[PATCH] x86/mm/dump_pagetables: Change to use DEFINE_SHOW_ATTRIBUTE macro

[PATCH] x86/mm/dump_pagetables: Change to use DEFINE_SHOW_ATTRIBUTE macro

[Yangtao Li]

Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
---
 arch/x86/mm/debug_pagetables.c | 58 ++++------------------------------
 1 file changed, 7 insertions(+), 51 deletions(-)

diff --git a/arch/x86/mm/debug_pagetables.c b/arch/x86/mm/debug_pagetables.c
index 225fe2f0bfec..cd84f067e41d 100644
--- a/arch/x86/mm/debug_pagetables.c
+++ b/arch/x86/mm/debug_pagetables.c
@@ -10,20 +10,9 @@ static int ptdump_show(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int ptdump_open(struct inode *inode, struct file *filp)
-{
-	return single_open(filp, ptdump_show, NULL);
-}
-
-static const struct file_operations ptdump_fops = {
-	.owner		= THIS_MODULE,
-	.open		= ptdump_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(ptdump);
 
-static int ptdump_show_curknl(struct seq_file *m, void *v)
+static int ptdump_curknl_show(struct seq_file *m, void *v)
 {
 	if (current->mm->pgd) {
 		down_read(&current->mm->mmap_sem);
@@ -33,23 +22,12 @@ static int ptdump_show_curknl(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int ptdump_open_curknl(struct inode *inode, struct file *filp)
-{
-	return single_open(filp, ptdump_show_curknl, NULL);
-}
-
-static const struct file_operations ptdump_curknl_fops = {
-	.owner		= THIS_MODULE,
-	.open		= ptdump_open_curknl,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(ptdump_curknl);
 
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 static struct dentry *pe_curusr;
 
-static int ptdump_show_curusr(struct seq_file *m, void *v)
+static int ptdump_curusr_show(struct seq_file *m, void *v)
 {
 	if (current->mm->pgd) {
 		down_read(&current->mm->mmap_sem);
@@ -59,42 +37,20 @@ static int ptdump_show_curusr(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int ptdump_open_curusr(struct inode *inode, struct file *filp)
-{
-	return single_open(filp, ptdump_show_curusr, NULL);
-}
-
-static const struct file_operations ptdump_curusr_fops = {
-	.owner		= THIS_MODULE,
-	.open		= ptdump_open_curusr,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(ptdump_curusr);
 #endif
 
 #if defined(CONFIG_EFI) && defined(CONFIG_X86_64)
 static struct dentry *pe_efi;
 
-static int ptdump_show_efi(struct seq_file *m, void *v)
+static int ptdump_efi_show(struct seq_file *m, void *v)
 {
 	if (efi_mm.pgd)
 		ptdump_walk_pgd_level_debugfs(m, efi_mm.pgd, false);
 	return 0;
 }
 
-static int ptdump_open_efi(struct inode *inode, struct file *filp)
-{
-	return single_open(filp, ptdump_show_efi, NULL);
-}
-
-static const struct file_operations ptdump_efi_fops = {
-	.owner		= THIS_MODULE,
-	.open		= ptdump_open_efi,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(ptdump_efi);
 #endif
 
 static struct dentry *dir, *pe_knl, *pe_curknl;
-- 
2.17.0

Re: [PATCH] x86/mm/dump_pagetables: Change to use DEFINE_SHOW_ATTRIBUTE macro

[Dave Hansen]

On 11/19/18 7:43 AM, Yangtao Li wrote:
> -static const struct file_operations ptdump_curusr_fops = {
> -	.owner		= THIS_MODULE,
> -	.open		= ptdump_open_curusr,
> -	.read		= seq_read,
> -	.llseek		= seq_lseek,
> -	.release	= single_release,
> -};
> +DEFINE_SHOW_ATTRIBUTE(ptdump_curusr);

FWIW, I rather dislike this conversion and the DEFINE_SHOW_ATTRIBUTE()
approach in general.  It makes it basically impossible to go from
ptdump_curusr to ptdump_open_curusr without opening up the macro and
reverse-engineering it.

My test is that for these macros to be sane, I need to be able to find
"ptdump_open_curusr" by grepping for "ptdump_curusr".  This fails the test.

I don't think saving a few lines of code is worth the obfuscation.

Re: [PATCH] x86/mm/dump_pagetables: Change to use DEFINE_SHOW_ATTRIBUTE macro

[Frank Lee]

Hi Dava:

How about just change the ptdump_fops and ptdump_open?

