[PATCH v1 1/8] powerpc/mem: Declare __flush_dcache_icache() static

[PATCH v1 1/8] powerpc/mem: Declare __flush_dcache_icache() static

[Christophe Leroy]

__flush_dcache_icache() is only used in mem.c.

Declare it static.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/include/asm/cacheflush.h | 1 -
 arch/powerpc/mm/mem.c                 | 4 +++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/cacheflush.h b/arch/powerpc/include/asm/cacheflush.h
index f63495109f63..9110489ea411 100644
--- a/arch/powerpc/include/asm/cacheflush.h
+++ b/arch/powerpc/include/asm/cacheflush.h
@@ -40,7 +40,6 @@ void flush_icache_user_page(struct vm_area_struct *vma, struct page *page,
 #define flush_icache_user_page flush_icache_user_page
 
 void flush_dcache_icache_page(struct page *page);
-void __flush_dcache_icache(void *page);
 
 /**
  * flush_dcache_range(): Write any modified data cache blocks out to memory and
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 7a59a5c9aa5d..ce6c81ce4362 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -472,6 +472,8 @@ void flush_dcache_page(struct page *page)
 }
 EXPORT_SYMBOL(flush_dcache_page);
 
+static void __flush_dcache_icache(void *p);
+
 static void flush_dcache_icache_hugepage(struct page *page)
 {
 	int i;
@@ -522,7 +524,7 @@ EXPORT_SYMBOL(flush_dcache_icache_page);
  *
  * @page: the address of the page to flush
  */
-void __flush_dcache_icache(void *p)
+static void __flush_dcache_icache(void *p)
 {
 	unsigned long addr = (unsigned long)p;
 
-- 
2.25.0

[PATCH v1 2/8] powerpc/mem: Remove address argument to flush_coherent_icache()

[Christophe Leroy]

flush_coherent_icache() can use any valid address as mentionned
by the comment.

Use PAGE_OFFSET as base address. This allows removing the
user access stuff.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/mm/mem.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index ce6c81ce4362..19f807b87697 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -342,10 +342,9 @@ void free_initmem(void)
 
 /**
  * flush_coherent_icache() - if a CPU has a coherent icache, flush it
- * @addr: The base address to use (can be any valid address, the whole cache will be flushed)
  * Return true if the cache was flushed, false otherwise
  */
-static inline bool flush_coherent_icache(unsigned long addr)
+static inline bool flush_coherent_icache(void)
 {
 	/*
 	 * For a snooping icache, we still need a dummy icbi to purge all the
@@ -355,9 +354,7 @@ static inline bool flush_coherent_icache(unsigned long addr)
 	 */
 	if (cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
 		mb(); /* sync */
-		allow_read_from_user((const void __user *)addr, L1_CACHE_BYTES);
-		icbi((void *)addr);
-		prevent_read_from_user((const void __user *)addr, L1_CACHE_BYTES);
+		icbi((void *)PAGE_OFFSET);
 		mb(); /* sync */
 		isync();
 		return true;
@@ -397,7 +394,7 @@ static void invalidate_icache_range(unsigned long start, unsigned long stop)
  */
 void flush_icache_range(unsigned long start, unsigned long stop)
 {
-	if (flush_coherent_icache(start))
+	if (flush_coherent_icache())
 		return;
 
 	clean_dcache_range(start, stop);
@@ -509,7 +506,7 @@ void flush_dcache_icache_page(struct page *page)
 	} else {
 		unsigned long addr = page_to_pfn(page) << PAGE_SHIFT;
 
-		if (flush_coherent_icache(addr))
+		if (flush_coherent_icache())
 			return;
 		flush_dcache_icache_phys(addr);
 	}
@@ -528,7 +525,7 @@ static void __flush_dcache_icache(void *p)
 {
 	unsigned long addr = (unsigned long)p;
 
-	if (flush_coherent_icache(addr))
+	if (flush_coherent_icache())
 		return;
 
 	clean_dcache_range(addr, addr + PAGE_SIZE);
-- 
2.25.0

[PATCH v1 3/8] powerpc/mem: Call flush_coherent_icache() at higher level

[Christophe Leroy]

flush_coherent_icache() doesn't need the address anymore,
so it can be called immediately when entering the public
functions and doesn't need to be disseminated among
lower level functions.

