || FTRACE - bool "Enable the -mlong-calls compiler option for big kernels" if MODULES && !UBSAN && !FTRACE + def_bool y if PARISC_HUGE_KERNEL + bool "Enable the -mlong-calls compiler option for big kernels" if !PARISC_HUGE_KERNEL depends on PA8X00 help If you configure the kernel to include many drivers built-in instead
