[PATCH v3 3/3] arm64: sysreg: Add validation checks to sysreg header generation script

[Fuad Tabba]

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 at kernel.org>
Signed-off-by: Fuad Tabba <tabba at google.com>
---
 arch/arm64/tools/gen-sysreg.awk | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/arm64/tools/gen-sysreg.awk b/arch/arm64/tools/gen-sysreg.awk
index f2a1732cb1f6..bbbb812603e8 100755
--- a/arch/arm64/tools/gen-sysreg.awk
+++ b/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
 }
-- 
2.51.0.338.gd7d06c2dae-goog