Yours,
    Yangtao
On Tue, Nov 20, 2018 at 1:06 AM Dave Hansen <dave.hansen@intel.com> wrote:
>
> On 11/19/18 7:43 AM, Yangtao Li wrote:
> > -static const struct file_operations ptdump_curusr_fops = {
> > -     .owner          = THIS_MODULE,
> > -     .open           = ptdump_open_curusr,
> > -     .read           = seq_read,
> > -     .llseek         = seq_lseek,
> > -     .release        = single_release,
> > -};
> > +DEFINE_SHOW_ATTRIBUTE(ptdump_curusr);
>
> FWIW, I rather dislike this conversion and the DEFINE_SHOW_ATTRIBUTE()
> approach in general.  It makes it basically impossible to go from
> ptdump_curusr to ptdump_open_curusr without opening up the macro and
> reverse-engineering it.
>
> My test is that for these macros to be sane, I need to be able to find
> "ptdump_open_curusr" by grepping for "ptdump_curusr".  This fails the test.
>
> I don't think saving a few lines of code is worth the obfuscation.

Re: [PATCH] x86/mm/dump_pagetables: Change to use DEFINE_SHOW_ATTRIBUTE macro

[Frank Lee]

Hi Kees:

I want to listen to you.

--Yangtao
On Tue, Nov 20, 2018 at 8:49 AM Frank Lee <tiny.windzz@gmail.com> wrote:
>
> Hi Dava:
>
> How about just change the ptdump_fops and ptdump_open?
>
> Yours,
>     Yangtao
> On Tue, Nov 20, 2018 at 1:06 AM Dave Hansen <dave.hansen@intel.com> wrote:
> >
> > On 11/19/18 7:43 AM, Yangtao Li wrote:
> > > -static const struct file_operations ptdump_curusr_fops = {
> > > -     .owner          = THIS_MODULE,
> > > -     .open           = ptdump_open_curusr,
> > > -     .read           = seq_read,
> > > -     .llseek         = seq_lseek,
> > > -     .release        = single_release,
> > > -};
> > > +DEFINE_SHOW_ATTRIBUTE(ptdump_curusr);
> >
> > FWIW, I rather dislike this conversion and the DEFINE_SHOW_ATTRIBUTE()
> > approach in general.  It makes it basically impossible to go from
> > ptdump_curusr to ptdump_open_curusr without opening up the macro and
> > reverse-engineering it.
> >
> > My test is that for these macros to be sane, I need to be able to find
> > "ptdump_open_curusr" by grepping for "ptdump_curusr".  This fails the test.
> >
> > I don't think saving a few lines of code is worth the obfuscation.

Re: [PATCH] x86/mm/dump_pagetables: Change to use DEFINE_SHOW_ATTRIBUTE macro

[Kees Cook]

On Mon, Nov 19, 2018 at 9:06 AM, Dave Hansen <dave.hansen@intel.com> wrote:
> On 11/19/18 7:43 AM, Yangtao Li wrote:
>> -static const struct file_operations ptdump_curusr_fops = {
>> -     .owner          = THIS_MODULE,
>> -     .open           = ptdump_open_curusr,
>> -     .read           = seq_read,
>> -     .llseek         = seq_lseek,
>> -     .release        = single_release,
>> -};
>> +DEFINE_SHOW_ATTRIBUTE(ptdump_curusr);
>
> FWIW, I rather dislike this conversion and the DEFINE_SHOW_ATTRIBUTE()
> approach in general.  It makes it basically impossible to go from
> ptdump_curusr to ptdump_open_curusr without opening up the macro and
> reverse-engineering it.
>
> My test is that for these macros to be sane, I need to be able to find
> "ptdump_open_curusr" by grepping for "ptdump_curusr".  This fails the test.

Er, "ptdump_curusr" matches the generated name "ptdump_curusr_show",
is that what you mean?

> I don't think saving a few lines of code is worth the obfuscation.

This is the standard boilerplate for attributes, though. I'd be nice
to drop all the copy/pasted code...

