efi: libstub: Move screen_info handling to common code

Currently, arm64, RISC-V and LoongArch rely on the fact that struct
screen_info can be accessed directly, due to the fact that the EFI stub
and the core kernel are part of the same image. This will change after a
future patch, so let's ensure that the screen_info handling is able to
deal with this, by adopting the arm32 approach of passing it as a
configuration table. While at it, switch to ACPI reclaim memory to hold
the screen_info data, which is more appropriate for this kind of
allocation.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

2 files changed, 22 insertions, 11 deletions

diff --git a/arch/loongarch/include/asm/efi.h b/arch/loongarch/include/asm/efi.h
index 174567b00ddb..60d6a170c18d 100644
--- a/arch/loongarch/include/asm/efi.h
+++ b/arch/loongarch/include/asm/efi.h
@@ -19,15 +19,6 @@ void efifb_setup_from_dmi(struct screen_info *si, const char *opt);
 #define EFI_ALLOC_ALIGN		SZ_64K
 #define EFI_RT_VIRTUAL_OFFSET	CSR_DMW0_BASE
 
-static inline struct screen_info *alloc_screen_info(void)
-{
-	return &screen_info;
-}
-
-static inline void free_screen_info(struct screen_info *si)
-{
-}
-
 static inline unsigned long efi_get_max_initrd_addr(unsigned long image_addr)
 {
 	return ULONG_MAX;
diff --git a/arch/loongarch/kernel/efi.c b/arch/loongarch/kernel/efi.c
index a31329971133..d75ce73e8ff8 100644
--- a/arch/loongarch/kernel/efi.c
+++ b/arch/loongarch/kernel/efi.c
@@ -52,6 +52,27 @@ void __init efi_runtime_init(void)
 	set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
 }
 
+unsigned long __initdata screen_info_table = EFI_INVALID_TABLE_ADDR;
+
+static void __init init_screen_info(void)
+{
+	struct screen_info *si;
+
+	if (screen_info_table == EFI_INVALID_TABLE_ADDR)
+		return;
+
+	si = early_memremap(screen_info_table, sizeof(*si));
+	if (!si) {
+		pr_err("Could not map screen_info config table\n");
+		return;
+	}
+	screen_info = *si;
+	memset(si, 0, sizeof(*si));
+	early_memunmap(si, sizeof(*si));
+
+	memblock_reserve(screen_info.lfb_base, screen_info.lfb_size);
+}
+
 void __init efi_init(void)
 {
 	int size;
@@ -80,8 +101,7 @@ void __init efi_init(void)
 
 	set_bit(EFI_CONFIG_TABLES, &efi.flags);
 
-	if (screen_info.orig_video_isVGA == VIDEO_TYPE_EFI)
-		memblock_reserve(screen_info.lfb_base, screen_info.lfb_size);
+	init_screen_info();
 
 	if (boot_memmap == EFI_INVALID_TABLE_ADDR)
 		return;