Re: Crash on FSL Book3E due to pte_pgprot()? (was Re: [PATCH v3 12/24] powerpc/mm: use pte helpers in generic code)

["Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>]

Christophe Leroy <christophe.leroy@c-s.fr> writes:

> On 10/17/2018 12:59 AM, Michael Ellerman wrote:
>> Christophe Leroy <christophe.leroy@c-s.fr> writes:
>> 
>>> Get rid of platform specific _PAGE_XXXX in powerpc common code and
>>> use helpers instead.
>>>
>>> mm/dump_linuxpagetables.c will be handled separately
>>>
>>> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>>> ---
>>>   arch/powerpc/include/asm/book3s/32/pgtable.h |  9 +++------
>>>   arch/powerpc/include/asm/nohash/32/pgtable.h | 12 ++++++++----
>>>   arch/powerpc/include/asm/nohash/pgtable.h    |  3 +--
>>>   arch/powerpc/mm/pgtable.c                    | 21 +++++++--------------
>>>   arch/powerpc/mm/pgtable_32.c                 | 15 ++++++++-------
>>>   arch/powerpc/mm/pgtable_64.c                 | 14 +++++++-------
>>>   arch/powerpc/xmon/xmon.c                     | 12 +++++++-----
>>>   7 files changed, 41 insertions(+), 45 deletions(-)
>> 
>> So turns out this patch *also* breaks my p5020ds :)
>> 
>> Even with patch 4 merged, see next.
>> 
>> It's the same crash:
>> 
>>    pcieport 2000:00:00.0: AER enabled with IRQ 480
>>    Unable to handle kernel paging request for data at address 0x8000080080080000
>>    Faulting instruction address: 0xc0000000000192cc
>>    Oops: Kernel access of bad area, sig: 11 [#1]
>>    BE SMP NR_CPUS=24 CoreNet Generic
>>    Modules linked in:
>>    CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc3-gcc7x-g98c847323b3a #1
>>    NIP:  c0000000000192cc LR: c0000000005d0f9c CTR: 0000000000100000
>>    REGS: c0000000f31bb400 TRAP: 0300   Not tainted  (4.19.0-rc3-gcc7x-g98c847323b3a)
>>    MSR:  0000000080029000 <CE,EE,ME>  CR: 24000224  XER: 00000000
>>    DEAR: 8000080080080000 ESR: 0000000000800000 IRQMASK: 0
>>    GPR00: c0000000005d0f84 c0000000f31bb688 c00000000117dc00 8000080080080000
>>    GPR04: 0000000000000000 0000000000400000 00000ffbff241010 c0000000f31b8000
>>    GPR08: 0000000000000000 0000000000100000 0000000000000000 c0000000012d4710
>>    GPR12: 0000000084000422 c0000000012ff000 c000000000002774 0000000000000000
>>    GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
>>    GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
>>    GPR24: 0000000000000000 0000000000000000 8000080080080000 c0000000ffff89a8
>>    GPR28: c0000000f3576400 c0000000f3576410 0000000000400000 c0000000012ecc98
>>    NIP [c0000000000192cc] ._memset_io+0x6c/0x9c
>>    LR [c0000000005d0f9c] .fsl_qman_probe+0x198/0x928
>>    Call Trace:
>>    [c0000000f31bb688] [c0000000005d0f84] .fsl_qman_probe+0x180/0x928 (unreliable)
>>    [c0000000f31bb728] [c0000000006432ec] .platform_drv_probe+0x60/0xb4
>>    [c0000000f31bb7a8] [c00000000064083c] .really_probe+0x294/0x35c
>>    [c0000000f31bb848] [c000000000640d2c] .__driver_attach+0x148/0x14c
>>    [c0000000f31bb8d8] [c00000000063d7dc] .bus_for_each_dev+0xb0/0x118
>>    [c0000000f31bb988] [c00000000063ff28] .driver_attach+0x34/0x4c
>>    [c0000000f31bba08] [c00000000063f648] .bus_add_driver+0x174/0x2bc
>>    [c0000000f31bbaa8] [c0000000006418bc] .driver_register+0x90/0x180
>>    [c0000000f31bbb28] [c000000000643270] .__platform_driver_register+0x60/0x7c
