Messages in this thread Patch in this message | | | Date | Mon, 15 Feb 2016 09:46:05 +0100 | Subject | Re: [PATCH v2] ARM: mm: mark section-aligned portion of rodata NX | From | Geert Uytterhoeven <> |
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On Fri, Feb 12, 2016 at 10:45 AM, Arnd Bergmann <arnd@arndb.de> wrote: > On Thursday 11 February 2016 18:00:32 Russell King - ARM Linux wrote: >> On Fri, Jan 22, 2016 at 01:19:03PM -0800, Kees Cook wrote: >> > On Tue, Dec 8, 2015 at 10:38 AM, Kees Cook <keescook@chromium.org> wrote: >> > > On Mon, Dec 7, 2015 at 11:47 PM, Ard Biesheuvel >> > > <ard.biesheuvel@linaro.org> wrote: >> > >> On 7 December 2015 at 23:35, Kees Cook <keescook@chromium.org> wrote: >> > >>> /* >> > >>> + * Without CONFIG_DEBUG_ALIGN_RODATA, __start_rodata_section_aligned will >> > >>> + * be the first section-aligned location after __start_rodata. Otherwise, >> > >>> + * it will be equal to __start_rodata. >> > >>> + */ >> > >>> +__start_rodata_section_aligned = ALIGN(__start_rodata, 1 << SECTION_SHIFT); >> ... >> >> I'm afraid this causes build errors on two configurations: >> >> ./arch/arm/kernel/vmlinux.lds:701: undefined symbol `SECTION_SHIFT' referenced in expression >> >> which I think is down to the new __start_rodata_section_aligned line. >> >> Olof's builder errored out with this for both allnoconfig and >> lpc18xx_defconfig builds. Both probably due to CONFIG_MMU being >> unset, and hence no definition for SECTION_SHIFT. >> >> I think you need to make this conditional on CONFIG_MMU. > > I've hit another problem with this patch, when using XIP_KERNEL, I now see > > arch/arm/mm/built-in.o:(.data+0x4bc): undefined reference to `__start_rodata_section_aligned' > > in linux-next, apparently because of the combination with "ARM: 8513/1: xip: Move > XIP linking to a separate file".
Is this due to the copy not taking into account the recent changes to vmlinux.lds.S?
"git show 538bf4694898b19e" with copy-rename detection shows:
copy from arch/arm/kernel/vmlinux.lds.S copy to arch/arm/kernel/vmlinux-xip.lds.S index a6e395c53a48e045..6f59ef290289e078 100644 --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux-xip.lds.S
[...]
@@ -117,7 +114,7 @@ SECTIONS ARM_CPU_KEEP(PROC_INFO) }
-#ifdef CONFIG_DEBUG_ALIGN_RODATA +#ifdef CONFIG_DEBUG_RODATA . = ALIGN(1<<SECTION_SHIFT); #endif RO_DATA(PAGE_SIZE) Gr{oetje,eeting}s, Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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