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Message-Id: <4e87c5bd5ffe886ca202a58e5c93358bd6a34dce.1525435203.git.christophe.leroy@c-s.fr>
In-Reply-To: <cover.1525435203.git.christophe.leroy@c-s.fr>
References: <cover.1525435203.git.christophe.leroy@c-s.fr>
From:   Christophe Leroy <christophe.leroy@c-s.fr>
Subject: [PATCH  11/17] powerpc/nohash32: set GUARDED attribute in the PMD
 directly
To:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        aneesh.kumar@linux.vnet.ibm.com
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Date:   Fri,  4 May 2018 14:34:12 +0200 (CEST)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On the 8xx, the GUARDED attribute of the pages is managed in the
L1 entry, therefore to avoid having to copy it into L1 entry
at each TLB miss, we set it in the PMD.

For this, we split the VM alloc space in two parts, one
for VM alloc and non Guarded IO, and one for Guarded IO.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/include/asm/nohash/32/pgalloc.h | 10 ++++++++++
 arch/powerpc/include/asm/nohash/32/pgtable.h | 18 ++++++++++++++++--
 arch/powerpc/include/asm/nohash/32/pte-8xx.h |  3 ++-
 arch/powerpc/kernel/head_8xx.S               | 18 +++++++-----------
 arch/powerpc/mm/dump_linuxpagetables.c       | 26 ++++++++++++++++++++++++--
 arch/powerpc/mm/ioremap.c                    | 11 ++++++++---
 arch/powerpc/mm/mem.c                        |  9 +++++++++
 arch/powerpc/mm/pgtable_32.c                 | 28 +++++++++++++++++++++++++++-
 arch/powerpc/platforms/Kconfig.cputype       |  3 +++
 9 files changed, 106 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/include/asm/nohash/32/pgalloc.h b/arch/powerpc/include/asm/nohash/32/pgalloc.h
index 29d37bd1f3b3..1c6461e7c6aa 100644
--- a/arch/powerpc/include/asm/nohash/32/pgalloc.h
+++ b/arch/powerpc/include/asm/nohash/32/pgalloc.h
@@ -58,6 +58,12 @@ static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmdp,
 	*pmdp = __pmd(__pa(pte) | _PMD_PRESENT);
 }
 
+static inline void pmd_populate_kernel_g(struct mm_struct *mm, pmd_t *pmdp,
+					 pte_t *pte)
+{
+	*pmdp = __pmd(__pa(pte) | _PMD_PRESENT | _PMD_GUARDED);
+}
+
 static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmdp,
 				pgtable_t pte_page)
 {
@@ -83,6 +89,10 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmdp,
 #define pmd_pgtable(pmd) pmd_page(pmd)
 #endif
 
+#define pte_alloc_kernel_g(pmd, address)			\
+	((unlikely(pmd_none(*(pmd))) && __pte_alloc_kernel_g(pmd, address))? \
+		NULL: pte_offset_kernel(pmd, address))
+
 extern pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr);
 extern pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long addr);
 
diff --git a/arch/powerpc/include/asm/nohash/32/pgtable.h b/arch/powerpc/include/asm/nohash/32/pgtable.h
index 93dc22dbe964..009a5b3d3192 100644
--- a/arch/powerpc/include/asm/nohash/32/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/32/pgtable.h
@@ -69,9 +69,14 @@ extern int icache_44x_need_flush;
  * virtual space that goes below PKMAP and FIXMAP
  */
 #ifdef CONFIG_HIGHMEM
-#define KVIRT_TOP	PKMAP_BASE
+#define _KVIRT_TOP	PKMAP_BASE
 #else
-#define KVIRT_TOP	(0xfe000000UL)	/* for now, could be FIXMAP_BASE ? */
+#define _KVIRT_TOP	(0xfe000000UL)	/* for now, could be FIXMAP_BASE ? */
+#endif
+#ifdef CONFIG_PPC_GUARDED_PAGE_IN_PMD
+#define KVIRT_TOP	_ALIGN_DOWN(_KVIRT_TOP, PGDIR_SIZE)
+#else
+#define KVIRT_TOP	_KVIRT_TOP
 #endif
 
 /*
@@ -84,7 +89,11 @@ extern int icache_44x_need_flush;
 #else
 #define IOREMAP_END	KVIRT_TOP
 #endif
+#ifdef CONFIG_PPC_GUARDED_PAGE_IN_PMD
+#define IOREMAP_BASE	_ALIGN_UP(VMALLOC_BASE + (IOREMAP_END - VMALLOC_BASE) / 2, PGDIR_SIZE)
+#else
 #define IOREMAP_BASE	VMALLOC_BASE
+#endif
 
 /*
  * Just any arbitrary offset to the start of the vmalloc VM area: the
@@ -103,8 +112,13 @@ extern int icache_44x_need_flush;
 #else
 #define VMALLOC_BASE _ALIGN_DOWN((long)high_memory + VMALLOC_OFFSET, VMALLOC_OFFSET)
 #endif
+#ifdef CONFIG_PPC_GUARDED_PAGE_IN_PMD
+#define VMALLOC_START	VMALLOC_BASE
+#define VMALLOC_END	IOREMAP_BASE
+#else
 #define VMALLOC_START	ioremap_bot
 #define VMALLOC_END	IOREMAP_END
+#endif
 
 /*
  * Bits in a linux-style PTE.  These match the bits in the
diff --git a/arch/powerpc/include/asm/nohash/32/pte-8xx.h b/arch/powerpc/include/asm/nohash/32/pte-8xx.h
index f04cb46ae8a1..a9a2919251e0 100644
--- a/arch/powerpc/include/asm/nohash/32/pte-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/pte-8xx.h
@@ -47,10 +47,11 @@
 #define _PAGE_RO	0x0600	/* Supervisor RO, User no access */
 
 #define _PMD_PRESENT	0x0001
-#define _PMD_BAD	0x0fd0
+#define _PMD_BAD	0x0fc0
 #define _PMD_PAGE_MASK	0x000c
 #define _PMD_PAGE_8M	0x000c
 #define _PMD_PAGE_512K	0x0004
+#define _PMD_GUARDED	0x0010
 #define _PMD_USER	0x0020	/* APG 1 */
 
 /* Until my rework is finished, 8xx still needs atomic PTE updates */
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index c3b831bb8bad..85b017c67e11 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -345,6 +345,10 @@ _ENTRY(ITLBMiss_cmp)
 	rlwinm	r10, r10, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
 #ifdef CONFIG_HUGETLB_PAGE
 	mtcr	r11
+#endif
+	/* Load the MI_TWC with the attributes for this "segment." */
+	mtspr	SPRN_MI_TWC, r11	/* Set segment attributes */
+#ifdef CONFIG_HUGETLB_PAGE
 	bt-	28, 10f		/* bit 28 = Large page (8M) */
 	bt-	29, 20f		/* bit 29 = Large page (8M or 512k) */
 #endif
@@ -354,8 +358,6 @@ _ENTRY(ITLBMiss_cmp)
 #if defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)
 	mtcr	r12
 #endif
-	/* Load the MI_TWC with the attributes for this "segment." */
-	mtspr	SPRN_MI_TWC, r11	/* Set segment attributes */
 
 #ifdef CONFIG_SWAP
 	rlwinm	r11, r10, 32-5, _PAGE_PRESENT
@@ -457,6 +459,9 @@ _ENTRY(DTLBMiss_jmp)
 	rlwinm	r10, r10, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
 #ifdef CONFIG_HUGETLB_PAGE
 	mtcr	r11
+#endif
+	mtspr	SPRN_MD_TWC, r11
+#ifdef CONFIG_HUGETLB_PAGE
 	bt-	28, 10f		/* bit 28 = Large page (8M) */
 	bt-	29, 20f		/* bit 29 = Large page (8M or 512k) */
 #endif
@@ -465,15 +470,6 @@ _ENTRY(DTLBMiss_jmp)
 4:
 	mtcr	r12
 
-	/* Insert the Guarded flag into the TWC from the Linux PTE.
-	 * It is bit 27 of both the Linux PTE and the TWC (at least
-	 * I got that right :-).  It will be better when we can put
-	 * this into the Linux pgd/pmd and load it in the operation
-	 * above.
-	 */
-	rlwimi	r11, r10, 0, _PAGE_GUARDED
-	mtspr	SPRN_MD_TWC, r11
-
 	/* Both _PAGE_ACCESSED and _PAGE_PRESENT has to be set.
 	 * We also need to know if the insn is a load/store, so:
 	 * Clear _PAGE_PRESENT and load that which will
diff --git a/arch/powerpc/mm/dump_linuxpagetables.c b/arch/powerpc/mm/dump_linuxpagetables.c
index 6022adb899b7..cd3797be5e05 100644
--- a/arch/powerpc/mm/dump_linuxpagetables.c
+++ b/arch/powerpc/mm/dump_linuxpagetables.c
@@ -74,9 +74,9 @@ struct addr_marker {
 
 static struct addr_marker address_markers[] = {
 	{ 0,	"Start of kernel VM" },
+#ifdef CONFIG_PPC64
 	{ 0,	"vmalloc() Area" },
 	{ 0,	"vmalloc() End" },
-#ifdef CONFIG_PPC64
 	{ 0,	"isa I/O start" },
 	{ 0,	"isa I/O end" },
 	{ 0,	"phb I/O start" },
@@ -85,8 +85,19 @@ static struct addr_marker address_markers[] = {
 	{ 0,	"I/O remap end" },
 	{ 0,	"vmemmap start" },
 #else
+#ifdef CONFIG_PPC_GUARDED_PAGE_IN_PMD
+	{ 0,	"vmalloc() Area" },
+	{ 0,	"vmalloc() End" },
 	{ 0,	"Early I/O remap start" },
 	{ 0,	"Early I/O remap end" },
+	{ 0,	"I/O remap start" },
+	{ 0,	"I/O remap end" },
+#else
+	{ 0,	"Early I/O remap start" },
+	{ 0,	"Early I/O remap end" },
+	{ 0,	"vmalloc() I/O remap start" },
+	{ 0,	"vmalloc() I/O remap end" },
+#endif
 #ifdef CONFIG_NOT_COHERENT_CACHE
 	{ 0,	"Consistent mem start" },
 	{ 0,	"Consistent mem end" },
@@ -437,9 +448,9 @@ static void populate_markers(void)
 	int i = 0;
 
 	address_markers[i++].start_address = PAGE_OFFSET;
+#ifdef CONFIG_PPC64
 	address_markers[i++].start_address = VMALLOC_START;
 	address_markers[i++].start_address = VMALLOC_END;
-#ifdef CONFIG_PPC64
 	address_markers[i++].start_address = ISA_IO_BASE;
 	address_markers[i++].start_address = ISA_IO_END;
 	address_markers[i++].start_address = PHB_IO_BASE;
@@ -452,8 +463,19 @@ static void populate_markers(void)
 	address_markers[i++].start_address =  VMEMMAP_BASE;
 #endif
 #else /* !CONFIG_PPC64 */
+#ifdef CONFIG_PPC_GUARDED_PAGE_IN_PMD
+	address_markers[i++].start_address = VMALLOC_START;
+	address_markers[i++].start_address = VMALLOC_END;
 	address_markers[i++].start_address = IOREMAP_BASE;
 	address_markers[i++].start_address = ioremap_bot;
+	address_markers[i++].start_address = ioremap_bot;
+	address_markers[i++].start_address = IOREMAP_END;
+#else
+	address_markers[i++].start_address = IOREMAP_BASE;
+	address_markers[i++].start_address = ioremap_bot;
+	address_markers[i++].start_address = ioremap_bot;
+	address_markers[i++].start_address = IOREMAP_END;
+#endif
 #ifdef CONFIG_NOT_COHERENT_CACHE
 	address_markers[i++].start_address = IOREMAP_END;
 	address_markers[i++].start_address = IOREMAP_END +
diff --git a/arch/powerpc/mm/ioremap.c b/arch/powerpc/mm/ioremap.c
index 59be5dfcb3e9..b8c347077e02 100644
--- a/arch/powerpc/mm/ioremap.c
+++ b/arch/powerpc/mm/ioremap.c
@@ -132,9 +132,14 @@ void __iomem * __ioremap_caller(phys_addr_t addr, unsigned long size,
 	if (slab_is_available()) {
 		struct vm_struct *area;
 
