On Thu, 10 Feb 2011, Catalin Marinas wrote: > On Thu, 2011-02-10 at 13:04 +0000, Russell King - ARM Linux wrote: > > On Wed, Feb 09, 2011 at 10:01:33AM +0000, Catalin Marinas wrote: > > > Could we make the domains usage a run-time feature based on the > > > architecture version? For ARMv7, we need to have the vectors page > > > read-only anyway if the SWP emulation is enabled (and I posted a > > > simple patch in a reply to your email). > > > > > > The issue I see is that ARM11MPCore is reported as v7 though we still > > > use domains on this processor (we could always remove the domains if > > > TLS register is available or use some more precise architecture > > > version identification). > > > > We could also do the below, which I think is more logical - SWP emulation > > requires that CPU domains aren't enabled, so let's make that explicit > > in the Kconfig. > > This may work but it is to restrictive IMHO. SWP emulation only requires > that RO user pages are also RO for the kernel. And there is a simple fix > for this: >
The patch below is making the code more straight forward regardless of any swp emulation issues. Acked-by: Nicolas Pitre <[email protected]> > diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c > index ee57640..6e0b349 100644 > --- a/arch/arm/kernel/traps.c > +++ b/arch/arm/kernel/traps.c > @@ -758,17 +758,21 @@ static void __init kuser_get_tls_init(unsigned long > vectors) > > void __init early_trap_init(void) > { > -#if defined(CONFIG_CPU_USE_DOMAINS) > - unsigned long vectors = CONFIG_VECTORS_BASE; > -#else > - unsigned long vectors = (unsigned long)vectors_page; > -#endif > + unsigned long vectors; > extern char __stubs_start[], __stubs_end[]; > extern char __vectors_start[], __vectors_end[]; > extern char __kuser_helper_start[], __kuser_helper_end[]; > int kuser_sz = __kuser_helper_end - __kuser_helper_start; > > /* > + * On ARMv7, user RO pages are mapped as kernel RO. > + */ > + if (cpu_architecture() >= 7) > + vectors = (unsigned long)vectors_page; > + else > + vectors = CONFIG_VECTORS_BASE; > + > + /* > * Copy the vectors, stubs and kuser helpers (in entry-armv.S) > * into the vector page, mapped at 0xffff0000, and ensure these > * are visible to the instruction stream. > diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S > index 0c1172b..5f51592 100644 > --- a/arch/arm/mm/proc-v7.S > +++ b/arch/arm/mm/proc-v7.S > @@ -146,11 +146,6 @@ ENTRY(cpu_v7_set_pte_ext) > > tst r1, #L_PTE_USER > orrne r3, r3, #PTE_EXT_AP1 > -#ifdef CONFIG_CPU_USE_DOMAINS > - @ allow kernel read/write access to read-only user pages > - tstne r3, #PTE_EXT_APX > - bicne r3, r3, #PTE_EXT_APX | PTE_EXT_AP0 > -#endif > > tst r1, #L_PTE_XN > orrne r3, r3, #PTE_EXT_XN > > > -- > Catalin > > > > _______________________________________________ > linux-arm-kernel mailing list > [email protected] > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
