On 1/5/2017 1:29 PM, Lorenzo Pieralisi wrote:
> Commit 618f535a6062 ("ACPI/IORT: Add single mapping function")
> introduced a function (iort_node_get_id()) to retrieve ids for IORT
> named components.
>
> iort_node_get_id() takes an index as input to refer to a specific
> mapping entry in the mapping array to retrieve the id at a specific
> index provided the index is below the total mapping count; currently the
> index is used to retrieve the mapping value from the correct entry but
> not to dereference the correct entry while retrieving the mapping
> output_reference (ie IORT parent pointer), which consequently always
> resolves to the output_reference of the first entry in the mapping
> array.
>
> Update the map array entry pointer computation in iort_node_get_id() to
> take into account the index value, fixing the issue.
>
> Fixes: 618f535a6062 ("ACPI/IORT: Add single mapping function")
> Reported-by: Hanjun Guo <hanjun....@linaro.org>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieral...@arm.com>
> Cc: Hanjun Guo <hanjun....@linaro.org>
> Cc: Sinan Kaya <ok...@codeaurora.org>
> Cc: Tomasz Nowicki <t...@semihalf.com>
> Cc: Nate Watterson <nwatt...@codeaurora.org>
> Cc: "Rafael J. Wysocki" <r...@rjwysocki.net>
> ---
> drivers/acpi/arm64/iort.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index e0d2e6e..ba156c5 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -333,7 +333,7 @@ struct acpi_iort_node *iort_node_get_id(struct
> acpi_iort_node *node,
> return NULL;
>
> map = ACPI_ADD_PTR(struct acpi_iort_id_mapping, node,
> - node->mapping_offset);
> + node->mapping_offset + index * sizeof(*map));
What does this give us that the previous code didn't do?
You are using map as a pointer and returning the offset of the first map entry
above
and then accessing the map at the indexed offset with map[index]
The new code is using map as a plain pointer, calculating the pointer location
with ACPI_ADD_PTR
instead and then collecting the output parameter with map->output_base.
>
> /* Firmware bug! */
> if (!map->output_reference) {
> @@ -348,10 +348,10 @@ struct acpi_iort_node *iort_node_get_id(struct
> acpi_iort_node *node,
> if (!(IORT_TYPE_MASK(parent->type) & type_mask))
> return NULL;
>
> - if (map[index].flags & ACPI_IORT_ID_SINGLE_MAPPING) {
> + if (map->flags & ACPI_IORT_ID_SINGLE_MAPPING) {
> if (node->type == ACPI_IORT_NODE_NAMED_COMPONENT ||
> node->type == ACPI_IORT_NODE_PCI_ROOT_COMPLEX) {
> - *id_out = map[index].output_base;
> + *id_out = map->output_base;
You are claiming that the existing code is collecting the output parameter from
the first mapping.
I don't see this happening above.
What am I missing?
> return parent;
> }
> }
>
If we are just doing a housekeeping, this is fine. I couldn't see an actual bug
getting fixed.
--
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux
Foundation Collaborative Project.
