Le 31/10/2023 à 11:15, Aneesh Kumar K.V a écrit :

Christophe Leroy [off-list ref] writes:

quoted

pte_user() is now only used in pte_access_permitted() to check
access on vmas. User flag is cleared to make a page unreadable.

So rename it pte_read() and remove pte_user() which isn't used
anymore.

For the time being it checks _PAGE_USER but in the near futur
all plateforms will be converted to _PAGE_READ so lets support
both for now.

Signed-off-by: Christophe Leroy <redacted>
---
  arch/powerpc/include/asm/nohash/32/pte-8xx.h |  7 -------
  arch/powerpc/include/asm/nohash/pgtable.h    | 13 +++++++------
  arch/powerpc/mm/ioremap.c                    |  4 ----
  3 files changed, 7 insertions(+), 17 deletions(-)

diff --git a/arch/powerpc/include/asm/nohash/32/pte-8xx.h b/arch/powerpc/include/asm/nohash/32/pte-8xx.h
index 62c965a4511a..1ee38befd29a 100644
--- a/arch/powerpc/include/asm/nohash/32/pte-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/pte-8xx.h

@@ -112,13 +112,6 @@ static inline pte_t pte_mkwrite_novma(pte_t pte)
  
  #define pte_mkwrite_novma pte_mkwrite_novma
  
-static inline bool pte_user(pte_t pte)
-{
-	return !(pte_val(pte) & _PAGE_SH);
-}
-
-#define pte_user pte_user
-
  static inline pte_t pte_mkhuge(pte_t pte)
  {
  	return __pte(pte_val(pte) | _PAGE_SPS | _PAGE_HUGE);

diff --git a/arch/powerpc/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h
index ee677162f9e6..aba56fe3b1c6 100644
--- a/arch/powerpc/include/asm/nohash/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/pgtable.h

@@ -160,9 +160,6 @@ static inline int pte_write(pte_t pte)
  	return pte_val(pte) & _PAGE_WRITE;
  }
  #endif
-#ifndef pte_read
-static inline int pte_read(pte_t pte)		{ return 1; }
-#endif
  static inline int pte_dirty(pte_t pte)		{ return pte_val(pte) & _PAGE_DIRTY; }
  static inline int pte_special(pte_t pte)	{ return pte_val(pte) & _PAGE_SPECIAL; }
  static inline int pte_none(pte_t pte)		{ return (pte_val(pte) & ~_PTE_NONE_MASK) == 0; }

@@ -190,10 +187,14 @@ static inline int pte_young(pte_t pte)
   * and PTE_64BIT, PAGE_KERNEL_X contains _PAGE_BAP_SR which is also in
   * _PAGE_USER.  Need to explicitly match _PAGE_BAP_UR bit in that case too.
   */
-#ifndef pte_user
-static inline bool pte_user(pte_t pte)
+#ifndef pte_read
+static inline bool pte_read(pte_t pte)
  {
+#ifdef _PAGE_READ
+	return (pte_val(pte) & _PAGE_READ) == _PAGE_READ;
+#else
  	return (pte_val(pte) & _PAGE_USER) == _PAGE_USER;
+#endif
  }
  #endif
  

@@ -208,7 +209,7 @@ static inline bool pte_access_permitted(pte_t pte, bool write)
  	 * A read-only access is controlled by _PAGE_USER bit.
  	 * We have _PAGE_READ set for WRITE and EXECUTE
  	 */
-	if (!pte_present(pte) || !pte_user(pte) || !pte_read(pte))
+	if (!pte_present(pte) || !pte_read(pte))
  		return false;
  
  	if (write && !pte_write(pte))

diff --git a/arch/powerpc/mm/ioremap.c b/arch/powerpc/mm/ioremap.c
index 7823c38f09de..7b0afcabd89f 100644
--- a/arch/powerpc/mm/ioremap.c
+++ b/arch/powerpc/mm/ioremap.c

@@ -50,10 +50,6 @@ void __iomem *ioremap_prot(phys_addr_t addr, size_t size, unsigned long flags)
  	if (pte_write(pte))
  		pte = pte_mkdirty(pte);
  
-	/* we don't want to let _PAGE_USER leak out */
-	if (WARN_ON(pte_user(pte)))
-		return NULL;

This check is still valid right? I understand that we want to remove
_PAGE_USER. But then loosing this check is ok?

Well, we may have to think about it for book3s/64. For all others 
_PAGE_USER is gone and replaced by a check of addresses versus TASK_SIZE.

As ioremap() will map into vmalloc space that address is necesserally 
correct.

quoted

-
  	if (iowa_is_active())
  		return iowa_ioremap(addr, size, pte_pgprot(pte), caller);
  	return __ioremap_caller(addr, size, pte_pgprot(pte), caller);
-- 
2.41.0