[PATCH 0/8] xtensa: highmem support on cores with aliasing cache

[PATCH 0/8] xtensa: highmem support on cores with aliasing cache

[Max Filippov]

Hi,

this series implements highmem support on xtensa cores with aliasing cache.
It does so by making sure that high memory pages are always mapped at
virtual addresses with color that match color of their physical address.

This involves changing the generic kmap code to make it aware of cache
coloring. This part with corresponding arch changes is cc'd linux-mm,
linux-arch and linux-mips.

The whole series can also be found at:
git://github.com/jcmvbkbc/linux-xtensa.git xtensa-highmem-ca

Leonid Yegoshin (1):
  mm/highmem: make kmap cache coloring aware

Max Filippov (7):
  xtensa: make fixmap region addressing grow with index
  xtensa: allow fixmap and kmap span more than one page table
  xtensa: fix TLBTEMP_BASE_2 region handling in fast_second_level_miss
  xtensa: implement clear_user_highpage and copy_user_highpage
  xtensa: support aliasing cache in k[un]map_atomic
  xtensa: support aliasing cache in kmap
  xtensa: support highmem in aliasing cache flushing code

 arch/xtensa/include/asm/cacheflush.h |   2 +
 arch/xtensa/include/asm/fixmap.h     |  30 +++++++--
 arch/xtensa/include/asm/highmem.h    |  18 +++++-
 arch/xtensa/include/asm/page.h       |  14 ++++-
 arch/xtensa/include/asm/pgtable.h    |   7 ++-
 arch/xtensa/kernel/entry.S           |   2 +-
 arch/xtensa/mm/cache.c               |  77 ++++++++++++++++++++---
 arch/xtensa/mm/highmem.c             |  24 +++++---
 arch/xtensa/mm/misc.S                | 116 ++++++++++++++++-------------------
 arch/xtensa/mm/mmu.c                 |  38 +++++++-----
 mm/highmem.c                         |  19 +++++-
 11 files changed, 235 insertions(+), 112 deletions(-)

Cc: linux-mm@kvack.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: David Rientjes <rientjes@google.com>
-- 
1.8.1.4

[PATCH 6/8] mm/highmem: make kmap cache coloring aware

[Max Filippov]

From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>

Provide hooks that allow architectures with aliasing cache to align
mapping address of high pages according to their color. Such architectures
may enforce similar coloring of low- and high-memory page mappings and
reuse existing cache management functions to support highmem.

Cc: linux-mm@kvack.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
[ Max: extract architecture-independent part of the original patch, clean
  up checkpatch and build warnings. ]
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
Changes since the initial version:
- define set_pkmap_color(pg, cl) as do { } while (0) instead of /* */;
- rename is_no_more_pkmaps to no_more_pkmaps;
- change 'if (count > 0)' to 'if (count)' to better match the original
  code behavior;

 mm/highmem.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/mm/highmem.c b/mm/highmem.c
index b32b70c..88fb62e 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -44,6 +44,14 @@ DEFINE_PER_CPU(int, __kmap_atomic_idx);
  */
 #ifdef CONFIG_HIGHMEM
 
+#ifndef ARCH_PKMAP_COLORING
+#define set_pkmap_color(pg, cl)		do { } while (0)
+#define get_last_pkmap_nr(p, cl)	(p)
+#define get_next_pkmap_nr(p, cl)	(((p) + 1) & LAST_PKMAP_MASK)
+#define no_more_pkmaps(p, cl)		(!(p))
+#define get_next_pkmap_counter(c, cl)	((c) - 1)
+#endif
+
 unsigned long totalhigh_pages __read_mostly;
 EXPORT_SYMBOL(totalhigh_pages);
 
@@ -161,19 +169,24 @@ static inline unsigned long map_new_virtual(struct page *page)
 {
 	unsigned long vaddr;
 	int count;
+	int color __maybe_unused;
+
+	set_pkmap_color(page, color);
+	last_pkmap_nr = get_last_pkmap_nr(last_pkmap_nr, color);
 
 start:
 	count = LAST_PKMAP;
 	/* Find an empty entry */
 	for (;;) {
-		last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
-		if (!last_pkmap_nr) {
+		last_pkmap_nr = get_next_pkmap_nr(last_pkmap_nr, color);
+		if (no_more_pkmaps(last_pkmap_nr, color)) {
 			flush_all_zero_pkmaps();
 			count = LAST_PKMAP;
 		}
 		if (!pkmap_count[last_pkmap_nr])
 			break;	/* Found a usable entry */
-		if (--count)
+		count = get_next_pkmap_counter(count, color);
+		if (count)
 			continue;
 
