Re: Kernel 4.7: PAGE_GUARDED and _PAGE_NO_CACHE

[Darren Stevens <darren@stevens-zone.net>]

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  AmigaOS...........: http://yam.ch/
  Unix/MacOS/Windows: http://www.mozilla.com/thunderbird/

General information about MIME can be found at:
http://en.wikipedia.org/wiki/MIME

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Hello Christian

On 07/06/2016, Christian Zigotzky wrote:
> "range.size, pgprot_val(pgprot_noncached(__pgprot(0))));" isn't the 
> problem. :-) It works.
>
> 764041e0f43cc7846f6d8eb246d65b53cc06c764 is the first bad commit
> commit 764041e0f43cc7846f6d8eb246d65b53cc06c764
> Author: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> Date:   Fri Apr 29 23:26:09 2016 +1000
>
>      powerpc/mm/radix: Add checks in slice code to catch radix usage
>
>      Radix doesn't need slice support. Catch incorrect usage of slice
>      code when radix is enabled.
>
>      Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>      Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
>

That's not where I ended up with my bisect, this commit is about 10 before the
one I found to be bad, which is:

commit d6a9996e84ac4beb7713e9485f4563e100a9b03e
Author: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Date:   Fri Apr 29 23:26:21 2016 +1000

    powerpc/mm: vmalloc abstraction in preparation for radix
    
    The vmalloc range differs between hash and radix config. Hence make
    VMALLOC_START and related constants a variable which will be runtime
    initialized depending on whether hash or radix mode is active.
    
    Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    [mpe: Fix missing init of ioremap_bot in pgtable_64.c for ppc64e]
    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Not sure how we are getting different results though. I have attached my
bisect log and the suspect commit, whcih is quite large. I'm not sure which
part of it is at fault. I have some jobs to do now, but hope to get tesing
this later today.

Regards
Darren

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git bisect start
# bad: [ed2608faa0f701b1dbc65277a9e5c7ff7118bfd4] Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
git bisect bad ed2608faa0f701b1dbc65277a9e5c7ff7118bfd4
# good: [8ffb4103f5e28d7e7890ed4774d8e009f253f56e] IB/qib: Use cache inhibitted and guarded mapping on powerpc
git bisect good 8ffb4103f5e28d7e7890ed4774d8e009f253f56e
# good: [801faf0db8947e01877920e848a4d338dd7a99e7] mm/slab: lockless decision to grow cache
git bisect good 801faf0db8947e01877920e848a4d338dd7a99e7
# bad: [2f37dd131c5d3a2eac21cd5baf80658b1b02a8ac] Merge tag 'staging-4.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging
git bisect bad 2f37dd131c5d3a2eac21cd5baf80658b1b02a8ac
# bad: [be1332c0994fbf016fa4ef0f0c4acda566fe6cb3] Merge tag 'gfs2-4.7.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2
git bisect bad be1332c0994fbf016fa4ef0f0c4acda566fe6cb3
# good: [f4c80d5a16eb4b08a0d9ade154af1ebdc63f5752] Merge tag 'sound-4.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
git bisect good f4c80d5a16eb4b08a0d9ade154af1ebdc63f5752
# good: [a1c28b75a95808161cacbb3531c418abe248994e] Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm
git bisect good a1c28b75a95808161cacbb3531c418abe248994e
# bad: [6eb59af580dcffc6f6982ac8ef6d27a1a5f26b27] Merge tag 'mfd-for-linus-4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd
git bisect bad 6eb59af580dcffc6f6982ac8ef6d27a1a5f26b27
# bad: [4fad494321351f0ac412945c6a464109ad96734a] powerpc/powernv: Simplify pnv_eeh_reset()
git bisect bad 4fad494321351f0ac412945c6a464109ad96734a
# bad: [43a5c684270ee9b5b13c91ec048831dd5b7e0cdc] powerpc/mm/radix: Make sure swapper pgdir is properly aligned
git bisect bad 43a5c684270ee9b5b13c91ec048831dd5b7e0cdc
# good: [a9252aaefe7e72133e7a37e0eff4e950a4f33af1] powerpc/mm: Move hugetlb and THP related pmd accessors to pgtable.h
git bisect good a9252aaefe7e72133e7a37e0eff4e950a4f33af1
# good: [177ba7c647f37bc3f31667192059ee794347d79d] powerpc/mm/radix: Limit paca allocation in radix
git bisect good 177ba7c647f37bc3f31667192059ee794347d79d
# good: [934828edfadc43be07e53429ce501741bedf4a5e] powerpc/mm: Make 4K and 64K use pte_t for pgtable_t
git bisect good 934828edfadc43be07e53429ce501741bedf4a5e
# bad: [a3dece6d69b0ad21b64104dff508c67a1a1f14dd] powerpc/radix: Update MMU cache
git bisect bad a3dece6d69b0ad21b64104dff508c67a1a1f14dd
# good: [4dfb88ca9b66690d21030ccacc1cca73db90655e] powerpc/mm: Update pte filter for radix
git bisect good 4dfb88ca9b66690d21030ccacc1cca73db90655e
# bad: [d6a9996e84ac4beb7713e9485f4563e100a9b03e] powerpc/mm: vmalloc abstraction in preparation for radix
git bisect bad d6a9996e84ac4beb7713e9485f4563e100a9b03e

