powerpc/32s: In add_hash_page(), calculate VSID later

VSID is only for create_hpte(). When _PAGE_HASHPTE is
already set, add_hash_page() bails out without calling
create_hpte() and doesn't need the value of VSID.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/3907199974c89b85a3441cf3f528751173b7649c.1606247495.git.christophe.leroy@csgroup.eu

arch/powerpc/mm/book3s32/hash_low.S

@@ -182,12 +182,6 @@ _GLOBAL(add_hash_page)
 	mflr	r0
 	stw	r0,4(r1)
 
-	/* Convert context and va to VSID */
-	mulli	r3,r3,897*16		/* multiply context by context skew */
-	rlwinm	r0,r4,4,28,31		/* get ESID (top 4 bits of va) */
-	mulli	r0,r0,0x111		/* multiply by ESID skew */
-	add	r3,r3,r0		/* note create_hpte trims to 24 bits */
-
 #ifdef CONFIG_SMP
 	lwz	r8,TASK_CPU(r2)		/* to go in mmu_hash_lock */
 	oris	r8,r8,12
@@ -251,6 +245,12 @@ _GLOBAL(add_hash_page)
 	stwcx.	r5,0,r8
 	bne-	1b
 
+	/* Convert context and va to VSID */
+	mulli	r3,r3,897*16		/* multiply context by context skew */
+	rlwinm	r0,r4,4,28,31		/* get ESID (top 4 bits of va) */
+	mulli	r0,r0,0x111		/* multiply by ESID skew */
+	add	r3,r3,r0		/* note create_hpte trims to 24 bits */
+
 	bl	create_hpte
 
 9: