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	Fri, 14 Jun 2002 12:13:38 -0400
Date: Fri, 14 Jun 2002 18:13:28 +0200
From: Andi Kleen <ak@suse.de>
To: Benjamin LaHaise <bcrl@redhat.com>
Cc: Andi Kleen <ak@suse.de>, Andrea Arcangeli <andrea@suse.de>,
        linux-kernel@vger.kernel.org,
        Richard Brunner <richard.brunner@amd.com>, mark.langsdorf@amd.com
Subject: Re: New version of pageattr caching conflict fix for 2.4
Message-ID: <20020614181328.A18643@wotan.suse.de>
In-Reply-To: <20020613221533.A2544@wotan.suse.de> <20020613210339.B21542@redhat.com> <20020614032429.A19018@wotan.suse.de> <20020613213724.C21542@redhat.com> <20020614040025.GA2093@inspiron.birch.net> <20020614001726.D21542@redhat.com> <20020614062754.A11232@wotan.suse.de> <20020614112849.A22888@redhat.com>
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On Fri, Jun 14, 2002 at 11:28:49AM -0400, Benjamin LaHaise wrote:
> On Fri, Jun 14, 2002 at 06:27:54AM +0200, Andi Kleen wrote:
> > Both AMD x86-64 and Intel IA32 documentation states that INVLPG flushes global
> > TLBs. The first version of change_page_attr did in fact use __flush_tlb_all,
> > but I changed it after checking the docs.
> 
> As Andrea pointed out, there is an errata whereby 4MB pages aren't flushed 
> on the Athlon.  If you mask off the low bits of the address for flushing, 
> that should fix the problem, and sounds like a plausible explanation for 
> the failure I saw.

Ok. I'm using __flush_tlb_all for now.

Here is the latest version; also fixing DRM and some more cleanups.

Review please.

-Andi


diff -burpN -X ../KDIFX -x *-o -x *.[ch]-* linux-2.4.19pre9/arch/i386/mm/Makefile linux-2.4.19pre9-work/arch/i386/mm/Makefile
--- linux-2.4.19pre9/arch/i386/mm/Makefile	Fri Dec 29 23:07:20 2000
+++ linux-2.4.19pre9-work/arch/i386/mm/Makefile	Wed Jun  5 02:35:11 2002
@@ -9,6 +9,7 @@
 
 O_TARGET := mm.o
 
-obj-y	 := init.o fault.o ioremap.o extable.o
+obj-y	 := init.o fault.o ioremap.o extable.o pageattr.o
+export-objs := pageattr.o
 
