diff mbox series

[v9,03/18] arm64: trans_pgd: make trans_pgd_map_page generic

Message ID 20200326032420.27220-4-pasha.tatashin@soleen.com (mailing list archive)
State New, archived
Headers show
Series arm64: MMU enabled kexec relocation | expand

Commit Message

Pasha Tatashin March 26, 2020, 3:24 a.m. UTC 
kexec is going to use a different allocator, so make
trans_pgd_map_page to accept allocator as an argument, and also
kexec is going to use a different map protection, so also pass
it via argument.

Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
---
 arch/arm64/include/asm/trans_pgd.h | 18 ++++++++++++++++--
 arch/arm64/kernel/hibernate.c      | 12 +++++++++++-
 arch/arm64/mm/trans_pgd.c          | 27 +++++++++++++++++++++------
 3 files changed, 48 insertions(+), 9 deletions(-)

Comments

James Morse April 29, 2020, 5:01 p.m. UTC | #1 
Hi Pavel,

On 26/03/2020 03:24, Pavel Tatashin wrote:
> kexec is going to use a different allocator, so make

> trans_pgd_map_page to accept allocator as an argument, and also
> kexec is going to use a different map protection, so also pass
> it via argument.

This trans_pgd_map_page() used to be create_single_mapping() It creates page tables that
map one page: the relocation code.

Why do you need a different pgprot? Surely PAGE_KERNEL_EXEC is exactly what you want.


> diff --git a/arch/arm64/include/asm/trans_pgd.h b/arch/arm64/include/asm/trans_pgd.h
> index 23153c13d1ce..ad5194ad178d 100644
> --- a/arch/arm64/include/asm/trans_pgd.h
> +++ b/arch/arm64/include/asm/trans_pgd.h
> @@ -12,10 +12,24 @@
>  #include <linux/types.h>
>  #include <asm/pgtable-types.h>
>  
> +/*
> + * trans_alloc_page
> + *	- Allocator that should return exactly one zeroed page, if this
> + *	 allocator fails, trans_pgd returns -ENOMEM error.

trans_pgd is what you pass in to trans_pgd_map_page() or trans_pgd_create_copy().
Do you mean what those functions return?


> + *
> + * trans_alloc_arg
> + *	- Passed to trans_alloc_page as an argument
> + */

> diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
> index 3d6f0fd73591..607bb1fbc349 100644
> --- a/arch/arm64/kernel/hibernate.c
> +++ b/arch/arm64/kernel/hibernate.c
> @@ -195,6 +200,11 @@ static int create_safe_exec_page(void *src_start, size_t length,
>  				 unsigned long dst_addr,
>  				 phys_addr_t *phys_dst_addr)
>  {
> +	struct trans_pgd_info trans_info = {
> +		.trans_alloc_page	= hibernate_page_alloc,
> +		.trans_alloc_arg	= (void *)GFP_ATOMIC,
> +	};

As you need another copy of this in the next patch, is it worth declaring this globally
and making it const?


> diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c
> index d20e48520cef..275a79935d7e 100644
> --- a/arch/arm64/mm/trans_pgd.c
> +++ b/arch/arm64/mm/trans_pgd.c
> @@ -180,8 +185,18 @@ int trans_pgd_create_copy(pgd_t **dst_pgdp, unsigned long start,
>  	return rc;
>  }
>  
> -int trans_pgd_map_page(pgd_t *trans_pgd, void *page, unsigned long dst_addr,
> -		       pgprot_t pgprot)
> +/*
> + * Add map entry to trans_pgd for a base-size page at PTE level.
> + * info:	contains allocator and its argument
> + * trans_pgd:	page table in which new map is added.
> + * page:	page to be mapped.

> + * dst_addr:	new VA address for the pages

~s/pages/page/

This thing only maps one page.


> + * pgprot:	protection for the page.
> + *
> + * Returns 0 on success, and -ENOMEM on failure.
> + */
> +int trans_pgd_map_page(struct trans_pgd_info *info, pgd_t *trans_pgd,
> +		       void *page, unsigned long dst_addr, pgprot_t pgprot)
>  {
>  	pgd_t *pgdp;
>  	pud_t *pudp;



Thanks,

James
Pasha Tatashin Jan. 22, 2021, 9:52 p.m. UTC | #2 
Hi James,

I am working on an updated version of this patch series. We had back
and forth discussion on the list and off the list about MMU-enabled
series. So, I decided to sync the last series I had with the current
mainline. Address your last comments (those that I can address), and
send it again, so we can take a fresh look. I will reply to some of
your comments, as I address them in the synced version of my series.