 		/*
-- 
1.8.1.4

[PATCH 6/8] mm/highmem: make kmap cache coloring aware

[Max Filippov]

From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>

Provide hooks that allow architectures with aliasing cache to align
mapping address of high pages according to their color. Such architectures
may enforce similar coloring of low- and high-memory page mappings and
reuse existing cache management functions to support highmem.

Cc: linux-mm@kvack.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
[ Max: extract architecture-independent part of the original patch, clean
  up checkpatch and build warnings. ]
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
Changes since the initial version:
- define set_pkmap_color(pg, cl) as do { } while (0) instead of /* */;
- rename is_no_more_pkmaps to no_more_pkmaps;
- change 'if (count > 0)' to 'if (count)' to better match the original
  code behavior;

 mm/highmem.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/mm/highmem.c b/mm/highmem.c
index b32b70c..88fb62e 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -44,6 +44,14 @@ DEFINE_PER_CPU(int, __kmap_atomic_idx);
  */
 #ifdef CONFIG_HIGHMEM
 
+#ifndef ARCH_PKMAP_COLORING
+#define set_pkmap_color(pg, cl)		do { } while (0)
+#define get_last_pkmap_nr(p, cl)	(p)
+#define get_next_pkmap_nr(p, cl)	(((p) + 1) & LAST_PKMAP_MASK)
+#define no_more_pkmaps(p, cl)		(!(p))
+#define get_next_pkmap_counter(c, cl)	((c) - 1)
+#endif
+
 unsigned long totalhigh_pages __read_mostly;
 EXPORT_SYMBOL(totalhigh_pages);
 
@@ -161,19 +169,24 @@ static inline unsigned long map_new_virtual(struct page *page)
 {
 	unsigned long vaddr;
 	int count;
+	int color __maybe_unused;
+
+	set_pkmap_color(page, color);
+	last_pkmap_nr = get_last_pkmap_nr(last_pkmap_nr, color);
 
 start:
 	count = LAST_PKMAP;
 	/* Find an empty entry */
 	for (;;) {
-		last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
-		if (!last_pkmap_nr) {
+		last_pkmap_nr = get_next_pkmap_nr(last_pkmap_nr, color);
+		if (no_more_pkmaps(last_pkmap_nr, color)) {
 			flush_all_zero_pkmaps();
 			count = LAST_PKMAP;
 		}
 		if (!pkmap_count[last_pkmap_nr])
 			break;	/* Found a usable entry */
-		if (--count)
+		count = get_next_pkmap_counter(count, color);
+		if (count)
 			continue;
 
 		/*
-- 
1.8.1.4

[PATCH 6/8] mm/highmem: make kmap cache coloring aware

[Max Filippov]

From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>

Provide hooks that allow architectures with aliasing cache to align
mapping address of high pages according to their color. Such architectures
may enforce similar coloring of low- and high-memory page mappings and
reuse existing cache management functions to support highmem.

Cc: linux-mm@kvack.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
[ Max: extract architecture-independent part of the original patch, clean
  up checkpatch and build warnings. ]
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
Changes since the initial version:
- define set_pkmap_color(pg, cl) as do { } while (0) instead of /* */;
- rename is_no_more_pkmaps to no_more_pkmaps;
- change 'if (count > 0)' to 'if (count)' to better match the original
  code behavior;

 mm/highmem.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/mm/highmem.c b/mm/highmem.c
index b32b70c..88fb62e 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -44,6 +44,14 @@ DEFINE_PER_CPU(int, __kmap_atomic_idx);
  */
 #ifdef CONFIG_HIGHMEM
 
+#ifndef ARCH_PKMAP_COLORING
+#define set_pkmap_color(pg, cl)		do { } while (0)
+#define get_last_pkmap_nr(p, cl)	(p)
+#define get_next_pkmap_nr(p, cl)	(((p) + 1) & LAST_PKMAP_MASK)
+#define no_more_pkmaps(p, cl)		(!(p))
+#define get_next_pkmap_counter(c, cl)	((c) - 1)
+#endif
+
 unsigned long totalhigh_pages __read_mostly;
 EXPORT_SYMBOL(totalhigh_pages);
 