 include $(TOPDIR)/Rules.make
diff -burpN -X ../KDIFX -x *-o -x *.[ch]-* linux-2.4.19pre9/arch/i386/mm/pageattr.c linux-2.4.19pre9-work/arch/i386/mm/pageattr.c
--- linux-2.4.19pre9/arch/i386/mm/pageattr.c	Thu Jan  1 01:00:00 1970
+++ linux-2.4.19pre9-work/arch/i386/mm/pageattr.c	Fri Jun 14 18:07:58 2002
@@ -0,0 +1,168 @@
+/* 
+ * Copyright 2002 Andi Kleen, SuSE Labs. 
+ * Thanks to Ben LaHaise for precious feedback.
+ */ 
+
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <asm/uaccess.h>
+#include <asm/processor.h>
+
+/* Should move most of this stuff into the appropiate includes */
+#define PAGE_LARGE (_PAGE_PSE|_PAGE_PRESENT) 
+#define LARGE_PAGE_MASK (~(LARGE_PAGE_SIZE-1))
+#define LARGE_PAGE_SIZE (1UL << PMD_SHIFT)
+
+static inline pte_t *lookup_address(unsigned long address) 
+{ 
+	pmd_t *pmd;	
+	pgd_t *pgd = pgd_offset(&init_mm, address); 
+
+	if ((pgd_val(*pgd) & PAGE_LARGE) == PAGE_LARGE)
+		return (pte_t *)pgd; 
+	pmd = pmd_offset(pgd, address); 	       
+	if ((pmd_val(*pmd) & PAGE_LARGE) == PAGE_LARGE)
+		return (pte_t *)pmd; 
+
+        return pte_offset(pmd, address);
+} 
+
+static struct page *split_large_page(unsigned long address, pgprot_t prot)
+{ 
+	int i; 
+	unsigned long addr;
+	struct page *base = alloc_pages(GFP_KERNEL, 0);
+	pte_t *pbase;
+	if (!base) 
+		return NULL;
+	address = __pa(address);
+	addr = address & LARGE_PAGE_MASK; 
+	pbase = (pte_t *)page_address(base);
+	for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
+		pbase[i] = mk_pte_phys(addr, 
+				      addr == address ? prot : PAGE_KERNEL);
+	}
+	return base;
+} 
+
+static void flush_kernel_map(void * address) 
+{ 
+	/* Could use CLFLUSH here if the CPU supports it (Hammer,P4) */
+	if (boot_cpu_data.x86_model >= 4) 
+		asm volatile("wbinvd":::"memory"); 
+	__flush_tlb_all(); 	
+}
+
+static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte) 
+{ 
+	set_pte_atomic(kpte, pte); 	/* change init_mm */
+#ifndef CONFIG_X86_PAE
+	{
+		struct list_head *l;
+		spin_lock(&mmlist_lock);
+		list_for_each(l, &init_mm.mmlist) { 
+			struct mm_struct *mm = list_entry(l, struct mm_struct, mmlist);
+			pmd_t *pmd = pmd_offset(pgd_offset(mm, address), address);
+			set_pte_atomic((pte_t *)pmd, pte);
+		} 
+		spin_unlock(&mmlist_lock);
+	}
+#endif
+}
+
+/* no more special protections in this 2/4MB area - revert to a
+   large page again. */
+static inline void revert_page(struct page *kpte_page, unsigned long address)
+{
+	pte_t *linear = (pte_t *) 
+		pmd_offset(pgd_offset(&init_mm, address), address);
+	set_pmd_pte(linear,  address,
+		mk_pte_phys(__pa(address & LARGE_PAGE_MASK),
+			    __pgprot(_KERNPG_TABLE|_PAGE_PSE)));
+}	
+ 
+/*
+ * Change the page attributes of an page in the linear mapping.
+ *
+ * This should be used when a page is mapped with a different caching policy
+ * than write-back somewhere - some CPUs do not like it when mappings with
+ * different caching policies exist. This changes the page attributes of the
+ * in kernel linear mapping too.
+ * 
+ * The caller needs to ensure that there are no conflicting mappings elsewhere.
+ * This function only deals with the kernel linear map.
+ * When page is in highmem it must never be kmap'ed.
+ */
+static int 
+__change_page_attr(struct page *page, pgprot_t prot, struct page **oldpage) 
+{ 
+	pte_t *kpte; 
+	unsigned long address;
+	struct page *kpte_page;
+
+#ifdef CONFIG_HIGHMEM
+	/* Hopefully not be mapped anywhere else. */
+	if (page >= highmem_start_page) 
+		return 0;
+#endif
+	address = (unsigned long)page_address(page);
+
+	kpte = lookup_address(address);
+	kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
+	if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) { 
+		if ((pte_val(*kpte) & _PAGE_PSE) == 0) { 
+			pte_t old = *kpte;
+			pte_t standard = mk_pte(page, PAGE_KERNEL); 
+
+			set_pte_atomic(kpte, mk_pte(page, prot)); 
+			if (pte_same(old,standard))
+				atomic_inc(&kpte_page->count);
+		} else {
+			struct page *split = split_large_page(address, prot); 
+			if (!split)
+				return -ENOMEM;
+			set_pmd_pte(kpte,address,mk_pte(split, PAGE_KERNEL));
+		}	
+	} else if ((pte_val(*kpte) & _PAGE_PSE) == 0) { 
+		set_pte_atomic(kpte, mk_pte(page, PAGE_KERNEL));
+		atomic_dec(&kpte_page->count); 
+	}
+
+	if (test_bit(X86_FEATURE_PSE, &boot_cpu_data.x86_capability) && 
+	    (atomic_read(&kpte_page->count) == 1)) { 
+		*oldpage = kpte_page;
+		revert_page(kpte_page, address);
+	} 
+	return 0;
+} 
+
+int change_page_attr(struct page *page, int numpages, pgprot_t prot)
+{
+	int err = 0; 
+	struct page *fpage; 
+	int i; 
+
+	down_write(&init_mm.mmap_sem);
+	for (i = 0; i < numpages; i++, page++) { 
+		fpage = NULL;
+		err = __change_page_attr(page, prot, &fpage); 
+		if (err) 
+			break; 
+		if (fpage || i == numpages-1) { 
+			void *address = page_address(page);
+#ifdef CONFIG_SMP 
+			smp_call_function(flush_kernel_map, address, 1, 1);
+#endif	
+			flush_kernel_map(address);
+			if (fpage)
+				__free_page(fpage);
+		} 
+	} 	
+	up_write(&init_mm.mmap_sem); 
+	return err;
+}
+
+EXPORT_SYMBOL(change_page_attr);
diff -burpN -X ../KDIFX -x *-o -x *.[ch]-* linux-2.4.19pre9/drivers/char/agp/agpgart_be.c linux-2.4.19pre9-work/drivers/char/agp/agpgart_be.c
--- linux-2.4.19pre9/drivers/char/agp/agpgart_be.c	Sun Jun  2 20:24:00 2002
+++ linux-2.4.19pre9-work/drivers/char/agp/agpgart_be.c	Fri Jun 14 17:37:46 2002
@@ -397,7 +397,7 @@ int agp_unbind_memory(agp_memory * curr)
 static void agp_generic_agp_enable(u32 mode)
 {
 	struct pci_dev *device = NULL;
-	u32 command, scratch, cap_id;
+	u32 command, scratch;
 	u8 cap_ptr;
 
