MIPS: Shrink the size of tlb handler

By combining swapper_pg_dir and module_pg_dir, several if conditions
can be eliminated from the tlb exception handler. The reason they
can be combined is that, the effective virtual address of vmalloc
returned is at the bottom, and of module_alloc returned is at the
top. It also fixes the bug in vmalloc(), which happens when its
return address is not covered by the first pgd.
Signed-off-by: Wu Fei <at.wufei@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/pgtable-64.h

@@ -109,13 +109,13 @@
 
 #define VMALLOC_START		MAP_BASE
 #define VMALLOC_END	\
-	(VMALLOC_START + PTRS_PER_PGD * PTRS_PER_PMD * PTRS_PER_PTE * PAGE_SIZE)
+	(VMALLOC_START + \
+	 PTRS_PER_PGD * PTRS_PER_PMD * PTRS_PER_PTE * PAGE_SIZE - (1UL << 32))
 #if defined(CONFIG_MODULES) && defined(KBUILD_64BIT_SYM32) && \
 	VMALLOC_START != CKSSEG
 /* Load modules into 32bit-compatible segment. */
 #define MODULE_START	CKSSEG
 #define MODULE_END	(FIXADDR_START-2*PAGE_SIZE)
-extern pgd_t module_pg_dir[PTRS_PER_PGD];
 #endif
 
 #define pte_ERROR(e) \
@@ -188,12 +188,7 @@ static inline void pud_clear(pud_t *pudp)
 #define __pmd_offset(address)	pmd_index(address)
 
 /* to find an entry in a kernel page-table-directory */
-#ifdef MODULE_START
-#define pgd_offset_k(address) \
-	((address) >= MODULE_START ? module_pg_dir : pgd_offset(&init_mm, 0UL))
-#else
-#define pgd_offset_k(address) pgd_offset(&init_mm, 0UL)
-#endif
+#define pgd_offset_k(address) pgd_offset(&init_mm, address)
 
 #define pgd_index(address)	(((address) >> PGDIR_SHIFT) & (PTRS_PER_PGD-1))
 #define pmd_index(address)	(((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))

arch/mips/mm/init.c

@@ -475,9 +475,6 @@ unsigned long pgd_current[NR_CPUS];
  */
 pgd_t swapper_pg_dir[_PTRS_PER_PGD] __page_aligned(_PGD_ORDER);
 #ifdef CONFIG_64BIT
-#ifdef MODULE_START
-pgd_t module_pg_dir[PTRS_PER_PGD] __page_aligned(PGD_ORDER);
-#endif
 pmd_t invalid_pmd_table[PTRS_PER_PMD] __page_aligned(PMD_ORDER);
 #endif
 pte_t invalid_pte_table[PTRS_PER_PTE] __page_aligned(PTE_ORDER);

arch/mips/mm/pgtable-64.c

@@ -59,9 +59,6 @@ void __init pagetable_init(void)
 
 	/* Initialize the entire pgd.  */
 	pgd_init((unsigned long)swapper_pg_dir);
-#ifdef MODULE_START
-	pgd_init((unsigned long)module_pg_dir);
-#endif
 	pmd_init((unsigned long)invalid_pmd_table, (unsigned long)invalid_pte_table);
 
 	pgd_base = swapper_pg_dir;

arch/mips/mm/tlbex.c

@@ -499,11 +499,7 @@ build_get_pmde64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 	 * The vmalloc handling is not in the hotpath.
 	 */
 	uasm_i_dmfc0(p, tmp, C0_BADVADDR);
-#ifdef MODULE_START
-	uasm_il_bltz(p, r, tmp, label_module_alloc);
-#else
 	uasm_il_bltz(p, r, tmp, label_vmalloc);
-#endif
 	/* No uasm_i_nop needed here, since the next insn doesn't touch TMP. */
 
 #ifdef CONFIG_SMP
@@ -556,52 +552,7 @@ build_get_pgd_vmalloc64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 {
 	long swpd = (long)swapper_pg_dir;
 
-#ifdef MODULE_START
-	long modd = (long)module_pg_dir;
-
-	uasm_l_module_alloc(l, *p);
-	/*
-	 * Assumption:
-	 * VMALLOC_START >= 0xc000000000000000UL
-	 * MODULE_START >= 0xe000000000000000UL
-	 */
-	UASM_i_SLL(p, ptr, bvaddr, 2);
-	uasm_il_bgez(p, r, ptr, label_vmalloc);
-
-	if (uasm_in_compat_space_p(MODULE_START) &&
-	    !uasm_rel_lo(MODULE_START)) {
-		uasm_i_lui(p, ptr, uasm_rel_hi(MODULE_START)); /* delay slot */
-	} else {
-		/* unlikely configuration */
-		uasm_i_nop(p); /* delay slot */
-		UASM_i_LA(p, ptr, MODULE_START);
-	}
-	uasm_i_dsubu(p, bvaddr, bvaddr, ptr);
-
-	if (uasm_in_compat_space_p(modd) && !uasm_rel_lo(modd)) {
-		uasm_il_b(p, r, label_vmalloc_done);
-		uasm_i_lui(p, ptr, uasm_rel_hi(modd));
-	} else {
-		UASM_i_LA_mostly(p, ptr, modd);
-		uasm_il_b(p, r, label_vmalloc_done);
-		if (uasm_in_compat_space_p(modd))
-			uasm_i_addiu(p, ptr, ptr, uasm_rel_lo(modd));
-		else
-			uasm_i_daddiu(p, ptr, ptr, uasm_rel_lo(modd));
-	}
-
 	uasm_l_vmalloc(l, *p);
-	if (uasm_in_compat_space_p(MODULE_START) &&
-	    !uasm_rel_lo(MODULE_START) &&
-	    MODULE_START << 32 == VMALLOC_START)
-		uasm_i_dsll32(p, ptr, ptr, 0);	/* typical case */
-	else
-		UASM_i_LA(p, ptr, VMALLOC_START);
-#else
-	uasm_l_vmalloc(l, *p);
-	UASM_i_LA(p, ptr, VMALLOC_START);
-#endif
-	uasm_i_dsubu(p, bvaddr, bvaddr, ptr);
 
 	if (uasm_in_compat_space_p(swpd) && !uasm_rel_lo(swpd)) {
 		uasm_il_b(p, r, label_vmalloc_done);