Le 04/07/2024 à 16:48, Peter Xu a écrit :
On Thu, Jul 04, 2024 at 08:30:05AM +0200, Christophe Leroy wrote:
Commit 2c8a81dc0cc5 ("riscv/mm: fix two page table check related
issues") added pud_leaf() in include/asm-generic/pgtable-nopmd.h
Do the same for p4d_leaf() and pgd_leaf() to avoid getting them
erroneously defined by architectures that do not implement the
related page level.
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
include/asm-generic/pgtable-nop4d.h | 1 +
include/asm-generic/pgtable-nopud.h | 1 +
include/linux/pgtable.h | 6 +++---
3 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/include/asm-generic/pgtable-nop4d.h b/include/asm-generic/pgtable-nop4d.h
index 03b7dae47dd4..75c96bbc5a96 100644
--- a/include/asm-generic/pgtable-nop4d.h
+++ b/include/asm-generic/pgtable-nop4d.h
@@ -21,6 +21,7 @@ typedef struct { pgd_t pgd; } p4d_t;
static inline int pgd_none(pgd_t pgd) { return 0; }
static inline int pgd_bad(pgd_t pgd) { return 0; }
static inline int pgd_present(pgd_t pgd) { return 1; }
+static inline int pgd_leaf(pgd_t pgd) { return 0; }
static inline void pgd_clear(pgd_t *pgd) { }
#define p4d_ERROR(p4d) (pgd_ERROR((p4d).pgd))
diff --git a/include/asm-generic/pgtable-nopud.h b/include/asm-generic/pgtable-nopud.h
index eb70c6d7ceff..14aeb8ef2d8a 100644
--- a/include/asm-generic/pgtable-nopud.h
+++ b/include/asm-generic/pgtable-nopud.h
@@ -28,6 +28,7 @@ typedef struct { p4d_t p4d; } pud_t;
static inline int p4d_none(p4d_t p4d) { return 0; }
static inline int p4d_bad(p4d_t p4d) { return 0; }
static inline int p4d_present(p4d_t p4d) { return 1; }
+static inline int p4d_leaf(p4d_t p4d) { return 0; }
static inline void p4d_clear(p4d_t *p4d) { }
#define pud_ERROR(pud) (p4d_ERROR((pud).p4d))
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 2a6a3cccfc36..b27e66f542d6 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1882,13 +1882,13 @@ typedef unsigned int pgtbl_mod_mask;
* - It should cover all kinds of huge mappings (e.g., pXd_trans_huge(),
* pXd_devmap(), or hugetlb mappings).
*/
-#ifndef pgd_leaf
+#if !defined(__PAGETABLE_P4D_FOLDED) && !defined(pgd_leaf)
#define pgd_leaf(x) false
#endif
-#ifndef p4d_leaf
+#if !defined(__PAGETABLE_PUD_FOLDED) && !defined(p4d_leaf)
#define p4d_leaf(x) false
#endif
-#ifndef pud_leaf
+#if !defined(__PAGETABLE_PMD_FOLDED) && !defined(pud_leaf)
#define pud_leaf(x) false
#endif
#ifndef pmd_leaf
Is it possible to do it the other way round, so that we can still rely on
"ifdef pxx_leaf" to decide whether to provide a fallback, and define them
properly when needed?
What do you mean by the "other way round" ? Did I do a mistake ? I can't
see it.
The purpose here is:
- If the architecture has the said level and implements pXd_leaf(),
that's fine
- If the architecture has the said level and doesn't implement
pXd_leaf(), that's also fine, a fallback is provided.
- If the architecture doesn't have the said level but implements
pXd_leaf(), it will conflict with the definition in
include/asm-generic/pgtable-nopXd.h and the build will fail.
The purpose is to make sure architectures don't implement pXd_leaf() at
the wrong level, for instance:
- an architecture without PMDs shall not implement anything else than
pmd_leaf()
- an architecture without P4Ds shall not implement pgd_leaf().
IMHO it was a neat way to avoid worrying on any macro defined; it'll be as
simple as "if function xxx not defined, let's define a fallback for xxx".
Per my limited experience it helped a lot on avoid compile issues here and
there..
That will still be the case.
This patch adds: "if function xxx is defined for wrong level, break the
build"
Christophe
