x86/vdso: Remove #ifdeffery around page setup variants

Replace the open-coded ifdefs in C sources files with IS_ENABLED().
This makes the code easier to read and enables the compiler to typecheck
also the disabled parts, before optimizing them away.
To make this work, also remove the ifdefs from declarations of used
variables.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Link: https://lore.kernel.org/r/20240910-x86-vdso-ifdef-v1-1-877c9df9b081@linutronix.de

Author: t-8ch

arch/x86/entry/vdso/vma.c

@@ -227,47 +227,40 @@ int map_vdso_once(const struct vdso_image *image, unsigned long addr)
 	return map_vdso(image, addr);
 }
 
-#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
 static int load_vdso32(void)
 {
 	if (vdso32_enabled != 1)  /* Other values all mean "disabled" */
 		return 0;
 
 	return map_vdso(&vdso_image_32, 0);
 }
-#endif
 
-#ifdef CONFIG_X86_64
 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 {
-	if (!vdso64_enabled)
-		return 0;
+	if (IS_ENABLED(CONFIG_X86_64)) {
+		if (!vdso64_enabled)
+			return 0;
+
+		return map_vdso(&vdso_image_64, 0);
+	}
 
-	return map_vdso(&vdso_image_64, 0);
+	return load_vdso32();
 }
 
 #ifdef CONFIG_COMPAT
 int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
 				       int uses_interp, bool x32)
 {
-#ifdef CONFIG_X86_X32_ABI
-	if (x32) {
+	if (IS_ENABLED(CONFIG_X86_X32_ABI) && x32) {
 		if (!vdso64_enabled)
 			return 0;
 		return map_vdso(&vdso_image_x32, 0);
 	}
-#endif
-#ifdef CONFIG_IA32_EMULATION
-	return load_vdso32();
-#else
+
+	if (IS_ENABLED(CONFIG_IA32_EMULATION))
+		return load_vdso32();
+
 	return 0;
-#endif
-}
-#endif
-#else
-int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
-{
-	return load_vdso32();
 }
 #endif
 

arch/x86/include/asm/elf.h

@@ -76,12 +76,8 @@ typedef struct user_i387_struct elf_fpregset_t;
 
 #include <asm/vdso.h>
 
-#ifdef CONFIG_X86_64
 extern unsigned int vdso64_enabled;
-#endif
-#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
 extern unsigned int vdso32_enabled;
-#endif
 
 /*
  * This is used to ensure we don't load something for the wrong architecture.

arch/x86/include/asm/vdso.h

@@ -27,17 +27,9 @@ struct vdso_image {
 	long sym_vdso32_rt_sigreturn_landing_pad;
 };
 
-#ifdef CONFIG_X86_64
 extern const struct vdso_image vdso_image_64;
-#endif
-
-#ifdef CONFIG_X86_X32_ABI
 extern const struct vdso_image vdso_image_x32;
-#endif
-
-#if defined CONFIG_X86_32 || defined CONFIG_COMPAT
 extern const struct vdso_image vdso_image_32;
-#endif
 
 extern int __init init_vdso_image(const struct vdso_image *image);