2022-10-11 23:47:18 +08:00
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// SPDX-License-Identifier: GPL-2.0
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/*
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2022-10-21 08:23:05 +08:00
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* Verified Boot for Embedded (VBE) OS request (device tree fixup) functions
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2022-10-11 23:47:18 +08:00
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*
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* Copyright 2022 Google LLC
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* Written by Simon Glass <sjg@chromium.org>
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*/
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#define LOG_CATEGORY LOGC_BOOT
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#include <common.h>
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#include <dm.h>
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#include <event.h>
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#include <image.h>
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#include <malloc.h>
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#include <rng.h>
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#include <dm/ofnode.h>
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#define VBE_PREFIX "vbe,"
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#define VBE_PREFIX_LEN (sizeof(VBE_PREFIX) - 1)
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#define VBE_ERR_STR_LEN 128
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#define VBE_MAX_RAND_SIZE 256
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struct vbe_result {
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int errnum;
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char err_str[VBE_ERR_STR_LEN];
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};
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typedef int (*vbe_req_func)(ofnode node, struct vbe_result *result);
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static int handle_random_req(ofnode node, int default_size,
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struct vbe_result *result)
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{
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char buf[VBE_MAX_RAND_SIZE];
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struct udevice *dev;
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u32 size;
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int ret;
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2023-02-23 00:33:53 +08:00
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if (!IS_ENABLED(CONFIG_DM_RNG))
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2022-10-11 23:47:18 +08:00
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return -ENOTSUPP;
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if (ofnode_read_u32(node, "vbe,size", &size)) {
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if (!default_size) {
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snprintf(result->err_str, VBE_ERR_STR_LEN,
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"Missing vbe,size property");
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return log_msg_ret("byt", -EINVAL);
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}
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size = default_size;
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}
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if (size > VBE_MAX_RAND_SIZE) {
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snprintf(result->err_str, VBE_ERR_STR_LEN,
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"vbe,size %#x exceeds max size %#x", size,
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VBE_MAX_RAND_SIZE);
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return log_msg_ret("siz", -E2BIG);
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}
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ret = uclass_first_device_err(UCLASS_RNG, &dev);
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if (ret) {
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snprintf(result->err_str, VBE_ERR_STR_LEN,
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"Cannot find random-number device (err=%d)", ret);
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return log_msg_ret("wr", ret);
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}
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ret = dm_rng_read(dev, buf, size);
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if (ret) {
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snprintf(result->err_str, VBE_ERR_STR_LEN,
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"Failed to read random-number device (err=%d)", ret);
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return log_msg_ret("rd", ret);
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}
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ret = ofnode_write_prop(node, "data", buf, size, true);
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if (ret)
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return log_msg_ret("wr", -EINVAL);
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return 0;
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}
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static int vbe_req_random_seed(ofnode node, struct vbe_result *result)
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{
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return handle_random_req(node, 0, result);
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}
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static int vbe_req_aslr_move(ofnode node, struct vbe_result *result)
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{
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return -ENOTSUPP;
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}
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static int vbe_req_aslr_rand(ofnode node, struct vbe_result *result)
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{
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return handle_random_req(node, 4, result);
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}
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static int vbe_req_efi_runtime_rand(ofnode node, struct vbe_result *result)
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{
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return handle_random_req(node, 4, result);
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}
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static struct vbe_req {
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const char *compat;
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vbe_req_func func;
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} vbe_reqs[] = {
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/* address space layout randomization - move the OS in memory */
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{ "aslr-move", vbe_req_aslr_move },
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/* provide random data for address space layout randomization */
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{ "aslr-rand", vbe_req_aslr_rand },
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/* provide random data for EFI-runtime-services address */
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{ "efi-runtime-rand", vbe_req_efi_runtime_rand },
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/* generate random data bytes to see the OS's rand generator */
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{ "random-rand", vbe_req_random_seed },
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};
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static int vbe_process_request(ofnode node, struct vbe_result *result)
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{
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const char *compat, *req_name;
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int i;
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compat = ofnode_read_string(node, "compatible");
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if (!compat)
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return 0;
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if (strlen(compat) <= VBE_PREFIX_LEN ||
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strncmp(compat, VBE_PREFIX, VBE_PREFIX_LEN))
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return -EINVAL;
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req_name = compat + VBE_PREFIX_LEN; /* drop "vbe," prefix */
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for (i = 0; i < ARRAY_SIZE(vbe_reqs); i++) {
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if (!strcmp(vbe_reqs[i].compat, req_name)) {
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int ret;
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ret = vbe_reqs[i].func(node, result);
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if (ret)
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return log_msg_ret("req", ret);
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return 0;
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}
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}
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snprintf(result->err_str, VBE_ERR_STR_LEN, "Unknown request: %s",
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req_name);
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return -ENOTSUPP;
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}
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/**
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* bootmeth_vbe_ft_fixup() - Process VBE OS requests and do device tree fixups
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*
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* If there are no images provided, this does nothing and returns 0.