And use page_to_phys() instead of open coding the calculation
of phys address to call flush_dcache_icache_phys().

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/mm/mem.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 19f807b87697..29ce215e491f 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -491,6 +491,8 @@ static void flush_dcache_icache_hugepage(struct page *page)
 
 void flush_dcache_icache_page(struct page *page)
 {
+	if (flush_coherent_icache())
+		return;
 
 	if (PageCompound(page))
 		return flush_dcache_icache_hugepage(page);
@@ -504,11 +506,7 @@ void flush_dcache_icache_page(struct page *page)
 		__flush_dcache_icache(start);
 		kunmap_atomic(start);
 	} else {
-		unsigned long addr = page_to_pfn(page) << PAGE_SHIFT;
-
-		if (flush_coherent_icache())
-			return;
-		flush_dcache_icache_phys(addr);
+		flush_dcache_icache_phys(page_to_phys(page));
 	}
 #endif
 }
@@ -525,9 +523,6 @@ static void __flush_dcache_icache(void *p)
 {
 	unsigned long addr = (unsigned long)p;
 
-	if (flush_coherent_icache())
-		return;
-
 	clean_dcache_range(addr, addr + PAGE_SIZE);
 
 	/*
-- 
2.25.0

[PATCH v1 4/8] powerpc/mem: Optimise flush_dcache_icache_hugepage()

[Christophe Leroy]

flush_dcache_icache_hugepage() is a static function, with
only one caller. That caller calls it when PageCompound() is true,
so bugging on !PageCompound() is useless if we can trust the
compiler a little. Remove the BUG_ON(!PageCompound()).

The number of elements of a page won't change over time, but
GCC doesn't know about it, so it gets the value at every iteration.

To avoid that, call compound_nr() outside the loop and save it in
a local variable.

Whether the page is a HIGHMEM page or not doesn't change over time.

But GCC doesn't know it so it does the test on every iteration.

Do the test outside the loop.

When the page is not a HIGHMEM page, page_address() will fallback on
lowmem_page_address(), so call lowmem_page_address() directly and
don't suffer the call to page_address() on every iteration.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/mm/mem.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 29ce215e491f..d2c66827d9fd 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -474,14 +474,14 @@ static void __flush_dcache_icache(void *p);
 static void flush_dcache_icache_hugepage(struct page *page)
 {
 	int i;
+	int nr = compound_nr(page);
 	void *start;
 
-	BUG_ON(!PageCompound(page));
-
-	for (i = 0; i < compound_nr(page); i++) {
-		if (!PageHighMem(page)) {
-			__flush_dcache_icache(page_address(page+i));
-		} else {
+	if (!PageHighMem(page)) {
+		for (i = 0; i < nr; i++)
+			__flush_dcache_icache(lowmem_page_address(page + i));
+	} else {
+		for (i = 0; i < nr; i++) {
 			start = kmap_atomic(page+i);
 			__flush_dcache_icache(start);
 			kunmap_atomic(start);
-- 
2.25.0

[PATCH v1 5/8] powerpc/mem: flush_dcache_icache_phys() is for HIGHMEM pages only

[Christophe Leroy]

__flush_dcache_icache() is usable for non HIGHMEM pages on
every platform.

It is only for HIGHMEM pages that BOOKE needs kmap() and
BOOK3S needs flush_dcache_icache_phys().

So make flush_dcache_icache_phys() dependent on CONFIG_HIGHMEM and
call it only when it is a HIGHMEM page.

We could make flush_dcache_icache_phys() available at all time,
but as it is declared NOKPROBE_SYMBOL(), GCC doesn't optimise
it out when it is not used.