On Wed, Apr 29, 2020 at 1:01 PM James Morse <james.morse@arm.com> wrote:
>
> Hi Pavel,
>
> On 26/03/2020 03:24, Pavel Tatashin wrote:
> > kexec is going to use a different allocator, so make
>
> > trans_pgd_map_page to accept allocator as an argument, and also
> > kexec is going to use a different map protection, so also pass
> > it via argument.
>
> This trans_pgd_map_page() used to be create_single_mapping() It creates page tables that
> map one page: the relocation code.
>
> Why do you need a different pgprot? Surely PAGE_KERNEL_EXEC is exactly what you want.

For hibernate case yes, but for MMU enabled kexec case, PAGE_KERNEL is
used, because it is used to copy data segments.

> > diff --git a/arch/arm64/include/asm/trans_pgd.h b/arch/arm64/include/asm/trans_pgd.h
> > index 23153c13d1ce..ad5194ad178d 100644
> > --- a/arch/arm64/include/asm/trans_pgd.h
> > +++ b/arch/arm64/include/asm/trans_pgd.h
> > @@ -12,10 +12,24 @@
> >  #include <linux/types.h>
> >  #include <asm/pgtable-types.h>
> >
> > +/*
> > + * trans_alloc_page
> > + *   - Allocator that should return exactly one zeroed page, if this
> > + *    allocator fails, trans_pgd returns -ENOMEM error.
>
> trans_pgd is what you pass in to trans_pgd_map_page() or trans_pgd_create_copy().
> Do you mean what those functions return?

I meant to say trans_pgd_*, but I will change the comment to
explicitly say trans_pgd_map_page() and trans_pgd_create_copy() will
return -ENOMEM.

>
>
> > + *
> > + * trans_alloc_arg
> > + *   - Passed to trans_alloc_page as an argument
> > + */
>
> > diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
> > index 3d6f0fd73591..607bb1fbc349 100644
> > --- a/arch/arm64/kernel/hibernate.c
> > +++ b/arch/arm64/kernel/hibernate.c
> > @@ -195,6 +200,11 @@ static int create_safe_exec_page(void *src_start, size_t length,
> >                                unsigned long dst_addr,
> >                                phys_addr_t *phys_dst_addr)
> >  {
> > +     struct trans_pgd_info trans_info = {
> > +             .trans_alloc_page       = hibernate_page_alloc,
> > +             .trans_alloc_arg        = (void *)GFP_ATOMIC,
> > +     };
>
> As you need another copy of this in the next patch, is it worth declaring this globally
> and making it const?

I think it is alright to have it on the stack instead of permanently
using the data section for this. Plus, we will have a different one
for the kexec case, so having this globally available will make it
strange.

>
>
> > diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c
> > index d20e48520cef..275a79935d7e 100644
> > --- a/arch/arm64/mm/trans_pgd.c
> > +++ b/arch/arm64/mm/trans_pgd.c
> > @@ -180,8 +185,18 @@ int trans_pgd_create_copy(pgd_t **dst_pgdp, unsigned long start,
> >       return rc;
> >  }
> >
> > -int trans_pgd_map_page(pgd_t *trans_pgd, void *page, unsigned long dst_addr,
> > -                    pgprot_t pgprot)
> > +/*
> > + * Add map entry to trans_pgd for a base-size page at PTE level.
> > + * info:     contains allocator and its argument
> > + * trans_pgd:        page table in which new map is added.
> > + * page:     page to be mapped.
>
> > + * dst_addr: new VA address for the pages
>
> ~s/pages/page/
>
> This thing only maps one page.

Sure, I will change that.

Thank you,
Pasha
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/trans_pgd.h b/arch/arm64/include/asm/trans_pgd.h
index 23153c13d1ce..ad5194ad178d 100644
--- a/arch/arm64/include/asm/trans_pgd.h
+++ b/arch/arm64/include/asm/trans_pgd.h
@@ -12,10 +12,24 @@ 
 #include <linux/types.h>
 #include <asm/pgtable-types.h>
 
+/*
+ * trans_alloc_page
+ *	- Allocator that should return exactly one zeroed page, if this
+ *	 allocator fails, trans_pgd returns -ENOMEM error.
+ *
+ * trans_alloc_arg
+ *	- Passed to trans_alloc_page as an argument
+ */
+
+struct trans_pgd_info {
+	void * (*trans_alloc_page)(void *arg);
+	void *trans_alloc_arg;
+};
+
 int trans_pgd_create_copy(pgd_t **dst_pgdp, unsigned long start,
 			  unsigned long end);
 
-int trans_pgd_map_page(pgd_t *trans_pgd, void *page, unsigned long dst_addr,
-		       pgprot_t pgprot);
+int trans_pgd_map_page(struct trans_pgd_info *info, pgd_t *trans_pgd,
+		       void *page, unsigned long dst_addr, pgprot_t pgprot);
 