@@ -161,19 +169,24 @@ static inline unsigned long map_new_virtual(struct page *page)
 {
 	unsigned long vaddr;
 	int count;
+	int color __maybe_unused;
+
+	set_pkmap_color(page, color);
+	last_pkmap_nr = get_last_pkmap_nr(last_pkmap_nr, color);
 
 start:
 	count = LAST_PKMAP;
 	/* Find an empty entry */
 	for (;;) {
-		last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
-		if (!last_pkmap_nr) {
+		last_pkmap_nr = get_next_pkmap_nr(last_pkmap_nr, color);
+		if (no_more_pkmaps(last_pkmap_nr, color)) {
 			flush_all_zero_pkmaps();
 			count = LAST_PKMAP;
 		}
 		if (!pkmap_count[last_pkmap_nr])
 			break;	/* Found a usable entry */
-		if (--count)
+		count = get_next_pkmap_counter(count, color);
+		if (count)
 			continue;
 
 		/*
-- 
1.8.1.4

[PATCH 7/8] xtensa: support aliasing cache in kmap

[Max Filippov]

Define ARCH_PKMAP_COLORING and provide corresponding macro definitions
on cores with aliasing data cache.

Instead of single last_pkmap_nr maintain an array last_pkmap_nr_arr of
pkmap counters for each page color. Make sure that kmap maps physical
page at virtual address with color matching its physical address.

Cc: linux-mm@kvack.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 arch/xtensa/include/asm/highmem.h | 18 ++++++++++++++++--
 arch/xtensa/mm/highmem.c          |  1 +
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/xtensa/include/asm/highmem.h b/arch/xtensa/include/asm/highmem.h
index 2653ef5..a5c3380 100644
--- a/arch/xtensa/include/asm/highmem.h
+++ b/arch/xtensa/include/asm/highmem.h
@@ -17,14 +17,28 @@
 #include <asm/kmap_types.h>
 #include <asm/pgtable.h>
 
-#define PKMAP_BASE		(FIXADDR_START - PMD_SIZE)
-#define LAST_PKMAP		PTRS_PER_PTE
+#define PKMAP_BASE		((FIXADDR_START - \
+				  (LAST_PKMAP + 1) * PAGE_SIZE) & PMD_MASK)
+#define LAST_PKMAP		(PTRS_PER_PTE * DCACHE_N_COLORS)
 #define LAST_PKMAP_MASK		(LAST_PKMAP - 1)
 #define PKMAP_NR(virt)		(((virt) - PKMAP_BASE) >> PAGE_SHIFT)
 #define PKMAP_ADDR(nr)		(PKMAP_BASE + ((nr) << PAGE_SHIFT))
 
 #define kmap_prot		PAGE_KERNEL
 
+#if DCACHE_WAY_SIZE > PAGE_SIZE
+#define ARCH_PKMAP_COLORING
+#define set_pkmap_color(pg, cl)		((cl) = DCACHE_ALIAS(page_to_phys(pg)))
+#define get_last_pkmap_nr(p, cl)	(last_pkmap_nr_arr[cl] + (cl))
+#define get_next_pkmap_nr(p, cl)	\
+	((last_pkmap_nr_arr[cl] = ((last_pkmap_nr_arr[cl] + DCACHE_N_COLORS) & \
+				   LAST_PKMAP_MASK)) + (cl))
+#define no_more_pkmaps(p, cl)		((p) < DCACHE_N_COLORS)
+#define get_next_pkmap_counter(c, cl)	((c) - DCACHE_N_COLORS)
+
+extern unsigned int last_pkmap_nr_arr[];
+#endif
+
 extern pte_t *pkmap_page_table;
 
 void *kmap_high(struct page *page);
diff --git a/arch/xtensa/mm/highmem.c b/arch/xtensa/mm/highmem.c
index 466abae..3742a37 100644
--- a/arch/xtensa/mm/highmem.c
+++ b/arch/xtensa/mm/highmem.c
@@ -12,6 +12,7 @@
 #include <linux/highmem.h>
 #include <asm/tlbflush.h>
 
+unsigned int last_pkmap_nr_arr[DCACHE_N_COLORS];
 static pte_t *kmap_pte;
 
 static inline enum fixed_addresses kmap_idx(int type, unsigned long color)
-- 
1.8.1.4

[PATCH 7/8] xtensa: support aliasing cache in kmap

[Max Filippov]

Define ARCH_PKMAP_COLORING and provide corresponding macro definitions
on cores with aliasing data cache.

