[PATCH 09/12] efi: libstub: install boot-time memory map as config table

[Ard Biesheuvel <ardb@kernel.org>]

Expose the EFI boot time memory map to the kernel via a configuration
table. This is arch agnostic and enables future changes that remove the
dependency on DT on architectures that don't otherwise rely on it.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 drivers/firmware/efi/libstub/arm64-stub.c      |  2 +-
 drivers/firmware/efi/libstub/efi-stub-helper.c |  2 +-
 drivers/firmware/efi/libstub/efistub.h         |  3 ++-
 drivers/firmware/efi/libstub/mem.c             | 26 ++++++++++++++++++--
 drivers/firmware/efi/libstub/randomalloc.c     |  2 +-
 drivers/firmware/efi/libstub/relocate.c        |  2 +-
 include/linux/efi.h                            |  1 +
 7 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c
index e9d516ad5f97..df05c53baa23 100644
--- a/drivers/firmware/efi/libstub/arm64-stub.c
+++ b/drivers/firmware/efi/libstub/arm64-stub.c
@@ -55,7 +55,7 @@ static bool check_image_region(u64 base, u64 size)
 	bool ret = false;
 	int map_offset;
 
-	status = efi_get_memory_map(&map);
+	status = efi_get_memory_map(&map, false);
 	if (status != EFI_SUCCESS)
 		return false;
 
diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index 742ecd9e0df3..f1f7a823be17 100644
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -438,7 +438,7 @@ efi_status_t efi_exit_boot_services(void *handle, void *priv,
 	struct efi_boot_memmap *map;
 	efi_status_t status;
 
-	status = efi_get_memory_map(&map);
+	status = efi_get_memory_map(&map, true);
 
 	if (status != EFI_SUCCESS)
 		goto fail;
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index f65a8a3844b8..b4fb6d4e8a59 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -897,7 +897,8 @@ void efi_apply_loadoptions_quirk(const void **load_options, u32 *load_options_si
 
 char *efi_convert_cmdline(efi_loaded_image_t *image, int *cmd_line_len);
 
-efi_status_t efi_get_memory_map(struct efi_boot_memmap **map);
+efi_status_t efi_get_memory_map(struct efi_boot_memmap **map,
+				bool install_cfg_tbl);
 
 efi_status_t efi_allocate_pages(unsigned long size, unsigned long *addr,
 				unsigned long max);
diff --git a/drivers/firmware/efi/libstub/mem.c b/drivers/firmware/efi/libstub/mem.c
index 40721573e494..ed4c145afe11 100644
--- a/drivers/firmware/efi/libstub/mem.c
+++ b/drivers/firmware/efi/libstub/mem.c
@@ -9,14 +9,20 @@
  * efi_get_memory_map() - get memory map
  * @map:		pointer to memory map pointer to which to assign the
  *			newly allocated memory map
+ * @install_cfg_tbl:	whether or not to install the boot memory map as a
+ *			configuration table
  *
  * Retrieve the UEFI memory map. The allocated memory leaves room for
  * up to EFI_MMAP_NR_SLACK_SLOTS additional memory map entries.
  *
  * Return:	status code
  */
-efi_status_t efi_get_memory_map(struct efi_boot_memmap **map)
+efi_status_t efi_get_memory_map(struct efi_boot_memmap **map,
+				bool install_cfg_tbl)
 {
+	int memtype = install_cfg_tbl ? EFI_ACPI_RECLAIM_MEMORY
+				      : EFI_LOADER_DATA;
+	efi_guid_t tbl_guid = LINUX_EFI_BOOT_MEMMAP_GUID;
 	struct efi_boot_memmap *m, tmp;
 	efi_status_t status;
 	unsigned long size;
@@ -28,11 +34,23 @@ efi_status_t efi_get_memory_map(struct efi_boot_memmap **map)
 		return EFI_LOAD_ERROR;
 
 	size = tmp.map_size + tmp.desc_size * EFI_MMAP_NR_SLACK_SLOTS;
-	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*m) + size,
+	status = efi_bs_call(allocate_pool, memtype, sizeof(*m) + size,
 			     (void **)&m);
 	if (status != EFI_SUCCESS)
 		return status;
 
