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

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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@xxxxxxxxxx> 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@xxxxxxxxxx>
> ---
>  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...
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