* [PATCH] arm64: sysreg: Remove unused and rotting SCTLR_ELx field definitions
@ 2019-07-30 14:41 Will Deacon
2019-07-30 14:58 ` Mark Rutland
0 siblings, 1 reply; 2+ messages in thread
From: Will Deacon @ 2019-07-30 14:41 UTC (permalink / raw)
To: linux-arm-kernel; +Cc: mark.rutland, Will Deacon, james.morse
Our SCTLR_ELx field definitions are somewhat over-engineered in that
they carefully define masks describing the RES0/RES1 bits and then use
these to construct further masks representing bits to be set/cleared for
the _EL1 and _EL2 registers.
However, most of the resulting definitions aren't actually used by
anybody and have subsequently started to bit-rot when new fields have
been added by the architecture, resulting in fields being part of the
RES0 mask despite being defined and used elsewhere.
Rather than fix up these masks, simply remove the unused parts entirely
so that we can drop the maintenance burden. We can always add things
back if we need them in the future.
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/include/asm/sysreg.h | 29 -----------------------------
1 file changed, 29 deletions(-)
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 06ebcfef73df..1df45c7ffcf7 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -499,28 +499,11 @@
#define SCTLR_EL2_RES1 ((BIT(4)) | (BIT(5)) | (BIT(11)) | (BIT(16)) | \
(BIT(18)) | (BIT(22)) | (BIT(23)) | (BIT(28)) | \
(BIT(29)))
-#define SCTLR_EL2_RES0 ((BIT(6)) | (BIT(7)) | (BIT(8)) | (BIT(9)) | \
- (BIT(10)) | (BIT(13)) | (BIT(14)) | (BIT(15)) | \
- (BIT(17)) | (BIT(20)) | (BIT(24)) | (BIT(26)) | \
- (BIT(27)) | (BIT(30)) | (BIT(31)) | \
- (0xffffefffUL << 32))
#ifdef CONFIG_CPU_BIG_ENDIAN
#define ENDIAN_SET_EL2 SCTLR_ELx_EE
-#define ENDIAN_CLEAR_EL2 0
#else
#define ENDIAN_SET_EL2 0
-#define ENDIAN_CLEAR_EL2 SCTLR_ELx_EE
-#endif
-
-/* SCTLR_EL2 value used for the hyp-stub */
-#define SCTLR_EL2_SET (SCTLR_ELx_IESB | ENDIAN_SET_EL2 | SCTLR_EL2_RES1)
-#define SCTLR_EL2_CLEAR (SCTLR_ELx_M | SCTLR_ELx_A | SCTLR_ELx_C | \
- SCTLR_ELx_SA | SCTLR_ELx_I | SCTLR_ELx_WXN | \
- SCTLR_ELx_DSSBS | ENDIAN_CLEAR_EL2 | SCTLR_EL2_RES0)
-
-#if (SCTLR_EL2_SET ^ SCTLR_EL2_CLEAR) != 0xffffffffffffffffUL
-#error "Inconsistent SCTLR_EL2 set/clear bits"
#endif
/* SCTLR_EL1 specific flags. */
@@ -539,16 +522,11 @@
#define SCTLR_EL1_RES1 ((BIT(11)) | (BIT(20)) | (BIT(22)) | (BIT(28)) | \
(BIT(29)))
-#define SCTLR_EL1_RES0 ((BIT(6)) | (BIT(10)) | (BIT(13)) | (BIT(17)) | \
- (BIT(27)) | (BIT(30)) | (BIT(31)) | \
- (0xffffefffUL << 32))
#ifdef CONFIG_CPU_BIG_ENDIAN
#define ENDIAN_SET_EL1 (SCTLR_EL1_E0E | SCTLR_ELx_EE)
-#define ENDIAN_CLEAR_EL1 0
#else
#define ENDIAN_SET_EL1 0
-#define ENDIAN_CLEAR_EL1 (SCTLR_EL1_E0E | SCTLR_ELx_EE)
#endif
#define SCTLR_EL1_SET (SCTLR_ELx_M | SCTLR_ELx_C | SCTLR_ELx_SA |\
@@ -556,13 +534,6 @@
SCTLR_EL1_DZE | SCTLR_EL1_UCT |\
SCTLR_EL1_NTWE | SCTLR_ELx_IESB | SCTLR_EL1_SPAN |\
ENDIAN_SET_EL1 | SCTLR_EL1_UCI | SCTLR_EL1_RES1)
-#define SCTLR_EL1_CLEAR (SCTLR_ELx_A | SCTLR_EL1_CP15BEN | SCTLR_EL1_ITD |\
- SCTLR_EL1_UMA | SCTLR_ELx_WXN | ENDIAN_CLEAR_EL1 |\
- SCTLR_ELx_DSSBS | SCTLR_EL1_NTWI | SCTLR_EL1_RES0)
-
-#if (SCTLR_EL1_SET ^ SCTLR_EL1_CLEAR) != 0xffffffffffffffffUL
-#error "Inconsistent SCTLR_EL1 set/clear bits"
-#endif
/* id_aa64isar0 */
#define ID_AA64ISAR0_TS_SHIFT 52
--
2.11.0
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^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] arm64: sysreg: Remove unused and rotting SCTLR_ELx field definitions
2019-07-30 14:41 [PATCH] arm64: sysreg: Remove unused and rotting SCTLR_ELx field definitions Will Deacon
@ 2019-07-30 14:58 ` Mark Rutland
0 siblings, 0 replies; 2+ messages in thread
From: Mark Rutland @ 2019-07-30 14:58 UTC (permalink / raw)
To: Will Deacon; +Cc: james.morse, linux-arm-kernel
On Tue, Jul 30, 2019 at 03:41:21PM +0100, Will Deacon wrote:
> Our SCTLR_ELx field definitions are somewhat over-engineered in that
> they carefully define masks describing the RES0/RES1 bits and then use
> these to construct further masks representing bits to be set/cleared for
> the _EL1 and _EL2 registers.
