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Message-ID: <87bko0g8m2.wl-maz@kernel.org>
Date: Sun, 18 Dec 2022 13:11:01 +0000
From: Marc Zyngier <maz@...nel.org>
To: Akihiko Odaki <akihiko.odaki@...nix.com>
Cc: linux-kernel@...r.kernel.org, kvmarm@...ts.linux.dev,
kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org,
Mathieu Poirier <mathieu.poirier@...aro.org>,
Oliver Upton <oliver.upton@...ux.dev>,
Suzuki K Poulose <suzuki.poulose@....com>,
Alexandru Elisei <alexandru.elisei@....com>,
James Morse <james.morse@....com>,
Will Deacon <will@...nel.org>,
Catalin Marinas <catalin.marinas@....com>,
asahi@...ts.linux.dev, Alyssa Rosenzweig <alyssa@...enzweig.io>,
Sven Peter <sven@...npeter.dev>,
Hector Martin <marcan@...can.st>
Subject: Re: [PATCH v3 1/7] arm64/sysreg: Convert CCSIDR_EL1 to automatic generation
On Sun, 18 Dec 2022 11:35:12 +0000,
Akihiko Odaki <akihiko.odaki@...nix.com> wrote:
>
> On 2022/12/18 20:23, Marc Zyngier wrote:
> > On Sun, 18 Dec 2022 05:14:06 +0000,
> > Akihiko Odaki <akihiko.odaki@...nix.com> wrote:
> >>
> >> Convert CCSIDR_EL1 to automatic generation as per DDI0487I.a. The field
> >> definition is for case when FEAT_CCIDX is not implemented. Fields WT,
> >> WB, RA and WA are defined as per A.j since they are now reserved and
> >> may have UNKNOWN values in I.a, which the file format cannot represent.
> >>
> >> Signed-off-by: Akihiko Odaki <akihiko.odaki@...nix.com>
> >> ---
> >> arch/arm64/include/asm/sysreg.h | 1 -
> >> arch/arm64/tools/sysreg | 11 +++++++++++
> >> 2 files changed, 11 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
> >> index 7d301700d1a9..910e960661d3 100644
> >> --- a/arch/arm64/include/asm/sysreg.h
> >> +++ b/arch/arm64/include/asm/sysreg.h
> >> @@ -425,7 +425,6 @@
> >> #define SYS_CNTKCTL_EL1 sys_reg(3, 0, 14, 1,
> >> 0)
> >> -#define SYS_CCSIDR_EL1 sys_reg(3, 1, 0, 0, 0)
> >> #define SYS_AIDR_EL1 sys_reg(3, 1, 0, 0, 7)
> >> #define SYS_RNDR_EL0 sys_reg(3, 3, 2, 4, 0)
> >> diff --git a/arch/arm64/tools/sysreg b/arch/arm64/tools/sysreg
> >> index 384757a7eda9..acc79b5ccf92 100644
> >> --- a/arch/arm64/tools/sysreg
> >> +++ b/arch/arm64/tools/sysreg
> >> @@ -871,6 +871,17 @@ Sysreg SCXTNUM_EL1 3 0 13 0 7
> >> Field 63:0 SoftwareContextNumber
> >> EndSysreg
> >> +Sysreg CCSIDR_EL1 3 1 0 0 0
> >> +Res0 63:32
> >> +Field 31:31 WT
> >> +Field 30:30 WB
> >> +Field 29:29 RA
> >> +Field 28:28 WA
> >
> > For fields described as a single bit, the tool supports simply
> > indicating the bit number (28 rather than 28:28).
> >
> > However, I strongly recommend against describing fields that have been
> > dropped from the architecture. This only happens when these fields
> > are never used by any implementation, so describing them is at best
> > useless.
>
> arch/arm64/tools/gen-sysreg.awk does not allow a hole and requires all
> bits are described hence these descriptions. If you have an
> alternative idea I'd like to hear.
