[PATCH v3 1/5] arm64/sysreg: Fix checks for incomplete sysreg definitions

Sascha Bischoff Sascha.Bischoff at arm.com
Wed Oct 22 06:45:36 PDT 2025


From: Sascha Bischoff <Sascha.Bischoff at arm.com>

The checks for incomplete sysreg definitions were checking if the
next_bit was greater than 0, which is incorrect and missed occasions
where bit 0 hasn't been defined for a sysreg. The reason is that
next_bit is -1 when all bits have been processed (LSB - 1).

Change the checks to use >= 0, instead. Also, set next_bit in Mapping
to -1 instead of 0 to match these new checks.

There are no changes to the generated sysreg definitons as part of
this change, and conveniently no definitions lack definitions for bit
0.

Signed-off-by: Sascha Bischoff <sascha.bischoff at arm.com>
Reviewed-by: Mark Brown <broonie at kernel.org>
---
 arch/arm64/tools/gen-sysreg.awk | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/tools/gen-sysreg.awk b/arch/arm64/tools/gen-sysreg.awk
index bbbb812603e8..b5e5705ddbb5 100755
--- a/arch/arm64/tools/gen-sysreg.awk
+++ b/arch/arm64/tools/gen-sysreg.awk
@@ -133,7 +133,7 @@ $1 == "SysregFields" && block_current() == "Root" {
 
 $1 == "EndSysregFields" && block_current() == "SysregFields" {
 	expect_fields(1)
-	if (next_bit > 0)
+	if (next_bit >= 0)
 		fatal("Unspecified bits in " reg)
 
 	define(reg "_RES0", "(" res0 ")")
@@ -188,7 +188,7 @@ $1 == "Sysreg" && block_current() == "Root" {
 
 $1 == "EndSysreg" && block_current() == "Sysreg" {
 	expect_fields(1)
-	if (next_bit > 0)
+	if (next_bit >= 0)
 		fatal("Unspecified bits in " reg)
 
 	if (res0 != null)
@@ -225,7 +225,7 @@ $1 == "EndSysreg" && block_current() == "Sysreg" {
 	print "/* For " reg " fields see " $2 " */"
 	print ""
 
-        next_bit = 0
+        next_bit = -1
 	res0 = null
 	res1 = null
 	unkn = null
-- 
2.34.1



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