efi: move screen_info into efi init code

After the vga console no longer relies on global screen_info, there are
only two remaining use cases:

 - on the x86 architecture, it is used for multiple boot methods
   (bzImage, EFI, Xen, kexec) to commucate the initial VGA or framebuffer
   settings to a number of device drivers.

 - on other architectures, it is only used as part of the EFI stub,
   and only for the three sysfb framebuffers (simpledrm, simplefb, efifb).

Remove the duplicate data structure definitions by moving it into the
efi-init.c file that sets it up initially for the EFI case, leaving x86
as an exception that retains its own definition for non-EFI boots.

The added #ifdefs here are optional, I added them to further limit the
reach of screen_info to configurations that have at least one of the
users enabled.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Helge Deller <deller@gmx.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20231017093947.3627976-1-arnd@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm64/kernel/efi.c

@@ -71,10 +71,6 @@ static __init pteval_t create_mapping_protection(efi_memory_desc_t *md)
 	return pgprot_val(PAGE_KERNEL_EXEC);
 }
 
-/* we will fill this structure from the stub, so don't put it in .bss */
-struct screen_info screen_info __section(".data");
-EXPORT_SYMBOL(screen_info);
-
 int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
 {
 	pteval_t prot_val = create_mapping_protection(md);

arch/arm64/kernel/image-vars.h

@@ -27,7 +27,9 @@ PROVIDE(__efistub__text			= _text);
 PROVIDE(__efistub__end			= _end);
 PROVIDE(__efistub___inittext_end       	= __inittext_end);
 PROVIDE(__efistub__edata		= _edata);
+#if defined(CONFIG_EFI_EARLYCON) || defined(CONFIG_SYSFB)
 PROVIDE(__efistub_screen_info		= screen_info);
+#endif
 PROVIDE(__efistub__ctype		= _ctype);
 
 PROVIDE(__pi___memcpy			= __pi_memcpy);

arch/loongarch/kernel/efi.c

@@ -68,6 +68,11 @@ void __init efi_runtime_init(void)
 
 unsigned long __initdata screen_info_table = EFI_INVALID_TABLE_ADDR;
 
+#if defined(CONFIG_SYSFB) || defined(CONFIG_EFI_EARLYCON)
+struct screen_info screen_info __section(".data");
+EXPORT_SYMBOL_GPL(screen_info);
+#endif
+
 static void __init init_screen_info(void)
 {
 	struct screen_info *si;
@@ -115,6 +120,7 @@ void __init efi_init(void)
 
 	set_bit(EFI_CONFIG_TABLES, &efi.flags);
 
+	if (IS_ENABLED(CONFIG_EFI_EARLYCON) || IS_ENABLED(CONFIG_SYSFB))
 		init_screen_info();
 
 	if (boot_memmap == EFI_INVALID_TABLE_ADDR)

arch/loongarch/kernel/image-vars.h

@@ -12,7 +12,9 @@ __efistub_kernel_entry		= kernel_entry;
 __efistub_kernel_asize		= kernel_asize;
 __efistub_kernel_fsize		= kernel_fsize;
 __efistub_kernel_offset		= kernel_offset;
+#if defined(CONFIG_EFI_EARLYCON) || defined(CONFIG_SYSFB)
 __efistub_screen_info		= screen_info;
+#endif
 
 #endif
 

arch/loongarch/kernel/setup.c

@@ -16,7 +16,6 @@
 #include <linux/dmi.h>
 #include <linux/efi.h>
 #include <linux/export.h>
-#include <linux/screen_info.h>
 #include <linux/memblock.h>
 #include <linux/initrd.h>
 #include <linux/ioport.h>
@@ -57,10 +56,6 @@
 #define SMBIOS_CORE_PACKAGE_OFFSET	0x23
 #define LOONGSON_EFI_ENABLE		(1 << 3)
 
-#ifdef CONFIG_EFI
-struct screen_info screen_info __section(".data");
-#endif
-
 unsigned long fw_arg0, fw_arg1, fw_arg2;
 DEFINE_PER_CPU(unsigned long, kernelsp);
 struct cpuinfo_loongarch cpu_data[NR_CPUS] __read_mostly;

arch/riscv/kernel/image-vars.h

@@ -28,7 +28,9 @@ __efistub__start_kernel		= _start_kernel;
 __efistub__end			= _end;
 __efistub__edata		= _edata;
 __efistub___init_text_end	= __init_text_end;
+#if defined(CONFIG_EFI_EARLYCON) || defined(CONFIG_SYSFB)
 __efistub_screen_info		= screen_info;
+#endif
 
 #endif
 

arch/riscv/kernel/setup.c

@@ -15,7 +15,6 @@
 #include <linux/memblock.h>
 #include <linux/sched.h>
 #include <linux/console.h>
-#include <linux/screen_info.h>
 #include <linux/of_fdt.h>
 #include <linux/sched/task.h>
 #include <linux/smp.h>
@@ -40,10 +39,6 @@
 
 #include "head.h"
 
-#if defined(CONFIG_EFI)
-struct screen_info screen_info __section(".data");
-#endif
-
 /*
  * The lucky hart to first increment this variable will boot the other cores.
  * This is used before the kernel initializes the BSS so it can't be in the

drivers/firmware/efi/efi-init.c

@@ -55,6 +55,15 @@ static phys_addr_t __init efi_to_phys(unsigned long addr)
 
 extern __weak const efi_config_table_type_t efi_arch_tables[];
 
+/*
+ * x86 defines its own screen_info and uses it even without EFI,
+ * everything else can get it from here.
+ */
+#if !defined(CONFIG_X86) && (defined(CONFIG_SYSFB) || defined(CONFIG_EFI_EARLYCON))
+struct screen_info screen_info __section(".data");
+EXPORT_SYMBOL_GPL(screen_info);
+#endif
+
 static void __init init_screen_info(void)
 {
 	struct screen_info *si;
@@ -240,5 +249,8 @@ void __init efi_init(void)
 	memblock_reserve(data.phys_map & PAGE_MASK,
 			 PAGE_ALIGN(data.size + (data.phys_map & ~PAGE_MASK)));
 
+	if (IS_ENABLED(CONFIG_X86) ||
+	    IS_ENABLED(CONFIG_SYSFB) ||
+	    IS_ENABLED(CONFIG_EFI_EARLYCON))
 		init_screen_info();
 }

drivers/firmware/efi/libstub/efi-stub-entry.c

@@ -13,7 +13,13 @@ struct screen_info *alloc_screen_info(void)
 {
 	if (IS_ENABLED(CONFIG_ARM))
 		return __alloc_screen_info();
+
+	if (IS_ENABLED(CONFIG_X86) ||
+	    IS_ENABLED(CONFIG_EFI_EARLYCON) ||
+	    IS_ENABLED(CONFIG_SYSFB))
 		return (void *)&screen_info + screen_info_offset;
+
+	return NULL;
 }
 
 /*