powerpc/32s: Make pte_update() non atomic on 603 core

On 603 core, TLB miss handler don't do any change to the
page tables so pte_update() doesn't need to be atomic.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/cc89d3c11fc9c742d0df3454a657a3a00be24046.1643538554.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index f8b94f78403f192b94d11ebb7cb9720376831008..772e00dc4ef1be463d73090245feb1b56219d83b 100644 (file)
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -298,28 +298,35 @@ static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, p
                                     unsigned long clr, unsigned long set, int huge)
 {
        pte_basic_t old;
-       unsigned long tmp;
 
-       __asm__ __volatile__(
+       if (mmu_has_feature(MMU_FTR_HPTE_TABLE)) {
+               unsigned long tmp;
+
+               asm volatile(
 #ifndef CONFIG_PTE_64BIT
-"1:    lwarx   %0, 0, %3\n"
-"      andc    %1, %0, %4\n"
+       "1:     lwarx   %0, 0, %3\n"
+       "       andc    %1, %0, %4\n"
 #else
-"1:    lwarx   %L0, 0, %3\n"
-"      lwz     %0, -4(%3)\n"
-"      andc    %1, %L0, %4\n"
+       "1:     lwarx   %L0, 0, %3\n"
+       "       lwz     %0, -4(%3)\n"
+       "       andc    %1, %L0, %4\n"
 #endif
-"      or      %1, %1, %5\n"
-"      stwcx.  %1, 0, %3\n"
-"      bne-    1b"
-       : "=&r" (old), "=&r" (tmp), "=m" (*p)
+       "       or      %1, %1, %5\n"
+       "       stwcx.  %1, 0, %3\n"
+       "       bne-    1b"
+               : "=&r" (old), "=&r" (tmp), "=m" (*p)
 #ifndef CONFIG_PTE_64BIT
-       : "r" (p),
+               : "r" (p),
 #else
-       : "b" ((unsigned long)(p) + 4),
+               : "b" ((unsigned long)(p) + 4),
 #endif
-         "r" (clr), "r" (set), "m" (*p)
-       : "cc" );
+                 "r" (clr), "r" (set), "m" (*p)
+               : "cc" );
+       } else {
+               old = pte_val(*p);
+
+               *p = __pte((old & ~(pte_basic_t)clr) | set);
+       }
 
        return old;
 }