That makes sense and I agree, it's better to fix it now so that it will be easier to add 16K paging later (on a side note is there any reason not to add it now if someone was willing to do the work?). Your patch is exactly the solution that I had in my head to fix it if the spec was correct.
There was talk in another thread about the possibility of adding a pagetable-4K-hwdef.h and pagetable-64K-hwdef.h. I think this is another example of why that might be a good idea as this stuff could be moved out of proc.S as to be bit more clean: +#ifdef CONFIG_ARM64_64K_PAGES +#define TCR_TG_FLAGS TCR_TG0_64K | TCR_TG1_64K +#else +#define TCR_TG_FLAGS TCR_TG0_4K | TCR_TG1_4K +#endif On Wed, Apr 2, 2014 at 12:07 PM, Catalin Marinas <[email protected]> wrote: > On Wed, Apr 02, 2014 at 01:38:44PM +0100, Catalin Marinas wrote: >> On Wed, Apr 02, 2014 at 05:00:38AM +0100, Joe Sylve wrote: >> > Section D7.2.83 TCR_EL1, Translation Control Register (EL1) of the >> > latest ARM Architecture Reference Manual, ARMv8, for ARMv8-A states >> > that TCR_EL1 TG1 (bits [31:30]) should be set to 11 for a 64KB >> > TTBR1_EL1 granule size. The mainline 3.14 kernel incorrectly sets >> > those bits to 01 (which is a 16KB granule size). >> > >> > Signed-off-by: Joe Sylve <[email protected]> >> > --- >> > >> > --- a/arch/arm64/include/asm/pgtable-hwdef.h 2014-04-01 22:13:22.619868978 >> > -0500 >> > +++ b/arch/arm64/include/asm/pgtable-hwdef.h 2014-04-01 22:13:58.071869886 >> > -0500 >> > @@ -121,7 +121,7 @@ >> > #define TCR_ORGN_MASK ((UL(3) << 10) | (UL(3) << 26)) >> > #define TCR_SHARED ((UL(3) << 12) | (UL(3) << 28)) >> > #define TCR_TG0_64K (UL(1) << 14) >> > -#define TCR_TG1_64K (UL(1) << 30) >> > +#define TCR_TG1_64K (UL(3) << 30) >> > #define TCR_IPS_40BIT (UL(2) << 32) >> > #define TCR_ASID16 (UL(1) << 36) >> > #define TCR_TBI0 (UL(1) << 37) >> >> According to the spec, 4K pages is also wrong. The strange thing is that >> it works fine on the model. I'll ask internally for clarification >> whether it's a typo in the manual or Linux needs fixing. > > You scared me first but the Linux code is *correct* because it sets bit > 31 to 1 in proc.S explicitly. The reason is that the code pre-dates the > 16K addition to the spec where bit 31 was RES1 and TG0/TG1 were one bit > wide and had the same value. Anyway, it's worth updating the kernel as > at some point will add 16K pages support. Something like below: > > --------8<--------------- > > From d43ca2701b5d66ab467ba3f8db52ee02020d38a2 Mon Sep 17 00:00:00 2001 > From: Catalin Marinas <[email protected]> > Date: Wed, 2 Apr 2014 17:55:40 +0100 > Subject: [PATCH] arm64: Update the TCR_EL1 translation granule definitions > for 16K pages > > The current TCR register setting in arch/arm64/mm/proc.S assumes that > TCR_EL1.TG* fields are one bit wide and bit 31 is RES1 (reserved, set to > 1). With the addition of 16K pages (currently unsupported in the > kernel), the TCR_EL1.TG* fields have been extended to two bits. This > patch updates the corresponding Linux definitions and drops the bit 31 > setting in proc.S in favour of the new macros. > > Signed-off-by: Catalin Marinas <[email protected]> > Reported-by: Joe Sylve <[email protected]> > --- > arch/arm64/include/asm/pgtable-hwdef.h | 6 +++++- > arch/arm64/mm/proc.S | 25 ++++++++++++++----------- > 2 files changed, 19 insertions(+), 12 deletions(-) > > diff --git a/arch/arm64/include/asm/pgtable-hwdef.h > b/arch/arm64/include/asm/pgtable-hwdef.h > index f7af66b54cb2..5fc8a66c3924 100644 > --- a/arch/arm64/include/asm/pgtable-hwdef.h > +++ b/arch/arm64/include/asm/pgtable-hwdef.h > @@ -120,8 +120,12 @@ > #define TCR_ORGN_WBnWA ((UL(3) << 10) | (UL(3) << 26)) > #define TCR_ORGN_MASK ((UL(3) << 10) | (UL(3) << 26)) > #define TCR_SHARED ((UL(3) << 12) | (UL(3) << 28)) > +#define TCR_TG0_4K (UL(0) << 14) > #define TCR_TG0_64K (UL(1) << 14) > -#define TCR_TG1_64K (UL(1) << 30) > +#define TCR_TG0_16K (UL(2) << 14) > +#define TCR_TG1_16K (UL(1) << 30) > +#define TCR_TG1_4K (UL(2) << 30) > +#define TCR_TG1_64K (UL(3) << 30) > #define TCR_ASID16 (UL(1) << 36) > #define TCR_TBI0 (UL(1) << 37) > > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S > index e085ee6ef4e2..9042aff5e9e3 100644 > --- a/arch/arm64/mm/proc.S > +++ b/arch/arm64/mm/proc.S > @@ -28,14 +28,21 @@ > > #include "proc-macros.S" > > -#ifndef CONFIG_SMP > -/* PTWs cacheable, inner/outer WBWA not shareable */ > -#define TCR_FLAGS TCR_IRGN_WBWA | TCR_ORGN_WBWA > +#ifdef CONFIG_ARM64_64K_PAGES > +#define TCR_TG_FLAGS TCR_TG0_64K | TCR_TG1_64K > +#else > +#define TCR_TG_FLAGS TCR_TG0_4K | TCR_TG1_4K > +#endif > + > +#ifdef CONFIG_SMP > +#define TCR_SMP_FLAGS TCR_SHARED > #else > -/* PTWs cacheable, inner/outer WBWA shareable */ > -#define TCR_FLAGS TCR_IRGN_WBWA | TCR_ORGN_WBWA | TCR_SHARED > +#define TCR_SMP_FLAGS 0 > #endif > > +/* PTWs cacheable, inner/outer WBWA */ > +#define TCR_CACHE_FLAGS TCR_IRGN_WBWA | TCR_ORGN_WBWA > + > #define MAIR(attr, mt) ((attr) << ((mt) * 8)) > > /* > @@ -209,18 +216,14 @@ ENTRY(__cpu_setup) > * Set/prepare TCR and TTBR. We use 512GB (39-bit) address range for > * both user and kernel. > */ > - ldr x10, =TCR_TxSZ(VA_BITS) | TCR_FLAGS | \ > - TCR_ASID16 | TCR_TBI0 | (1 << 31) > + ldr x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \ > + TCR_TG_FLAGS | TCR_ASID16 | TCR_TBI0 > /* > * Read the PARange bits from ID_AA64MMFR0_EL1 and set the IPS bits in > * TCR_EL1. > */ > mrs x9, ID_AA64MMFR0_EL1 > bfi x10, x9, #32, #3 > -#ifdef CONFIG_ARM64_64K_PAGES > - orr x10, x10, TCR_TG0_64K > - orr x10, x10, TCR_TG1_64K > -#endif > msr tcr_el1, x10 > ret // return to head.S > ENDPROC(__cpu_setup) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
