* [PATCH] mm: debug_vm_pgtable: Don't use __P000 directly
@ 2021-09-21 20:18 guoren
2021-09-24 3:31 ` Anshuman Khandual
0 siblings, 1 reply; 5+ messages in thread
From: guoren @ 2021-09-21 20:18 UTC (permalink / raw)
To: guoren, akpm; +Cc: linux-mm, linux-kernel, Guo Ren
From: Guo Ren <guoren@linux.alibaba.com>
The __Pxxx/__Sxxx macros are only for init protection_map[]. All
usage of them in linux should come from protection_map array.
Becasue a lot of architectures would re-initilize protection_map[]
array, eg: x86-mem_encrypt, m68k-motorola, mips, arm, sparc.
Using __P000 maybe won't cause bug because hw would deny access
with PROT_NONE permission, but it's not rigorous.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
mm/debug_vm_pgtable.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 1403639302e4..a6ebbf6e53dd 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -1104,13 +1104,13 @@ static int __init init_args(struct pgtable_debug_args *args)
/*
* Initialize the debugging data.
*
- * __P000 (or even __S000) will help create page table entries with
+ * __P000 (protection_map[0]) will help create page table entries with
* PROT_NONE permission as required for pxx_protnone_tests().
*/
memset(args, 0, sizeof(*args));
args->vaddr = get_random_vaddr();
args->page_prot = vm_get_page_prot(VMFLAGS);
- args->page_prot_none = __P000;
+ args->page_prot_none = protection_map[0];
args->is_contiguous_page = false;
args->pud_pfn = ULONG_MAX;
args->pmd_pfn = ULONG_MAX;
--
2.25.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: debug_vm_pgtable: Don't use __P000 directly
2021-09-21 20:18 [PATCH] mm: debug_vm_pgtable: Don't use __P000 directly guoren
@ 2021-09-24 3:31 ` Anshuman Khandual
2021-09-24 5:11 ` Guo Ren
0 siblings, 1 reply; 5+ messages in thread
From: Anshuman Khandual @ 2021-09-24 3:31 UTC (permalink / raw)
To: guoren, akpm; +Cc: linux-mm, linux-kernel, Guo Ren
Hello Guo,
On 9/22/21 1:48 AM, guoren@kernel.org wrote:
> From: Guo Ren <guoren@linux.alibaba.com>
>
> The __Pxxx/__Sxxx macros are only for init protection_map[]. All
s/init protection_map[]/protection_map[] int/
Or rephrase with something similar.
> usage of them in linux should come from protection_map array.
Agreed.
>
> Becasue a lot of architectures would re-initilize protection_map[]
s/Becasue/Because/
./scripts/checkpatch.pl ./0001-mm-debug_vm_pgtable-Don-t-use-__P000-directly.patch
WARNING: 'Becasue' may be misspelled - perhaps 'Because'?
#9:
Becasue a lot of architectures would re-initilize protection_map[]
^^^^^^^
total: 0 errors, 1 warnings, 15 lines checked
> array, eg: x86-mem_encrypt, m68k-motorola, mips, arm, sparc.
>
> Using __P000 maybe won't cause bug because hw would deny access
Not very clear. Could you please rephrase.
> with PROT_NONE permission, but it's not rigorous.
Agreed.
>
> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> ---
> mm/debug_vm_pgtable.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index 1403639302e4..a6ebbf6e53dd 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -1104,13 +1104,13 @@ static int __init init_args(struct pgtable_debug_args *args)
> /*
> * Initialize the debugging data.
> *
> - * __P000 (or even __S000) will help create page table entries with
> + * __P000 (protection_map[0]) will help create page table entries with
Please just replace __P000 and __S000 with protection_map[0] and
protection_map[8] respectively. Also reformat this comment section
if required.
> * PROT_NONE permission as required for pxx_protnone_tests().
