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

Marc Zyngier
2020-11-25T11:22:11Z

On 2020-11-25 10:31, David Brazdil wrote:
> 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))
>> > +

Wait: You now have MAIR_ELx_SET defined at two locations. Surely that's
one too many.

>> > /* 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.

M.

diff --git a/arch/arm64/include/asm/memory.h
b/arch/arm64/include/asm/memory.h
index 8ae8fd883a0c..01685d81e9d4 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -13,7 +13,6 @@
#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
@@ -139,17 +138,19 @@
#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.
+ * 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 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))
+#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

#ifdef CONFIG_ARM64_4K_PAGES
#define IOREMAP_MAX_ORDER (PUD_SHIFT)
diff --git a/arch/arm64/include/asm/sysreg.h
b/arch/arm64/include/asm/sysreg.h
index 24e773414cb4..c9534fba3afe 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -635,21 +635,6 @@
/* 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.
@@ -1020,7 +1005,6 @@
/* Safe value for MPIDR_EL1: Bit31:RES1, Bit30:U:0, Bit24:MT:0 */
#define SYS_MPIDR_SAFE_VAL (BIT(31))

-#ifndef LINKER_SCRIPT
#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
@@ -1138,6 +1122,5 @@
})

#endif
-#endif /* LINKER_SCRIPT */

#endif /* __ASM_SYSREG_H */

--
Jazz is not dead. It just smells funny...