htab_get_table_size() either retrieve the size of the hash page table (HPT)
from the device tree - if the HPT size is determined by firmware - or
uses a heuristic to determine a good size based on RAM size if the kernel
is responsible for allocating the HPT.
To support a PAPR extension allowing resizing of the HPT, we're going to
want the memory size -> HPT size logic elsewhere, so split it out into a
helper function.
Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
---
arch/powerpc/include/asm/mmu-hash64.h | 3 +++
arch/powerpc/mm/hash_utils_64.c | 30 +++++++++++++++++-------------
2 files changed, 20 insertions(+), 13 deletions(-)
diff --git a/arch/powerpc/include/asm/mmu-hash64.h
b/arch/powerpc/include/asm/mmu-hash64.h
index 7352d3f..cf070fd 100644
--- a/arch/powerpc/include/asm/mmu-hash64.h
+++ b/arch/powerpc/include/asm/mmu-hash64.h
@@ -607,6 +607,9 @@ static inline unsigned long get_kernel_vsid(unsigned long
ea, int ssize)
context = (MAX_USER_CONTEXT) + ((ea >> 60) - 0xc) + 1;
return get_vsid(context, ea, ssize);
}
+
+unsigned htab_shift_for_mem_size(unsigned long mem_size);
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_POWERPC_MMU_HASH64_H_ */
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index e88a86e..d63f7dc 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -606,10 +606,24 @@ static int __init htab_dt_scan_pftsize(unsigned long node,
return 0;
}
-static unsigned long __init htab_get_table_size(void)
+unsigned htab_shift_for_mem_size(unsigned long mem_size)
{
- unsigned long mem_size, rnd_mem_size, pteg_count, psize;
+ unsigned memshift = __ilog2(mem_size);
+ unsigned pshift = mmu_psize_defs[mmu_virtual_psize].shift;
+ unsigned pteg_shift;
+
+ /* round mem_size up to next power of 2 */
+ if ((1UL << memshift) < mem_size)
+ memshift += 1;
+
+ /* aim for 2 pages / pteg */
+ pteg_shift = memshift - (pshift + 1);
+
+ return max(pteg_shift + 7, 18U);
+}
+static unsigned long __init htab_get_table_size(void)
+{
/* If hash size isn't already provided by the platform, we try to
* retrieve it from the device-tree. If it's not there neither, we
* calculate it now based on the total RAM size
@@ -619,17 +633,7 @@ static unsigned long __init htab_get_table_size(void)
if (ppc64_pft_size)
return 1UL << ppc64_pft_size;
- /* round mem_size up to next power of 2 */
- mem_size = memblock_phys_mem_size();
- rnd_mem_size = 1UL << __ilog2(mem_size);
- if (rnd_mem_size < mem_size)
- rnd_mem_size <<= 1;
-
- /* # pages / 2 */
- psize = mmu_psize_defs[mmu_virtual_psize].shift;
- pteg_count = max(rnd_mem_size >> (psize + 1), 1UL << 11);
-
- return pteg_count << 7;
+ return htab_shift_for_mem_size(memblock_phys_mem_size());
}
#ifdef CONFIG_MEMORY_HOTPLUG
--
2.5.0
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