>>    [c0000000f31bbba8] [c000000000ee2a70] .fsl_qman_driver_init+0x24/0x38
>>    [c0000000f31bbc18] [c0000000000023fc] .do_one_initcall+0x64/0x2b8
>>    [c0000000f31bbcf8] [c000000000e9f480] .kernel_init_freeable+0x3a8/0x494
>>    [c0000000f31bbda8] [c000000000002798] .kernel_init+0x24/0x148
>>    [c0000000f31bbe28] [c0000000000009e8] .ret_from_kernel_thread+0x58/0x70
>>    Instruction dump:
>>    4e800020 2ba50003 40dd003c 3925fffc 5488402e 7929f082 7d082378 39290001
>>    550a801e 7d2903a6 7d4a4378 794a0020 <91430000> 38630004 4200fff8 70a50003
>> 
>> 
>> Comparing a working vs broken kernel, it seems to boil down to the fact
>> that we're filtering out more PTE bits now that we use pte_pgprot() in
>> ioremap_prot().
>> 
>> With the old code we get:
>>    ioremap_prot: addr 0xff800000 flags 0x241215
>>    ioremap_prot: addr 0xff800000 flags 0x241215
>>    map_kernel_page: ea 0x8000080080080000 pa 0xff800000 pte 0xff800241215
>> 
>> 
>> And now we get:
>>    ioremap_prot: addr 0xff800000 flags 0x241215 pte 0x241215
>>    ioremap_prot: addr 0xff800000 pte 0x241215
>>    ioremap_prot: addr 0xff800000 prot 0x241014
>>    map_kernel_page: ea 0x8000080080080000 pa 0xff800000 pte 0xff800241014
>> 
>> So we're losing 0x201, which for nohash book3e is:
>> 
>>    #define _PAGE_PRESENT	0x000001 /* software: pte contains a translation */
>>    #define _PAGE_PSIZE_4K	0x000200
>> 
>> 
>> I haven't worked out if it's one or both of those that matter.
>
> At least missing _PAGE_PRESENT is an issue I believe.
>> 
>> The question is what's the right way to fix it? Should pte_pgprot() not
>> be filtering those bits out on book3e?
>
> I think we should not use pte_pggrot() for that then. What about the 
> below fix ?
>
> Christophe
>
> From: Christophe Leroy <christophe.leroy@c-s.fr>
> Date: Wed, 17 Oct 2018 05:56:25 +0000
> Subject: [PATCH] powerpc/mm: don't use pte_pgprot() in ioremap_prot()
>
> pte_pgprot() filters out some required flags like _PAGE_PRESENT.
>
> This patch replaces pte_pgprot() by __pgprot(pte_val())
> in ioremap_prot()
>
> Fixes: 26973fa5ac0e ("powerpc/mm: use pte helpers in generic code")
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
>   arch/powerpc/mm/pgtable_32.c | 3 ++-
>   arch/powerpc/mm/pgtable_64.c | 4 ++--
>   2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
> index 5877f5aa8f5d..a606e2f4937b 100644
> --- a/arch/powerpc/mm/pgtable_32.c
> +++ b/arch/powerpc/mm/pgtable_32.c
> @@ -122,7 +122,8 @@ ioremap_prot(phys_addr_t addr, unsigned long size, 
> unsigned long flags)
>   	pte = pte_exprotect(pte);
>   	pte = pte_mkprivileged(pte);
>
> -	return __ioremap_caller(addr, size, pte_pgprot(pte), 
> __builtin_return_address(0));
> +	return __ioremap_caller(addr, size, __pgprot(pte_val(pte)),
> +				__builtin_return_address(0));


That means we pass the pfn bits also to __ioremap_caller right? How about

>From b4d5e0f24f8482375b2dd86afaced26ebf716600 Mon Sep 17 00:00:00 2001
From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Date: Wed, 17 Oct 2018 14:07:50 +0530
Subject: [PATCH] powerpc/mm: Make pte_pgprot return all pte bits

Other archs do the same and instead of adding required pte bits (which got
masked out) in __ioremap_at, make sure we filter only pfn bits out.

