arch/mips/kernel/traps: use vma_lookup() instead of find_vma()

Use vma_lookup() to find the VMA at a specific address.  As vma_lookup()
will return NULL if the address is not within any VMA, the start address
no longer needs to be validated.

Link: https://lkml.kernel.org/r/20210521174745.2219620-8-Liam.Howlett@Oracle.comSigned-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/mips/kernel/traps.c

@@ -784,7 +784,6 @@ void force_fcr31_sig(unsigned long fcr31, void __user *fault_addr,
 int process_fpemu_return(int sig, void __user *fault_addr, unsigned long fcr31)
 {
 	int si_code;
-	struct vm_area_struct *vma;
 
 	switch (sig) {
 	case 0:
@@ -800,8 +799,7 @@ int process_fpemu_return(int sig, void __user *fault_addr, unsigned long fcr31)
 
 	case SIGSEGV:
 		mmap_read_lock(current->mm);
-		vma = find_vma(current->mm, (unsigned long)fault_addr);
-		if (vma && (vma->vm_start <= (unsigned long)fault_addr))
+		if (vma_lookup(current->mm, (unsigned long)fault_addr))
 			si_code = SEGV_ACCERR;
 		else
 			si_code = SEGV_MAPERR;