Re: [PATCH v7 13/15] ACPI / processor: Add acpi_map_madt_entry().

From: Hanjun Guo
Date: Tue May 31 2016 - 09:05:31 EST

On 2016/5/25 6:35, David Daney wrote:
From: David Daney <david.daney@xxxxxxxxxx>

Follow-on arm64 ACPI/NUMA patches need to map MADT entries very early
(before kmalloc is usable).

Add acpi_map_madt_entry() which, indirectly, uses
early_memremap()/early_memunmap() to access the table and parse out
the mpidr. The existing implementation of map_madt_entry() is
modified to take a pointer to the MADT as a parameter and the callers

Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
drivers/acpi/processor_core.c | 26 ++++++++++++++++++++++----
include/acpi/processor.h | 1 +
2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index 33a38d6..9125d7d 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -108,13 +108,12 @@ static int map_gicc_mpidr(struct acpi_subtable_header *entry,
return -EINVAL;

-static phys_cpuid_t map_madt_entry(int type, u32 acpi_id)
+static phys_cpuid_t map_madt_entry(struct acpi_table_madt *madt,
+ int type, u32 acpi_id)
unsigned long madt_end, entry;
phys_cpuid_t phys_id = PHYS_CPUID_INVALID; /* CPU hardware ID */
- struct acpi_table_madt *madt;

- madt = get_madt_table();
if (!madt)
return phys_id;

@@ -145,6 +144,25 @@ static phys_cpuid_t map_madt_entry(int type, u32 acpi_id)
return phys_id;

+phys_cpuid_t __init acpi_map_madt_entry(u32 acpi_id)
+ struct acpi_table_madt *madt = NULL;
+ acpi_size tbl_size;
+ phys_cpuid_t rv;
+ acpi_get_table_with_size(ACPI_SIG_MADT, 0,
+ (struct acpi_table_header **)&madt,
+ &tbl_size);
+ if (!madt)
+ rv = map_madt_entry(madt, 1, acpi_id);

Just nit-pick, pass 1 here means we need to define an acpi processor
device object in DSDT (see function map_gicc_mpidr(),
device_declaration), it would be fine for x2apic and gic mode,
but not for lapic mode, since the function name is acpi_map_madt_entry
which is general for all architecture, it will confuse people I think.

How about rename acpi_map_madt_entry() to acpi_map_madt_gicc_entry()?
It's only used for AMR64 to get mpidrs from GICC entries using acpi_id,
other than that, it's good to me.