 	pci_read_config_dword(agp_bridge.dev,
@@ -561,6 +561,7 @@ static int agp_generic_create_gatt_table
 					    agp_bridge.current_size;
 					break;
 				}
+				temp = agp_bridge.current_size;
 			} else {
 				agp_bridge.aperture_size_idx = i;
 			}
@@ -578,23 +579,21 @@ static int agp_generic_create_gatt_table
 	}
 	table_end = table + ((PAGE_SIZE * (1 << page_order)) - 1);
 
-	for (page = virt_to_page(table); page <= virt_to_page(table_end); page++)
+	page = virt_to_page(table);
+
+#ifdef __i386__
+	if (change_page_attr(page, 1<<page_order, PAGE_KERNEL_NOCACHE) < 0) 
+		return -ENOMEM;
+#endif
+	for (; page <= virt_to_page(table_end); page++) { 
 		SetPageReserved(page);
+	}
 
 	agp_bridge.gatt_table_real = (unsigned long *) table;
 	CACHE_FLUSH();
-	agp_bridge.gatt_table = ioremap_nocache(virt_to_phys(table),
-					(PAGE_SIZE * (1 << page_order)));
+	agp_bridge.gatt_table = agp_bridge.gatt_table_real;
 	CACHE_FLUSH();
 
-	if (agp_bridge.gatt_table == NULL) {
-		for (page = virt_to_page(table); page <= virt_to_page(table_end); page++)
-			ClearPageReserved(page);
-
-		free_pages((unsigned long) table, page_order);
-
-		return -ENOMEM;
-	}
 	agp_bridge.gatt_bus_addr = virt_to_phys(agp_bridge.gatt_table_real);
 
 	for (i = 0; i < num_entries; i++) {
@@ -651,7 +650,6 @@ static int agp_generic_free_gatt_table(v
 	 * from the table.
 	 */
 
-	iounmap(agp_bridge.gatt_table);
 	table = (char *) agp_bridge.gatt_table_real;
 	table_end = table + ((PAGE_SIZE * (1 << page_order)) - 1);
 
@@ -769,6 +767,13 @@ static unsigned long agp_generic_alloc_p
 	if (page == NULL) {
 		return 0;
 	}
+#ifdef __i386__
+	if (change_page_attr(page, 1, PAGE_KERNEL_NOCACHE) < 0) { 
+	        __free_page(page); 			   
+		return 0; 
+	}
+#endif
+
 	get_page(page);
 	LockPage(page);
 	atomic_inc(&agp_bridge.current_memory_agp);
@@ -785,6 +790,11 @@ static void agp_generic_destroy_page(uns
 	}
 	
