[RFC PATCH 1/4] arm64: acpi: Refactor FADT table verification

Suzuki K Poulose
2026-04-29T10:36:12Z

Refactor the FADT sanity check, such that this could be reused. We are soon
going to consume the FADT early at boot for probing the PSCI conduit, and this
will be of use.

Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
arch/arm64/kernel/acpi.c | 55 +++++++++++++++++++++-------------------
1 file changed, 29 insertions(+), 26 deletions(-)

diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index af90128cfed5..30c7b11a8a9d 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -118,6 +118,34 @@ bool acpi_psci_use_hvc(void)
return acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_USE_HVC;
}

+static int __init __acpi_fadt_sanity_check(struct acpi_table_fadt *fadt)
+{
+ struct acpi_table_header *table = (struct acpi_table_header *)fadt;
+
+ /*
+ * Revision in table header is the FADT Major revision, and there
+ * is a minor revision of FADT which was introduced by ACPI 5.1,
+ * we only deal with ACPI 5.1 or newer revision to get GIC and SMP
+ * boot protocol configuration data.
+ */
+ if (table->revision < 5 ||
+ (table->revision == 5 && fadt->minor_revision < 1)) {
+ pr_err(FW_BUG "Unsupported FADT revision %d.%d, should be 5.1+\n",
+ table->revision, fadt->minor_revision);
+
+ if (!fadt->arm_boot_flags) {
+ return -EINVAL;
+ }
+ pr_err("FADT has ARM boot flags set, assuming 5.1\n");
+ }
+
+ if (!(fadt->flags & ACPI_FADT_HW_REDUCED)) {
+ pr_err("FADT not ACPI hardware reduced compliant\n");
+ return -EINVAL;
+ }
+ return 0;
+}
+
/*
* acpi_fadt_sanity_check() - Check FADT presence and carry out sanity
* checks on it
@@ -127,7 +155,6 @@ bool acpi_psci_use_hvc(void)
static int __init acpi_fadt_sanity_check(void)
{
struct acpi_table_header *table;
- struct acpi_table_fadt *fadt;
acpi_status status;
int ret = 0;

@@ -143,32 +170,8 @@ static int __init acpi_fadt_sanity_check(void)
return -ENODEV;
}

- fadt = (struct acpi_table_fadt *)table;
+ ret = __acpi_fadt_sanity_check((struct acpi_table_fadt *)table);

- /*
- * Revision in table header is the FADT Major revision, and there
- * is a minor revision of FADT which was introduced by ACPI 5.1,
- * we only deal with ACPI 5.1 or newer revision to get GIC and SMP
- * boot protocol configuration data.
- */
- if (table->revision < 5 ||
- (table->revision == 5 && fadt->minor_revision < 1)) {
- pr_err(FW_BUG "Unsupported FADT revision %d.%d, should be 5.1+\n",
- table->revision, fadt->minor_revision);
-
- if (!fadt->arm_boot_flags) {
- ret = -EINVAL;
- goto out;
- }
- pr_err("FADT has ARM boot flags set, assuming 5.1\n");
- }
-
- if (!(fadt->flags & ACPI_FADT_HW_REDUCED)) {
- pr_err("FADT not ACPI hardware reduced compliant\n");
- ret = -EINVAL;
- }
-
-out:
/*
* acpi_get_table() creates FADT table mapping that
* should be released after parsing and before resuming boot
--
2.43.0