On Tue, 13 Sep 2016 13:25:22 -0700 Guenter Roeck <li...@roeck-us.net> wrote:
> On 09/12/2016 08:51 PM, Nicholas Piggin wrote: > > On Mon, 12 Sep 2016 20:17:30 -0700 > > Guenter Roeck <li...@roeck-us.net> wrote: > > > >> Hi Nicholas, > >> > >> On 09/12/2016 07:00 PM, Nicholas Piggin wrote: > >>> On Mon, 12 Sep 2016 15:24:43 -0700 > >>> Guenter Roeck <li...@roeck-us.net> wrote: > >>> > >>>> Hi, > >>>> > >>>> your commit 'kbuild: allow archs to select link dead code/data > >>>> elimination' > >>>> is causing the following build failure in -next when building > >>>> score:defconfig. > >>>> > >>>> arch/score/kernel/built-in.o: In function `work_resched': > >>>> arch/score/kernel/entry.o:(.text+0xe84): > >>>> relocation truncated to fit: R_SCORE_PC19 against `schedule' > >>>> > >>>> Reverting the commit fixes the problem. > >>>> > >>>> Please let me know if I can help tracking down the problem. > >>>> In case you need a score toochain, you can find the one I use at > >>>> http://server.roeck-us.net/toolchains/score.tgz. > >>>> > >>>> Thanks, > >>>> Guenter > >>> > >>> It's not supposed to have any real effect unless the > >>> option is selected, but there are a few changes to linker > >>> script which must be causing it. > >>> > >>> There are two changes to vmlinux.lds.h. One is to KEEP a > >>> few input sections, that *should* be kept anyway. The other > >>> is to bring in additional sections into their correct output > >>> section. > >>> > >>> Could you try reverting those lines of vmlinux.lds.h that > >>> change the latter, i.e.: > >>> > >>> - *(.text.hot .text .text.fixup .text.unlikely) \ > >>> + *(.text.hot .text .text.fixup .text.unlikely .text.*) \ > >> > >> This is the culprit. After removing " .text.*" it builds fine. > > > > Thanks for testing it. Some architectures have .text.x sections > > not included here, I should have seen that. We should possibly > > just revert that line and require implementing archs to do the > > right thing. > > > I would call the build failure a regression, so it should either be > reverted, or we'll need some other solution to fix the build failure. Yes it's definitely a regression and that part should be reverted. To confirm, the following patch fixes your build? Thanks, Nick commit 0ae28be83b4d6cd03ef5b481487d042f2b91954e Author: Nicholas Piggin <npig...@gmail.com> Date: Wed Sep 14 12:24:03 2016 +1000 kbuild: -ffunction-sections fix for archs with conflicting sections Enabling -ffunction-sections modified the generic linker script to pull .text.* sections into regular TEXT_TEXT section, conflicting with some architectures. Revert that change and require archs that enable the option to ensure they have no conflicting section names, and do the appropriate merging. Signed-off-by: Nicholas Piggin <npig...@gmail.com> diff --git a/arch/Kconfig b/arch/Kconfig index 6d5b631..8248037 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -487,7 +487,9 @@ config LD_DEAD_CODE_DATA_ELIMINATION This requires that the arch annotates or otherwise protects its external entry points from being discarded. Linker scripts must also merge .text.*, .data.*, and .bss.* correctly into - output sections. + output sections. Care must be taken not to pull in unrelated + sections (e.g., '.text.init'). Typically '.' in section names + is used to distinguish them from label names / C identifiers. config HAVE_CONTEXT_TRACKING bool diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index ad9d8f9..48dd44f 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -198,9 +198,9 @@ /* * .data section - * -fdata-sections generates .data.identifier which needs to be pulled in - * with .data, but don't want to pull in .data..stuff which has its own - * requirements. Same for bss. + * LD_DEAD_CODE_DATA_ELIMINATION option enables -fdata-sections generates + * .data.identifier which needs to be pulled in with .data, but don't want to + * pull in .data..stuff which has its own requirements. Same for bss. */ #define DATA_DATA \ *(.data .data.[0-9a-zA-Z_]*) \ @@ -434,10 +434,15 @@ } /* .text section. Map to function alignment to avoid address changes - * during second ld run in second ld pass when generating System.map */ + * during second ld run in second ld pass when generating System.map + * LD_DEAD_CODE_DATA_ELIMINATION option enables -ffunction-sections generates + * .text.identifier which needs to be pulled in with .text , but some + * architectures define .text.foo which is not intended to be pulled in here. + * Those enabling LD_DEAD_CODE_DATA_ELIMINATION must ensure they don't have + * conflicting section names, and must pull in .text.[0-9a-zA-Z_]* */ #define TEXT_TEXT \ ALIGN_FUNCTION(); \ - *(.text.hot .text .text.fixup .text.unlikely .text.*) \ + *(.text.hot .text .text.fixup .text.unlikely) \ *(.ref.text) \ MEM_KEEP(init.text) \ MEM_KEEP(exit.text) \