+	if (install_cfg_tbl) {
+		/*
+		 * Installing a configuration table might allocate memory, and
+		 * this may modify the memory map. This means we should install
+		 * the configuration table first, and re-install or delete it
+		 * as needed.
+		 */
+		status = efi_bs_call(install_configuration_table, &tbl_guid, m);
+		if (status != EFI_SUCCESS)
+			goto free_map;
+	}
+
 	m->buff_size = m->map_size = size;
 	status = efi_bs_call(get_memory_map, &m->map_size, m->map, &m->map_key,
 			     &m->desc_size, &m->desc_ver);
@@ -40,6 +58,10 @@ efi_status_t efi_get_memory_map(struct efi_boot_memmap **map)
 	if (status == EFI_SUCCESS) {
 		*map = m;
 	} else {
+		if (install_cfg_tbl)
+			efi_bs_call(install_configuration_table, &tbl_guid,
+				    NULL);
+free_map:
 		efi_bs_call(free_pool, m);
 	}
 
diff --git a/drivers/firmware/efi/libstub/randomalloc.c b/drivers/firmware/efi/libstub/randomalloc.c
index 5d6000c717cc..9fb5869896be 100644
--- a/drivers/firmware/efi/libstub/randomalloc.c
+++ b/drivers/firmware/efi/libstub/randomalloc.c
@@ -61,7 +61,7 @@ efi_status_t efi_random_alloc(unsigned long size,
 	efi_status_t status;
 	int map_offset;
 
-	status = efi_get_memory_map(&map);
+	status = efi_get_memory_map(&map, false);
 	if (status != EFI_SUCCESS)
 		return status;
 
diff --git a/drivers/firmware/efi/libstub/relocate.c b/drivers/firmware/efi/libstub/relocate.c
index cd80db33ab1e..bf6fbd5d22a1 100644
--- a/drivers/firmware/efi/libstub/relocate.c
+++ b/drivers/firmware/efi/libstub/relocate.c
@@ -28,7 +28,7 @@ efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,
 	unsigned long nr_pages;
 	int i;
 
-	status = efi_get_memory_map(&map);
+	status = efi_get_memory_map(&map, false);
 	if (status != EFI_SUCCESS)
 		goto fail;
 
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 8668d9769bb0..89f16ec3ebab 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -414,6 +414,7 @@ void efi_native_runtime_setup(void);
 #define LINUX_EFI_ZBOOT_MEDIA_GUID		EFI_GUID(0xe565a30d, 0x47da, 0x4dbd,  0xb3, 0x54, 0x9b, 0xb5, 0xc8, 0x4f, 0x8b, 0xe2)
 #define LINUX_EFI_MOK_VARIABLE_TABLE_GUID	EFI_GUID(0xc451ed2b, 0x9694, 0x45d3,  0xba, 0xba, 0xed, 0x9f, 0x89, 0x88, 0xa3, 0x89)
 #define LINUX_EFI_COCO_SECRET_AREA_GUID		EFI_GUID(0xadf956ad, 0xe98c, 0x484c,  0xae, 0x11, 0xb5, 0x1c, 0x7d, 0x33, 0x64, 0x47)
+#define LINUX_EFI_BOOT_MEMMAP_GUID		EFI_GUID(0x800f683f, 0xd08b, 0x423a,  0xa2, 0x93, 0x96, 0x5c, 0x3c, 0x6f, 0xe2, 0xb4)
 
 #define RISCV_EFI_BOOT_PROTOCOL_GUID		EFI_GUID(0xccd15fec, 0x6f73, 0x4eec,  0x83, 0x95, 0x3e, 0x69, 0xe4, 0xb9, 0x40, 0xbf)
 
-- 
2.35.1