Messages in this thread | | | Date | Tue, 16 Feb 2016 12:16:30 -0800 | Subject | Re: [PATCH] ARM: fix __start_rodata_section_aligned on XIP | From | Kees Cook <> |
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On Tue, Feb 16, 2016 at 11:20 AM, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > Hi Kees, > > On Tue, Feb 16, 2016 at 7:38 PM, Kees Cook <keescook@chromium.org> wrote: >> This fixes the build for both allnoconfig (!CONFIG_MMU) and with >> XIP_KERNEL (due to missing pieces in the linker script), as seen after >> both "ARM: 8502/1: mm: mark section-aligned portion of rodata NX" and >> "ARM: 8513/1: xip: Move XIP linking to a separate file". >> >> Reported-by: Russell King <linux@arm.linux.org.uk> >> Reported-by: Arnd Bergmann <arnd@arndb.de> >> Signed-off-by: Kees Cook <keescook@chromium.org> > >> diff --git a/arch/arm/kernel/vmlinux-xip.lds.S b/arch/arm/kernel/vmlinux-xip.lds.S >> index 40bc4cadb959..2da60cd1b295 100644 >> --- a/arch/arm/kernel/vmlinux-xip.lds.S >> +++ b/arch/arm/kernel/vmlinux-xip.lds.S > >> @@ -310,6 +311,17 @@ SECTIONS >> } >> >> /* >> + * 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. >> + */ >> +#ifdef CONFIG_MMU > > CONFIG_DEBUG_ALIGN_RODATA or CONFIG_MMU? > >> +__start_rodata_section_aligned = ALIGN(__start_rodata, 1 << SECTION_SHIFT);
CONFIG_MMU controls the availability of SECTION_SHIFT, so I used that. Either will work, since without CONFIG_DEBUG_ALIGN_RODATA, the values will end up being identical, as in the #else.
Though it looks like XIP_KERNEL should kill all of the CONFIG_DEBUG_*RODATA defines anyway. I think we need a different version of this combined with the patch from Ard...
-Kees
>> +#else >> +__start_rodata_section_aligned = __start_rodata; >> +#endif >> + >> +/* >> * These must never be empty >> * If you have to comment these two assert statements out, your >> * binutils is too old (for other reasons as well) >> diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S >> index 1707b9431761..f13960e44955 100644 >> --- a/arch/arm/kernel/vmlinux.lds.S >> +++ b/arch/arm/kernel/vmlinux.lds.S >> @@ -328,7 +328,11 @@ SECTIONS >> * be the first section-aligned location after __start_rodata. Otherwise, >> * it will be equal to __start_rodata. >> */ >> +#ifdef CONFIG_MMU > > Likewise (the out-of-scope comment says CONFIG_DEBUG_ALIGN_RODATA)? > >> __start_rodata_section_aligned = ALIGN(__start_rodata, 1 << SECTION_SHIFT); >> +#else >> +__start_rodata_section_aligned = __start_rodata; >> +#endif > > 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
-- Kees Cook Chrome OS & Brillo Security
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