[V2,08/11] arch/kmap: Ensure kmap_prot visibility

Commit Message

Ira Weiny May 4, 2020, 1:09 a.m. UTC

From: Ira Weiny <[e-mail]>

We want to support kmap_atomic_prot() on all architectures and it makes
sense to define kmap_atomic() to use the default kmap_prot.

So we ensure all arch's have a globally available kmap_prot either as a
define or exported symbol.

Signed-off-by: Ira Weiny <[e-mail]>
---
 arch/microblaze/include/asm/highmem.h | 2 +-
 arch/microblaze/mm/init.c             | 3 ---
 arch/powerpc/include/asm/highmem.h    | 2 +-
 arch/powerpc/mm/mem.c                 | 3 ---
 arch/sparc/mm/highmem.c               | 1 +
 5 files changed, 3 insertions(+), 8 deletions(-)

Comments

Christoph Hellwig May 6, 2020, 6:13 a.m. UTC | #1

On Sun, May 03, 2020 at 06:09:09PM -0700, [e-mail] wrote:
> From: Ira Weiny <[e-mail]>
> 
> We want to support kmap_atomic_prot() on all architectures and it makes
> sense to define kmap_atomic() to use the default kmap_prot.
> 
> So we ensure all arch's have a globally available kmap_prot either as a
> define or exported symbol.

FYI, I still think a

#ifndef kmap_prot
#define kmap_prot PAGE_KERNEL
#endif

in linux/highmem.h would be nicer.  Then only xtensa and sparc need
to override it and clearly stand out.

Ira Weiny May 6, 2020, 8:33 p.m. UTC | #2

On Tue, May 05, 2020 at 11:13:26PM -0700, Christoph Hellwig wrote:
> On Sun, May 03, 2020 at 06:09:09PM -0700, [e-mail] wrote:
> > From: Ira Weiny <[e-mail]>
> > 
> > We want to support kmap_atomic_prot() on all architectures and it makes
> > sense to define kmap_atomic() to use the default kmap_prot.
> > 
> > So we ensure all arch's have a globally available kmap_prot either as a
> > define or exported symbol.
> 
> FYI, I still think a
> 
> #ifndef kmap_prot
> #define kmap_prot PAGE_KERNEL
> #endif
> 
> in linux/highmem.h would be nicer.  Then only xtensa and sparc need
> to override it and clearly stand out.

That would be nice...  But...  in this particular patch kmap_prot needs to be
in arch/microblaze/include/asm/highmem.h to preserve bisect-ability.

So there would be an inversion with this define and the core #ifndef...

I like the change but I'm going to add this change as a follow on patch because
at the end of the series microblaze no longer needs this.

If this is reasonable could I get a review on this patch to add to the next
series?

Ira

Christoph Hellwig May 7, 2020, 4:56 a.m. UTC | #3

On Sun, May 03, 2020 at 06:09:09PM -0700, [e-mail] wrote:
> From: Ira Weiny <[e-mail]>
> 
> We want to support kmap_atomic_prot() on all architectures and it makes
> sense to define kmap_atomic() to use the default kmap_prot.
> 
> So we ensure all arch's have a globally available kmap_prot either as a
> define or exported symbol.
> 
> Signed-off-by: Ira Weiny <[e-mail]>

Looks good,

Reviewed-by: Christoph Hellwig <[e-mail]>

Patch

diff --git a/arch/microblaze/include/asm/highmem.h b/arch/microblaze/include/asm/highmem.h
index 1b8a3c5102bd..033ac5b5c2da 100644
--- a/arch/microblaze/include/asm/highmem.h
+++ b/arch/microblaze/include/asm/highmem.h
@@ -25,8 +25,8 @@ 
 #include <linux/uaccess.h>
 #include <asm/fixmap.h>
 
+#define kmap_prot		PAGE_KERNEL
 extern pte_t *kmap_pte;
-extern pgprot_t kmap_prot;
 extern pte_t *pkmap_page_table;
 
 /*
diff --git a/arch/microblaze/mm/init.c b/arch/microblaze/mm/init.c
index 1ffbfa96b9b8..a467686c13af 100644
--- a/arch/microblaze/mm/init.c
+++ b/arch/microblaze/mm/init.c
@@ -49,8 +49,6 @@  unsigned long lowmem_size;
 #ifdef CONFIG_HIGHMEM
 pte_t *kmap_pte;
 EXPORT_SYMBOL(kmap_pte);
-pgprot_t kmap_prot;
-EXPORT_SYMBOL(kmap_prot);
 
 static inline pte_t *virt_to_kpte(unsigned long vaddr)
 {
@@ -68,7 +66,6 @@  static void __init highmem_init(void)
 	pkmap_page_table = virt_to_kpte(PKMAP_BASE);
 
 	kmap_pte = virt_to_kpte(__fix_to_virt(FIX_KMAP_BEGIN));
-	kmap_prot = PAGE_KERNEL;
 }
 
 static void highmem_setup(void)
diff --git a/arch/powerpc/include/asm/highmem.h b/arch/powerpc/include/asm/highmem.h
index 373a470df205..ee5de974c5ef 100644
--- a/arch/powerpc/include/asm/highmem.h
+++ b/arch/powerpc/include/asm/highmem.h
@@ -29,8 +29,8 @@ 
 #include <asm/page.h>
 #include <asm/fixmap.h>
 
+#define kmap_prot		PAGE_KERNEL
 extern pte_t *kmap_pte;
-extern pgprot_t kmap_prot;
 extern pte_t *pkmap_page_table;
 
 /*
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 041ed7cfd341..3f642b058731 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -64,8 +64,6 @@  bool init_mem_is_free;
 #ifdef CONFIG_HIGHMEM
 pte_t *kmap_pte;
 EXPORT_SYMBOL(kmap_pte);
-pgprot_t kmap_prot;
-EXPORT_SYMBOL(kmap_prot);
 #endif
 
 pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
@@ -245,7 +243,6 @@  void __init paging_init(void)
 	pkmap_page_table = virt_to_kpte(PKMAP_BASE);
 
 	kmap_pte = virt_to_kpte(__fix_to_virt(FIX_KMAP_BEGIN));
-	kmap_prot = PAGE_KERNEL;
 #endif /* CONFIG_HIGHMEM */
 
 	printk(KERN_DEBUG "Top of RAM: 0x%llx, Total RAM: 0x%llx\n",
diff --git a/arch/sparc/mm/highmem.c b/arch/sparc/mm/highmem.c
index 469786bc430f..9f06d75e88e1 100644
--- a/arch/sparc/mm/highmem.c
+++ b/arch/sparc/mm/highmem.c
@@ -33,6 +33,7 @@ 
 #include <asm/vaddrs.h>
 
 pgprot_t kmap_prot;
+EXPORT_SYMBOL(kmap_prot);
 
 static pte_t *kmap_pte;