[PATCH] ACPI: OSL: Handle the return value of acpi_os_map_generic_address() for a non-register GAS

[james.liu@hpe.com]

From: James Liu <james.liu@hpe.com>

Modify acpi_os_map_generic_address() to correctly handle a non-register
GAS (i.e., a pointer to a data structure), whose bit width is expected
to be 0 according to Table 5.1 in ACPI spec. 6.4.

For example, the RegisterRegion field in SET_ERROR_TYPE_WITH_ADDRESS is a
non-register GAS, which points to a data structure whose format is defined
in Table 18.30 in ACPI Spec. 6.4.

This fix can prevent EINJ (Error Injection module) from loading failure
when a platform firmware can correctly support the format of Injection
Instruction Entry in an EINJ table.

Signed-off-by: James Liu <james.liu@hpe.com>
---
 drivers/acpi/osl.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 45c5c0e45e33..74de9341fadf 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -456,13 +456,23 @@ void __iomem *acpi_os_map_generic_address(struct acpi_generic_address *gas)
 
 	if (gas->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
 		return NULL;
+	/* Handle a non-register GAS (i.e., a pointer to a data structure),
+	 * whose bit width is expected to be 0 according to ACPI spec. 6.4.
+	 * For example, The RegisterRegion field in SET_ERROR_TYPE_WITH_ADDRESS
+	 * points to a data structure whose format is defined in Table 18.30 in
+	 * ACPI Spec. 6.4
+	 */
+	if (!gas->bit_width) {
+		pr_info("Mapping IOMEM for a non-register GAS.\n");
+		return  acpi_os_map_iomem(addr, sizeof(unsigned long long));
+	}
 
 	/* Handle possible alignment issues */
 	memcpy(&addr, &gas->address, sizeof(addr));
-	if (!addr || !gas->bit_width)
+	if (!addr)
 		return NULL;
-
-	return acpi_os_map_iomem(addr, gas->bit_width / 8);
+	else
+		return acpi_os_map_iomem(addr, gas->bit_width / 8);
 }
 EXPORT_SYMBOL(acpi_os_map_generic_address);
 
-- 
2.25.1