So define a stub for !CONFIG_HIGHMEM in order to remove the #ifdef in
flush_dcache_icache_page() and use IS_ENABLED() instead.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/mm/mem.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index d2c66827d9fd..9a5542f4de92 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -413,7 +413,7 @@ void flush_icache_range(unsigned long start, unsigned long stop)
 }
 EXPORT_SYMBOL(flush_icache_range);
 
-#if !defined(CONFIG_PPC_8xx) && !defined(CONFIG_PPC64)
+#ifdef CONFIG_HIGHMEM
 /**
  * flush_dcache_icache_phys() - Flush a page by it's physical address
  * @physaddr: the physical address of the page
@@ -452,7 +452,11 @@ static void flush_dcache_icache_phys(unsigned long physaddr)
 		: "ctr", "memory");
 }
 NOKPROBE_SYMBOL(flush_dcache_icache_phys)
-#endif // !defined(CONFIG_PPC_8xx) && !defined(CONFIG_PPC64)
+#else
+static void flush_dcache_icache_phys(unsigned long physaddr)
+{
+}
+#endif
 
 /*
  * This is called when a page has been modified by the kernel.
@@ -497,18 +501,15 @@ void flush_dcache_icache_page(struct page *page)
 	if (PageCompound(page))
 		return flush_dcache_icache_hugepage(page);
 
-#if defined(CONFIG_PPC_8xx) || defined(CONFIG_PPC64)
-	/* On 8xx there is no need to kmap since highmem is not supported */
-	__flush_dcache_icache(page_address(page));
-#else
-	if (IS_ENABLED(CONFIG_BOOKE) || sizeof(phys_addr_t) > sizeof(void *)) {
+	if (!PageHighMem(page)) {
+		__flush_dcache_icache(lowmem_page_address(page));
+	} else if (IS_ENABLED(CONFIG_BOOKE) || sizeof(phys_addr_t) > sizeof(void *)) {
 		void *start = kmap_atomic(page);
 		__flush_dcache_icache(start);
 		kunmap_atomic(start);
 	} else {
 		flush_dcache_icache_phys(page_to_phys(page));
 	}
-#endif
 }
 EXPORT_SYMBOL(flush_dcache_icache_page);
 
-- 
2.25.0

[PATCH v1 6/8] powerpc/mem: Help GCC realise __flush_dcache_icache() flushes single pages

[Christophe Leroy]

'And' the given page address with PAGE_MASK to help GCC.

With the patch:

	00000024 <__flush_dcache_icache>:
	  24:	54 63 00 26 	rlwinm  r3,r3,0,0,19
	  28:	39 40 00 40 	li      r10,64
	  2c:	7c 69 1b 78 	mr      r9,r3
	  30:	7d 49 03 a6 	mtctr   r10
	  34:	7c 00 48 6c 	dcbst   0,r9
	  38:	39 29 00 20 	addi    r9,r9,32
	  3c:	7c 00 48 6c 	dcbst   0,r9
	  40:	39 29 00 20 	addi    r9,r9,32
	  44:	42 00 ff f0 	bdnz    34 <__flush_dcache_icache+0x10>
	  48:	7c 00 04 ac 	hwsync
	  4c:	39 20 00 40 	li      r9,64
	  50:	7d 29 03 a6 	mtctr   r9
	  54:	7c 00 1f ac 	icbi    0,r3
	  58:	38 63 00 20 	addi    r3,r3,32
	  5c:	7c 00 1f ac 	icbi    0,r3
	  60:	38 63 00 20 	addi    r3,r3,32
	  64:	42 00 ff f0 	bdnz    54 <__flush_dcache_icache+0x30>
	  68:	7c 00 04 ac 	hwsync
	  6c:	4c 00 01 2c 	isync
	  70:	4e 80 00 20 	blr

Without the patch:

	00000024 <__flush_dcache_icache>:
	  24:	54 6a 00 34 	rlwinm  r10,r3,0,0,26
	  28:	39 23 10 1f 	addi    r9,r3,4127
	  2c:	7d 2a 48 50 	subf    r9,r10,r9
	  30:	55 29 d9 7f 	rlwinm. r9,r9,27,5,31
	  34:	41 82 00 94 	beq     c8 <__flush_dcache_icache+0xa4>
	  38:	71 28 00 01 	andi.   r8,r9,1
	  3c:	38 c9 ff ff 	addi    r6,r9,-1
	  40:	7d 48 53 78 	mr      r8,r10
	  44:	7d 27 4b 78 	mr      r7,r9
	  48:	40 82 00 6c 	bne     b4 <__flush_dcache_icache+0x90>
	  4c:	54 e7 f8 7e 	rlwinm  r7,r7,31,1,31
	  50:	7c e9 03 a6 	mtctr   r7
	  54:	7c 00 40 6c 	dcbst   0,r8
	  58:	39 08 00 20 	addi    r8,r8,32
	  5c:	7c 00 40 6c 	dcbst   0,r8
	  60:	39 08 00 20 	addi    r8,r8,32
	  64:	42 00 ff f0 	bdnz    54 <__flush_dcache_icache+0x30>
	  68:	7c 00 04 ac 	hwsync
	  6c:	71 28 00 01 	andi.   r8,r9,1
	  70:	39 09 ff ff 	addi    r8,r9,-1
	  74:	40 82 00 2c 	bne     a0 <__flush_dcache_icache+0x7c>
	  78:	55 29 f8 7e 	rlwinm  r9,r9,31,1,31
	  7c:	7d 29 03 a6 	mtctr   r9
	  80:	7c 00 57 ac 	icbi    0,r10
	  84:	39 4a 00 20 	addi    r10,r10,32
	  88:	7c 00 57 ac 	icbi    0,r10
	  8c:	39 4a 00 20 	addi    r10,r10,32
	  90:	42 00 ff f0 	bdnz    80 <__flush_dcache_icache+0x5c>
	  94:	7c 00 04 ac 	hwsync
	  98:	4c 00 01 2c 	isync
	  9c:	4e 80 00 20 	blr
	  a0:	7c 00 57 ac 	icbi    0,r10
	  a4:	2c 08 00 00 	cmpwi   r8,0
	  a8:	39 4a 00 20 	addi    r10,r10,32
	  ac:	40 82 ff cc 	bne     78 <__flush_dcache_icache+0x54>
	  b0:	4b ff ff e4 	b       94 <__flush_dcache_icache+0x70>
	  b4:	7c 00 50 6c 	dcbst   0,r10
	  b8:	2c 06 00 00 	cmpwi   r6,0
	  bc:	39 0a 00 20 	addi    r8,r10,32
	  c0:	40 82 ff 8c 	bne     4c <__flush_dcache_icache+0x28>
	  c4:	4b ff ff a4 	b       68 <__flush_dcache_icache+0x44>
	  c8:	7c 00 04 ac 	hwsync
	  cc:	7c 00 04 ac 	hwsync
	  d0:	4c 00 01 2c 	isync
	  d4:	4e 80 00 20 	blr

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/mm/mem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 9a5542f4de92..460ab5000a3f 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -522,7 +522,7 @@ EXPORT_SYMBOL(flush_dcache_icache_page);
  */
 static void __flush_dcache_icache(void *p)
 {
-	unsigned long addr = (unsigned long)p;
+	unsigned long addr = (unsigned long)p & PAGE_MASK;
 
 	clean_dcache_range(addr, addr + PAGE_SIZE);
 
-- 
2.25.0

[PATCH v1 7/8] powerpc/mem: Inline flush_dcache_page()

[Christophe Leroy]

flush_dcache_page() is only a few lines, it is worth
inlining.

ia64, csky, mips, openrisc and riscv have a similar
flush_dcache_page() and inline it.

On pmac32_defconfig, we get a small size reduction.
On ppc64_defconfig, we get a very small size increase.