Instead of single last_pkmap_nr maintain an array last_pkmap_nr_arr of
pkmap counters for each page color. Make sure that kmap maps physical
page at virtual address with color matching its physical address.

Cc: linux-mm@kvack.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 arch/xtensa/include/asm/highmem.h | 18 ++++++++++++++++--
 arch/xtensa/mm/highmem.c          |  1 +
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/xtensa/include/asm/highmem.h b/arch/xtensa/include/asm/highmem.h
index 2653ef5..a5c3380 100644
--- a/arch/xtensa/include/asm/highmem.h
+++ b/arch/xtensa/include/asm/highmem.h
@@ -17,14 +17,28 @@
 #include <asm/kmap_types.h>
 #include <asm/pgtable.h>
 
-#define PKMAP_BASE		(FIXADDR_START - PMD_SIZE)
-#define LAST_PKMAP		PTRS_PER_PTE
+#define PKMAP_BASE		((FIXADDR_START - \
+				  (LAST_PKMAP + 1) * PAGE_SIZE) & PMD_MASK)
+#define LAST_PKMAP		(PTRS_PER_PTE * DCACHE_N_COLORS)
 #define LAST_PKMAP_MASK		(LAST_PKMAP - 1)
 #define PKMAP_NR(virt)		(((virt) - PKMAP_BASE) >> PAGE_SHIFT)
 #define PKMAP_ADDR(nr)		(PKMAP_BASE + ((nr) << PAGE_SHIFT))
 
 #define kmap_prot		PAGE_KERNEL
 
+#if DCACHE_WAY_SIZE > PAGE_SIZE
+#define ARCH_PKMAP_COLORING
+#define set_pkmap_color(pg, cl)		((cl) = DCACHE_ALIAS(page_to_phys(pg)))
+#define get_last_pkmap_nr(p, cl)	(last_pkmap_nr_arr[cl] + (cl))
+#define get_next_pkmap_nr(p, cl)	\
+	((last_pkmap_nr_arr[cl] = ((last_pkmap_nr_arr[cl] + DCACHE_N_COLORS) & \
+				   LAST_PKMAP_MASK)) + (cl))
+#define no_more_pkmaps(p, cl)		((p) < DCACHE_N_COLORS)
+#define get_next_pkmap_counter(c, cl)	((c) - DCACHE_N_COLORS)
+
+extern unsigned int last_pkmap_nr_arr[];
+#endif
+
 extern pte_t *pkmap_page_table;
 
 void *kmap_high(struct page *page);
diff --git a/arch/xtensa/mm/highmem.c b/arch/xtensa/mm/highmem.c
index 466abae..3742a37 100644
--- a/arch/xtensa/mm/highmem.c
+++ b/arch/xtensa/mm/highmem.c
@@ -12,6 +12,7 @@
 #include <linux/highmem.h>
 #include <asm/tlbflush.h>
 
+unsigned int last_pkmap_nr_arr[DCACHE_N_COLORS];
 static pte_t *kmap_pte;
 
 static inline enum fixed_addresses kmap_idx(int type, unsigned long color)
-- 
1.8.1.4

[PATCH 7/8] xtensa: support aliasing cache in kmap

[Max Filippov]

Define ARCH_PKMAP_COLORING and provide corresponding macro definitions
on cores with aliasing data cache.

Instead of single last_pkmap_nr maintain an array last_pkmap_nr_arr of
pkmap counters for each page color. Make sure that kmap maps physical
page at virtual address with color matching its physical address.

