[PATCH v6 08/12] arm64: Add sysreg header generation scripting
Mark Brown
broonie at kernel.org
Tue May 3 10:02:29 PDT 2022
From: Mark Rutland <mark.rutland at arm.com>
The arm64 kernel requires some metadata for each system register it may
need to access. Currently we have:
* A SYS_<regname> definition which sorresponds to a sys_reg() macro.
This is used both to look up a sysreg by encoding (e.g. in KVM), and
also to generate code to access a sysreg where the assembler is
unaware of the specific sysreg encoding.
Where assemblers support the S3_<op1>_C<crn>_C<crm>_<op2> syntax for
system registers, we could use this rather than manually assembling
the instructions. However, we don't have consistent definitions for
these and we currently still need to handle toolchains that lack this
feature.
* A set of <regname>_<fieldname>_SHIFT and <regname>_<fieldname>_MASK
definitions, which can be used to extract fields from the register, or
to construct a register from a set of fields.
These do not follow the convention used by <linux/bitfield.h>, and the
masks are not shifted into place, preventing their use in FIELD_PREP()
and FIELD_GET(). We require the SHIFT definitions for inline assembly
(and WIDTH definitions would be helpful for UBFX/SBFX), so we cannot
only define a shifted MASK. Defining a SHIFT, WIDTH, shifted MASK and
unshifted MASK is tedious and error-prone and life is much easier when
they can be relied up to exist when writing code.
* A set of <regname>_<fieldname>_<valname> definitions for each
enumerated value a field may hold. These are used when identifying the
presence of features.
Atop of this, other code has to build up metadata at runtime (e.g. the
sets of RES0/RES1 bits in a register).
This patch adds scripting so that we can have an easier-to-manage
canonical representation of this metadata, from which we can generate
all the definitions necessary for various use-cases, e.g.
| #define REG_ID_AA64ISAR0_EL1 S3_0_C0_C6_0
| #define SYS_ID_AA64ISAR0_EL1 sys_reg(3, 0, 0, 6, 0)
| #define SYS_ID_AA64ISAR0_EL1_Op0 3
| #define SYS_ID_AA64ISAR0_EL1_Op1 0
| #define SYS_ID_AA64ISAR0_EL1_CRn 0
| #define SYS_ID_AA64ISAR0_EL1_CRm 6
| #define SYS_ID_AA64ISAR0_EL1_Op2 0
| #define ID_AA64ISAR0_EL1_RNDR GENMASK(63, 60)
| #define ID_AA64ISAR0_EL1_RNDR_MASK GENMASK(63, 60)
| #define ID_AA64ISAR0_EL1_RNDR_SHIFT 60
| #define ID_AA64ISAR0_EL1_RNDR_WIDTH 4
| #define ID_AA64ISAR0_EL1_RNDR_NI UL(0b0000)
| #define ID_AA64ISAR0_EL1_RNDR_IMP UL(0b0001)
The script requires that all bits in the register be specified and that
there be no overlapping fields. This helps the script spot errors in the
input but means that the few registers which change layout at runtime
depending on things like virtualisation settings will need some manual
handling. No actual register conversions are done here but a header for
the register data with some documention of the format is provided.
For cases where multiple registers share a layout (eg, when identical
controls are provided at multiple ELs) the register fields can be
defined once and referenced from the actual registers, currently we do
not generate actual defines for the individual registers.
At the moment this is only intended to express metadata from the
architecture, and does not handle policy imposed by the kernel, such as
values exposed to userspace or VMs. In future this could be extended to
express such information.
This script was mostly written by Mark Rutland but has been extended by
Mark Brown to improve validation of input and better integrate with the
kernel.
Signed-off-by: Mark Rutland <mark.rutland at arm.com>
Co-Developed-by: Mark Brown <broonie at kernel.org>
Signed-off-by: Mark Brown <broonie at kernel.org>
---
arch/arm64/tools/gen-sysreg.awk | 261 ++++++++++++++++++++++++++++++++
arch/arm64/tools/sysreg | 48 ++++++
2 files changed, 309 insertions(+)
create mode 100755 arch/arm64/tools/gen-sysreg.awk
create mode 100644 arch/arm64/tools/sysreg
diff --git a/arch/arm64/tools/gen-sysreg.awk b/arch/arm64/tools/gen-sysreg.awk
new file mode 100755
index 000000000000..3ffd77cbb499
--- /dev/null
+++ b/arch/arm64/tools/gen-sysreg.awk
@@ -0,0 +1,261 @@
+#!/bin/awk -f
+# SPDX-License-Identifier: GPL-2.0
+# gen-sysreg.awk: arm64 sysreg header generator
+#
+# Usage: awk -f gen-sysreg.awk sysregs.txt
+
+# Log an error and terminate
+function fatal(msg) {
+ print "Error at " NR ": " msg > "/dev/stderr"
+ exit 1
+}
+
+# Sanity check that the start or end of a block makes sense at this point in
+# the file. If not, produce an error and terminate.
