Re: [PATCH v2 04/24] arm64: Move MAIR_EL1_SET to asm/memory.h

David Brazdil
2020-11-25T10:31:58Z

On Mon, Nov 23, 2020 at 01:52:54PM +0000, Marc Zyngier wrote:
> On Mon, 16 Nov 2020 20:42:58 +0000,
> David Brazdil <dbrazdil@google.com> wrote:
> >
> > KVM currently initializes MAIR_EL2 to the value of MAIR_EL1. In
> > preparation for initializing MAIR_EL2 before MAIR_EL1, move the constant
> > into a shared header file. Since it is used for EL1 and EL2, rename to
> > MAIR_ELx_SET.
> >
> > Signed-off-by: David Brazdil <dbrazdil@google.com>
> > ---
> > arch/arm64/include/asm/memory.h | 29 ++++++++++++++---------------
> > arch/arm64/include/asm/sysreg.h | 30 ++++++++++++++++++++++++++++++
> > arch/arm64/mm/proc.S | 15 +--------------
> > 3 files changed, 45 insertions(+), 29 deletions(-)
> >
> > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> > index cd61239bae8c..8ae8fd883a0c 100644
> > --- a/arch/arm64/include/asm/memory.h
> > +++ b/arch/arm64/include/asm/memory.h
> > @@ -13,6 +13,7 @@
> > #include <linux/const.h>
> > #include <linux/sizes.h>
> > #include <asm/page-def.h>
> > +#include <asm/sysreg.h>
> >
> > /*
> > * Size of the PCI I/O space. This must remain a power of two so that
> > @@ -124,21 +125,6 @@
> > */
> > #define SEGMENT_ALIGN SZ_64K
> >
> > -/*
> > - * Memory types available.
> > - *
> > - * IMPORTANT: MT_NORMAL must be index 0 since vm_get_page_prot() may 'or' in
> > - * the MT_NORMAL_TAGGED memory type for PROT_MTE mappings. Note
> > - * that protection_map[] only contains MT_NORMAL attributes.
> > - */
> > -#define MT_NORMAL 0
> > -#define MT_NORMAL_TAGGED 1
> > -#define MT_NORMAL_NC 2
> > -#define MT_NORMAL_WT 3
> > -#define MT_DEVICE_nGnRnE 4
> > -#define MT_DEVICE_nGnRE 5
> > -#define MT_DEVICE_GRE 6
> > -
> > /*
> > * Memory types for Stage-2 translation
> > */
> > @@ -152,6 +138,19 @@
> > #define MT_S2_FWB_NORMAL 6
> > #define MT_S2_FWB_DEVICE_nGnRE 1
> >
> > +/*
> > + * Default MAIR_EL1. MT_NORMAL_TAGGED is initially mapped as Normal memory and
> > + * changed during __cpu_setup to Normal Tagged if the system supports MTE.
> > + */
> > +#define MAIR_ELx_SET \
> > + (MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRnE, MT_DEVICE_nGnRnE) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRE, MT_DEVICE_nGnRE) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_DEVICE_GRE, MT_DEVICE_GRE) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_NORMAL_NC, MT_NORMAL_NC) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_NORMAL_WT, MT_NORMAL_WT) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL_TAGGED))
> > +
> > #ifdef CONFIG_ARM64_4K_PAGES
> > #define IOREMAP_MAX_ORDER (PUD_SHIFT)
> > #else
> > diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> > index e2ef4c2edf06..24e773414cb4 100644
> > --- a/arch/arm64/include/asm/sysreg.h
> > +++ b/arch/arm64/include/asm/sysreg.h
> > @@ -635,6 +635,34 @@
> > /* Position the attr at the correct index */
> > #define MAIR_ATTRIDX(attr, idx) ((attr) << ((idx) * 8))
> >
> > +/*
> > + * Memory types available.
> > + *
> > + * IMPORTANT: MT_NORMAL must be index 0 since vm_get_page_prot() may 'or' in
> > + * the MT_NORMAL_TAGGED memory type for PROT_MTE mappings. Note
> > + * that protection_map[] only contains MT_NORMAL attributes.
> > + */
> > +#define MT_NORMAL 0
> > +#define MT_NORMAL_TAGGED 1
> > +#define MT_NORMAL_NC 2
> > +#define MT_NORMAL_WT 3
> > +#define MT_DEVICE_nGnRnE 4
> > +#define MT_DEVICE_nGnRE 5
> > +#define MT_DEVICE_GRE 6
> > +
> > +/*
> > + * Default MAIR_ELx. MT_NORMAL_TAGGED is initially mapped as Normal memory and
> > + * changed during __cpu_setup to Normal Tagged if the system supports MTE.
> > + */
> > +#define MAIR_ELx_SET \
> > + (MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRnE, MT_DEVICE_nGnRnE) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRE, MT_DEVICE_nGnRE) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_DEVICE_GRE, MT_DEVICE_GRE) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_NORMAL_NC, MT_NORMAL_NC) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_NORMAL_WT, MT_NORMAL_WT) | \
> > + MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL_TAGGED))
> > +
> > /* id_aa64isar0 */
> > #define ID_AA64ISAR0_RNDR_SHIFT 60
> > #define ID_AA64ISAR0_TLB_SHIFT 56
> > @@ -992,6 +1020,7 @@
> > /* Safe value for MPIDR_EL1: Bit31:RES1, Bit30:U:0, Bit24:MT:0 */
> > #define SYS_MPIDR_SAFE_VAL (BIT(31))
> >
> > +#ifndef LINKER_SCRIPT
>
> This is terribly ugly. Why is this included by the linker script? Does
> it actually define __ASSEMBLY__?