-		area = __get_vm_area_caller(size, VM_IOREMAP,
-					    ioremap_bot, IOREMAP_END,
-					    caller);
+		if (flags & _PAGE_GUARDED)
+			area = __get_vm_area_caller(size, VM_IOREMAP,
+						    ioremap_bot, IOREMAP_END,
+						    caller);
+		else
+			area = __get_vm_area_caller(size, VM_IOREMAP,
+						    VMALLOC_START, VMALLOC_END,
+						    caller);
 		if (area == NULL)
 			return NULL;
 
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index b680aa78a4ac..fd7af7af5b58 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -386,10 +386,19 @@ void __init mem_init(void)
 	pr_info("  * 0x%08lx..0x%08lx  : consistent mem\n",
 		IOREMAP_END, IOREMAP_END + CONFIG_CONSISTENT_SIZE);
 #endif /* CONFIG_NOT_COHERENT_CACHE */
+#ifdef CONFIG_PPC_GUARDED_PAGE_IN_PMD
+	pr_info("  * 0x%08lx..0x%08lx  : ioremap\n",
+		ioremap_bot, IOREMAP_END);
 	pr_info("  * 0x%08lx..0x%08lx  : early ioremap\n",
 		IOREMAP_BASE, ioremap_bot);
+	pr_info("  * 0x%08lx..0x%08lx  : vmalloc\n",
+		VMALLOC_START, VMALLOC_END);
+#else
 	pr_info("  * 0x%08lx..0x%08lx  : vmalloc & ioremap\n",
 		VMALLOC_START, VMALLOC_END);
+	pr_info("  * 0x%08lx..0x%08lx  : early ioremap\n",
+		IOREMAP_BASE, ioremap_bot);
+#endif
 #endif /* CONFIG_PPC32 */
 }
 
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 54a5bc0767a9..3aa0c78db95d 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -70,6 +70,27 @@ pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
 	return ptepage;
 }
 
+#ifdef CONFIG_PPC_GUARDED_PAGE_IN_PMD
+int __pte_alloc_kernel_g(pmd_t *pmd, unsigned long address)
+{
+	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
+	if (!new)
+		return -ENOMEM;
+
+	smp_wmb(); /* See comment in __pte_alloc */
+
+	spin_lock(&init_mm.page_table_lock);
+	if (likely(pmd_none(*pmd))) {	/* Has another populated it ? */
+		pmd_populate_kernel_g(&init_mm, pmd, new);
+		new = NULL;
+	}
+	spin_unlock(&init_mm.page_table_lock);
+	if (new)
+		pte_free_kernel(&init_mm, new);
+	return 0;
+}
+#endif
+
 int map_kernel_page(unsigned long va, phys_addr_t pa, int flags)
 {
 	pmd_t *pd;
@@ -79,7 +100,12 @@ int map_kernel_page(unsigned long va, phys_addr_t pa, int flags)
 	/* Use upper 10 bits of VA to index the first level map */
 	pd = pmd_offset(pud_offset(pgd_offset_k(va), va), va);
 	/* Use middle 10 bits of VA to index the second-level map */
-	pg = pte_alloc_kernel(pd, va);
+#ifdef CONFIG_PPC_GUARDED_PAGE_IN_PMD
+	if (flags & _PAGE_GUARDED)
+		pg = pte_alloc_kernel_g(pd, va);
+	else
+#endif
+		pg = pte_alloc_kernel(pd, va);
 	if (pg != 0) {
 		err = 0;
 		/* The PTE should never be already set nor present in the
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 67d3125d0610..f860f0326c78 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -319,6 +319,9 @@ config ARCH_ENABLE_HUGEPAGE_MIGRATION
 	def_bool y
 	depends on PPC_BOOK3S_64 && HUGETLB_PAGE && MIGRATION
 
+config PPC_GUARDED_PAGE_IN_PMD
+	def_bool y
+	depends on PPC_8xx
 
 config PPC_MMU_NOHASH
 	def_bool y
-- 
2.13.3