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*
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* @ctx: Context for event
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* @event: Event to process
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* @return 0 if OK, -ve on error
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*/
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static int bootmeth_vbe_ft_fixup(void *ctx, struct event *event)
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{
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const struct event_ft_fixup *fixup = &event->data.ft_fixup;
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const struct bootm_headers *images = fixup->images;
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ofnode parent, dest_parent, root, node;
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oftree fit;
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if (!images || !images->fit_hdr_os)
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return 0;
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/* Get the image node with requests in it */
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log_debug("fit=%p, noffset=%d\n", images->fit_hdr_os,
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images->fit_noffset_os);
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fit = oftree_from_fdt(images->fit_hdr_os);
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root = oftree_root(fit);
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if (of_live_active()) {
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log_warning("Cannot fix up live tree\n");
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return 0;
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}
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if (!ofnode_valid(root))
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return log_msg_ret("rt", -EINVAL);
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parent = noffset_to_ofnode(root, images->fit_noffset_os);
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if (!ofnode_valid(parent))
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return log_msg_ret("img", -EINVAL);
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dest_parent = oftree_path(fixup->tree, "/chosen");
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if (!ofnode_valid(dest_parent))
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return log_msg_ret("dst", -EINVAL);
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ofnode_for_each_subnode(node, parent) {
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const char *name = ofnode_get_name(node);
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struct vbe_result result;
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ofnode dest;
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int ret;
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log_debug("copy subnode: %s\n", name);
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ret = ofnode_add_subnode(dest_parent, name, &dest);
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if (ret && ret != -EEXIST)
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return log_msg_ret("add", ret);
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ret = ofnode_copy_props(node, dest);
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if (ret)
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return log_msg_ret("cp", ret);
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*result.err_str = '\0';
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ret = vbe_process_request(dest, &result);
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if (ret) {
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result.errnum = ret;
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2022-10-21 08:23:06 +08:00
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log_warning("Failed to process VBE request %s (err=%d)\n",
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ofnode_get_name(dest), ret);
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2022-10-11 23:47:18 +08:00
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if (*result.err_str) {
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char *msg = strdup(result.err_str);
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if (!msg)
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return log_msg_ret("msg", -ENOMEM);
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ret = ofnode_write_string(dest, "vbe,error",
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msg);
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if (ret) {
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free(msg);
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return log_msg_ret("str", -ENOMEM);
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}
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}
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if (result.errnum) {
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ret = ofnode_write_u32(dest, "vbe,errnum",
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result.errnum);
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if (ret)
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return log_msg_ret("num", -ENOMEM);
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if (result.errnum != -ENOTSUPP)
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return log_msg_ret("pro",
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result.errnum);
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if (result.errnum == -ENOTSUPP &&
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ofnode_read_bool(dest, "vbe,required")) {
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log_err("Cannot handle required request: %s\n",
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ofnode_get_name(dest));
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return log_msg_ret("req",
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result.errnum);
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}
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}
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}
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}
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return 0;
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}
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EVENT_SPY(EVT_FT_FIXUP, bootmeth_vbe_ft_fixup);
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