lkml.org 
[lkml]   [2020]   [Nov]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH v2 6/6] powerpc/8xx: Implement pXX_leaf_size() support
Christophe Leroy wrote:

> I can help with powerpc 8xx. It is a 32 bits powerpc. The PGD has 1024
> entries, that means each entry maps 4M.
>
> Page sizes are 4k, 16k, 512k and 8M.
>
> For the 8M pages we use hugepd with a single entry. The two related PGD
> entries point to the same hugepd.
>
> For the other sizes, they are in standard page tables. 16k pages appear
> 4 times in the page table. 512k entries appear 128 times in the page
> table.
>
> When the PGD entry has _PMD_PAGE_8M bits, the PMD entry points to a
> hugepd with holds the single 8M entry.
>
> In the PTE, we have two bits: _PAGE_SPS and _PAGE_HUGE
>
> _PAGE_HUGE means it is a 512k page
> _PAGE_SPS means it is not a 4k page
>
> The kernel can by build either with 4k pages as standard page size, or
> 16k pages. It doesn't change the page table layout though.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/powerpc/include/asm/nohash/32/pte-8xx.h | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)

--- a/arch/powerpc/include/asm/nohash/32/pte-8xx.h
+++ b/arch/powerpc/include/asm/nohash/32/pte-8xx.h
@@ -135,6 +135,29 @@ static inline pte_t pte_mkhuge(pte_t pte
}

#define pte_mkhuge pte_mkhuge
+
+static inline unsigned long pgd_leaf_size(pgd_t pgd)
+{
+ if (pgd_val(pgd) & _PMD_PAGE_8M)
+ return SZ_8M;
+ return SZ_4M;
+}
+
+#define pgd_leaf_size pgd_leaf_size
+
+static inline unsigned long pte_leaf_size(pte_t pte)
+{
+ pte_basic_t val = pte_val(pte);
+
+ if (val & _PAGE_HUGE)
+ return SZ_512K;
+ if (val & _PAGE_SPS)
+ return SZ_16K;
+ return SZ_4K;
+}
+
+#define pte_leaf_size pte_leaf_size
+
#endif

#endif /* __KERNEL__ */

\
 
 \ /
  Last update: 2020-11-26 13:15    [W:1.247 / U:0.952 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site