 	page = virt_to_page(pt);
+#ifdef __i386__
+	change_page_attr(page, 1, PAGE_KERNEL);
+#endif
+	
+
 	put_page(page);
 	UnlockPage(page);
 	free_page((unsigned long) pt);
@@ -2241,17 +2251,15 @@ static int amd_create_page_map(amd_page_
 	if (page_map->real == NULL) {
 		return -ENOMEM;
 	}
-	SetPageReserved(virt_to_page(page_map->real));
-	CACHE_FLUSH();
-	page_map->remapped = ioremap_nocache(virt_to_phys(page_map->real), 
-					    PAGE_SIZE);
-	if (page_map->remapped == NULL) {
-		ClearPageReserved(virt_to_page(page_map->real));
-		free_page((unsigned long) page_map->real);
-		page_map->real = NULL;
+#ifdef __i386__
+	if (change_page_attr(virt_to_page(page_map->real), 
+			     1, PAGE_KERNEL_NOCACHE)) {
+		free_page(page_map->real); 
 		return -ENOMEM;
 	}
-	CACHE_FLUSH();
+#endif
+	SetPageReserved(virt_to_page(page_map->real));
+	page_map->remapped = page_map->real; 
 
 	for(i = 0; i < PAGE_SIZE / sizeof(unsigned long); i++) {
 		page_map->remapped[i] = agp_bridge.scratch_page;
@@ -2262,7 +2270,6 @@ static int amd_create_page_map(amd_page_
 
 static void amd_free_page_map(amd_page_map *page_map)
 {
-	iounmap(page_map->remapped);
 	ClearPageReserved(virt_to_page(page_map->real));
 	free_page((unsigned long) page_map->real);
 }
@@ -2744,27 +2751,22 @@ static void ali_cache_flush(void)
 
 static unsigned long ali_alloc_page(void)
 {
-	struct page *page;
-	u32 temp;
-
-	page = alloc_page(GFP_KERNEL);
-	if (page == NULL)
+	unsigned long p = agp_generic_alloc_page(); 
+	if (!p) 
 		return 0;
 
-	get_page(page);
-	LockPage(page);
-	atomic_inc(&agp_bridge.current_memory_agp);
-
+	/* probably not needed anymore */
 	global_cache_flush();
 
 	if (agp_bridge.type == ALI_M1541) {
+		u32 temp;
 		pci_read_config_dword(agp_bridge.dev, ALI_CACHE_FLUSH_CTRL, &temp);
 		pci_write_config_dword(agp_bridge.dev, ALI_CACHE_FLUSH_CTRL,
 				(((temp & ALI_CACHE_FLUSH_ADDR_MASK) |
-				  virt_to_phys(page_address(page))) |
+				  virt_to_phys(p)) |
 				    ALI_CACHE_FLUSH_EN ));
 	}
-	return (unsigned long)page_address(page);
+	return p;
 }
 
 static void ali_destroy_page(unsigned long addr)
@@ -2786,11 +2788,7 @@ static void ali_destroy_page(unsigned lo
 				    ALI_CACHE_FLUSH_EN));
 	}
 
-	page = virt_to_page(pt);
-	put_page(page);
-	UnlockPage(page);
-	free_page((unsigned long) pt);
-	atomic_dec(&agp_bridge.current_memory_agp);
+	agp_generic_destroy_page(pt);
 }
 
 /* Setup function */
@@ -2870,17 +2868,15 @@ static int serverworks_create_page_map(s
 	if (page_map->real == NULL) {
 		return -ENOMEM;
 	}
-	SetPageReserved(virt_to_page(page_map->real));
-	CACHE_FLUSH();
-	page_map->remapped = ioremap_nocache(virt_to_phys(page_map->real), 
-					    PAGE_SIZE);
-	if (page_map->remapped == NULL) {
-		ClearPageReserved(virt_to_page(page_map->real));
-		free_page((unsigned long) page_map->real);
-		page_map->real = NULL;
+#ifdef __i386__
+	if (change_page_attr(virt_to_page(page_map->real), 1, 
+			     PAGE_KERNEL_NOCACHE) < 0) {
+		free_page(page_map->real);
 		return -ENOMEM;
 	}
-	CACHE_FLUSH();
+#endif
+	SetPageReserved(virt_to_page(page_map->real));
+	page_map->remapped = page_map->real;
 
 	for(i = 0; i < PAGE_SIZE / sizeof(unsigned long); i++) {
 		page_map->remapped[i] = agp_bridge.scratch_page;
@@ -2891,7 +2887,6 @@ static int serverworks_create_page_map(s
 
