[PATCH 0/2] arm64: Add some missing userspace ABI documentation

[PATCH 0/2] arm64: Add some missing userspace ABI documentation

[Mark Brown]

I noticed that we've added HWCAP2_HBC without updating the
documentation, and in the process also noticed that some user visible
fields in ID_AA64ISAR2_EL1 are not documented.  Fix these issues.

Given the lack of any automatic generation or auditing there's almost
certainly more fields that are broken in cpu-feature-registers.rst, I
didn't check any other registers.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
Mark Brown (2):
      arm64/hbc: Document HWCAP2_HBC
      arm64: Document missing userspace visible fields in ID_AA64ISAR2_EL1

 Documentation/arch/arm64/cpu-feature-registers.rst | 10 ++++++++++
 Documentation/arch/arm64/elf_hwcaps.rst            |  3 +++
 2 files changed, 13 insertions(+)
---
base-commit: 0bb80ecc33a8fb5a682236443c1e740d5c917d1d
change-id: 20230913-arm64-feat-hbc-doc-08e3d1741fdb

Best regards,
-- 
Mark Brown <broonie@kernel.org>

[PATCH 1/2] arm64/hbc: Document HWCAP2_HBC

[Mark Brown]

When we added support for FEAT_HBC we added a new hwcap but did not
document that we had done so, add the documentation.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 Documentation/arch/arm64/elf_hwcaps.rst | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/arch/arm64/elf_hwcaps.rst b/Documentation/arch/arm64/elf_hwcaps.rst
index 8c8addb4194c..76ff9d7398fd 100644
--- a/Documentation/arch/arm64/elf_hwcaps.rst
+++ b/Documentation/arch/arm64/elf_hwcaps.rst
@@ -305,6 +305,9 @@ HWCAP2_SMEF16F16
 HWCAP2_MOPS
     Functionality implied by ID_AA64ISAR2_EL1.MOPS == 0b0001.
 
+HWCAP2_HBC
+    Functionality implied by ID_AA64ISAR2_EL1.BC == 0b0001.
+
 4. Unused AT_HWCAP bits
 -----------------------
 

-- 
2.30.2

[PATCH 2/2] arm64: Document missing userspace visible fields in ID_AA64ISAR2_EL1

[Mark Brown]

We have exposed a number of fields in ID_AA64ISAR2_EL1 to usersapce without
adding the matching documentation in cpu-feature-registers.rst, update it
to match the implementation.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 Documentation/arch/arm64/cpu-feature-registers.rst | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/arch/arm64/cpu-feature-registers.rst b/Documentation/arch/arm64/cpu-feature-registers.rst
index 4e4625f2455f..46fd82acafab 100644
--- a/Documentation/arch/arm64/cpu-feature-registers.rst
+++ b/Documentation/arch/arm64/cpu-feature-registers.rst
@@ -288,8 +288,18 @@ infrastructure:
      +------------------------------+---------+---------+
      | Name                         |  bits   | visible |
      +------------------------------+---------+---------+
+     | CSSC                         | [55-52] |    y    |
+     +------------------------------+---------+---------+
+     | RPRFM                        | [51-48] |    y    |
+     +------------------------------+---------+---------+
+     | BC                           | [23-20] |    y    |
+     +------------------------------+---------+---------+
      | MOPS                         | [19-16] |    y    |
      +------------------------------+---------+---------+
+     | APA3                         | [15-12] |    y    |
+     +------------------------------+---------+---------+
+     | GPA3                         | [11-8]  |    y    |
+     +------------------------------+---------+---------+
      | RPRES                        | [7-4]   |    y    |
      +------------------------------+---------+---------+
      | WFXT                         | [3-0]   |    y    |

-- 
2.30.2

Re: [PATCH 0/2] arm64: Add some missing userspace ABI documentation

[Joey Gouly]

On Thu, Sep 14, 2023 at 11:09:28AM +0100, Mark Brown wrote:
> I noticed that we've added HWCAP2_HBC without updating the
> documentation, and in the process also noticed that some user visible
> fields in ID_AA64ISAR2_EL1 are not documented.  Fix these issues.
> 
> Given the lack of any automatic generation or auditing there's almost
> certainly more fields that are broken in cpu-feature-registers.rst, I
> didn't check any other registers.
> 
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
> Mark Brown (2):
>       arm64/hbc: Document HWCAP2_HBC
>       arm64: Document missing userspace visible fields in ID_AA64ISAR2_EL1
> 
>  Documentation/arch/arm64/cpu-feature-registers.rst | 10 ++++++++++
>  Documentation/arch/arm64/elf_hwcaps.rst            |  3 +++
>  2 files changed, 13 insertions(+)
> ---
> base-commit: 0bb80ecc33a8fb5a682236443c1e740d5c917d1d
> change-id: 20230913-arm64-feat-hbc-doc-08e3d1741fdb
> 
> Best regards,
> -- 
> Mark Brown <broonie@kernel.org>
> 

I sent out a fix for this yesterday:
	https://lore.kernel.org/linux-arm-kernel/6162249d-dc0f-8755-9439-3ada8a88f424@arm.com/T/#t

Kristina also noticed cpu-feature-registers.rst hadn't been updated either, so I was just about to
send out a v2 that matches your patches. I won't do that since you've just done it!

Reviewed-by: Joey Gouly <joey.gouly@arm.com>

Thanks,
Joey

Re: [PATCH 0/2] arm64: Add some missing userspace ABI documentation

[Will Deacon]

On Thu, 14 Sep 2023 11:09:28 +0100, Mark Brown wrote:
> I noticed that we've added HWCAP2_HBC without updating the
> documentation, and in the process also noticed that some user visible
> fields in ID_AA64ISAR2_EL1 are not documented.  Fix these issues.
> 
> Given the lack of any automatic generation or auditing there's almost
> certainly more fields that are broken in cpu-feature-registers.rst, I
> didn't check any other registers.
> 
> [...]

Applied to arm64 (for-next/fixes), thanks!

[1/2] arm64/hbc: Document HWCAP2_HBC
      https://git.kernel.org/arm64/c/5ad361f42fe4
[2/2] arm64: Document missing userspace visible fields in ID_AA64ISAR2_EL1
      https://git.kernel.org/arm64/c/44a5b6b5c7fe

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev