On Fri, Oct 22, 2021 at 3:18 AM <james.liu@xxxxxxx> wrote:
>
> From: James Liu <james.liu@xxxxxxx>
>
> 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.
IIUC, the RegisterRegion field is defined in Section 18.6.2 that says
"This structure describes the physical address of a register as well
as the bit range that corresponds to a desired region of the
register". This doesn't appear to be a non-register GAS to me.
> 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@xxxxxxx>
> ---
> 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),
Check CodingStyle for the expected format of comments.
> + * 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));
It is not clear to me at all why sizeof(unsigned long long) is the
right size to use here.
IIUC, there is a data structure located at addr that needs to be
accessed, but what if it is larger than the above size?
> + }
>
> /* 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);
>
> --