> */
> memset(args, 0, sizeof(*args));
> args->vaddr = get_random_vaddr();
> args->page_prot = vm_get_page_prot(VMFLAGS);
> - args->page_prot_none = __P000;
> + args->page_prot_none = protection_map[0];
> args->is_contiguous_page = false;
> args->pud_pfn = ULONG_MAX;
> args->pmd_pfn = ULONG_MAX;
>
With the above changes in place.
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: debug_vm_pgtable: Don't use __P000 directly
2021-09-24 3:31 ` Anshuman Khandual
@ 2021-09-24 5:11 ` Guo Ren
0 siblings, 0 replies; 5+ messages in thread
From: Guo Ren @ 2021-09-24 5:11 UTC (permalink / raw)
To: Anshuman Khandual
Cc: Andrew Morton, Linux-MM, Linux Kernel Mailing List, Guo Ren
On Fri, Sep 24, 2021 at 11:30 AM Anshuman Khandual
<anshuman.khandual@arm.com> wrote:
>
> Hello Guo,
>
> On 9/22/21 1:48 AM, guoren@kernel.org wrote:
> > From: Guo Ren <guoren@linux.alibaba.com>
> >
> > The __Pxxx/__Sxxx macros are only for init protection_map[]. All
>
> s/init protection_map[]/protection_map[] int/
^^^
Okay, protection_map[] init
>
> Or rephrase with something similar.
>
> > usage of them in linux should come from protection_map array.
>
> Agreed.
>
> >
> > Becasue a lot of architectures would re-initilize protection_map[]
>
> s/Becasue/Because/
>
> ./scripts/checkpatch.pl ./0001-mm-debug_vm_pgtable-Don-t-use-__P000-directly.patch
> WARNING: 'Becasue' may be misspelled - perhaps 'Because'?
> #9:
> Becasue a lot of architectures would re-initilize protection_map[]
> ^^^^^^^
>
> total: 0 errors, 1 warnings, 15 lines checked
I would use checkpatch.pl next time, thx.
>
> > array, eg: x86-mem_encrypt, m68k-motorola, mips, arm, sparc.
> >
> > Using __P000 maybe won't cause bug because hw would deny access
>
> Not very clear. Could you please rephrase.
Using __P000 directly wouldn't equal protection_map[0] in many arches,
but the reason why it didn't cause the problem is the hardware ignores
the other bits when prot-attribute is denied.
>
> > with PROT_NONE permission, but it's not rigorous.
>
> Agreed.
>
> >
> > Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > ---
> > mm/debug_vm_pgtable.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> > index 1403639302e4..a6ebbf6e53dd 100644
> > --- a/mm/debug_vm_pgtable.c
> > +++ b/mm/debug_vm_pgtable.c
> > @@ -1104,13 +1104,13 @@ static int __init init_args(struct pgtable_debug_args *args)
> > /*
> > * Initialize the debugging data.
> > *
> > - * __P000 (or even __S000) will help create page table entries with
> > + * __P000 (protection_map[0]) will help create page table entries with
>
> Please just replace __P000 and __S000 with protection_map[0] and
> protection_map[8] respectively. Also reformat this comment section
> if required.
>
> > * PROT_NONE permission as required for pxx_protnone_tests().
> > */
> > memset(args, 0, sizeof(*args));
> > args->vaddr = get_random_vaddr();
> > args->page_prot = vm_get_page_prot(VMFLAGS);
> > - args->page_prot_none = __P000;
> > + args->page_prot_none = protection_map[0];
> > args->is_contiguous_page = false;
> > args->pud_pfn = ULONG_MAX;
> > args->pmd_pfn = ULONG_MAX;
> >
>
> With the above changes in place.
>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] mm: debug_vm_pgtable: Don't use __P000 directly
@ 2021-09-24 6:06 guoren
2021-09-24 6:09 ` Guo Ren
0 siblings, 1 reply; 5+ messages in thread
From: guoren @ 2021-09-24 6:06 UTC (permalink / raw)
To: guoren, akpm; +Cc: linux-mm, linux-kernel, Guo Ren
From: Guo Ren <guoren@linux.alibaba.com>
The __Pxxx/__Sxxx macros are only for protection_map[] init. All
usage of them in linux should come from protection_map array.