Cc: linux-mm@kvack.org
Cc: linux-arch@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 arch/xtensa/include/asm/highmem.h | 18 ++++++++++++++++--
 arch/xtensa/mm/highmem.c          |  1 +
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/xtensa/include/asm/highmem.h b/arch/xtensa/include/asm/highmem.h
index 2653ef5..a5c3380 100644
--- a/arch/xtensa/include/asm/highmem.h
+++ b/arch/xtensa/include/asm/highmem.h
@@ -17,14 +17,28 @@
 #include <asm/kmap_types.h>
 #include <asm/pgtable.h>
 
-#define PKMAP_BASE		(FIXADDR_START - PMD_SIZE)
-#define LAST_PKMAP		PTRS_PER_PTE
+#define PKMAP_BASE		((FIXADDR_START - \
+				  (LAST_PKMAP + 1) * PAGE_SIZE) & PMD_MASK)
+#define LAST_PKMAP		(PTRS_PER_PTE * DCACHE_N_COLORS)
 #define LAST_PKMAP_MASK		(LAST_PKMAP - 1)
 #define PKMAP_NR(virt)		(((virt) - PKMAP_BASE) >> PAGE_SHIFT)
 #define PKMAP_ADDR(nr)		(PKMAP_BASE + ((nr) << PAGE_SHIFT))
 
 #define kmap_prot		PAGE_KERNEL
 
+#if DCACHE_WAY_SIZE > PAGE_SIZE
+#define ARCH_PKMAP_COLORING
+#define set_pkmap_color(pg, cl)		((cl) = DCACHE_ALIAS(page_to_phys(pg)))
+#define get_last_pkmap_nr(p, cl)	(last_pkmap_nr_arr[cl] + (cl))
+#define get_next_pkmap_nr(p, cl)	\
+	((last_pkmap_nr_arr[cl] = ((last_pkmap_nr_arr[cl] + DCACHE_N_COLORS) & \
+				   LAST_PKMAP_MASK)) + (cl))
+#define no_more_pkmaps(p, cl)		((p) < DCACHE_N_COLORS)
+#define get_next_pkmap_counter(c, cl)	((c) - DCACHE_N_COLORS)
+
+extern unsigned int last_pkmap_nr_arr[];
+#endif
+
 extern pte_t *pkmap_page_table;
 
 void *kmap_high(struct page *page);
diff --git a/arch/xtensa/mm/highmem.c b/arch/xtensa/mm/highmem.c
index 466abae..3742a37 100644
--- a/arch/xtensa/mm/highmem.c
+++ b/arch/xtensa/mm/highmem.c
@@ -12,6 +12,7 @@
 #include <linux/highmem.h>
 #include <asm/tlbflush.h>
 
+unsigned int last_pkmap_nr_arr[DCACHE_N_COLORS];
 static pte_t *kmap_pte;
 
 static inline enum fixed_addresses kmap_idx(int type, unsigned long color)
-- 
1.8.1.4

Re: [PATCH 6/8] mm/highmem: make kmap cache coloring aware

[Leonid Yegoshin]

On 07/22/2014 12:01 PM, Max Filippov wrote:
> From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
>
> Provide hooks that allow architectures with aliasing cache to align
> mapping address of high pages according to their color. Such architectures
> may enforce similar coloring of low- and high-memory page mappings and
> reuse existing cache management functions to support highmem.
>
> Cc: linux-mm@kvack.org
> Cc: linux-arch@vger.kernel.org
> Cc: linux-mips@linux-mips.org
> Cc: David Rientjes <rientjes@google.com>
> Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
> [ Max: extract architecture-independent part of the original patch, clean
>    up checkpatch and build warnings. ]
> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
> ---
> Changes since the initial version:
> - define set_pkmap_color(pg, cl) as do { } while (0) instead of /* */;
> - rename is_no_more_pkmaps to no_more_pkmaps;
> - change 'if (count > 0)' to 'if (count)' to better match the original
>    code behavior;
>
>   mm/highmem.c | 19 ++++++++++++++++---
>   1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/mm/highmem.c b/mm/highmem.c
> index b32b70c..88fb62e 100644
> --- a/mm/highmem.c
> +++ b/mm/highmem.c
> @@ -44,6 +44,14 @@ DEFINE_PER_CPU(int, __kmap_atomic_idx);
>    */
>   #ifdef CONFIG_HIGHMEM
>   
> +#ifndef ARCH_PKMAP_COLORING
> +#define set_pkmap_color(pg, cl)		do { } while (0)
> +#define get_last_pkmap_nr(p, cl)	(p)
> +#define get_next_pkmap_nr(p, cl)	(((p) + 1) & LAST_PKMAP_MASK)
> +#define no_more_pkmaps(p, cl)		(!(p))
> +#define get_next_pkmap_counter(c, cl)	((c) - 1)
> +#endif
> +
>   unsigned long totalhigh_pages __read_mostly;
>   EXPORT_SYMBOL(totalhigh_pages);
>   
> @@ -161,19 +169,24 @@ static inline unsigned long map_new_virtual(struct page *page)
>   {
>   	unsigned long vaddr;
>   	int count;
> +	int color __maybe_unused;
> +
> +	set_pkmap_color(page, color);
> +	last_pkmap_nr = get_last_pkmap_nr(last_pkmap_nr, color);
>   
>   start:
>   	count = LAST_PKMAP;
>   	/* Find an empty entry */
>   	for (;;) {
> -		last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
> -		if (!last_pkmap_nr) {
> +		last_pkmap_nr = get_next_pkmap_nr(last_pkmap_nr, color);
> +		if (no_more_pkmaps(last_pkmap_nr, color)) {
>   			flush_all_zero_pkmaps();
>   			count = LAST_PKMAP;
>   		}
>   		if (!pkmap_count[last_pkmap_nr])
>   			break;	/* Found a usable entry */
> -		if (--count)
> +		count = get_next_pkmap_counter(count, color);
> +		if (count)
>   			continue;
>   
>   		/*
I would like to return back to "if (count >0)".

