[PATCH 4/5] x86: shstk: Use the new common vm_mmap_shadow_stack() helper

[Catalin Marinas <catalin.marinas@arm.com>]

Replace part of the x86 alloc_shstk() content with a call to
vm_mmap_shadow_stack().

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
 arch/x86/kernel/shstk.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c
index 978232b6d48d..9725e7d89b1e 100644
--- a/arch/x86/kernel/shstk.c
+++ b/arch/x86/kernel/shstk.c
@@ -100,17 +100,9 @@ static int create_rstor_token(unsigned long ssp, unsigned long *token_addr)
 static unsigned long alloc_shstk(unsigned long addr, unsigned long size,
 				 unsigned long token_offset, bool set_res_tok)
 {
-	int flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_ABOVE4G;
-	struct mm_struct *mm = current->mm;
-	unsigned long mapped_addr, unused;
+	unsigned long mapped_addr;
 
-	if (addr)
-		flags |= MAP_FIXED_NOREPLACE;
-
-	mmap_write_lock(mm);
-	mapped_addr = do_mmap(NULL, addr, size, PROT_READ, flags,
-			      VM_SHADOW_STACK | VM_WRITE, 0, &unused, NULL);
-	mmap_write_unlock(mm);
+	mapped_addr = vm_mmap_shadow_stack(addr, size, MAP_ABOVE4G);
 
 	if (!set_res_tok || IS_ERR_VALUE(mapped_addr))
 		goto out;