git: 4bc68fa98f68 - main - arm64: Support managing features from loader
- Go to: [ bottom of page ] [ top of archives ] [ this month ]
Date: Thu, 04 Sep 2025 16:28:48 UTC
The branch main has been updated by andrew:
URL: https://cgit.FreeBSD.org/src/commit/?id=4bc68fa98f68211ee7943d77cfc91f60ccb5880d
commit 4bc68fa98f68211ee7943d77cfc91f60ccb5880d
Author: Andrew Turner <andrew@FreeBSD.org>
AuthorDate: 2025-09-04 14:45:09 +0000
Commit: Andrew Turner <andrew@FreeBSD.org>
CommitDate: 2025-09-04 14:45:09 +0000
arm64: Support managing features from loader
Allow the user to enable/disable supported cpu features/errata from a
known tunable. This will allow the user to disable features, e.g. to
work around broken firmware. It can also be used to enable workarounds
for rare errata.
Reviewed by: imp
Sponsored by: Arm Ltd
Differential Revision: https://reviews.freebsd.org/D52358
---
sys/arm/arm/generic_timer.c | 9 ++++++---
sys/arm64/arm64/cpu_feat.c | 22 +++++++++++++++++++++-
sys/arm64/arm64/identcpu.c | 10 +++++-----
sys/arm64/arm64/machdep.c | 7 +++++--
sys/arm64/arm64/pmap.c | 9 ++++++---
sys/arm64/arm64/ptrauth.c | 8 ++++----
sys/arm64/include/cpu_feat.h | 27 ++++++++++++++++++++++++++-
7 files changed, 73 insertions(+), 19 deletions(-)
diff --git a/sys/arm/arm/generic_timer.c b/sys/arm/arm/generic_timer.c
index 27c985c5fcbe..97976408c943 100644
--- a/sys/arm/arm/generic_timer.c
+++ b/sys/arm/arm/generic_timer.c
@@ -882,14 +882,17 @@ DELAY(int usec)
TSEXIT();
}
-static bool
+static cpu_feat_en
wfxt_check(const struct cpu_feat *feat __unused, u_int midr __unused)
{
uint64_t id_aa64isar2;
if (!get_kernel_reg(ID_AA64ISAR2_EL1, &id_aa64isar2))
- return (false);
- return (ID_AA64ISAR2_WFxT_VAL(id_aa64isar2) != ID_AA64ISAR2_WFxT_NONE);
+ return (FEAT_ALWAYS_DISABLE);
+ if (ID_AA64ISAR2_WFxT_VAL(id_aa64isar2) >= ID_AA64ISAR2_WFxT_NONE)
+ return (FEAT_DEFAULT_ENABLE);
+
+ return (FEAT_ALWAYS_DISABLE);
}
static bool
diff --git a/sys/arm64/arm64/cpu_feat.c b/sys/arm64/arm64/cpu_feat.c
index fd1b8429295f..986d5079e980 100644
--- a/sys/arm64/arm64/cpu_feat.c
+++ b/sys/arm64/arm64/cpu_feat.c
@@ -40,10 +40,13 @@ static cpu_feat_errata_check_fn cpu_feat_check_cb = NULL;
void
enable_cpu_feat(uint32_t stage)
{
+ char tunable[32];
struct cpu_feat **featp, *feat;
uint32_t midr;
u_int errata_count, *errata_list;
cpu_feat_errata errata_status;
+ cpu_feat_en check_status;
+ bool val;
MPASS((stage & ~CPU_FEAT_STAGE_MASK) == 0);
@@ -60,9 +63,26 @@ enable_cpu_feat(uint32_t stage)
PCPU_GET(cpuid) != 0)
continue;
- if (feat->feat_check != NULL && !feat->feat_check(feat, midr))
+ if (feat->feat_check != NULL)
continue;
+ check_status = feat->feat_check(feat, midr);
+ /* Ignore features that are not present */
+ if (check_status == FEAT_ALWAYS_DISABLE)
+ continue;
+
+ snprintf(tunable, sizeof(tunable), "hw.feat.%s",
+ feat->feat_name);
+ if (TUNABLE_BOOL_FETCH(tunable, &val)) {
+ /* Is the feature disabled by the tunable? */
+ if (!val)
+ continue;
+ /* If enabled by the tunable then enable it */
+ } else if (check_status == FEAT_DEFAULT_DISABLE) {
+ /* No tunable set and disabled by default */
+ continue;
+ }
+
/*
* Check if the feature has any errata that may need a
* workaround applied (or it is to install the workaround for
diff --git a/sys/arm64/arm64/identcpu.c b/sys/arm64/arm64/identcpu.c
index 6d70692fdf5d..f271891f423d 100644
--- a/sys/arm64/arm64/identcpu.c
+++ b/sys/arm64/arm64/identcpu.c
@@ -2293,16 +2293,16 @@ user_ctr_has_neoverse_n1_1542419(uint32_t midr, uint64_t ctr)
return (false);
}
-static bool
-user_ctr_check(const struct cpu_feat *feat __unused, u_int midr __unused)
+static cpu_feat_en
+user_ctr_check(const struct cpu_feat *feat __unused, u_int midr)
{
if (emulate_ctr)
- return (true);
+ return (FEAT_DEFAULT_ENABLE);
if (user_ctr_has_neoverse_n1_1542419(midr, READ_SPECIALREG(ctr_el0)))