The reason is in easy way to jump through the same coloured pages - next 
element is calculated via decrementing by non "1" value of colours and 
it can easy become negative on last page available:

#define     get_next_pkmap_counter(c,cl)    (c - FIX_N_COLOURS)

where FIX_N_COLOURS is a max number of page colours.

Besides that it is a good practice in stopping cycle.

- Leonid.

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Re: [PATCH 6/8] mm/highmem: make kmap cache coloring aware

[Leonid Yegoshin]

On 07/22/2014 12:01 PM, Max Filippov wrote:
> From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
>
> Provide hooks that allow architectures with aliasing cache to align
> mapping address of high pages according to their color. Such architectures
> may enforce similar coloring of low- and high-memory page mappings and
> reuse existing cache management functions to support highmem.
>
> Cc: linux-mm@kvack.org
> Cc: linux-arch@vger.kernel.org
> Cc: linux-mips@linux-mips.org
> Cc: David Rientjes <rientjes@google.com>
> Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
> [ Max: extract architecture-independent part of the original patch, clean
>    up checkpatch and build warnings. ]
> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
> ---
> Changes since the initial version:
> - define set_pkmap_color(pg, cl) as do { } while (0) instead of /* */;
> - rename is_no_more_pkmaps to no_more_pkmaps;
> - change 'if (count > 0)' to 'if (count)' to better match the original
>    code behavior;
>
>   mm/highmem.c | 19 ++++++++++++++++---
>   1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/mm/highmem.c b/mm/highmem.c
> index b32b70c..88fb62e 100644
> --- a/mm/highmem.c
> +++ b/mm/highmem.c
> @@ -44,6 +44,14 @@ DEFINE_PER_CPU(int, __kmap_atomic_idx);
>    */
>   #ifdef CONFIG_HIGHMEM
>   
> +#ifndef ARCH_PKMAP_COLORING
> +#define set_pkmap_color(pg, cl)		do { } while (0)
> +#define get_last_pkmap_nr(p, cl)	(p)
> +#define get_next_pkmap_nr(p, cl)	(((p) + 1) & LAST_PKMAP_MASK)
> +#define no_more_pkmaps(p, cl)		(!(p))
> +#define get_next_pkmap_counter(c, cl)	((c) - 1)
> +#endif
> +
>   unsigned long totalhigh_pages __read_mostly;
>   EXPORT_SYMBOL(totalhigh_pages);
>   
> @@ -161,19 +169,24 @@ static inline unsigned long map_new_virtual(struct page *page)
>   {
>   	unsigned long vaddr;
>   	int count;
> +	int color __maybe_unused;
> +
> +	set_pkmap_color(page, color);
> +	last_pkmap_nr = get_last_pkmap_nr(last_pkmap_nr, color);
>   
>   start:
>   	count = LAST_PKMAP;
>   	/* Find an empty entry */
>   	for (;;) {
> -		last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
> -		if (!last_pkmap_nr) {
> +		last_pkmap_nr = get_next_pkmap_nr(last_pkmap_nr, color);
> +		if (no_more_pkmaps(last_pkmap_nr, color)) {
>   			flush_all_zero_pkmaps();
>   			count = LAST_PKMAP;
>   		}
>   		if (!pkmap_count[last_pkmap_nr])
>   			break;	/* Found a usable entry */
> -		if (--count)
> +		count = get_next_pkmap_counter(count, color);
> +		if (count)
>   			continue;
>   
>   		/*
I would like to return back to "if (count >0)".