In both case that's in the noise (less than 0.1%).

text		data	bss	dec		hex	filename
18991155	5934744	1497624	26423523	19330e3	vmlinux64.before
18994829	5936732	1497624	26429185	1934701	vmlinux64.after
9150963		2467502	 184548	11803013	 b41985	vmlinux32.before
9149689		2467302	 184548	11801539	 b413c3	vmlinux32.after

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/include/asm/cacheflush.h | 14 +++++++++++++-
 arch/powerpc/mm/mem.c                 | 15 ---------------
 2 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/include/asm/cacheflush.h b/arch/powerpc/include/asm/cacheflush.h
index 9110489ea411..7564dd4fd12b 100644
--- a/arch/powerpc/include/asm/cacheflush.h
+++ b/arch/powerpc/include/asm/cacheflush.h
@@ -30,7 +30,19 @@ static inline void flush_cache_vmap(unsigned long start, unsigned long end)
 #endif /* CONFIG_PPC_BOOK3S_64 */
 
 #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1
-extern void flush_dcache_page(struct page *page);
+/*
+ * This is called when a page has been modified by the kernel.
+ * It just marks the page as not i-cache clean.  We do the i-cache
+ * flush later when the page is given to a user process, if necessary.
+ */
+static inline void flush_dcache_page(struct page *page)
+{
+	if (cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
+		return;
+	/* avoid an atomic op if possible */
+	if (test_bit(PG_dcache_clean, &page->flags))
+		clear_bit(PG_dcache_clean, &page->flags);
+}
 
 void flush_icache_range(unsigned long start, unsigned long stop);
 #define flush_icache_range flush_icache_range
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 460ab5000a3f..65b2205839fe 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -458,21 +458,6 @@ static void flush_dcache_icache_phys(unsigned long physaddr)
 }
 #endif
 
-/*
- * This is called when a page has been modified by the kernel.
- * It just marks the page as not i-cache clean.  We do the i-cache
- * flush later when the page is given to a user process, if necessary.
- */
-void flush_dcache_page(struct page *page)
-{
-	if (cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
-		return;
-	/* avoid an atomic op if possible */
-	if (test_bit(PG_dcache_clean, &page->flags))
-		clear_bit(PG_dcache_clean, &page->flags);
-}
-EXPORT_SYMBOL(flush_dcache_page);
-
 static void __flush_dcache_icache(void *p);
 
 static void flush_dcache_icache_hugepage(struct page *page)
-- 
2.25.0

[PATCH v1 8/8] powerpc/mem: Use kmap_local_page() in flushing functions

[Christophe Leroy]

Flushing functions don't rely on preemption being disabled, so
use kmap_local_page() instead of kmap_atomic().

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/mm/mem.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 65b2205839fe..1895bd64191a 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -464,16 +464,16 @@ static void flush_dcache_icache_hugepage(struct page *page)
 {
 	int i;
 	int nr = compound_nr(page);
-	void *start;
 
 	if (!PageHighMem(page)) {
 		for (i = 0; i < nr; i++)
 			__flush_dcache_icache(lowmem_page_address(page + i));
 	} else {
 		for (i = 0; i < nr; i++) {
-			start = kmap_atomic(page+i);
+			void *start = kmap_local_page(page + i);
+
 			__flush_dcache_icache(start);
-			kunmap_atomic(start);
+			kunmap_local(start);
 		}
 	}
 }
@@ -489,9 +489,10 @@ void flush_dcache_icache_page(struct page *page)
 	if (!PageHighMem(page)) {
 		__flush_dcache_icache(lowmem_page_address(page));
 	} else if (IS_ENABLED(CONFIG_BOOKE) || sizeof(phys_addr_t) > sizeof(void *)) {
-		void *start = kmap_atomic(page);
+		void *start = kmap_local_page(page);
+
 		__flush_dcache_icache(start);
-		kunmap_atomic(start);
+		kunmap_local(start);
 	} else {
 		flush_dcache_icache_phys(page_to_phys(page));
 	}
@@ -564,11 +565,11 @@ void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
 void flush_icache_user_page(struct vm_area_struct *vma, struct page *page,
 			     unsigned long addr, int len)
 {
-	unsigned long maddr;
+	void *maddr;
 