vmlinux.lds.S includes memory.h for PAGE_SIZE. And yes, linker scripts are
built with this rule:

cmd_cpp_lds_S = $(CPP) $(cpp_flags) -P -U$(ARCH) \
-D__ASSEMBLY__ -DLINKER_SCRIPT -o $@ $<

I tried a few things and wasn't completely happy with any of them. I think in
the previous spin you suggested moving this constant to sysreg.h. That works
too but sysreg.h seems to have only architecture constants, memory.h about a
Linux-specific configuration, so I wanted to keep it here.

>
> > #ifdef __ASSEMBLY__
> >
> > .irp num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30
> > @@ -1109,5 +1138,6 @@
> > })
> >
> > #endif
> > +#endif /* LINKER_SCRIPT */
> >
> > #endif /* __ASM_SYSREG_H */
> > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
> > index 23c326a06b2d..e3b9aa372b96 100644
> > --- a/arch/arm64/mm/proc.S
> > +++ b/arch/arm64/mm/proc.S
> > @@ -45,19 +45,6 @@
> > #define TCR_KASAN_FLAGS 0
> > #endif
> >
> > -/*
> > - * Default MAIR_EL1. MT_NORMAL_TAGGED is initially mapped as Normal memory and
> > - * changed during __cpu_setup to Normal Tagged if the system supports MTE.
> > - */
> > -#define MAIR_EL1_SET \
> > - (MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRnE, MT_DEVICE_nGnRnE) | \
> > - MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRE, MT_DEVICE_nGnRE) | \
> > - MAIR_ATTRIDX(MAIR_ATTR_DEVICE_GRE, MT_DEVICE_GRE) | \
> > - MAIR_ATTRIDX(MAIR_ATTR_NORMAL_NC, MT_NORMAL_NC) | \
> > - MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL) | \
> > - MAIR_ATTRIDX(MAIR_ATTR_NORMAL_WT, MT_NORMAL_WT) | \
> > - MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL_TAGGED))
> > -
> > #ifdef CONFIG_CPU_PM
> > /**
> > * cpu_do_suspend - save CPU registers context
> > @@ -425,7 +412,7 @@ SYM_FUNC_START(__cpu_setup)
> > /*
> > * Memory region attributes
> > */
> > - mov_q x5, MAIR_EL1_SET
> > + mov_q x5, MAIR_ELx_SET
> > #ifdef CONFIG_ARM64_MTE
> > /*
> > * Update MAIR_EL1, GCR_EL1 and TFSR*_EL1 if MTE is supported
> > --
> > 2.29.2.299.gdc1121823c-goog
> >
> >
>
> Thanks,
>
> M.
>
> --
> Without deviation from the norm, progress is not possible.