arm64: Allow the idreg override to deal with variable field width

Currently, the override mechanism can only deal with 4bit fields,
which is the most common case. However, we now have a bunch of
ID registers that have more diverse field widths, such as
ID_AA64SMFR0_EL1, which has fields that are a single bit wide.

Add the support for variable width, and a macro that encodes
a feature width of 4 for all existing override.

No functional change.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220630160500.1536744-6-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index 03185bc..1e5f3db 100644 (file)
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -27,10 +27,13 @@ struct ftr_set_desc {
        struct {
                char                    name[FTR_DESC_FIELD_LEN];
                u8                      shift;
+               u8                      width;
                bool                    (*filter)(u64 val);
        }                               fields[];
 };
 
+#define FIELD(n, s, f) { .name = n, .shift = s, .width = 4, .filter = f }
+
 static bool __init mmfr1_vh_filter(u64 val)
 {
        /*
@@ -47,7 +50,7 @@ static const struct ftr_set_desc mmfr1 __initconst = {
        .name           = "id_aa64mmfr1",
        .override       = &id_aa64mmfr1_override,
        .fields         = {
-               { "vh", ID_AA64MMFR1_VHE_SHIFT, mmfr1_vh_filter },
+               FIELD("vh", ID_AA64MMFR1_VHE_SHIFT, mmfr1_vh_filter),
                {}
        },
 };
@@ -56,8 +59,8 @@ static const struct ftr_set_desc pfr1 __initconst = {
        .name           = "id_aa64pfr1",
        .override       = &id_aa64pfr1_override,
        .fields         = {
-               { "bt", ID_AA64PFR1_BT_SHIFT },
-               { "mte", ID_AA64PFR1_MTE_SHIFT},
+               FIELD("bt", ID_AA64PFR1_BT_SHIFT, NULL),
+               FIELD("mte", ID_AA64PFR1_MTE_SHIFT, NULL),
                {}
        },
 };
@@ -66,10 +69,10 @@ static const struct ftr_set_desc isar1 __initconst = {
        .name           = "id_aa64isar1",
        .override       = &id_aa64isar1_override,
        .fields         = {
-               { "gpi", ID_AA64ISAR1_GPI_SHIFT },
-               { "gpa", ID_AA64ISAR1_GPA_SHIFT },
-               { "api", ID_AA64ISAR1_API_SHIFT },
-               { "apa", ID_AA64ISAR1_APA_SHIFT },
+               FIELD("gpi", ID_AA64ISAR1_GPI_SHIFT, NULL),
+               FIELD("gpa", ID_AA64ISAR1_GPA_SHIFT, NULL),
+               FIELD("api", ID_AA64ISAR1_API_SHIFT, NULL),
+               FIELD("apa", ID_AA64ISAR1_APA_SHIFT, NULL),
                {}
        },
 };
@@ -78,8 +81,8 @@ static const struct ftr_set_desc isar2 __initconst = {
        .name           = "id_aa64isar2",
        .override       = &id_aa64isar2_override,
        .fields         = {
-               { "gpa3", ID_AA64ISAR2_GPA3_SHIFT },
-               { "apa3", ID_AA64ISAR2_APA3_SHIFT },
+               FIELD("gpa3", ID_AA64ISAR2_GPA3_SHIFT, NULL),
+               FIELD("apa3", ID_AA64ISAR2_APA3_SHIFT, NULL),
                {}
        },
 };
@@ -92,7 +95,7 @@ static const struct ftr_set_desc kaslr __initconst = {
        .override       = &kaslr_feature_override,
 #endif
        .fields         = {
-               { "disabled", 0 },
+               FIELD("disabled", 0, NULL),
                {}
        },
 };
@@ -147,7 +150,8 @@ static void __init match_options(const char *cmdline)
 
                for (f = 0; strlen(regs[i]->fields[f].name); f++) {
                        u64 shift = regs[i]->fields[f].shift;
-                       u64 mask = 0xfUL << shift;
+                       u64 width = regs[i]->fields[f].width ?: 4;
+                       u64 mask = GENMASK_ULL(shift + width - 1, shift);
                        u64 v;
 
                        if (find_field(cmdline, regs[i], f, &v))
@@ -155,7 +159,7 @@ static void __init match_options(const char *cmdline)
 
                        /*
                         * If an override gets filtered out, advertise
-                        * it by setting the value to 0xf, but
+                        * it by setting the value to the all-ones while
                         * clearing the mask... Yes, this is fragile.
                         */
                        if (regs[i]->fields[f].filter &&