-- 
Kees Cook

Re: [PATCH] x86/mm/dump_pagetables: Change to use DEFINE_SHOW_ATTRIBUTE macro

[Frank Lee]

On Wed, Nov 28, 2018 at 6:50 AM Kees Cook <keescook@chromium.org> wrote:
>
> On Mon, Nov 19, 2018 at 9:06 AM, Dave Hansen <dave.hansen@intel.com> wrote:
> > On 11/19/18 7:43 AM, Yangtao Li wrote:
> >> -static const struct file_operations ptdump_curusr_fops = {
> >> -     .owner          = THIS_MODULE,
> >> -     .open           = ptdump_open_curusr,
> >> -     .read           = seq_read,
> >> -     .llseek         = seq_lseek,
> >> -     .release        = single_release,
> >> -};
> >> +DEFINE_SHOW_ATTRIBUTE(ptdump_curusr);
> >
> > FWIW, I rather dislike this conversion and the DEFINE_SHOW_ATTRIBUTE()
> > approach in general.  It makes it basically impossible to go from
> > ptdump_curusr to ptdump_open_curusr without opening up the macro and
> > reverse-engineering it.
> >
> > My test is that for these macros to be sane, I need to be able to find
> > "ptdump_open_curusr" by grepping for "ptdump_curusr".  This fails the test.
>
> Er, "ptdump_curusr" matches the generated name "ptdump_curusr_show",
> is that what you mean?
>
> > I don't think saving a few lines of code is worth the obfuscation.
>
> This is the standard boilerplate for attributes, though. I'd be nice
> to drop all the copy/pasted code...
>
> --
> Kees Cook
I also think that we should delete the duplicate code which doesn't
make much sense.

MBR,
Yangtao

Re: [PATCH] x86/mm/dump_pagetables: Change to use DEFINE_SHOW_ATTRIBUTE macro

[Dave Hansen]

On 11/27/18 2:50 PM, Kees Cook wrote:
> On Mon, Nov 19, 2018 at 9:06 AM, Dave Hansen <dave.hansen@intel.com> wrote:
>> On 11/19/18 7:43 AM, Yangtao Li wrote:
>>> -static const struct file_operations ptdump_curusr_fops = {
>>> -     .owner          = THIS_MODULE,
>>> -     .open           = ptdump_open_curusr,
>>> -     .read           = seq_read,
>>> -     .llseek         = seq_lseek,
>>> -     .release        = single_release,
>>> -};
>>> +DEFINE_SHOW_ATTRIBUTE(ptdump_curusr);
>>
>> FWIW, I rather dislike this conversion and the DEFINE_SHOW_ATTRIBUTE()
>> approach in general.  It makes it basically impossible to go from
>> ptdump_curusr to ptdump_open_curusr without opening up the macro and
>> reverse-engineering it.
>>
>> My test is that for these macros to be sane, I need to be able to find
>> "ptdump_open_curusr" by grepping for "ptdump_curusr".  This fails the test.
> 
> Er, "ptdump_curusr" matches the generated name "ptdump_curusr_show",
> is that what you mean?

Ahh, I also missed some of the renames to make this OK, like:

> -static int ptdump_show_efi(struct seq_file *m, void *v)
> +static int ptdump_efi_show(struct seq_file *m, void *v)

I thought there was some macro magic going on that screwed the names up.

This looks fine to me.

Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>

Re: [PATCH] x86/mm/dump_pagetables: Change to use DEFINE_SHOW_ATTRIBUTE macro

[Kees Cook]

On Wed, Nov 28, 2018 at 10:45 AM Dave Hansen <dave.hansen@intel.com> wrote:
>
> On 11/27/18 2:50 PM, Kees Cook wrote:
> > On Mon, Nov 19, 2018 at 9:06 AM, Dave Hansen <dave.hansen@intel.com> wrote:
> >> On 11/19/18 7:43 AM, Yangtao Li wrote:
> >>> -static const struct file_operations ptdump_curusr_fops = {
> >>> -     .owner          = THIS_MODULE,
> >>> -     .open           = ptdump_open_curusr,
> >>> -     .read           = seq_read,
> >>> -     .llseek         = seq_lseek,
> >>> -     .release        = single_release,
> >>> -};
> >>> +DEFINE_SHOW_ATTRIBUTE(ptdump_curusr);
> >>
> >> FWIW, I rather dislike this conversion and the DEFINE_SHOW_ATTRIBUTE()
> >> approach in general.  It makes it basically impossible to go from
> >> ptdump_curusr to ptdump_open_curusr without opening up the macro and
> >> reverse-engineering it.
> >>
> >> My test is that for these macros to be sane, I need to be able to find
> >> "ptdump_open_curusr" by grepping for "ptdump_curusr".  This fails the test.
> >
> > Er, "ptdump_curusr" matches the generated name "ptdump_curusr_show",
> > is that what you mean?
>
> Ahh, I also missed some of the renames to make this OK, like:
>
> > -static int ptdump_show_efi(struct seq_file *m, void *v)
> > +static int ptdump_efi_show(struct seq_file *m, void *v)
>
> I thought there was some macro magic going on that screwed the names up.
>
> This looks fine to me.
>
> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>

Cool, thanks!