Fixes: 26973fa5ac0e ("powerpc/mm: use pte helpers in generic code")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
 arch/powerpc/include/asm/book3s/32/pgtable.h       |  6 ------
 arch/powerpc/include/asm/book3s/64/pgtable.h       |  8 --------
 arch/powerpc/include/asm/nohash/32/pte-40x.h       |  5 -----
 arch/powerpc/include/asm/nohash/32/pte-44x.h       |  5 -----
 arch/powerpc/include/asm/nohash/32/pte-8xx.h       |  5 -----
 arch/powerpc/include/asm/nohash/32/pte-fsl-booke.h |  5 -----
 arch/powerpc/include/asm/nohash/pgtable.h          |  1 -
 arch/powerpc/include/asm/nohash/pte-book3e.h       |  5 -----
 arch/powerpc/include/asm/pgtable.h                 | 10 ++++++++++
 9 files changed, 10 insertions(+), 40 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index 0fbd4c642b51..e61dd3ae5bc0 100644
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -48,11 +48,6 @@ static inline bool pte_user(pte_t pte)
 #define _PAGE_CHG_MASK	(PTE_RPN_MASK | _PAGE_HASHPTE | _PAGE_DIRTY | \
 			 _PAGE_ACCESSED | _PAGE_SPECIAL)
 
-/* Mask of bits returned by pte_pgprot() */
-#define PAGE_PROT_BITS	(_PAGE_GUARDED | _PAGE_COHERENT | _PAGE_NO_CACHE | \
-			 _PAGE_WRITETHRU | _PAGE_USER | _PAGE_ACCESSED | \
-			 _PAGE_RW | _PAGE_DIRTY)
-
 /*
  * We define 2 sets of base prot bits, one for basic pages (ie,
  * cacheable kernel and user pages) and one for non cacheable
@@ -396,7 +391,6 @@ static inline int pte_young(pte_t pte)		{ return !!(pte_val(pte) & _PAGE_ACCESSE
 static inline int pte_special(pte_t pte)	{ return !!(pte_val(pte) & _PAGE_SPECIAL); }
 static inline int pte_none(pte_t pte)		{ return (pte_val(pte) & ~_PTE_NONE_MASK) == 0; }
 static inline bool pte_exec(pte_t pte)		{ return true; }
-static inline pgprot_t pte_pgprot(pte_t pte)	{ return __pgprot(pte_val(pte) & PAGE_PROT_BITS); }
 
 static inline int pte_present(pte_t pte)
 {
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index c34a161dc651..cb5dd4078d42 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -128,13 +128,6 @@
 
 #define H_PTE_PKEY  (H_PTE_PKEY_BIT0 | H_PTE_PKEY_BIT1 | H_PTE_PKEY_BIT2 | \
 		     H_PTE_PKEY_BIT3 | H_PTE_PKEY_BIT4)
-/*
- * Mask of bits returned by pte_pgprot()
- */
-#define PAGE_PROT_BITS  (_PAGE_SAO | _PAGE_NON_IDEMPOTENT | _PAGE_TOLERANT | \
-			 H_PAGE_4K_PFN | _PAGE_PRIVILEGED | _PAGE_ACCESSED | \
-			 _PAGE_READ | _PAGE_WRITE |  _PAGE_DIRTY | _PAGE_EXEC | \
-			 _PAGE_SOFT_DIRTY | H_PTE_PKEY)
 /*
  * We define 2 sets of base prot bits, one for basic pages (ie,
  * cacheable kernel and user pages) and one for non cacheable
@@ -496,7 +489,6 @@ static inline bool pte_exec(pte_t pte)
 	return !!(pte_raw(pte) & cpu_to_be64(_PAGE_EXEC));
 }
 
