arm64: arm64_ftr_reg->name may not be a human-readable string

The id argument of ARM64_FTR_REG_OVERRIDE() is used for two purposes:
one as the system register encoding (used for the sys_id field of
__ftr_reg_entry), and the other as the register name (stringified
and used for the name field of arm64_ftr_reg), which is debug
information. The id argument is supposed to be a macro that
indicates an encoding of the register (eg. SYS_ID_AA64PFR0_EL1, etc).

ARM64_FTR_REG(), which also has the same id argument,
uses ARM64_FTR_REG_OVERRIDE() and passes the id to the macro.
Since the id argument is completely macro-expanded before it is
substituted into a macro body of ARM64_FTR_REG_OVERRIDE(),
the stringified id in the body of ARM64_FTR_REG_OVERRIDE is not
a human-readable register name, but a string of numeric bitwise
operations.

Fix this so that human-readable register names are available as
debug information.

Fixes: 8f266a5d878a ("arm64: cpufeature: Add global feature override facility")
Signed-off-by: Reiji Watanabe <reijiw@google.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211101045421.2215822-1-reijiw@google.com
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index ecbdff7..7de9619 100644 (file)
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -573,15 +573,19 @@ static const struct arm64_ftr_bits ftr_raz[] = {
        ARM64_FTR_END,
 };
 
-#define ARM64_FTR_REG_OVERRIDE(id, table, ovr) {               \
+#define __ARM64_FTR_REG_OVERRIDE(id_str, id, table, ovr) {     \
                .sys_id = id,                                   \
                .reg =  &(struct arm64_ftr_reg){                \
-                       .name = #id,                            \
+                       .name = id_str,                         \
                        .override = (ovr),                      \
                        .ftr_bits = &((table)[0]),              \
        }}
 
-#define ARM64_FTR_REG(id, table) ARM64_FTR_REG_OVERRIDE(id, table, &no_override)
+#define ARM64_FTR_REG_OVERRIDE(id, table, ovr) \
+       __ARM64_FTR_REG_OVERRIDE(#id, id, table, ovr)
+
+#define ARM64_FTR_REG(id, table)               \
+       __ARM64_FTR_REG_OVERRIDE(#id, id, table, &no_override)
 
 struct arm64_ftr_override __ro_after_init id_aa64mmfr1_override;
 struct arm64_ftr_override __ro_after_init id_aa64pfr1_override;