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commit d6a9996e84ac4beb7713e9485f4563e100a9b03e
Author: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Date:   Fri Apr 29 23:26:21 2016 +1000

    powerpc/mm: vmalloc abstraction in preparation for radix
    
    The vmalloc range differs between hash and radix config. Hence make
    VMALLOC_START and related constants a variable which will be runtime
    initialized depending on whether hash or radix mode is active.
    
    Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    [mpe: Fix missing init of ioremap_bot in pgtable_64.c for ppc64e]
    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h
index cd3e915..f61cad3 100644
--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h
@@ -45,17 +45,17 @@
 /*
  * Define the address range of the kernel non-linear virtual area
  */
-#define KERN_VIRT_START ASM_CONST(0xD000000000000000)
-#define KERN_VIRT_SIZE	ASM_CONST(0x0000100000000000)
+#define H_KERN_VIRT_START ASM_CONST(0xD000000000000000)
+#define H_KERN_VIRT_SIZE	ASM_CONST(0x0000100000000000)
 
 /*
  * The vmalloc space starts at the beginning of that region, and
  * occupies half of it on hash CPUs and a quarter of it on Book3E
  * (we keep a quarter for the virtual memmap)
  */
-#define VMALLOC_START	KERN_VIRT_START
-#define VMALLOC_SIZE	(KERN_VIRT_SIZE >> 1)
-#define VMALLOC_END	(VMALLOC_START + VMALLOC_SIZE)
+#define H_VMALLOC_START	H_KERN_VIRT_START
+#define H_VMALLOC_SIZE	(H_KERN_VIRT_SIZE >> 1)
+#define H_VMALLOC_END	(H_VMALLOC_START + H_VMALLOC_SIZE)
 
 /*
  * Region IDs
@@ -64,7 +64,7 @@
 #define REGION_MASK		(0xfUL << REGION_SHIFT)
 #define REGION_ID(ea)		(((unsigned long)(ea)) >> REGION_SHIFT)
 
-#define VMALLOC_REGION_ID	(REGION_ID(VMALLOC_START))
+#define VMALLOC_REGION_ID	(REGION_ID(H_VMALLOC_START))
 #define KERNEL_REGION_ID	(REGION_ID(PAGE_OFFSET))
 #define VMEMMAP_REGION_ID	(0xfUL)	/* Server only */
 #define USER_REGION_ID		(0UL)
@@ -73,7 +73,7 @@
  * Defines the address of the vmemap area, in its own region on
  * hash table CPUs.
  */
-#define VMEMMAP_BASE		(VMEMMAP_REGION_ID << REGION_SHIFT)
+#define H_VMEMMAP_BASE		(VMEMMAP_REGION_ID << REGION_SHIFT)
 
 #ifdef CONFIG_PPC_MM_SLICES
 #define HAVE_ARCH_UNMAPPED_AREA
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 32a9756..f5628f9 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -208,6 +208,18 @@ extern unsigned long __pgd_val_bits;
 #define PUD_MASKED_BITS		0xc0000000000000ffUL
 /* Bits to mask out from a PGD to get to the PUD page */
 #define PGD_MASKED_BITS		0xc0000000000000ffUL
+
+extern unsigned long __vmalloc_start;
+extern unsigned long __vmalloc_end;
+#define VMALLOC_START	__vmalloc_start
+#define VMALLOC_END	__vmalloc_end
+
+extern unsigned long __kernel_virt_start;
+extern unsigned long __kernel_virt_size;
+#define KERN_VIRT_START __kernel_virt_start
+#define KERN_VIRT_SIZE  __kernel_virt_size
+extern struct page *vmemmap;
+extern unsigned long ioremap_bot;
 #endif /* __ASSEMBLY__ */
 
