Re: [PATCH v7 1/8] efi: Export boot-services code and data as debugfs-blobs

Luis Chamberlain
2019-10-14T09:11:38Z

On Fri, Oct 04, 2019 at 04:50:49PM +0200, Hans de Goede wrote:
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 8d3e778e988b..abba49c4c46d 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -314,6 +315,55 @@ static __init int efivar_ssdt_load(void)
> static inline int efivar_ssdt_load(void) { return 0; }
> #endif
>
> +#ifdef CONFIG_DEBUG_FS
> +
> +#define EFI_DEBUGFS_MAX_BLOBS 32
> +
> +static struct debugfs_blob_wrapper debugfs_blob[EFI_DEBUGFS_MAX_BLOBS];
> +
> +static void __init efi_debugfs_init(void)
> +{
> + struct dentry *efi_debugfs;
> + efi_memory_desc_t *md;
> + char name[32];
> + int type_count[EFI_BOOT_SERVICES_DATA + 1] = {};
> + int i = 0;
> +
> + efi_debugfs = debugfs_create_dir("efi", NULL);
> + if (IS_ERR_OR_NULL(efi_debugfs))
> + return;
> +
> + for_each_efi_memory_desc(md) {
> + switch (md->type) {
> + case EFI_BOOT_SERVICES_CODE:
> + snprintf(name, sizeof(name), "boot_services_code%d",
> + type_count[md->type]++);
> + break;
> + case EFI_BOOT_SERVICES_DATA:
> + snprintf(name, sizeof(name), "boot_services_data%d",
> + type_count[md->type]++);
> + break;
> + default:
> + continue;
> + }
> +
> + debugfs_blob[i].size = md->num_pages << EFI_PAGE_SHIFT;
> + debugfs_blob[i].data = memremap(md->phys_addr,
> + debugfs_blob[i].size,
> + MEMREMAP_WB);
> + if (!debugfs_blob[i].data)
> + continue;
> +
> + debugfs_create_blob(name, 0400, efi_debugfs, &debugfs_blob[i]);
> + i++;
> + if (i == EFI_DEBUGFS_MAX_BLOBS)
> + break;

Why do we silently ignore more entries ? And could documentation be
added for ways in which this could be used in practice?

Luis