1// SPDX-License-Identifier: GPL-2.0
 2
 3#include <linux/efi.h>
 4#include <linux/screen_info.h>
 5
 6#include <asm/efi.h>
 7
 8#include "efistub.h"
 9
10/*
11 * There are two ways of populating the core kernel's struct screen_info via the stub:
12 * - using a configuration table, like below, which relies on the EFI init code
13 *   to locate the table and copy the contents;
14 * - by linking directly to the core kernel's copy of the global symbol.
15 *
16 * The latter is preferred because it makes the EFIFB earlycon available very
17 * early, but it only works if the EFI stub is part of the core kernel image
18 * itself. The zboot decompressor can only use the configuration table
19 * approach.
 
 
 
 
 
 
20 */
 
21
22static efi_guid_t screen_info_guid = LINUX_EFI_SCREEN_INFO_TABLE_GUID;
23
24struct screen_info *__alloc_screen_info(void)
25{
26	struct screen_info *si;
27	efi_status_t status;
28
29	status = efi_bs_call(allocate_pool, EFI_ACPI_RECLAIM_MEMORY,
30			     sizeof(*si), (void **)&si);
31
32	if (status != EFI_SUCCESS)
33		return NULL;
34
35	status = efi_bs_call(install_configuration_table,
36			     &screen_info_guid, si);
37	if (status == EFI_SUCCESS)
38		return si;
39
40	efi_bs_call(free_pool, si);
41	return NULL;
42}
43
44void free_screen_info(struct screen_info *si)
45{
46	if (!si)
47		return;
48
49	efi_bs_call(install_configuration_table, &screen_info_guid, NULL);
50	efi_bs_call(free_pool, si);
51}

 1// SPDX-License-Identifier: GPL-2.0
 2
 3#include <linux/efi.h>
 
 
 4#include <asm/efi.h>
 5
 6#include "efistub.h"
 7
 8/*
 9 * There are two ways of populating the core kernel's struct screen_info via the stub:
10 * - using a configuration table, like below, which relies on the EFI init code
11 *   to locate the table and copy the contents;
12 * - by linking directly to the core kernel's copy of the global symbol.
13 *
14 * The latter is preferred because it makes the EFIFB earlycon available very
15 * early, but it only works if the EFI stub is part of the core kernel image
16 * itself. The zboot decompressor can only use the configuration table
17 * approach.
18 *
19 * In order to support both methods from the same build of the EFI stub
20 * library, provide this dummy global definition of struct screen_info. If it
21 * is required to satisfy a link dependency, it means we need to override the
22 * __weak alloc and free methods with the ones below, and those will be pulled
23 * in as well.
24 */
25struct screen_info screen_info;
26
27static efi_guid_t screen_info_guid = LINUX_EFI_SCREEN_INFO_TABLE_GUID;
28
29struct screen_info *alloc_screen_info(void)
30{
31	struct screen_info *si;
32	efi_status_t status;
33
34	status = efi_bs_call(allocate_pool, EFI_ACPI_RECLAIM_MEMORY,
35			     sizeof(*si), (void **)&si);
36
37	if (status != EFI_SUCCESS)
38		return NULL;
39
40	status = efi_bs_call(install_configuration_table,
41			     &screen_info_guid, si);
42	if (status == EFI_SUCCESS)
43		return si;
44
45	efi_bs_call(free_pool, si);
46	return NULL;
47}
48
49void free_screen_info(struct screen_info *si)
50{
51	if (!si)
52		return;
53
54	efi_bs_call(install_configuration_table, &screen_info_guid, NULL);
55	efi_bs_call(free_pool, si);
56}