[PATCH 4/5] ARM64: kernel: acpi: refactor ACPI tables init and checks
Lorenzo Pieralisi
lorenzo.pieralisi at arm.com
Wed Mar 25 08:13:56 PDT 2015
On Wed, Mar 25, 2015 at 02:26:23PM +0000, Will Deacon wrote:
> On Tue, Mar 24, 2015 at 05:58:54PM +0000, Lorenzo Pieralisi wrote:
[...]
> > void __init acpi_boot_table_init(void)
> > {
> > + int err;
> > +
> > /*
> > * Enable ACPI instead of device tree unless
> > * - ACPI has been disabled explicitly (acpi=off), or
> > @@ -278,19 +301,32 @@ void __init acpi_boot_table_init(void)
> > (!param_acpi_force && of_scan_flat_dt(dt_scan_depth1_nodes, NULL)))
> > return;
> >
> > + /*
> > + * ACPI is disabled at this point. Enable it in order to parse
> > + * the ACPI tables and carry out sanity checks
> > + */
> > enable_acpi();
> >
> > /* Initialize the ACPI boot-time table parser. */
> > - if (acpi_table_init()) {
> > - disable_acpi();
> > - return;
> > + err = acpi_table_init();
> > + if (err) {
> > + pr_err("Failed to init ACPI tables\n");
> > + goto out;
> > }
> >
> > - if (acpi_table_parse(ACPI_SIG_FADT, acpi_parse_fadt)) {
> > - /* disable ACPI if no FADT is found */
> > + /*
> > + * Check FADT presence and carry out FADT sanity checks
> > + */
> > + err = acpi_fadt_sanity_check();
> > +
> > +out:
> > + /*
> > + * If ACPI tables are initialized and FADT sanity checks passed,
> > + * leave ACPI enabled and carry on booting; otherwise disable ACPI
> > + * on initialization error.
> > + */
> > + if (err)
> > disable_acpi();
> > - pr_err("Can't find FADT\n");
> > - }
>
> Could you rewrite most of this as:
>
> enable_acpi();
> if (acpi_table_init() || acpi_fadt_sanity_check()) {
> pr_err("Failed to init ACPI tables\n");
> disable_acpi();
> }
>
> I think it reads a bit better without the out: label.
Yes it makes sense acpi_fadt_sanity_check() already spits some errors
but there is not really a point in jumping around.
Here is the updated patch (please note this requires updating patch 5
too, I will send it inline shortly), thanks.
-- >8 --
Subject: [PATCH] ARM64: kernel: acpi: refactor ACPI tables init and checks
Current ACPI init code on ARM64 relies on acpi_table_parse() API to
check if the FADT is present and to carry out sanity checks on that.
The handler passed to the acpi_table_parse() function and used to
carry out the parsing on the requested table returns a value that is
ignored by the acpi_table_parse() function, so it is not possible
to propagate errors back to the acpi_table_parse() caller through
the handler.
This forces ARM64 ACPI init code to have disable_acpi() calls scattered
all over the place that makes code unwieldy and not easy to follow.
This patch refactors the ARM64 ACPI init code, by creating a
self-contained function (ie acpi_fadt_sanity_check()) that carries
out the required checks on FADT and returns an adequate return value
to the caller. This allows creating a common error path that disables
ACPI and makes code more readable and easy to parse and change were
further checks FADT to be added in the future.
