powerpc/8xx: Simplify pte_update() with 16k pages

While looking at code generated for code patching, I saw that
pte_clear generated:

 2d8:	38 a0 00 00 	li      r5,0
 2dc:	38 e0 10 00 	li      r7,4096
 2e0:	39 00 20 00 	li      r8,8192
 2e4:	39 40 30 00 	li      r10,12288
 2e8:	90 a9 00 00 	stw     r5,0(r9)
 2ec:	90 e9 00 04 	stw     r7,4(r9)
 2f0:	91 09 00 08 	stw     r8,8(r9)
 2f4:	91 49 00 0c 	stw     r10,12(r9)

With 16k pages, only the first entry is used by the kernel, so no need
to adapt the address of other entries. Only duplicate the first entry
for hardware.

Now it is:

 2cc:	39 40 00 00 	li      r10,0
 2d0:	91 49 00 00 	stw     r10,0(r9)
 2d4:	91 49 00 04 	stw     r10,4(r9)
 2d8:	91 49 00 08 	stw     r10,8(r9)
 2dc:	91 49 00 0c 	stw     r10,12(r9)

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/65f76300de07091a59a042a3db2d0ce9b939a05c.1664346532.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/include/asm/nohash/32/pgtable.h b/arch/powerpc/include/asm/nohash/32/pgtable.h
index 0d40b33184ebe9a7c1f3372c3dbaaa78aa1b4e9a..0e861e59b76952523078f74ab3820c39d161ae84 100644 (file)
--- a/arch/powerpc/include/asm/nohash/32/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/32/pgtable.h
@@ -256,8 +256,14 @@ static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, p
 
        num = number_of_cells_per_pte(pmd, new, huge);
 
-       for (i = 0; i < num; i++, entry++, new += SZ_4K)
-               *entry = new;
+       for (i = 0; i < num; i += PAGE_SIZE / SZ_4K, new += PAGE_SIZE) {
+               *entry++ = new;
+               if (IS_ENABLED(CONFIG_PPC_16K_PAGES) && num != 1) {
+                       *entry++ = new;
+                       *entry++ = new;
+                       *entry++ = new;
+               }
+       }
 
        return old;
 }