The reason is in easy way to jump through the same coloured pages - next 
element is calculated via decrementing by non "1" value of colours and 
it can easy become negative on last page available:

#define     get_next_pkmap_counter(c,cl)    (c - FIX_N_COLOURS)

where FIX_N_COLOURS is a max number of page colours.

Besides that it is a good practice in stopping cycle.

- Leonid.

Re: [PATCH 6/8] mm/highmem: make kmap cache coloring aware

[Max Filippov]

On Tue, Jul 22, 2014 at 11:35 PM, Leonid Yegoshin
<Leonid.Yegoshin@imgtec.com> wrote:
> On 07/22/2014 12:01 PM, Max Filippov wrote:
>>
>> From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
>>
>> Provide hooks that allow architectures with aliasing cache to align
>> mapping address of high pages according to their color. Such architectures
>> may enforce similar coloring of low- and high-memory page mappings and
>> reuse existing cache management functions to support highmem.
>>
>> Cc: linux-mm@kvack.org
>> Cc: linux-arch@vger.kernel.org
>> Cc: linux-mips@linux-mips.org
>> Cc: David Rientjes <rientjes@google.com>
>> Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
>> [ Max: extract architecture-independent part of the original patch, clean
>>    up checkpatch and build warnings. ]
>> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
>> ---
>> Changes since the initial version:
>> - define set_pkmap_color(pg, cl) as do { } while (0) instead of /* */;
>> - rename is_no_more_pkmaps to no_more_pkmaps;
>> - change 'if (count > 0)' to 'if (count)' to better match the original
>>    code behavior;
>>
>>   mm/highmem.c | 19 ++++++++++++++++---
>>   1 file changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/mm/highmem.c b/mm/highmem.c
>> index b32b70c..88fb62e 100644
>> --- a/mm/highmem.c
>> +++ b/mm/highmem.c
>> @@ -44,6 +44,14 @@ DEFINE_PER_CPU(int, __kmap_atomic_idx);
>>    */
>>   #ifdef CONFIG_HIGHMEM
>>   +#ifndef ARCH_PKMAP_COLORING
>> +#define set_pkmap_color(pg, cl)                do { } while (0)
>> +#define get_last_pkmap_nr(p, cl)       (p)
>> +#define get_next_pkmap_nr(p, cl)       (((p) + 1) & LAST_PKMAP_MASK)
>> +#define no_more_pkmaps(p, cl)          (!(p))
>> +#define get_next_pkmap_counter(c, cl)  ((c) - 1)
>> +#endif
>> +
>>   unsigned long totalhigh_pages __read_mostly;
>>   EXPORT_SYMBOL(totalhigh_pages);
>>   @@ -161,19 +169,24 @@ static inline unsigned long map_new_virtual(struct
>> page *page)
>>   {
>>         unsigned long vaddr;
>>         int count;
>> +       int color __maybe_unused;
>> +
>> +       set_pkmap_color(page, color);
>> +       last_pkmap_nr = get_last_pkmap_nr(last_pkmap_nr, color);
>>     start:
>>         count = LAST_PKMAP;
>>         /* Find an empty entry */
>>         for (;;) {
>> -               last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
>> -               if (!last_pkmap_nr) {
>> +               last_pkmap_nr = get_next_pkmap_nr(last_pkmap_nr, color);
>> +               if (no_more_pkmaps(last_pkmap_nr, color)) {
>>                         flush_all_zero_pkmaps();
>>                         count = LAST_PKMAP;
>>                 }
>>                 if (!pkmap_count[last_pkmap_nr])
>>                         break;  /* Found a usable entry */
>> -               if (--count)
>> +               count = get_next_pkmap_counter(count, color);
>> +               if (count)
>>                         continue;
>>                 /*
>
> I would like to return back to "if (count >0)".
>
> The reason is in easy way to jump through the same coloured pages - next
> element is calculated via decrementing by non "1" value of colours and it
> can easy become negative on last page available:
>
> #define     get_next_pkmap_counter(c,cl)    (c - FIX_N_COLOURS)
>
> where FIX_N_COLOURS is a max number of page colours.