 #endif /* _ASM_TRANS_TABLE_H */
diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index 3d6f0fd73591..607bb1fbc349 100644
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -179,6 +179,11 @@  int arch_hibernation_header_restore(void *addr)
 }
 EXPORT_SYMBOL(arch_hibernation_header_restore);
 
+static void *hibernate_page_alloc(void *arg)
+{
+	return (void *)get_safe_page((gfp_t)(unsigned long)arg);
+}
+
 /*
  * Copies length bytes, starting at src_start into an new page,
  * perform cache maintenance, then maps it at the specified address low
@@ -195,6 +200,11 @@  static int create_safe_exec_page(void *src_start, size_t length,
 				 unsigned long dst_addr,
 				 phys_addr_t *phys_dst_addr)
 {
+	struct trans_pgd_info trans_info = {
+		.trans_alloc_page	= hibernate_page_alloc,
+		.trans_alloc_arg	= (void *)GFP_ATOMIC,
+	};
+
 	void *page = (void *)get_safe_page(GFP_ATOMIC);
 	pgd_t *trans_pgd;
 	int rc;
@@ -209,7 +219,7 @@  static int create_safe_exec_page(void *src_start, size_t length,
 	if (!trans_pgd)
 		return -ENOMEM;
 
-	rc = trans_pgd_map_page(trans_pgd, page, dst_addr,
+	rc = trans_pgd_map_page(&trans_info, trans_pgd, page, dst_addr,
 				PAGE_KERNEL_EXEC);
 	if (rc)
 		return rc;
diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c
index d20e48520cef..275a79935d7e 100644
--- a/arch/arm64/mm/trans_pgd.c
+++ b/arch/arm64/mm/trans_pgd.c
@@ -25,6 +25,11 @@ 
 #include <linux/mm.h>
 #include <linux/mmzone.h>
 
+static void *trans_alloc(struct trans_pgd_info *info)
+{
+	return info->trans_alloc_page(info->trans_alloc_arg);
+}
+
 static void _copy_pte(pte_t *dst_ptep, pte_t *src_ptep, unsigned long addr)
 {
 	pte_t pte = READ_ONCE(*src_ptep);
@@ -180,8 +185,18 @@  int trans_pgd_create_copy(pgd_t **dst_pgdp, unsigned long start,
 	return rc;
 }
 
-int trans_pgd_map_page(pgd_t *trans_pgd, void *page, unsigned long dst_addr,
-		       pgprot_t pgprot)
+/*
+ * Add map entry to trans_pgd for a base-size page at PTE level.
+ * info:	contains allocator and its argument
+ * trans_pgd:	page table in which new map is added.
+ * page:	page to be mapped.
+ * dst_addr:	new VA address for the pages
+ * pgprot:	protection for the page.
+ *
+ * Returns 0 on success, and -ENOMEM on failure.
+ */
+int trans_pgd_map_page(struct trans_pgd_info *info, pgd_t *trans_pgd,
+		       void *page, unsigned long dst_addr, pgprot_t pgprot)
 {
 	pgd_t *pgdp;
 	pud_t *pudp;
@@ -190,7 +205,7 @@  int trans_pgd_map_page(pgd_t *trans_pgd, void *page, unsigned long dst_addr,
 
 	pgdp = pgd_offset_raw(trans_pgd, dst_addr);
 	if (pgd_none(READ_ONCE(*pgdp))) {
-		pudp = (void *)get_safe_page(GFP_ATOMIC);
+		pudp = trans_alloc(info);
 		if (!pudp)
 			return -ENOMEM;
 		pgd_populate(&init_mm, pgdp, pudp);
@@ -198,7 +213,7 @@  int trans_pgd_map_page(pgd_t *trans_pgd, void *page, unsigned long dst_addr,
 
 	pudp = pud_offset(pgdp, dst_addr);
 	if (pud_none(READ_ONCE(*pudp))) {
-		pmdp = (void *)get_safe_page(GFP_ATOMIC);
+		pmdp = trans_alloc(info);
 		if (!pmdp)
 			return -ENOMEM;
 		pud_populate(&init_mm, pudp, pmdp);
@@ -206,14 +221,14 @@  int trans_pgd_map_page(pgd_t *trans_pgd, void *page, unsigned long dst_addr,
 
 	pmdp = pmd_offset(pudp, dst_addr);
 	if (pmd_none(READ_ONCE(*pmdp))) {
-		ptep = (void *)get_safe_page(GFP_ATOMIC);
+		ptep = trans_alloc(info);
 		if (!ptep)
 			return -ENOMEM;
 		pmd_populate_kernel(&init_mm, pmdp, ptep);
 	}
 
 	ptep = pte_offset_kernel(pmdp, dst_addr);
-	set_pte(ptep, pfn_pte(virt_to_pfn(page), PAGE_KERNEL_EXEC));
+	set_pte(ptep, pfn_pte(virt_to_pfn(page), pgprot));
 
 	return 0;
 }