>
> However, most of the resulting definitions aren't actually used by
> anybody and have subsequently started to bit-rot when new fields have
> been added by the architecture, resulting in fields being part of the
> RES0 mask despite being defined and used elsewhere.
>
> Rather than fix up these masks, simply remove the unused parts entirely
> so that we can drop the maintenance burden. We can always add things
> back if we need them in the future.
>
> Signed-off-by: Will Deacon <will@kernel.org>
I have no strong feelings either way, so FWIW:
Acked-by: Mark Rutland <mark.rutland@arm.com>
Mark.
> ---
> arch/arm64/include/asm/sysreg.h | 29 -----------------------------
> 1 file changed, 29 deletions(-)
>
> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> index 06ebcfef73df..1df45c7ffcf7 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -499,28 +499,11 @@
> #define SCTLR_EL2_RES1 ((BIT(4)) | (BIT(5)) | (BIT(11)) | (BIT(16)) | \
> (BIT(18)) | (BIT(22)) | (BIT(23)) | (BIT(28)) | \
> (BIT(29)))
> -#define SCTLR_EL2_RES0 ((BIT(6)) | (BIT(7)) | (BIT(8)) | (BIT(9)) | \
> - (BIT(10)) | (BIT(13)) | (BIT(14)) | (BIT(15)) | \
> - (BIT(17)) | (BIT(20)) | (BIT(24)) | (BIT(26)) | \
> - (BIT(27)) | (BIT(30)) | (BIT(31)) | \
> - (0xffffefffUL << 32))
>
> #ifdef CONFIG_CPU_BIG_ENDIAN
> #define ENDIAN_SET_EL2 SCTLR_ELx_EE
> -#define ENDIAN_CLEAR_EL2 0
> #else
> #define ENDIAN_SET_EL2 0
> -#define ENDIAN_CLEAR_EL2 SCTLR_ELx_EE
> -#endif
> -
> -/* SCTLR_EL2 value used for the hyp-stub */
> -#define SCTLR_EL2_SET (SCTLR_ELx_IESB | ENDIAN_SET_EL2 | SCTLR_EL2_RES1)
> -#define SCTLR_EL2_CLEAR (SCTLR_ELx_M | SCTLR_ELx_A | SCTLR_ELx_C | \
> - SCTLR_ELx_SA | SCTLR_ELx_I | SCTLR_ELx_WXN | \
> - SCTLR_ELx_DSSBS | ENDIAN_CLEAR_EL2 | SCTLR_EL2_RES0)
> -
> -#if (SCTLR_EL2_SET ^ SCTLR_EL2_CLEAR) != 0xffffffffffffffffUL
> -#error "Inconsistent SCTLR_EL2 set/clear bits"
> #endif
>
> /* SCTLR_EL1 specific flags. */
> @@ -539,16 +522,11 @@
>
> #define SCTLR_EL1_RES1 ((BIT(11)) | (BIT(20)) | (BIT(22)) | (BIT(28)) | \
> (BIT(29)))
> -#define SCTLR_EL1_RES0 ((BIT(6)) | (BIT(10)) | (BIT(13)) | (BIT(17)) | \
> - (BIT(27)) | (BIT(30)) | (BIT(31)) | \
> - (0xffffefffUL << 32))
>
> #ifdef CONFIG_CPU_BIG_ENDIAN
> #define ENDIAN_SET_EL1 (SCTLR_EL1_E0E | SCTLR_ELx_EE)
> -#define ENDIAN_CLEAR_EL1 0
> #else
> #define ENDIAN_SET_EL1 0
> -#define ENDIAN_CLEAR_EL1 (SCTLR_EL1_E0E | SCTLR_ELx_EE)
> #endif
>
> #define SCTLR_EL1_SET (SCTLR_ELx_M | SCTLR_ELx_C | SCTLR_ELx_SA |\
> @@ -556,13 +534,6 @@
> SCTLR_EL1_DZE | SCTLR_EL1_UCT |\
> SCTLR_EL1_NTWE | SCTLR_ELx_IESB | SCTLR_EL1_SPAN |\
> ENDIAN_SET_EL1 | SCTLR_EL1_UCI | SCTLR_EL1_RES1)
> -#define SCTLR_EL1_CLEAR (SCTLR_ELx_A | SCTLR_EL1_CP15BEN | SCTLR_EL1_ITD |\
> - SCTLR_EL1_UMA | SCTLR_ELx_WXN | ENDIAN_CLEAR_EL1 |\
> - SCTLR_ELx_DSSBS | SCTLR_EL1_NTWI | SCTLR_EL1_RES0)
> -
> -#if (SCTLR_EL1_SET ^ SCTLR_EL1_CLEAR) != 0xffffffffffffffffUL
> -#error "Inconsistent SCTLR_EL1 set/clear bits"
> -#endif
>
> /* id_aa64isar0 */
> #define ID_AA64ISAR0_TS_SHIFT 52
> --
> 2.11.0
>
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2019-07-30 14:41 [PATCH] arm64: sysreg: Remove unused and rotting SCTLR_ELx field definitions Will Deacon
2019-07-30 14:58 ` Mark Rutland
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