powerpc/mm: Fix attribute confusion with htab_bolt_mapping()

The function htab_bolt_mapping() is used to create permanent
mappings in the MMU hash table, for example, in order to create
the linear mapping of vmemmap.  It's also used by early boot
ioremap (before mem_init_done).

However, the way ioremap uses it is incorrect as it passes it the
protection flags in the "linux PTE" form while htab_bolt_mapping()
expects them in the hash table format.  This is made more confusing by
the fact that some of those flags are actually in the same position in
both cases.

This fixes it all by making htab_bolt_mapping() take normal linux
protection flags instead, and use a little helper to convert them to
htab flags. Callers can now use the usual PAGE_* definitions safely.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

 arch/powerpc/include/asm/mmu-hash64.h |    2 -
 arch/powerpc/mm/hash_utils_64.c       |   65 ++++++++++++++++++++--------------
 arch/powerpc/mm/init_64.c             |    9 +---
 3 files changed, 44 insertions(+), 32 deletions(-)
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/include/asm/mmu-hash64.h

@@ -278,7 +278,7 @@ extern int hash_huge_page(struct mm_struct *mm, unsigned long access,
 			  unsigned long trap);
 
 extern int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
-			     unsigned long pstart, unsigned long mode,
+			     unsigned long pstart, unsigned long prot,
 			     int psize, int ssize);
 extern void set_huge_psize(int psize);
 extern void add_gpage(unsigned long addr, unsigned long page_size,

arch/powerpc/mm/hash_utils_64.c

@@ -151,39 +151,53 @@ static struct mmu_psize_def mmu_psize_defaults_gp[] = {
 	},
 };
 
+static unsigned long htab_convert_pte_flags(unsigned long pteflags)
+{
+	unsigned long rflags = pteflags & 0x1fa;
+
+	/* _PAGE_EXEC -> NOEXEC */
+	if ((pteflags & _PAGE_EXEC) == 0)
+		rflags |= HPTE_R_N;
+
+	/* PP bits. PAGE_USER is already PP bit 0x2, so we only
+	 * need to add in 0x1 if it's a read-only user page
+	 */
+	if ((pteflags & _PAGE_USER) && !((pteflags & _PAGE_RW) &&
+					 (pteflags & _PAGE_DIRTY)))
+		rflags |= 1;
+
+	/* Always add C */
+	return rflags | HPTE_R_C;
+}
 
 int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
-		      unsigned long pstart, unsigned long mode,
+		      unsigned long pstart, unsigned long prot,
 		      int psize, int ssize)
 {
 	unsigned long vaddr, paddr;
 	unsigned int step, shift;
-	unsigned long tmp_mode;
 	int ret = 0;
 
 	shift = mmu_psize_defs[psize].shift;
 	step = 1 << shift;
 
+	prot = htab_convert_pte_flags(prot);
+
+	DBG("htab_bolt_mapping(%lx..%lx -> %lx (%lx,%d,%d)\n",
+	    vstart, vend, pstart, prot, psize, ssize);
+
 	for (vaddr = vstart, paddr = pstart; vaddr < vend;
 	     vaddr += step, paddr += step) {
 		unsigned long hash, hpteg;
 		unsigned long vsid = get_kernel_vsid(vaddr, ssize);
 		unsigned long va = hpt_va(vaddr, vsid, ssize);
 
-		tmp_mode = mode;
-		
-		/* Make non-kernel text non-executable */
-		if (!in_kernel_text(vaddr))
-			tmp_mode = mode | HPTE_R_N;
-
 		hash = hpt_hash(va, shift, ssize);
 		hpteg = ((hash & htab_hash_mask) * HPTES_PER_GROUP);
 
-		DBG("htab_bolt_mapping: calling %p\n", ppc_md.hpte_insert);
-
 		BUG_ON(!ppc_md.hpte_insert);
-		ret = ppc_md.hpte_insert(hpteg, va, paddr,
-				tmp_mode, HPTE_V_BOLTED, psize, ssize);
+		ret = ppc_md.hpte_insert(hpteg, va, paddr, prot,
+					 HPTE_V_BOLTED, psize, ssize);
 
 		if (ret < 0)
 			break;
@@ -520,8 +534,8 @@ static unsigned long __init htab_get_table_size(void)
 void create_section_mapping(unsigned long start, unsigned long end)
 {
 	BUG_ON(htab_bolt_mapping(start, end, __pa(start),
-			_PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_COHERENT | PP_RWXX,
-			mmu_linear_psize, mmu_kernel_ssize));
+				 PAGE_KERNEL, mmu_linear_psize,
+				 mmu_kernel_ssize));
 }
 
 int remove_section_mapping(unsigned long start, unsigned long end)
@@ -570,7 +584,7 @@ void __init htab_initialize(void)
 {
 	unsigned long table;
 	unsigned long pteg_count;
-	unsigned long mode_rw;
+	unsigned long prot, tprot;
 	unsigned long base = 0, size = 0, limit;
 	int i;
 