Reviewed-by: Kees Cook <keescook@chromium.org>

Ingo, can you toss this in -tip please?

-- 
Kees Cook

[tip:x86/mm] x86/mm/dump_pagetables: Use DEFINE_SHOW_ATTRIBUTE()

[tip-bot for Yangtao Li]

Commit-ID:  6848ac7ca39a226ede5df7af0efcc4ef0611e99c
Gitweb:     https://git.kernel.org/tip/6848ac7ca39a226ede5df7af0efcc4ef0611e99c
Author:     Yangtao Li <tiny.windzz@gmail.com>
AuthorDate: Mon, 19 Nov 2018 10:43:34 -0500
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 18 Dec 2018 13:05:54 +0100

x86/mm/dump_pagetables: Use DEFINE_SHOW_ATTRIBUTE()

Use DEFINE_SHOW_ATTRIBUTE() instead of open coding it.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: keescook@chromium.org
Cc: luto@kernel.org
Cc: peterz@infradead.org
Cc: bp@alien8.de
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/20181119154334.18265-1-tiny.windzz@gmail.com

---
 arch/x86/mm/debug_pagetables.c | 58 +++++-------------------------------------
 1 file changed, 7 insertions(+), 51 deletions(-)

diff --git a/arch/x86/mm/debug_pagetables.c b/arch/x86/mm/debug_pagetables.c
index 225fe2f0bfec..cd84f067e41d 100644
--- a/arch/x86/mm/debug_pagetables.c
+++ b/arch/x86/mm/debug_pagetables.c
@@ -10,20 +10,9 @@ static int ptdump_show(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int ptdump_open(struct inode *inode, struct file *filp)
-{
-	return single_open(filp, ptdump_show, NULL);
-}
-
-static const struct file_operations ptdump_fops = {
-	.owner		= THIS_MODULE,
-	.open		= ptdump_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(ptdump);
 
-static int ptdump_show_curknl(struct seq_file *m, void *v)
+static int ptdump_curknl_show(struct seq_file *m, void *v)
 {
 	if (current->mm->pgd) {
 		down_read(&current->mm->mmap_sem);
@@ -33,23 +22,12 @@ static int ptdump_show_curknl(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int ptdump_open_curknl(struct inode *inode, struct file *filp)
-{
-	return single_open(filp, ptdump_show_curknl, NULL);
-}
-
-static const struct file_operations ptdump_curknl_fops = {
-	.owner		= THIS_MODULE,
-	.open		= ptdump_open_curknl,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(ptdump_curknl);
 
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 static struct dentry *pe_curusr;
 
-static int ptdump_show_curusr(struct seq_file *m, void *v)
+static int ptdump_curusr_show(struct seq_file *m, void *v)
 {
 	if (current->mm->pgd) {
 		down_read(&current->mm->mmap_sem);
@@ -59,42 +37,20 @@ static int ptdump_show_curusr(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int ptdump_open_curusr(struct inode *inode, struct file *filp)
-{
-	return single_open(filp, ptdump_show_curusr, NULL);
-}
-
-static const struct file_operations ptdump_curusr_fops = {
-	.owner		= THIS_MODULE,
-	.open		= ptdump_open_curusr,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(ptdump_curusr);
 #endif
 
 #if defined(CONFIG_EFI) && defined(CONFIG_X86_64)
 static struct dentry *pe_efi;
 
-static int ptdump_show_efi(struct seq_file *m, void *v)
+static int ptdump_efi_show(struct seq_file *m, void *v)
 {
 	if (efi_mm.pgd)
 		ptdump_walk_pgd_level_debugfs(m, efi_mm.pgd, false);
 	return 0;
 }
 
-static int ptdump_open_efi(struct inode *inode, struct file *filp)
-{
-	return single_open(filp, ptdump_show_efi, NULL);
-}
-
-static const struct file_operations ptdump_efi_fops = {
-	.owner		= THIS_MODULE,
-	.open		= ptdump_open_efi,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(ptdump_efi);
 #endif
 
 static struct dentry *dir, *pe_knl, *pe_curknl;