Because a lot of architectures would re-initilize protection_map[]
array, eg: x86-mem_encrypt, m68k-motorola, mips, arm, sparc.
Using __P000 is not rigorous.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
---
Changes since V2:
- s/init protection_map[]/protection_map[] init/
- s/Becasue/Because/
- Remove unclear part
- Replace __P000 and __S000 with protection_map[0] and
protection_map[8]
---
mm/debug_vm_pgtable.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 1403639302e4..228e3954b90c 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -1104,13 +1104,14 @@ static int __init init_args(struct pgtable_debug_args *args)
/*
* Initialize the debugging data.
*
- * __P000 (or even __S000) will help create page table entries with
- * PROT_NONE permission as required for pxx_protnone_tests().
+ * protection_map[0] (or even protection_map[8]) will help create
+ * page table entries with PROT_NONE permission as required for
+ * pxx_protnone_tests().
*/
memset(args, 0, sizeof(*args));
args->vaddr = get_random_vaddr();
args->page_prot = vm_get_page_prot(VMFLAGS);
- args->page_prot_none = __P000;
+ args->page_prot_none = protection_map[0];
args->is_contiguous_page = false;
args->pud_pfn = ULONG_MAX;
args->pmd_pfn = ULONG_MAX;
--
2.25.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: debug_vm_pgtable: Don't use __P000 directly
2021-09-24 6:06 guoren
@ 2021-09-24 6:09 ` Guo Ren
0 siblings, 0 replies; 5+ messages in thread
From: Guo Ren @ 2021-09-24 6:09 UTC (permalink / raw)
To: Guo Ren, Andrew Morton; +Cc: Linux-MM, Linux Kernel Mailing List, Guo Ren
Sorry, the patch forgets to add --prefix PATCH V2, abandon.
Review the V2, thx.
On Fri, Sep 24, 2021 at 2:07 PM <guoren@kernel.org> wrote:
>
> From: Guo Ren <guoren@linux.alibaba.com>
>
> The __Pxxx/__Sxxx macros are only for protection_map[] init. All
> usage of them in linux should come from protection_map array.
>
> Because a lot of architectures would re-initilize protection_map[]
> array, eg: x86-mem_encrypt, m68k-motorola, mips, arm, sparc.
>
> Using __P000 is not rigorous.
>
> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
>
> ---
>
> Changes since V2:
> - s/init protection_map[]/protection_map[] init/
> - s/Becasue/Because/
> - Remove unclear part
> - Replace __P000 and __S000 with protection_map[0] and
> protection_map[8]
> ---
> mm/debug_vm_pgtable.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index 1403639302e4..228e3954b90c 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -1104,13 +1104,14 @@ static int __init init_args(struct pgtable_debug_args *args)
> /*
> * Initialize the debugging data.
> *
> - * __P000 (or even __S000) will help create page table entries with
> - * PROT_NONE permission as required for pxx_protnone_tests().
> + * protection_map[0] (or even protection_map[8]) will help create
> + * page table entries with PROT_NONE permission as required for
> + * pxx_protnone_tests().
> */
> memset(args, 0, sizeof(*args));
> args->vaddr = get_random_vaddr();
> args->page_prot = vm_get_page_prot(VMFLAGS);
> - args->page_prot_none = __P000;
> + args->page_prot_none = protection_map[0];
> args->is_contiguous_page = false;
> args->pud_pfn = ULONG_MAX;
> args->pmd_pfn = ULONG_MAX;
> --
> 2.25.1
>
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/
^ permalink raw reply [flat|nested] 5+ messages in thread
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2021-09-21 20:18 [PATCH] mm: debug_vm_pgtable: Don't use __P000 directly guoren
2021-09-24 3:31 ` Anshuman Khandual
2021-09-24 5:11 ` Guo Ren
2021-09-24 6:06 guoren
2021-09-24 6:09 ` Guo Ren
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