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
Reviewed-by: Hanjun Guo <hanjun.guo at linaro.org>
Cc: Will Deacon <will.deacon at arm.com>
Cc: Hanjun Guo <hanjun.guo at linaro.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Rafael J. Wysocki <rjw at rjwysocki.net>
---
arch/arm64/kernel/acpi.c | 95 ++++++++++++++++++++++++++++++------------------
1 file changed, 59 insertions(+), 36 deletions(-)
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index a70f714..172b7c9 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -218,43 +218,60 @@ void __init acpi_init_cpus(void)
pr_info("%d CPUs enabled, %d CPUs total\n", enabled_cpus, total_cpus);
}
-static int __init acpi_parse_fadt(struct acpi_table_header *table)
+/*
+ * acpi_fadt_sanity_check() - Check FADT presence and carry out sanity
+ * checks on it
+ *
+ * Return 0 on success, <0 on failure
+ */
+static int __init acpi_fadt_sanity_check(void)
{
- struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table;
+ struct acpi_table_header *table;
+ struct acpi_table_fadt *fadt;
+ acpi_status status;
+ acpi_size tbl_size;
+ int ret = 0;
+
+ /*
+ * FADT is required on arm64; retrieve it to check its presence
+ * and carry out revision and ACPI HW reduced compliancy tests
+ */
+ status = acpi_get_table_with_size(ACPI_SIG_FADT, 0, &table, &tbl_size);
+ if (ACPI_FAILURE(status)) {
+ const char *msg = acpi_format_exception(status);
+
+ pr_err("Failed to get FADT table, %s\n", msg);
+ return -ENODEV;
+ }
+
+ fadt = (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, or we will disable ACPI.
+ * boot protocol configuration data.
*/
- if (table->revision > 5 ||
- (table->revision == 5 && fadt->minor_revision >= 1)) {
- if (!acpi_gbl_reduced_hardware) {
- pr_err("Not hardware reduced ACPI mode, will not be supported\n");
- goto disable_acpi;
- }
-
- /*
- * ACPI 5.1 only has two explicit methods to boot up SMP,
- * PSCI and Parking protocol, but the Parking protocol is
- * only specified for ARMv7 now, so make PSCI as the only
- * way for the SMP boot protocol before some updates for
- * the Parking protocol spec.
- */
- if (acpi_psci_present())
- return 0;
-
- pr_warn("No PSCI support, will not bring up secondary CPUs\n");
- return -EOPNOTSUPP;
+ if (table->revision < 5 ||
+ (table->revision == 5 && fadt->minor_revision < 1)) {
+ pr_err("Unsupported FADT revision %d.%d, should be 5.1+\n",
+ table->revision, fadt->minor_revision);
+ ret = -EINVAL;
+ goto out;
}
- pr_warn("Unsupported FADT revision %d.%d, should be 5.1+, will disable ACPI\n",
- table->revision, fadt->minor_revision);
+ if (!(fadt->flags & ACPI_FADT_HW_REDUCED)) {
+ pr_err("FADT not ACPI hardware reduced compliant\n");
+ ret = -EINVAL;
+ }
-disable_acpi:
- disable_acpi();
- return -EINVAL;
+out:
+ /*
+ * acpi_get_table_with_size() creates FADT table mapping that
+ * should be released after parsing and before resuming boot
+ */
+ early_acpi_os_unmap_memory(table, tbl_size);
+ return ret;
}
/*
@@ -262,9 +279,13 @@ disable_acpi:
* 1. find RSDP and get its address, and then find XSDT
* 2. extract all tables and checksums them all
* 3. check ACPI FADT revision
+ * 4. check ACPI FADT HW reduced flag
*
* We can parse ACPI boot-time tables such as MADT after
* this function is called.
+ *
+ * ACPI is enabled on return if ACPI tables initialized and sanity checks
+ * passed, disabled otherwise
*/
void __init acpi_boot_table_init(void)
{
@@ -278,18 +299,20 @@ void __init acpi_boot_table_init(void)
(!param_acpi_force && of_scan_flat_dt(dt_scan_depth1_nodes, NULL)))
return;
+ /*
+ * ACPI is disabled at this point. Enable it in order to parse
+ * the ACPI tables and carry out sanity checks
+ */
enable_acpi();
- /* Initialize the ACPI boot-time table parser. */
- if (acpi_table_init()) {
- disable_acpi();
- return;
- }
-
- if (acpi_table_parse(ACPI_SIG_FADT, acpi_parse_fadt)) {
- /* disable ACPI if no FADT is found */
+ /*
+ * If ACPI tables are initialized and FADT sanity checks passed,
+ * leave ACPI enabled and carry on booting; otherwise disable ACPI
+ * on initialization error.
+ */
+ if (acpi_table_init() || acpi_fadt_sanity_check()) {
+ pr_err("Failed to init ACPI tables\n");
disable_acpi();
- pr_err("Can't find FADT\n");
}
}
--
2.2.1
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