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Date: Thu, 7 Dec 2017 11:24:01 -0200 From: Desnes Augusto Nunes do Rosário <desnesn@...ux.vnet.ibm.com> To: Michael Ellerman <mpe@...erman.id.au>, linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org, amodra@...il.com Cc: benh@...nel.crashing.org, paulus@...ba.org, ard.biesheuvel@...aro.org, rusty@...tcorp.com.au Subject: Re: [PATCH] [powerpc-next] Fix powerpc64 alignment of .toc section in kernel modules Hello Michael, On 12/07/2017 10:25 AM, Michael Ellerman wrote: > Hi Desnes, > > Am I right that Alan largely wrote this patch? > > If so it should probably be From: him, so that he is the author in the > git log. Yes, Alan Modra is the main author and I am just committing it with minor changes. Thus, the author change is necessary. > > > Desnes Augusto Nunes do Rosario <desnesn@...ux.vnet.ibm.com> writes: >> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile >> index 1381693..c472f5b 100644 >> --- a/arch/powerpc/Makefile >> +++ b/arch/powerpc/Makefile >> @@ -63,6 +63,7 @@ UTS_MACHINE := $(subst $(space),,$(machine-y)) >> ifdef CONFIG_PPC32 >> KBUILD_LDFLAGS_MODULE += arch/powerpc/lib/crtsavres.o >> else >> +KBUILD_LDFLAGS_MODULE += -T arch/powerpc/kernel/module.lds > > This needs to be: > > KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/powerpc/kernel/module.lds > > Otherwise building with O=../build fails with: > > ld: cannot open linker script file arch/powerpc/kernel/module.lds: No such file or directory > > I'll fix it up. Indeed; this change is necessary to avoid any path errors. > >> diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c >> index 759104b..9b2c5c1 100644 >> --- a/arch/powerpc/kernel/module_64.c >> +++ b/arch/powerpc/kernel/module_64.c >> @@ -374,11 +377,13 @@ int module_frob_arch_sections(Elf64_Ehdr *hdr, >> } >> >> /* r2 is the TOC pointer: it actually points 0x8000 into the TOC (this >> - gives the value maximum span in an instruction which uses a signed >> - offset) */ >> + * gives the value maximum span in an instruction which uses a signed >> + * offset). Round down to a 256 byte boundary for the odd case where >> + * we are setting up r2 without a .toc section. >> + */ >> static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me) >> { >> - return sechdrs[me->arch.toc_section].sh_addr + 0x8000; >> + return (sechdrs[me->arch.toc_section].sh_addr & -256) + 0x8000; > > I think it's more typical in the kernel to write -256 as ~0xff. > > Again I can fix it up. Good to know! > > cheers > Lastly, will you fix it up or do you want me to send a second version then? Whatever is best for you. Thank you for the review. -- Desnes Augusto Nunes do Rosário ------------------------------------------ Linux Developer - IBM / Brazil M.Sc. in Electrical and Computer Engineering - UFRN (11) 9595-30-900 desnesn@...ibm.com
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