 static void serverworks_free_page_map(serverworks_page_map *page_map)
 {
-	iounmap(page_map->remapped);
 	ClearPageReserved(virt_to_page(page_map->real));
 	free_page((unsigned long) page_map->real);
 }
diff -burpN -X ../KDIFX -x *-o -x *.[ch]-* linux-2.4.19pre9/drivers/char/drm/drm_vm.h linux-2.4.19pre9-work/drivers/char/drm/drm_vm.h
--- linux-2.4.19pre9/drivers/char/drm/drm_vm.h	Wed Jun  5 18:08:30 2002
+++ linux-2.4.19pre9-work/drivers/char/drm/drm_vm.h	Fri Jun 14 06:05:08 2002
@@ -531,6 +531,11 @@ int DRM(mmap)(struct file *filp, struct 
 			vma->vm_flags |= VM_IO;	/* not in core dump */
 		}
 		offset = DRIVER_GET_REG_OFS();
+#ifdef __i386__
+		change_page_attr(vma->vm_pgoff, 
+				 (vma->vm_end - vma->vm_start)>>PAGE_SHIFT,
+				 vma->vm_page_prot); 
+#endif
 #ifdef __sparc__
 		if (io_remap_page_range(vma->vm_start,
 					VM_OFFSET(vma) + offset,
diff -burpN -X ../KDIFX -x *-o -x *.[ch]-* linux-2.4.19pre9/include/asm-i386/pgtable-2level.h linux-2.4.19pre9-work/include/asm-i386/pgtable-2level.h
--- linux-2.4.19pre9/include/asm-i386/pgtable-2level.h	Thu Jul 26 22:40:32 2001
+++ linux-2.4.19pre9-work/include/asm-i386/pgtable-2level.h	Thu Jun 13 16:52:53 2002
@@ -40,6 +40,8 @@ static inline int pgd_present(pgd_t pgd)
  * hook is made available.
  */
 #define set_pte(pteptr, pteval) (*(pteptr) = pteval)
+#define set_pte_atomic(pteptr, pteval) (*(pteptr) = pteval)
+
 /*
  * (pmds are folded into pgds so this doesnt get actually called,
  * but the define is needed for a generic inline function.)
diff -burpN -X ../KDIFX -x *-o -x *.[ch]-* linux-2.4.19pre9/include/asm-i386/pgtable-3level.h linux-2.4.19pre9-work/include/asm-i386/pgtable-3level.h
--- linux-2.4.19pre9/include/asm-i386/pgtable-3level.h	Thu Jul 26 22:40:32 2001
+++ linux-2.4.19pre9-work/include/asm-i386/pgtable-3level.h	Thu Jun 13 17:15:14 2002
@@ -53,6 +53,9 @@ static inline void set_pte(pte_t *ptep, 
 		set_64bit((unsigned long long *)(pmdptr),pmd_val(pmdval))
 #define set_pgd(pgdptr,pgdval) \
 		set_64bit((unsigned long long *)(pgdptr),pgd_val(pgdval))
+#define set_pte_atomic(pteptr,pteval) \
+		set_64bit((unsigned long long *)(pteptr),pte_val(pteval))
+
 
 /*
  * Pentium-II erratum A13: in PAE mode we explicitly have to flush
diff -burpN -X ../KDIFX -x *-o -x *.[ch]-* linux-2.4.19pre9/include/asm-i386/pgtable.h linux-2.4.19pre9-work/include/asm-i386/pgtable.h
--- linux-2.4.19pre9/include/asm-i386/pgtable.h	Mon Jun  3 21:15:18 2002
+++ linux-2.4.19pre9-work/include/asm-i386/pgtable.h	Fri Jun 14 17:45:29 2002
@@ -347,6 +347,9 @@ static inline pte_t pte_modify(pte_t pte
 #define pte_to_swp_entry(pte)		((swp_entry_t) { (pte).pte_low })
 #define swp_entry_to_pte(x)		((pte_t) { (x).val })
 
+struct page;
+int change_page_attr(struct page *, int, pgprot_t prot);
+
 #endif /* !__ASSEMBLY__ */
 
 /* Needs to be defined here and not in linux/mm.h, as it is arch dependent */


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