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

David Brazdil
2020-11-25T13:26:38Z

> > > > +/*
> > > > + * 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))
> > > > +
>
> Wait: You now have MAIR_ELx_SET defined at two locations. Surely that's
> one too many.
>

Oops, told you I tried different things...

> > > > /* 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.
>
> MAIR_ELx_SET isn't really Linux specific. Or rather, not more specific than
> any of the other configurations we have. On the other hand, the S1 MT_*
> stuff
> is totally arbitrary, and does fit in memory.h, together with the rest of
> the indexes for the memory types.
>
> I came up with the following patch on top of this series that seems to
> compile without issue.

That seems to have an implicit dependency of sysreg.h on memory.h, doesn't it?
I had it the other way round initially. I also tried including memory.h in
sysreg.h. That creates a circular dependency mmdebug.h -> bug.h -> ... ->
sysreg.h -> memory.h -> mmdebug.h. Pretty annoying. I could try to fix that,
or create a new header file... :(