- return (true);
+ return (FEAT_DEFAULT_ENABLE);
- return (false);
+ return (FEAT_ALWAYS_DISABLE);
}
static bool
diff --git a/sys/arm64/arm64/machdep.c b/sys/arm64/arm64/machdep.c
index c0aeae072570..627b02e82d34 100644
--- a/sys/arm64/arm64/machdep.c
+++ b/sys/arm64/arm64/machdep.c
@@ -173,13 +173,16 @@ SYSINIT(ssp_warn, SI_SUB_COPYRIGHT, SI_ORDER_ANY, print_ssp_warning, NULL);
SYSINIT(ssp_warn2, SI_SUB_LAST, SI_ORDER_ANY, print_ssp_warning, NULL);
#endif
-static bool
+static cpu_feat_en
pan_check(const struct cpu_feat *feat __unused, u_int midr __unused)
{
uint64_t id_aa64mfr1;
id_aa64mfr1 = READ_SPECIALREG(id_aa64mmfr1_el1);
- return (ID_AA64MMFR1_PAN_VAL(id_aa64mfr1) != ID_AA64MMFR1_PAN_NONE);
+ if (ID_AA64MMFR1_PAN_VAL(id_aa64mfr1) == ID_AA64MMFR1_PAN_NONE)
+ return (FEAT_ALWAYS_DISABLE);
+
+ return (FEAT_DEFAULT_ENABLE);
}
static bool
diff --git a/sys/arm64/arm64/pmap.c b/sys/arm64/arm64/pmap.c
index 96bde42d2711..0ef23edbc0bf 100644
--- a/sys/arm64/arm64/pmap.c
+++ b/sys/arm64/arm64/pmap.c
@@ -1656,14 +1656,17 @@ pmap_init_pv_table(void)
}
}
-static bool
+static cpu_feat_en
pmap_dbm_check(const struct cpu_feat *feat __unused, u_int midr __unused)
{
uint64_t id_aa64mmfr1;
id_aa64mmfr1 = READ_SPECIALREG(id_aa64mmfr1_el1);
- return (ID_AA64MMFR1_HAFDBS_VAL(id_aa64mmfr1) >=
- ID_AA64MMFR1_HAFDBS_AF_DBS);
+ if (ID_AA64MMFR1_HAFDBS_VAL(id_aa64mmfr1) >=
+ ID_AA64MMFR1_HAFDBS_AF_DBS)
+ return (FEAT_DEFAULT_ENABLE);
+
+ return (FEAT_ALWAYS_DISABLE);
}
static bool
diff --git a/sys/arm64/arm64/ptrauth.c b/sys/arm64/arm64/ptrauth.c
index 7f453dfa278d..fdab5414e24c 100644
--- a/sys/arm64/arm64/ptrauth.c
+++ b/sys/arm64/arm64/ptrauth.c
@@ -82,7 +82,7 @@ ptrauth_disable(void)
return (false);
}
-static bool
+static cpu_feat_en
ptrauth_check(const struct cpu_feat *feat __unused, u_int midr __unused)
{
uint64_t isar;
@@ -116,14 +116,14 @@ ptrauth_check(const struct cpu_feat *feat __unused, u_int midr __unused)
if (get_kernel_reg(ID_AA64ISAR1_EL1, &isar)) {
if (ID_AA64ISAR1_APA_VAL(isar) > 0 ||
ID_AA64ISAR1_API_VAL(isar) > 0) {
- return (true);
+ return (FEAT_DEFAULT_ENABLE);
}
}
/* The QARMA3 algorithm is reported in ID_AA64ISAR2_EL1. */
if (get_kernel_reg(ID_AA64ISAR2_EL1, &isar)) {
if (ID_AA64ISAR2_APA3_VAL(isar) > 0) {
- return (true);
+ return (FEAT_DEFAULT_ENABLE);
}
}
@@ -138,7 +138,7 @@ out:
ID_AA64ISAR1_GPI_MASK, 0);
update_special_reg(ID_AA64ISAR2_EL1, ID_AA64ISAR2_APA3_MASK, 0);
- return (false);
+ return (FEAT_ALWAYS_DISABLE);
}
static bool
diff --git a/sys/arm64/include/cpu_feat.h b/sys/arm64/include/cpu_feat.h
index f62f3e334dc1..6a554b6baedf 100644
--- a/sys/arm64/include/cpu_feat.h
+++ b/sys/arm64/include/cpu_feat.h
@@ -40,6 +40,31 @@ typedef enum {
/* kernel component. */
} cpu_feat_errata;
+typedef enum {
+ /*
+ * Don't implement the feature or erratum wrokarount,
+ * e.g. the feature is not implemented or erratum is
+ * for another CPU.
+ */
+ FEAT_ALWAYS_DISABLE,
+
+ /*
+ * Disable by default, but allow the user to enable,
+ * e.g. For a rare erratum with a workaround, Arm
+ * Category B (rare) or similar.
+ */
+ FEAT_DEFAULT_DISABLE,
+
+ /*
+ * Enabled by default, bit allow the user to disable,
+ * e.g. For a common erratum with a workaround, Arm
+ * Category A or B or similar.
+ */
+ FEAT_DEFAULT_ENABLE,
+
+ /* We could add FEAT_ALWAYS_ENABLE if a need was found. */
+} cpu_feat_en;
+
#define CPU_FEAT_STAGE_MASK 0x00000001
#define CPU_FEAT_EARLY_BOOT 0x00000000
#define CPU_FEAT_AFTER_DEV 0x00000001
@@ -50,7 +75,7 @@ typedef enum {
struct cpu_feat;
-typedef bool (cpu_feat_check)(const struct cpu_feat *, u_int);
+typedef cpu_feat_en (cpu_feat_check)(const struct cpu_feat *, u_int);
typedef bool (cpu_feat_has_errata)(const struct cpu_feat *, u_int,
u_int **, u_int *);
typedef bool (cpu_feat_enable)(const struct cpu_feat *, cpu_feat_errata,