x86/boot: Drop references to startup_64

The x86 boot image generation tool assign a default value to startup_64
and subsequently parses the actual value from zoffset.h but it never
actually uses the value anywhere. So remove this code.

This change has no impact on the resulting bzImage binary.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230912090051.4014114-25-ardb@google.com

arch/x86/boot/Makefile

@@ -89,7 +89,7 @@ $(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE
 
 SETUP_OBJS = $(addprefix $(obj)/,$(setup-y))
 
-sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|startup_64\|efi32_stub_entry\|efi64_stub_entry\|efi_pe_entry\|efi32_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|z_.*\)$$/\#define ZO_\2 0x\1/p'
+sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi32_stub_entry\|efi64_stub_entry\|efi_pe_entry\|efi32_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|z_.*\)$$/\#define ZO_\2 0x\1/p'
 
 quiet_cmd_zoffset = ZOFFSET $@
       cmd_zoffset = $(NM) $< | sed -n $(sed-zoffset) > $@

arch/x86/boot/tools/build.c

@@ -60,7 +60,6 @@ static unsigned long efi64_stub_entry;
 static unsigned long efi_pe_entry;
 static unsigned long efi32_pe_entry;
 static unsigned long kernel_info;
-static unsigned long startup_64;
 static unsigned long _end;
 
 /*----------------------------------------------------------------------*/
@@ -264,7 +263,6 @@ static void efi_stub_defaults(void)
 	efi_pe_entry = 0x10;
 #else
 	efi_pe_entry = 0x210;
-	startup_64 = 0x200;
 #endif
 }
 
@@ -340,7 +338,6 @@ static void parse_zoffset(char *fname)
 		PARSE_ZOFS(p, efi_pe_entry);
 		PARSE_ZOFS(p, efi32_pe_entry);
 		PARSE_ZOFS(p, kernel_info);
-		PARSE_ZOFS(p, startup_64);
 		PARSE_ZOFS(p, _end);
 
 		p = strchr(p, '\n');