arm64: sysreg: Add validation checks to sysreg header generation script

JIRA: https://issues.redhat.com/browse/RHEL-101059

commit 382cbbe
Author: Fuad Tabba <tabba@google.com>
Date: Fri, 29 Aug 2025 10:51:43 +0100

    The gen_sysreg.awk script processes the system register specification in
    the sysreg text file to generate C macro definitions. The current script
    will silently accept certain errors in the specification file, leading
    to incorrect header generation.

    For example, a Sysreg or SysregFields can be accidentally duplicated,
    causing its macros to be emitted twice. An Enum can contain duplicate
    values for different items, which is architecturally incorrect.

    Add checks to catch these errors at build time. The script now tracks
    all seen Sysreg and SysregFields definitions and checks for duplicates.
    It also tracks values within each Enum block to ensure entries are
    unique.

    Acked-by: Marc Zyngier <maz@kernel.org>
    Signed-off-by: Fuad Tabba <tabba@google.com>
    Acked-by: Mark Rutland <mark.rutland@arm.com>
    Signed-off-by: Will Deacon <will@kernel.org>

Signed-off-by: Mark Salter <msalter@redhat.com>

Author: mosalter

arch/arm64/tools/gen-sysreg.awk

@@ -122,6 +122,10 @@ $1 == "SysregFields" && block_current() == "Root" {
 	res1 = "UL(0)"
 	unkn = "UL(0)"
 
+	if (reg in defined_fields)
+		fatal("Duplicate SysregFields definition for " reg)
+	defined_fields[reg] = 1
+
 	next_bit = 63
 
 	next
@@ -162,6 +166,10 @@ $1 == "Sysreg" && block_current() == "Root" {
 	res1 = "UL(0)"
 	unkn = "UL(0)"
 
+	if (reg in defined_regs)
+		fatal("Duplicate Sysreg definition for " reg)
+	defined_regs[reg] = 1
+
 	define("REG_" reg, "S" op0 "_" op1 "_C" crn "_C" crm "_" op2)
 	define("SYS_" reg, "sys_reg(" op0 ", " op1 ", " crn ", " crm ", " op2 ")")
 
@@ -284,6 +292,8 @@ $1 == "SignedEnum" && (block_current() == "Sysreg" || block_current() == "Sysreg
 	define_field(reg, field, msb, lsb)
 	define_field_sign(reg, field, "true")
 
+	delete seen_enum_vals
+
 	next
 }
 
@@ -297,6 +307,8 @@ $1 == "UnsignedEnum" && (block_current() == "Sysreg" || block_current() == "Sysr
 	define_field(reg, field, msb, lsb)
 	define_field_sign(reg, field, "false")
 
+	delete seen_enum_vals
+
 	next
 }
 
@@ -309,6 +321,8 @@ $1 == "Enum" && (block_current() == "Sysreg" || block_current() == "SysregFields
 
 	define_field(reg, field, msb, lsb)
 
+	delete seen_enum_vals
+
 	next
 }
 
@@ -320,6 +334,8 @@ $1 == "EndEnum" && block_current() == "Enum" {
 	lsb = null
 	print ""
 
+	delete seen_enum_vals
+
 	block_pop()
 	next
 }
@@ -329,6 +345,10 @@ $1 == "EndEnum" && block_current() == "Enum" {
 	val = $1
 	name = $2
 
+	if (val in seen_enum_vals)
+		fatal("Duplicate Enum value " val " for " name)
+	seen_enum_vals[val] = 1
+
 	define(reg "_" field "_" name, "UL(" val ")")
 	next
 }