-static inline pgprot_t pte_pgprot(pte_t pte)	{ return __pgprot(pte_val(pte) & PAGE_PROT_BITS); }
 
 #ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
 static inline bool pte_soft_dirty(pte_t pte)
diff --git a/arch/powerpc/include/asm/nohash/32/pte-40x.h b/arch/powerpc/include/asm/nohash/32/pte-40x.h
index 7a8b3c94592f..661f4599f2fc 100644
--- a/arch/powerpc/include/asm/nohash/32/pte-40x.h
+++ b/arch/powerpc/include/asm/nohash/32/pte-40x.h
@@ -73,11 +73,6 @@
 /* Until my rework is finished, 40x still needs atomic PTE updates */
 #define PTE_ATOMIC_UPDATES	1
 
-/* Mask of bits returned by pte_pgprot() */
-#define PAGE_PROT_BITS	(_PAGE_GUARDED | _PAGE_NO_CACHE | \
-			 _PAGE_WRITETHRU | _PAGE_USER | _PAGE_ACCESSED | \
-			 _PAGE_RW | _PAGE_HWWRITE | _PAGE_DIRTY | _PAGE_EXEC)
-
 #define _PAGE_BASE_NC	(_PAGE_PRESENT | _PAGE_ACCESSED)
 #define _PAGE_BASE	(_PAGE_BASE_NC)
 
diff --git a/arch/powerpc/include/asm/nohash/32/pte-44x.h b/arch/powerpc/include/asm/nohash/32/pte-44x.h
index 8d6b268a986f..78bc304f750e 100644
--- a/arch/powerpc/include/asm/nohash/32/pte-44x.h
+++ b/arch/powerpc/include/asm/nohash/32/pte-44x.h
@@ -93,11 +93,6 @@
 #define _PAGE_KERNEL_RW		(_PAGE_DIRTY | _PAGE_RW)
 #define _PAGE_KERNEL_RWX	(_PAGE_DIRTY | _PAGE_RW | _PAGE_EXEC)
 
-/* Mask of bits returned by pte_pgprot() */
-#define PAGE_PROT_BITS	(_PAGE_GUARDED | _PAGE_COHERENT | _PAGE_NO_CACHE | \
-			 _PAGE_WRITETHRU | _PAGE_USER | _PAGE_ACCESSED | \
-			 _PAGE_RW | _PAGE_DIRTY | _PAGE_EXEC)
-
 /* TODO: Add large page lowmem mapping support */
 #define _PMD_PRESENT	0
 #define _PMD_PRESENT_MASK (PAGE_MASK)
diff --git a/arch/powerpc/include/asm/nohash/32/pte-8xx.h b/arch/powerpc/include/asm/nohash/32/pte-8xx.h
index 1c57efac089d..6bfe041ef59d 100644
--- a/arch/powerpc/include/asm/nohash/32/pte-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/pte-8xx.h
@@ -55,11 +55,6 @@
 #define _PAGE_KERNEL_RW		(_PAGE_SH | _PAGE_DIRTY)
 #define _PAGE_KERNEL_RWX	(_PAGE_SH | _PAGE_DIRTY | _PAGE_EXEC)
 