+#
+# @this - the $Block or $EndBlock
+# @prev - the only valid block to already be in (value of @block)
+# @new - the new value of @block
+function change_block(this, prev, new) {
+ if (block != prev)
+ fatal("unexpected " this " (inside " block ")")
+
+ block = new
+}
+
+# Sanity check the number of records for a field makes sense. If not, produce
+# an error and terminate.
+function expect_fields(nf) {
+ if (NF != nf)
+ fatal(NF " fields found where " nf " expected")
+}
+
+# Print a CPP macro definition, padded with spaces so that the macro bodies
+# line up in a column
+function define(name, val) {
+ printf "%-48s%s\n", "#define " name, val
+}
+
+# Print standard BITMASK/SHIFT/WIDTH CPP definitions for a field
+function define_field(reg, field, msb, lsb) {
+ define(reg "_" field, "GENMASK(" msb ", " lsb ")")
+ define(reg "_" field "_MASK", "GENMASK(" msb ", " lsb ")")
+ define(reg "_" field "_SHIFT", lsb)
+ define(reg "_" field "_WIDTH", msb - lsb + 1)
+}
+
+# Parse a "<msb>[:<lsb>]" string into the global variables @msb and @lsb
+function parse_bitdef(reg, field, bitdef, _bits)
+{
+ if (bitdef ~ /^[0-9]+$/) {
+ msb = bitdef
+ lsb = bitdef
+ } else if (split(bitdef, _bits, ":") == 2) {
+ msb = _bits[1]
+ lsb = _bits[2]
+ } else {
+ fatal("invalid bit-range definition '" bitdef "'")
+ }
+
+
+ if (msb != next_bit)
+ fatal(reg "." field " starts at " msb " not " next_bit)
+ if (63 < msb || msb < 0)
+ fatal(reg "." field " invalid high bit in '" bitdef "'")
+ if (63 < lsb || lsb < 0)
+ fatal(reg "." field " invalid low bit in '" bitdef "'")
+ if (msb < lsb)
+ fatal(reg "." field " invalid bit-range '" bitdef "'")
+ if (low > high)
+ fatal(reg "." field " has invalid range " high "-" low)
+
+ next_bit = lsb - 1
+}
+
+BEGIN {
+ print "#ifndef __ASM_SYSREG_DEFS_H"
+ print "#define __ASM_SYSREG_DEFS_H"
+ print ""
+ print "/* Generated file - do not edit */"
+
+ block = "None"
+}
+
+END {
+ print "#endif /* __ASM_SYSREG_DEFS_H */"
+}
+
+# skip blank lines and comment lines
+/^$/ { next }
+/^#/ { next }
+
+/^SysregFields/ {
+ change_block("SysregFields", "None", "SysregFields")
+ expect_fields(2)
+
+ reg = $2
+
+ res0 = "UL(0)"
+ res1 = "UL(0)"
+
+ print ""
+
+ next_bit = 63
+
+ next
+}
+
+/^EndSysregFields/ {
+ if (next_bit > 0)
+ fatal("Unspecified bits in " reg)
+
+ change_block("EndSysregFields", "SysregFields", "None")
+
+ define(reg "_RES0", "(" res0 ")")
+ define(reg "_RES1", "(" res1 ")")
+ print ""
+
+ reg = null
+ res0 = null
+ res1 = null
+
+ next
+}
+
+/^Sysreg/ {
+ change_block("Sysreg", "None", "Sysreg")
+ expect_fields(7)
+
+ reg = $2
+ op0 = $3
+ op1 = $4
+ crn = $5
+ crm = $6
+ op2 = $7
+
+ res0 = "UL(0)"
+ res1 = "UL(0)"
+
+ define("REG_" reg, "S" op0 "_" op1 "_C" crn "_C" crm "_" op2)
+ define("SYS_" reg, "sys_reg(" op0 ", " op1 ", " crn ", " crm ", " op2 ")")
+
+ define("SYS_" reg "_Op0", op0)
+ define("SYS_" reg "_Op1", op1)
+ define("SYS_" reg "_CRn", crn)
+ define("SYS_" reg "_CRm", crm)
+ define("SYS_" reg "_Op2", op2)
+
+ print ""
+
+ next_bit = 63
+
+ next
+}
+
+/^EndSysreg/ {
+ if (next_bit > 0)
+ fatal("Unspecified bits in " reg)
+
+ change_block("EndSysreg", "Sysreg", "None")
+
+ if (res0 != null)
+ define(reg "_RES0", "(" res0 ")")
+ if (res1 != null)
+ define(reg "_RES1", "(" res1 ")")
+ print ""
+
+ reg = null
+ op0 = null
+ op1 = null
+ crn = null
+ crm = null
+ op2 = null
+ res0 = null
+ res1 = null
+
+ next
+}
+
+# Currently this is effectivey a comment, in future we may want to emit
+# defines for the fields.
