Re: [PATCH] powerpc/vdso32: mark __kernel_datapage_offset as STV_PROTECTED
Fangrui Song writes: > A PC-relative relocation (R_PPC_REL16_LO in this case) referencing a > preemptible symbol in a -shared link is not allowed. GNU ld's powerpc > port is permissive and allows it [1], but lld will report an error after > https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?id=ec0895f08f99515194e9fcfe1338becf6f759d38 > > Make the symbol protected so that it is non-preemptible but still > exported. "preemptible" means something different to me, and I assume we're not using it to mean the same thing. Can you explain it using small words that a kernel developer can understand? :) cheers > [1]: https://sourceware.org/bugzilla/show_bug.cgi?id=25500 > > Link: https://github.com/ClangBuiltLinux/linux/issues/851 > Signed-off-by: Fangrui Song > --- > arch/powerpc/kernel/vdso32/datapage.S | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/kernel/vdso32/datapage.S > b/arch/powerpc/kernel/vdso32/datapage.S > index 217bb630f8f9..2831a8676365 100644 > --- a/arch/powerpc/kernel/vdso32/datapage.S > +++ b/arch/powerpc/kernel/vdso32/datapage.S > @@ -13,7 +13,8 @@ > #include > > .text > - .global __kernel_datapage_offset; > + .global __kernel_datapage_offset > + .protected __kernel_datapage_offset > __kernel_datapage_offset: > .long 0 > > -- > 2.25.0.341.g760bfbb309-goog
Re: [PATCH] powerpc/vdso32: mark __kernel_datapage_offset as STV_PROTECTED
On Wed, Feb 05, 2020 at 07:25:59AM +0100, Christophe Leroy wrote: > > > Le 05/02/2020 à 01:50, Fangrui Song a écrit : > > A PC-relative relocation (R_PPC_REL16_LO in this case) referencing a > > preemptible symbol in a -shared link is not allowed. GNU ld's powerpc > > port is permissive and allows it [1], but lld will report an error after > > https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?id=ec0895f08f99515194e9fcfe1338becf6f759d38 > > Note that there is a series whose first two patches aim at dropping > __kernel_datapage_offset . See > https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=156045 and > especially patches https://patchwork.ozlabs.org/patch/1231467/ and > https://patchwork.ozlabs.org/patch/1231461/ > > Those patches can be applied independentely of the rest. > > Christophe If that is the case, it would be nice if those could be fast tracked to 5.6 because as it stands now, all PowerPC builds that were working with ld.lld are now broken. Either that or take this patch and rebase that series on this one. Cheers, Nathan
Re: [PATCH] powerpc/vdso32: mark __kernel_datapage_offset as STV_PROTECTED
Le 05/02/2020 à 01:50, Fangrui Song a écrit : A PC-relative relocation (R_PPC_REL16_LO in this case) referencing a preemptible symbol in a -shared link is not allowed. GNU ld's powerpc port is permissive and allows it [1], but lld will report an error after https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?id=ec0895f08f99515194e9fcfe1338becf6f759d38 Note that there is a series whose first two patches aim at dropping __kernel_datapage_offset . See https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=156045 and especially patches https://patchwork.ozlabs.org/patch/1231467/ and https://patchwork.ozlabs.org/patch/1231461/ Those patches can be applied independentely of the rest. Christophe Make the symbol protected so that it is non-preemptible but still exported. [1]: https://sourceware.org/bugzilla/show_bug.cgi?id=25500 Link: https://github.com/ClangBuiltLinux/linux/issues/851 Signed-off-by: Fangrui Song --- arch/powerpc/kernel/vdso32/datapage.S | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/vdso32/datapage.S b/arch/powerpc/kernel/vdso32/datapage.S index 217bb630f8f9..2831a8676365 100644 --- a/arch/powerpc/kernel/vdso32/datapage.S +++ b/arch/powerpc/kernel/vdso32/datapage.S @@ -13,7 +13,8 @@ #include .text - .global __kernel_datapage_offset; + .global __kernel_datapage_offset + .protected __kernel_datapage_offset __kernel_datapage_offset: .long 0