Initial value of c (i.e. LAST_PKMAP) should be a multiple of FIX_N_COLOURS,
so that should not be a problem.

> Besides that it is a good practice in stopping cycle.

But I agree with that.

-- 
Thanks.
-- Max

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Re: [PATCH 6/8] mm/highmem: make kmap cache coloring aware

[Max Filippov]

On Tue, Jul 22, 2014 at 11:35 PM, Leonid Yegoshin
<Leonid.Yegoshin@imgtec.com> wrote:
> On 07/22/2014 12:01 PM, Max Filippov wrote:
>>
>> From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
>>
>> Provide hooks that allow architectures with aliasing cache to align
>> mapping address of high pages according to their color. Such architectures
>> may enforce similar coloring of low- and high-memory page mappings and
>> reuse existing cache management functions to support highmem.
>>
>> Cc: linux-mm@kvack.org
>> Cc: linux-arch@vger.kernel.org
>> Cc: linux-mips@linux-mips.org
>> Cc: David Rientjes <rientjes@google.com>
>> Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
>> [ Max: extract architecture-independent part of the original patch, clean
>>    up checkpatch and build warnings. ]
>> Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
>> ---
>> Changes since the initial version:
>> - define set_pkmap_color(pg, cl) as do { } while (0) instead of /* */;
>> - rename is_no_more_pkmaps to no_more_pkmaps;
>> - change 'if (count > 0)' to 'if (count)' to better match the original
>>    code behavior;
>>
>>   mm/highmem.c | 19 ++++++++++++++++---
>>   1 file changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/mm/highmem.c b/mm/highmem.c
>> index b32b70c..88fb62e 100644
>> --- a/mm/highmem.c
>> +++ b/mm/highmem.c
>> @@ -44,6 +44,14 @@ DEFINE_PER_CPU(int, __kmap_atomic_idx);
>>    */
>>   #ifdef CONFIG_HIGHMEM
>>   +#ifndef ARCH_PKMAP_COLORING
>> +#define set_pkmap_color(pg, cl)                do { } while (0)
>> +#define get_last_pkmap_nr(p, cl)       (p)
>> +#define get_next_pkmap_nr(p, cl)       (((p) + 1) & LAST_PKMAP_MASK)
>> +#define no_more_pkmaps(p, cl)          (!(p))
>> +#define get_next_pkmap_counter(c, cl)  ((c) - 1)
>> +#endif
>> +
>>   unsigned long totalhigh_pages __read_mostly;
>>   EXPORT_SYMBOL(totalhigh_pages);
>>   @@ -161,19 +169,24 @@ static inline unsigned long map_new_virtual(struct
>> page *page)
>>   {
>>         unsigned long vaddr;
>>         int count;
>> +       int color __maybe_unused;
>> +
>> +       set_pkmap_color(page, color);
>> +       last_pkmap_nr = get_last_pkmap_nr(last_pkmap_nr, color);
>>     start:
>>         count = LAST_PKMAP;
>>         /* Find an empty entry */
>>         for (;;) {
>> -               last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
>> -               if (!last_pkmap_nr) {
>> +               last_pkmap_nr = get_next_pkmap_nr(last_pkmap_nr, color);
>> +               if (no_more_pkmaps(last_pkmap_nr, color)) {
>>                         flush_all_zero_pkmaps();
>>                         count = LAST_PKMAP;
>>                 }
>>                 if (!pkmap_count[last_pkmap_nr])
>>                         break;  /* Found a usable entry */
>> -               if (--count)
>> +               count = get_next_pkmap_counter(count, color);
>> +               if (count)
>>                         continue;
>>                 /*
>
> I would like to return back to "if (count >0)".
>
> The reason is in easy way to jump through the same coloured pages - next
> element is calculated via decrementing by non "1" value of colours and it
> can easy become negative on last page available:
>
> #define     get_next_pkmap_counter(c,cl)    (c - FIX_N_COLOURS)
>
> where FIX_N_COLOURS is a max number of page colours.

Initial value of c (i.e. LAST_PKMAP) should be a multiple of FIX_N_COLOURS,
so that should not be a problem.

> Besides that it is a good practice in stopping cycle.

But I agree with that.

-- 
Thanks.
-- Max