The following commit has been merged into the perf/core branch of tip: Commit-ID: c5eecbb58f65bf1c4effab9a7f283184b469768c Gitweb: https://git.kernel.org/tip/c5eecbb58f65bf1c4effab9a7f283184b469768c Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Thu, 26 Nov 2020 11:53:33 +01:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Wed, 09 Dec 2020 17:08:56 +01:00 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@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20201126121121.364451610@xxxxxxxxxxxxx --- arch/powerpc/include/asm/nohash/32/pte-8xx.h | 23 +++++++++++++++++++- 1 file changed, 23 insertions(+) diff --git a/arch/powerpc/include/asm/nohash/32/pte-8xx.h b/arch/powerpc/include/asm/nohash/32/pte-8xx.h index 1581204..fcc48d5 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__ */
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