+/^Fields/ && (block == "Sysreg") {
+ expect_fields(2)
+
+ if (next_bit != 63)
+ fatal("Some fields already defined for " reg)
+
+ print "/* See " $2 " */"
+ print ""
+
+ next_bit = 0
+ res0 = null
+ res1 = null
+
+ next
+}
+
+
+/^Res0/ && (block == "Sysreg" || block == "SysregFields") {
+ expect_fields(2)
+ parse_bitdef(reg, "RES0", $2)
+ field = "RES0_" msb "_" lsb
+
+ res0 = res0 " | GENMASK_ULL(" msb ", " lsb ")"
+
+ next
+}
+
+/^Res1/ && (block == "Sysreg" || block == "SysregFields") {
+ expect_fields(2)
+ parse_bitdef(reg, "RES1", $2)
+ field = "RES1_" msb "_" lsb
+
+ res1 = res1 " | GENMASK_ULL(" msb ", " lsb ")"
+
+ next
+}
+
+/^Field/ && (block == "Sysreg" || block == "SysregFields") {
+ expect_fields(3)
+ field = $3
+ parse_bitdef(reg, field, $2)
+
+ define_field(reg, field, msb, lsb)
+ print ""
+
+ next
+}
+
+/^Enum/ {
+ change_block("Enum", "Sysreg", "Enum")
+ expect_fields(3)
+ field = $3
+ parse_bitdef(reg, field, $2)
+
+ define_field(reg, field, msb, lsb)
+
+ next
+}
+
+/^EndEnum/ {
+ change_block("EndEnum", "Enum", "Sysreg")
+ field = null
+ msb = null
+ lsb = null
+ print ""
+ next
+}
+
+/0b[01]+/ && block = "Enum" {
+ expect_fields(2)
+ val = $1
+ name = $2
+
+ define(reg "_" field "_" name, "UL(" val ")")
+ next
+}
+
+# Any lines not handled by previous rules are unexpected
+{
+ fatal("unhandled statement")
+}
diff --git a/arch/arm64/tools/sysreg b/arch/arm64/tools/sysreg
new file mode 100644
index 000000000000..8e39c718c1b8
--- /dev/null
+++ b/arch/arm64/tools/sysreg
@@ -0,0 +1,48 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# System register metadata
+
+# Each System register is described by a Sysreg block:
+
+# Sysreg <name> <op0> <op1> <crn> <crm> <op2>
+# <field>
+# ...
+# EndSysreg
+
+# Within a Sysreg block, each field can be described as one of:
+
+# Res0 <msb>[:<lsb>]
+
+# Res1 <msb>[:<lsb>]
+
+# Field <msb>[:<lsb>] <name>
+
+# Enum <msb>[:<lsb>] <name>
+# <enumval> <enumname>
+# ...
+# EndEnum
+
+# Alternatively if multiple registers share the same layout then
+# a SysregFields block can be used to describe the shared layout
+
+# SysregFields <fieldsname>
+# <field>
+# ...
+# EndSysregFields
+
+# and referenced from within the Sysreg:
+
+# Sysreg <name> <op0> <op1> <crn> <crm> <op2>
+# Fields <fieldsname>
+# EndSysreg
+
+# For ID registers we adopt a few conventions for translating the
+# language in the ARM into defines:
+#
+# NI - Not implemented
+# IMP - Implemented
+#
+# In general it is recommended that new enumeration items be named for the
+# feature that introduces them (eg, FEAT_LS64_ACCDATA introduces enumeration
+# item ACCDATA) though it may be more taseful to do something else.
+
--
2.30.2
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