@@ -628,7 +642,7 @@ void __init htab_initialize(void)
 		mtspr(SPRN_SDR1, _SDR1);
 	}
 
-	mode_rw = _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_COHERENT | PP_RWXX;
+	prot = PAGE_KERNEL;
 
 #ifdef CONFIG_DEBUG_PAGEALLOC
 	linear_map_hash_count = lmb_end_of_DRAM() >> PAGE_SHIFT;
@@ -646,8 +660,10 @@ void __init htab_initialize(void)
 	for (i=0; i < lmb.memory.cnt; i++) {
 		base = (unsigned long)__va(lmb.memory.region[i].base);
 		size = lmb.memory.region[i].size;
+		tprot = prot | (in_kernel_text(base) ? _PAGE_EXEC : 0);
 
-		DBG("creating mapping for region: %lx : %lx\n", base, size);
+		DBG("creating mapping for region: %lx..%lx (prot: %x)\n",
+		    base, size, tprot);
 
 #ifdef CONFIG_U3_DART
 		/* Do not map the DART space. Fortunately, it will be aligned
@@ -664,21 +680,21 @@ void __init htab_initialize(void)
 			unsigned long dart_table_end = dart_tablebase + 16 * MB;
 			if (base != dart_tablebase)
 				BUG_ON(htab_bolt_mapping(base, dart_tablebase,
-							__pa(base), mode_rw,
+							__pa(base), tprot,
 							mmu_linear_psize,
 							mmu_kernel_ssize));
 			if ((base + size) > dart_table_end)
 				BUG_ON(htab_bolt_mapping(dart_tablebase+16*MB,
 							base + size,
 							__pa(dart_table_end),
-							 mode_rw,
+							 tprot,
 							 mmu_linear_psize,
 							 mmu_kernel_ssize));
 			continue;
 		}
 #endif /* CONFIG_U3_DART */
 		BUG_ON(htab_bolt_mapping(base, base + size, __pa(base),
-				mode_rw, mmu_linear_psize, mmu_kernel_ssize));
+				tprot, mmu_linear_psize, mmu_kernel_ssize));
        }
 
 	/*
@@ -696,7 +712,7 @@ void __init htab_initialize(void)
 			tce_alloc_start = base + size + 1;
 
 		BUG_ON(htab_bolt_mapping(tce_alloc_start, tce_alloc_end,
-					 __pa(tce_alloc_start), mode_rw,
+					 __pa(tce_alloc_start), prot,
 					 mmu_linear_psize, mmu_kernel_ssize));
 	}
 
@@ -1117,8 +1133,7 @@ static void kernel_map_linear_page(unsigned long vaddr, unsigned long lmi)
 	unsigned long hash, hpteg;
 	unsigned long vsid = get_kernel_vsid(vaddr, mmu_kernel_ssize);
 	unsigned long va = hpt_va(vaddr, vsid, mmu_kernel_ssize);
-	unsigned long mode = _PAGE_ACCESSED | _PAGE_DIRTY |
-		_PAGE_COHERENT | PP_RWXX | HPTE_R_N;
+	unsigned long mode = htab_convert_pte_flags(PAGE_KERNEL);
 	int ret;
 
 	hash = hpt_hash(va, PAGE_SHIFT, mmu_kernel_ssize);

arch/powerpc/mm/init_64.c

@@ -206,13 +206,10 @@ static int __meminit vmemmap_populated(unsigned long start, int page_size)
 int __meminit vmemmap_populate(struct page *start_page,
 			       unsigned long nr_pages, int node)
 {
-	unsigned long mode_rw;
 	unsigned long start = (unsigned long)start_page;
 	unsigned long end = (unsigned long)(start_page + nr_pages);
 	unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
 
-	mode_rw = _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_COHERENT | PP_RWXX;
-
 	/* Align to the page size of the linear mapping. */
 	start = _ALIGN_DOWN(start, page_size);
 
@@ -230,8 +227,8 @@ int __meminit vmemmap_populate(struct page *start_page,
 		pr_debug("vmemmap %08lx allocated at %p, physical %08lx.\n",
 			start, p, __pa(p));
 
-		mapped = htab_bolt_mapping(start, start + page_size,
-					__pa(p), mode_rw, mmu_vmemmap_psize,
+		mapped = htab_bolt_mapping(start, start + page_size, __pa(p),
+					   PAGE_KERNEL, mmu_vmemmap_psize,
 					   mmu_kernel_ssize);
 		BUG_ON(mapped < 0);
 	}