-	maddr = (unsigned long) kmap(page) + (addr & ~PAGE_MASK);
-	flush_icache_range(maddr, maddr + len);
-	kunmap(page);
+	maddr = kmap_local_page(page) + (addr & ~PAGE_MASK);
+	flush_icache_range((unsigned long)maddr, (unsigned long)maddr + len);
+	kunmap_local(maddr);
 }
 
 /*
-- 
2.25.0

Re: [PATCH v1 2/8] powerpc/mem: Remove address argument to flush_coherent_icache()

[Aneesh Kumar K.V]

Christophe Leroy <christophe.leroy@csgroup.eu> writes:

> flush_coherent_icache() can use any valid address as mentionned
> by the comment.
>
> Use PAGE_OFFSET as base address. This allows removing the
> user access stuff.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
>  arch/powerpc/mm/mem.c | 13 +++++--------
>  1 file changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> index ce6c81ce4362..19f807b87697 100644
> --- a/arch/powerpc/mm/mem.c
> +++ b/arch/powerpc/mm/mem.c
> @@ -342,10 +342,9 @@ void free_initmem(void)
>  
>  /**
>   * flush_coherent_icache() - if a CPU has a coherent icache, flush it
> - * @addr: The base address to use (can be any valid address, the whole cache will be flushed)
>   * Return true if the cache was flushed, false otherwise
>   */
> -static inline bool flush_coherent_icache(unsigned long addr)
> +static inline bool flush_coherent_icache(void)
>  {
>  	/*
>  	 * For a snooping icache, we still need a dummy icbi to purge all the
> @@ -355,9 +354,7 @@ static inline bool flush_coherent_icache(unsigned long addr)
>  	 */
>  	if (cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
>  		mb(); /* sync */
> -		allow_read_from_user((const void __user *)addr, L1_CACHE_BYTES);
> -		icbi((void *)addr);
> -		prevent_read_from_user((const void __user *)addr, L1_CACHE_BYTES);
> +		icbi((void *)PAGE_OFFSET);
>  		mb(); /* sync */
>  		isync();
>  		return true;

do we need that followup sync? Usermanual suggest sync; icbi(any address);
isync sequence. 

-aneesh

Re: [PATCH v1 2/8] powerpc/mem: Remove address argument to flush_coherent_icache()

[Christophe Leroy]

Le 08/04/2021 à 10:50, Aneesh Kumar K.V a écrit :
> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> 
>> flush_coherent_icache() can use any valid address as mentionned
>> by the comment.
>>
>> Use PAGE_OFFSET as base address. This allows removing the
>> user access stuff.
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>> ---
>>   arch/powerpc/mm/mem.c | 13 +++++--------
>>   1 file changed, 5 insertions(+), 8 deletions(-)
>>
>> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
>> index ce6c81ce4362..19f807b87697 100644
>> --- a/arch/powerpc/mm/mem.c
>> +++ b/arch/powerpc/mm/mem.c
>> @@ -342,10 +342,9 @@ void free_initmem(void)
>>   
>>   /**
>>    * flush_coherent_icache() - if a CPU has a coherent icache, flush it
>> - * @addr: The base address to use (can be any valid address, the whole cache will be flushed)
>>    * Return true if the cache was flushed, false otherwise
>>    */
>> -static inline bool flush_coherent_icache(unsigned long addr)
>> +static inline bool flush_coherent_icache(void)
>>   {
>>   	/*
>>   	 * For a snooping icache, we still need a dummy icbi to purge all the
>> @@ -355,9 +354,7 @@ static inline bool flush_coherent_icache(unsigned long addr)
>>   	 */
>>   	if (cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
>>   		mb(); /* sync */
>> -		allow_read_from_user((const void __user *)addr, L1_CACHE_BYTES);
>> -		icbi((void *)addr);
>> -		prevent_read_from_user((const void __user *)addr, L1_CACHE_BYTES);
>> +		icbi((void *)PAGE_OFFSET);
>>   		mb(); /* sync */
>>   		isync();
>>   		return true;
> 
> do we need that followup sync? Usermanual suggest sync; icbi(any address);
> isync sequence.

I don't know.

The original implementation is here: https://github.com/linuxppc/linux/commit/0ce636700

Christophe