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| author | Peter Zijlstra <peterz@infradead.org> | 2020-11-26 13:53:33 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-12-09 19:08:56 +0300 |
| commit | c5eecbb58f65bf1c4effab9a7f283184b469768c (patch) | |
| tree | ca562dc2cb5fe999331a2c23f523329ebb7b2c4a /arch/powerpc | |
| parent | d55863db1dfec8845067f5625f1b0ab18c8948be (diff) | |
| download | linux-c5eecbb58f65bf1c4effab9a7f283184b469768c.tar.xz | |
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>
Link: https://lkml.kernel.org/r/20201126121121.364451610@infradead.org
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/include/asm/nohash/32/pte-8xx.h | 23 |
1 files changed, 23 insertions, 0 deletions
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__ */ |