From c5eecbb58f65bf1c4effab9a7f283184b469768c Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 26 Nov 2020 11:53:33 +0100 Subject: 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) Link: https://lkml.kernel.org/r/20201126121121.364451610@infradead.org --- arch/powerpc/include/asm/nohash/32/pte-8xx.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'arch/powerpc/include/asm/nohash/32/pte-8xx.h') diff --git a/arch/powerpc/include/asm/nohash/32/pte-8xx.h b/arch/powerpc/include/asm/nohash/32/pte-8xx.h index 1581204467e1..fcc48d590d88 100644 --- 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__ */ -- cgit v1.2.3