 #include <asm/book3s/64/hash.h>
@@ -220,7 +232,6 @@ extern unsigned long __pgd_val_bits;
 #endif
 
 #include <asm/barrier.h>
-
 /*
  * The second half of the kernel virtual space is used for IO mappings,
  * it's itself carved into the PIO region (ISA and PHB IO space) and
@@ -239,8 +250,6 @@ extern unsigned long __pgd_val_bits;
 #define IOREMAP_BASE	(PHB_IO_END)
 #define IOREMAP_END	(KERN_VIRT_START + KERN_VIRT_SIZE)
 
-#define vmemmap			((struct page *)VMEMMAP_BASE)
-
 /* Advertise special mapping type for AGP */
 #define HAVE_PAGE_AGP
 
diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h
index 63eb629..f470902 100644
--- a/arch/powerpc/include/asm/book3s/64/radix.h
+++ b/arch/powerpc/include/asm/book3s/64/radix.h
@@ -31,6 +31,74 @@
 			      RADIX_PUD_INDEX_SIZE + RADIX_PGD_INDEX_SIZE + PAGE_SHIFT)
 #define RADIX_PGTABLE_RANGE (ASM_CONST(1) << RADIX_PGTABLE_EADDR_SIZE)
 
+/*
+ * We support 52 bit address space, Use top bit for kernel
+ * virtual mapping. Also make sure kernel fit in the top
+ * quadrant.
+ *
+ *           +------------------+
+ *           +------------------+  Kernel virtual map (0xc008000000000000)
+ *           |                  |
+ *           |                  |
+ *           |                  |
+ * 0b11......+------------------+  Kernel linear map (0xc....)
+ *           |                  |
+ *           |     2 quadrant   |
+ *           |                  |
+ * 0b10......+------------------+
+ *           |                  |
+ *           |    1 quadrant    |
+ *           |                  |
+ * 0b01......+------------------+
+ *           |                  |
+ *           |    0 quadrant    |
+ *           |                  |
+ * 0b00......+------------------+
+ *
+ *
+ * 3rd quadrant expanded:
+ * +------------------------------+
+ * |                              |
+ * |                              |
+ * |                              |
+ * +------------------------------+  Kernel IO map end (0xc010000000000000)
+ * |                              |
+ * |                              |
+ * |      1/2 of virtual map      |
+ * |                              |
+ * |                              |
+ * +------------------------------+  Kernel IO map start
+ * |                              |
+ * |      1/4 of virtual map      |
+ * |                              |
+ * +------------------------------+  Kernel vmemap start
+ * |                              |
+ * |     1/4 of virtual map       |
+ * |                              |
+ * +------------------------------+  Kernel virt start (0xc008000000000000)
+ * |                              |
+ * |                              |
+ * |                              |
+ * +------------------------------+  Kernel linear (0xc.....)
+ */
+
+#define RADIX_KERN_VIRT_START ASM_CONST(0xc008000000000000)
+#define RADIX_KERN_VIRT_SIZE  ASM_CONST(0x0008000000000000)
+
+/*
+ * The vmalloc space starts at the beginning of that region, and
+ * occupies a quarter of it on radix config.
+ * (we keep a quarter for the virtual memmap)
+ */
+#define RADIX_VMALLOC_START	RADIX_KERN_VIRT_START
+#define RADIX_VMALLOC_SIZE	(RADIX_KERN_VIRT_SIZE >> 2)
+#define RADIX_VMALLOC_END	(RADIX_VMALLOC_START + RADIX_VMALLOC_SIZE)
+/*
+ * Defines the address of the vmemap area, in its own region on
+ * hash table CPUs.
+ */
+#define RADIX_VMEMMAP_BASE		(RADIX_VMALLOC_END)
+
 #ifndef __ASSEMBLY__
 #define RADIX_PTE_TABLE_SIZE	(sizeof(pte_t) << RADIX_PTE_INDEX_SIZE)
 #define RADIX_PMD_TABLE_SIZE	(sizeof(pmd_t) << RADIX_PMD_INDEX_SIZE)
diff --git a/arch/powerpc/kernel/pci_64.c b/arch/powerpc/kernel/pci_64.c
index 41503d7..3759df5 100644
--- a/arch/powerpc/kernel/pci_64.c
+++ b/arch/powerpc/kernel/pci_64.c
@@ -38,7 +38,7 @@
  * ISA drivers use hard coded offsets.  If no ISA bus exists nothing
  * is mapped on the first 64K of IO space
  */
-unsigned long pci_io_base = ISA_IO_BASE;
+unsigned long pci_io_base;
 EXPORT_SYMBOL(pci_io_base);
 
 static int __init pcibios_init(void)
@@ -47,6 +47,7 @@ static int __init pcibios_init(void)
 
 	printk(KERN_INFO "PCI: Probing PCI hardware\n");
 