I'd simply suggest creating an UNKNOWN field encompassing bits
[21:28]. Alternatively, feel free to try the patch below, which allows
you to describe these 4 bits as "Unkn 31:28", similar to Res0/Res1.
>
> >
> >> +Field 27:13 NumSets
> >> +Field 12:3 Associavity
Also, you may want to fix the typo here (Associativity).
Thanks,
M.
From 3112be25ec785de4c92d11d5964d54f216a2289c Mon Sep 17 00:00:00 2001
From: Marc Zyngier <maz@...nel.org>
Date: Sun, 18 Dec 2022 12:55:23 +0000
Subject: [PATCH] arm64: Allow the definition of UNKNOWN system register fields
The CCSIDR_EL1 register contains an UNKNOWN field (which replaces
fields that were actually defined in previous revisions of the
architecture).
Define an 'Unkn' field type modeled after the Res0/Res1 types
to allow such description. This allows the generation of
#define CCSIDR_EL1_UNKN (UL(0) | GENMASK_ULL(31, 28))
which may have its use one day. Hopefully the architecture doesn't
add too many of those in the future.
Signed-off-by: Marc Zyngier <maz@...nel.org>
---
arch/arm64/tools/gen-sysreg.awk | 20 +++++++++++++++++++-
arch/arm64/tools/sysreg | 2 ++
2 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/tools/gen-sysreg.awk b/arch/arm64/tools/gen-sysreg.awk
index c350164a3955..e1df4b956596 100755
--- a/arch/arm64/tools/gen-sysreg.awk
+++ b/arch/arm64/tools/gen-sysreg.awk
@@ -98,6 +98,7 @@ END {
res0 = "UL(0)"
res1 = "UL(0)"
+ unkn = "UL(0)"
next_bit = 63
@@ -112,11 +113,13 @@ END {
define(reg "_RES0", "(" res0 ")")
define(reg "_RES1", "(" res1 ")")
+ define(reg "_UNKN", "(" unkn ")")
print ""
reg = null
res0 = null
res1 = null
+ unkn = null
next
}
@@ -134,6 +137,7 @@ END {
res0 = "UL(0)"
res1 = "UL(0)"
+ unkn = "UL(0)"
define("REG_" reg, "S" op0 "_" op1 "_C" crn "_C" crm "_" op2)
define("SYS_" reg, "sys_reg(" op0 ", " op1 ", " crn ", " crm ", " op2 ")")
@@ -161,7 +165,9 @@ END {
define(reg "_RES0", "(" res0 ")")
if (res1 != null)
define(reg "_RES1", "(" res1 ")")
- if (res0 != null || res1 != null)
+ if (unkn != null)
+ define(reg "_UNKN", "(" unkn ")")
+ if (res0 != null || res1 != null || unkn != null)
print ""
reg = null
@@ -172,6 +178,7 @@ END {
op2 = null
res0 = null
res1 = null
+ unkn = null
next
}
@@ -190,6 +197,7 @@ END {
next_bit = 0
res0 = null
res1 = null
+ unkn = null
next
}
@@ -215,6 +223,16 @@ END {
next
}
+/^Unkn/ && (block == "Sysreg" || block == "SysregFields") {
+ expect_fields(2)
+ parse_bitdef(reg, "UNKN", $2)
+ field = "UNKN_" msb "_" lsb
+
+ unkn = unkn " | GENMASK_ULL(" msb ", " lsb ")"
+
+ next
+}
+
/^Field/ && (block == "Sysreg" || block == "SysregFields") {
expect_fields(3)
field = $3
diff --git a/arch/arm64/tools/sysreg b/arch/arm64/tools/sysreg
index bd5fceb26c54..472f68f020d9 100644
--- a/arch/arm64/tools/sysreg
+++ b/arch/arm64/tools/sysreg
@@ -15,6 +15,8 @@
# Res1 <msb>[:<lsb>]
+# Unkn <msb>[:<lsb>]
+
# Field <msb>[:<lsb>] <name>
# Enum <msb>[:<lsb>] <name>
--
2.34.1
--
Without deviation from the norm, progress is not possible.
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