mm: remove arch_bprm_mm_init() hook

From: Dave Hansen <[e-mail]>

MPX is being removed from the kernel due to a lack of support
in the toolchain going forward (gcc).

arch_bprm_mm_init() is used at execve() time. The only non-stub
implementation is on x86 for MPX. Remove the hook entirely from
all architectures and generic code.

Cc: Peter Zijlstra (Intel) <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: [e-mail]
Cc: Linus Torvalds <[e-mail]>
Cc: [e-mail]
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Michael Ellerman <[e-mail]>
Cc: Jeff Dike <[e-mail]>
Cc: Richard Weinberger <[e-mail]>
Cc: Anton Ivanov <[e-mail]>
Cc: Guan Xuetao <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Signed-off-by: Dave Hansen <[e-mail]>

arch/powerpc/include/asm/mmu_context.h

···
 		mm->context.vdso_base = 0;
 }
 
-static inline void arch_bprm_mm_init(struct mm_struct *mm,
-				     struct vm_area_struct *vma)
-{
-}
-
 #ifdef CONFIG_PPC_MEM_KEYS
 bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write,
 			       bool execute, bool foreign);

arch/um/include/asm/mmu_context.h

···
 			unsigned long start, unsigned long end)
 {
 }
-static inline void arch_bprm_mm_init(struct mm_struct *mm,
-				     struct vm_area_struct *vma)
-{
-}
-
 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
 		bool write, bool execute, bool foreign)
 {

arch/unicore32/include/asm/mmu_context.h

···
 {
 }
 
-static inline void arch_bprm_mm_init(struct mm_struct *mm,
-				     struct vm_area_struct *vma)
-{
-}
-
 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
 		bool write, bool execute, bool foreign)
 {

arch/x86/include/asm/mmu_context.h

···
 }
 #endif
 
-static inline void arch_bprm_mm_init(struct mm_struct *mm,
-		struct vm_area_struct *vma)
-{
-	mpx_mm_init(mm);
-}
-
 static inline void arch_unmap(struct mm_struct *mm, unsigned long start,
 			      unsigned long end)
 {

fs/exec.c

···
 		goto err;
 
 	mm->stack_vm = mm->total_vm = 1;
-	arch_bprm_mm_init(mm, vma);
 	up_write(&mm->mmap_sem);
 	bprm->p = vma->vm_end - sizeof(void *);
 	return 0;

include/asm-generic/mm_hooks.h

···
 {
 }
 
-static inline void arch_bprm_mm_init(struct mm_struct *mm,
-				     struct vm_area_struct *vma)
-{
-}
-
 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
 		bool write, bool execute, bool foreign)
 {