+	pci_io_base = ISA_IO_BASE;
 	/* For now, override phys_mem_access_prot. If we need it,g
 	 * later, we may move that initialization to each ppc_md
 	 */
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 64165a7..68aee43 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -889,6 +889,14 @@ void __init hash__early_init_mmu(void)
 	__pmd_val_bits = 0;
 	__pud_val_bits = 0;
 	__pgd_val_bits = 0;
+
+	__kernel_virt_start = H_KERN_VIRT_START;
+	__kernel_virt_size = H_KERN_VIRT_SIZE;
+	__vmalloc_start = H_VMALLOC_START;
+	__vmalloc_end = H_VMALLOC_END;
+	vmemmap = (struct page *)H_VMEMMAP_BASE;
+	ioremap_bot = IOREMAP_BASE;
+
 	/* Initialize the MMU Hash table and create the linear mapping
 	 * of memory. Has to be done before SLB initialization as this is
 	 * currently where the page size encoding is obtained.
diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c
index 6182b6c..13afacd 100644
--- a/arch/powerpc/mm/pgtable-radix.c
+++ b/arch/powerpc/mm/pgtable-radix.c
@@ -328,6 +328,13 @@ void __init radix__early_init_mmu(void)
 	__pud_val_bits = RADIX_PUD_VAL_BITS;
 	__pgd_val_bits = RADIX_PGD_VAL_BITS;
 
+	__kernel_virt_start = RADIX_KERN_VIRT_START;
+	__kernel_virt_size = RADIX_KERN_VIRT_SIZE;
+	__vmalloc_start = RADIX_VMALLOC_START;
+	__vmalloc_end = RADIX_VMALLOC_END;
+	vmemmap = (struct page *)RADIX_VMEMMAP_BASE;
+	ioremap_bot = IOREMAP_BASE;
+
 	radix_init_page_sizes();
 	if (!firmware_has_feature(FW_FEATURE_LPAR))
 		radix_init_partition_table();
diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index b8c75e6..216e2bd 100644
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c
@@ -97,9 +97,20 @@ unsigned long __pud_val_bits;
 EXPORT_SYMBOL(__pud_val_bits);
 unsigned long __pgd_val_bits;
 EXPORT_SYMBOL(__pgd_val_bits);
-
-#endif
+unsigned long __kernel_virt_start;
+EXPORT_SYMBOL(__kernel_virt_start);
+unsigned long __kernel_virt_size;
+EXPORT_SYMBOL(__kernel_virt_size);
+unsigned long __vmalloc_start;
+EXPORT_SYMBOL(__vmalloc_start);
+unsigned long __vmalloc_end;
+EXPORT_SYMBOL(__vmalloc_end);
+struct page *vmemmap;
+EXPORT_SYMBOL(vmemmap);
+unsigned long ioremap_bot;
+#else /* !CONFIG_PPC_BOOK3S_64 */
 unsigned long ioremap_bot = IOREMAP_BASE;
+#endif
 
 /**
  * __ioremap_at - Low level function to establish the page tables
diff --git a/arch/powerpc/mm/slb_low.S b/arch/powerpc/mm/slb_low.S
index 15b8f71..dfdb90c 100644
--- a/arch/powerpc/mm/slb_low.S
+++ b/arch/powerpc/mm/slb_low.S
@@ -91,7 +91,7 @@ slb_miss_kernel_load_vmemmap:
 	 * can be demoted from 64K -> 4K dynamically on some machines
 	 */
 	clrldi	r11,r10,48
-	cmpldi	r11,(VMALLOC_SIZE >> 28) - 1
+	cmpldi	r11,(H_VMALLOC_SIZE >> 28) - 1
 	bgt	5f
 	lhz	r11,PACAVMALLOCSLLP(r13)
 	b	6f