[PATCH v4 09/25] mm: unexport vm_brk_flags() and eliminate vm_flags parameter

["Lorenzo Stoakes (Oracle)" <ljs@kernel.org>]

This function is only used by elf_load(), and that is a static function
that doesn't need an exported symbol to invoke an internal function, so
un-EXPORT_SYMBOLS() it.

Also, the vm_flags parameter is unnecessary, as we only ever set VM_EXEC,
so simply make this parameter a boolean.

While we're here, clean up the mm.h definitions for the various vm_xxx()
helpers so we actually specify parameter names and elide the redundant
extern's.

Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
---
 fs/binfmt_elf.c    |  3 +--
 include/linux/mm.h | 12 ++++++------
 mm/mmap.c          |  8 ++------
 3 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index fb857faaf0d6..16a56b6b3f6c 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -453,14 +453,13 @@ static unsigned long elf_load(struct file *filep, unsigned long addr,
 		zero_end = ELF_PAGEALIGN(zero_end);
 
 		error = vm_brk_flags(zero_start, zero_end - zero_start,
-				     prot & PROT_EXEC ? VM_EXEC : 0);
+				     prot & PROT_EXEC);
 		if (error)
 			map_addr = error;
 	}
 	return map_addr;
 }
 
-
 static unsigned long total_mapping_size(const struct elf_phdr *phdr, int nr)
 {
 	elf_addr_t min_addr = -1;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0c35423177bf..42d346684678 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -4005,12 +4005,12 @@ static inline void mm_populate(unsigned long addr, unsigned long len) {}
 #endif
 
 /* This takes the mm semaphore itself */
-extern int __must_check vm_brk_flags(unsigned long, unsigned long, unsigned long);
-extern int vm_munmap(unsigned long, size_t);
-extern unsigned long __must_check vm_mmap(struct file *, unsigned long,
-        unsigned long, unsigned long,
-        unsigned long, unsigned long);
-extern unsigned long __must_check vm_mmap_shadow_stack(unsigned long addr,
+int __must_check vm_brk_flags(unsigned long addr, unsigned long request, bool is_exec);
+int vm_munmap(unsigned long start, size_t len);
+unsigned long __must_check vm_mmap(struct file *file, unsigned long addr,
+		unsigned long len, unsigned long prot,
+		unsigned long flag, unsigned long offset);
+unsigned long __must_check vm_mmap_shadow_stack(unsigned long addr,
 		unsigned long len, unsigned long flags);
 
 struct vm_unmapped_area_info {
diff --git a/mm/mmap.c b/mm/mmap.c
index 79544d893411..2d2b814978bf 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1201,8 +1201,9 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 	return ret;
 }
 
-int vm_brk_flags(unsigned long addr, unsigned long request, vm_flags_t vm_flags)
+int vm_brk_flags(unsigned long addr, unsigned long request, bool is_exec)
 {
+	const vm_flags_t vm_flags = is_exec ? VM_EXEC : 0;
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma = NULL;
 	unsigned long len;
@@ -1217,10 +1218,6 @@ int vm_brk_flags(unsigned long addr, unsigned long request, vm_flags_t vm_flags)
 	if (!len)
 		return 0;
 
-	/* Until we need other flags, refuse anything except VM_EXEC. */
-	if ((vm_flags & (~VM_EXEC)) != 0)
-		return -EINVAL;
-
 	if (mmap_write_lock_killable(mm))
 		return -EINTR;
 
@@ -1246,7 +1243,6 @@ int vm_brk_flags(unsigned long addr, unsigned long request, vm_flags_t vm_flags)
 	mmap_write_unlock(mm);
 	return ret;
 }
-EXPORT_SYMBOL(vm_brk_flags);
 
 static
 unsigned long tear_down_vmas(struct mm_struct *mm, struct vma_iterator *vmi,
-- 
2.53.0