Hello Sascha,
On 08.08.22 13:11, Sascha Hauer wrote:
> On Mon, Aug 08, 2022 at 08:56:48AM +0200, Ahmad Fatoum wrote:
>> FIT image contents are often compressed, but we got by so far, because
>> a compressed initramfs is usually meant to be decompressed by the kernel
>> (and so has compression = "none") and arm32 kernels had their own
>> decompresser embedded. On ARM64, bootloader is responsible for
>> uncompressing kernel, so we should properly process the compression
>> property we so far ignored.
>>
>> The decompression isn't as efficient as one would hope for, because
>> the FIT format only describes length of the compressed data. We thus
>> have two options:
>>
>> - define an output size up-front, e.g. by guessing the uncompressed
>> buffer size for decompression or hardcoding it (e.g. U-Boot's
>> CONFIG_SYS_BOOTM_LEN).
>>
>> - Uncompress to a file descriptor
>>
>> We choose the second one to play it safe, but it comes with worse
>> performance because of extra memory copies. Intention is to go with
>> first option for the kernel image: We know how much size we can spare
>> for the kernel image and can have bootm_load_os uncompress there
>> directly without intermittent memory copies. This would involve slight
>> change to the barebox decompresser API to align it with the kernel's,
>> which allows to have it accept and observe an output buffer size.
>> So far, we had the kernel PREBOOT API, which lacks such a parameter,
>> but that's an optimization for another day.
>>
>> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
>> ---
>> common/image-fit.c | 38 +++++++++++++++++++++++++++++++++++---
>> include/uncompress.h | 6 ++++++
>> lib/uncompress.c | 40 ++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 81 insertions(+), 3 deletions(-)
>>
>> diff --git a/common/image-fit.c b/common/image-fit.c
>> index 507a857cadb4..e692fcdaa737 100644
>> --- a/common/image-fit.c
>> +++ b/common/image-fit.c
>> @@ -21,6 +21,7 @@
>> #include <linux/err.h>
>> #include <stringlist.h>
>> #include <rsa.h>
>> +#include <uncompress.h>
>> #include <image-fit.h>
>>
>> #define FDT_MAX_DEPTH 32
>> @@ -559,6 +560,11 @@ int fit_get_image_address(struct fit_handle *handle, void *configuration,
>> return ret;
>> }
>>
>> +static void fit_uncompress_error_fn(char *x)
>> +{
>> + pr_err("%s\n", x);
>> +}
>> +
>> /**
>> * fit_open_image - Open an image in a FIT image
>> * @handle: The FIT image handle
>> @@ -581,8 +587,10 @@ int fit_open_image(struct fit_handle *handle, void *configuration,
>> unsigned long *outsize)
>> {
>> struct device_node *image;
>> - const char *unit = name, *type = NULL, *desc= "(no description)";
>> - const void *data;
>> + const char *unit = name, *type = NULL, *compression = NULL,
>> + *desc= "(no description)";
>> + struct property *dataprop;
>> + const void *data = NULL;
>> int data_len;
>> int ret = 0;
>>
>> @@ -599,7 +607,9 @@ int fit_open_image(struct fit_handle *handle, void *configuration,
>> return -EINVAL;
>> }
>>
>> - data = of_get_property(image, "data", &data_len);
>> + dataprop = of_find_property(image, "data", &data_len);
>> + if (dataprop)
>> + data = of_property_get_value(dataprop);
>> if (!data) {
>> pr_err("data not found\n");
>> return -EINVAL;
>> @@ -613,6 +623,28 @@ int fit_open_image(struct fit_handle *handle, void *configuration,
>> if (ret < 0)
>> return ret;
>>
>> + of_property_read_string(image, "compression", &compression);
>> + if (compression && strcmp(compression, "none") != 0) {
>> + if (!IS_ENABLED(CONFIG_UNCOMPRESS)) {
>> + pr_err("image has compression = \"%s\", but support not compiled in\n");
>> + return -ENOSYS;
>> + }
>> + if (!dataprop->value) {
>> + void *uc_data;
>> +
>> + data_len = uncompress_buf_to_buf(data, data_len, &uc_data,
>> + fit_uncompress_error_fn);
>> + if (data_len < 0) {
>> + pr_err("data couldn't be decompressed\n");
>> + return data_len;
>> + }
>> +
>> + /* associate buffer with FIT, so it's not leaked */
>> + data = dataprop->value = uc_data;
>> + dataprop->length = data_len;
>
> Why are you fiddling with struct property fields directly?
> of_get_property() and of_set_property() should do what you want.
of_set_property copies the data into a new buffer, which I want
to avoid doing again.
Cheers,
Ahmad
>
> Sascha
>
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