-/* Mask of bits returned by pte_pgprot() */
-#define PAGE_PROT_BITS	(_PAGE_GUARDED | _PAGE_NO_CACHE | \
-			 _PAGE_ACCESSED | _PAGE_RO | _PAGE_NA | \
-			 _PAGE_SH | _PAGE_DIRTY | _PAGE_EXEC)
-
 #define _PMD_PRESENT	0x0001
 #define _PMD_PRESENT_MASK	_PMD_PRESENT
 #define _PMD_BAD	0x0fd0
diff --git a/arch/powerpc/include/asm/nohash/32/pte-fsl-booke.h b/arch/powerpc/include/asm/nohash/32/pte-fsl-booke.h
index 1ecf60fe0909..0fc1bd42bb3e 100644
--- a/arch/powerpc/include/asm/nohash/32/pte-fsl-booke.h
+++ b/arch/powerpc/include/asm/nohash/32/pte-fsl-booke.h
@@ -39,11 +39,6 @@
 /* No page size encoding in the linux PTE */
 #define _PAGE_PSIZE		0
 
-/* Mask of bits returned by pte_pgprot() */
-#define PAGE_PROT_BITS	(_PAGE_GUARDED | _PAGE_COHERENT | _PAGE_NO_CACHE | \
-			 _PAGE_WRITETHRU | _PAGE_USER | _PAGE_ACCESSED | \
-			 _PAGE_RW | _PAGE_DIRTY | _PAGE_EXEC)
-
 #define _PMD_PRESENT	0
 #define _PMD_PRESENT_MASK (PAGE_MASK)
 #define _PMD_BAD	(~PAGE_MASK)
diff --git a/arch/powerpc/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h
index 04e9f0922ad4..70ff23974b59 100644
--- a/arch/powerpc/include/asm/nohash/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/pgtable.h
@@ -52,7 +52,6 @@ static inline int pte_none(pte_t pte)		{ return (pte_val(pte) & ~_PTE_NONE_MASK)
 static inline bool pte_hashpte(pte_t pte)	{ return false; }
 static inline bool pte_ci(pte_t pte)		{ return pte_val(pte) & _PAGE_NO_CACHE; }
 static inline bool pte_exec(pte_t pte)		{ return pte_val(pte) & _PAGE_EXEC; }
-static inline pgprot_t pte_pgprot(pte_t pte)	{ return __pgprot(pte_val(pte) & PAGE_PROT_BITS); }
 
 #ifdef CONFIG_NUMA_BALANCING
 /*
diff --git a/arch/powerpc/include/asm/nohash/pte-book3e.h b/arch/powerpc/include/asm/nohash/pte-book3e.h
index 58eef8cb569d..f95ab6eaf441 100644
--- a/arch/powerpc/include/asm/nohash/pte-book3e.h
+++ b/arch/powerpc/include/asm/nohash/pte-book3e.h
@@ -82,11 +82,6 @@
 #define _PTE_NONE_MASK	0
 #endif
 
-/* Mask of bits returned by pte_pgprot() */
-#define PAGE_PROT_BITS	(_PAGE_GUARDED | _PAGE_COHERENT | _PAGE_NO_CACHE | \
-			 _PAGE_WRITETHRU | _PAGE_USER | _PAGE_ACCESSED | \
-			 _PAGE_PRIVILEGED | _PAGE_RW | _PAGE_DIRTY | _PAGE_EXEC)
-
 /*
  * We define 2 sets of base prot bits, one for basic pages (ie,
  * cacheable kernel and user pages) and one for non cacheable
diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index fb4b85bba110..9679b7519a35 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -46,6 +46,16 @@ struct mm_struct;
 /* Keep these as a macros to avoid include dependency mess */
 #define pte_page(x)		pfn_to_page(pte_pfn(x))
 #define mk_pte(page, pgprot)	pfn_pte(page_to_pfn(page), (pgprot))
+/*
+ * Select all bits except the pfn
+ */
+static inline pgprot_t pte_pgprot(pte_t pte)
+{
+	unsigned long pte_flags;
+
+	pte_flags = pte_val(pte) & ~PTE_RPN_MASK;
+	return __pgprot(pte_flags);
+}
 
 /*
  * ZERO_PAGE is a global shared page that is always zero: used
-- 
2.17.2