Re: [PATCH V2 2/2] powerpc/mm/autonuma: Switch ppc64 to its own implementeation of saved write

Michael Ellerman [off-list ref] writes:

"Aneesh Kumar K.V" [off-list ref] writes:

quoted

diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
index 0735d5a8049f..8720a406bbbe 100644
--- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h

@@ -16,6 +16,9 @@
 #include <asm/page.h>
 #include <asm/bug.h>
 
+#ifndef __ASSEMBLY__
+#include <linux/mmdebug.h>
+#endif

I assume that's for the VM_BUG_ON() you add below. But if so wouldn't
the #include be better placed in book3s/64/pgtable.h also?

mmu-hash.h has got a hack that is explained below

#ifndef __ASSEMBLY__
#include <linux/mmdebug.h>
#endif
/*
 * This is necessary to get the definition of PGTABLE_RANGE which we
 * need for various slices related matters. Note that this isn't the
 * complete pgtable.h but only a portion of it.
 */
#include <asm/book3s/64/pgtable.h>

This is the only place where we do that book3s/64/pgtable.h include this
way. Everybody should include asm/pgable.h which picks the righ version
based on different config option.

#

quoted

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index fef738229a68..c684ef6cbd10 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h

@@ -512,6 +512,32 @@ static inline pte_t pte_mkhuge(pte_t pte)
 	return pte;
 }
 
+#define pte_mk_savedwrite pte_mk_savedwrite
+static inline pte_t pte_mk_savedwrite(pte_t pte)
+{
+	/*
+	 * Used by Autonuma subsystem to preserve the write bit
+	 * while marking the pte PROT_NONE. Only allow this
+	 * on PROT_NONE pte
+	 */
+	VM_BUG_ON((pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT | _PAGE_RWX | _PAGE_PRIVILEGED)) !=
+		  cpu_to_be64(_PAGE_PRESENT | _PAGE_PRIVILEGED));
+	return __pte(pte_val(pte) & ~_PAGE_PRIVILEGED);
+}
+

cheers

-aneesh