On 29.01.21 08:39, Anshuman Khandual wrote:
There are multiple instances of pfn_to_section_nr() and __pfn_to_section()
when CONFIG_SPARSEMEM is enabled. This can be just optimized if the memory
section is fetched earlier. Hence bifurcate pfn_valid() into two different
definitions depending on whether CONFIG_SPARSEMEM is enabled. Also replace
the open coded pfn <--> addr conversion with __[pfn|phys]_to_[phys|pfn]().
This does not cause any functional change.
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
arch/arm64/mm/init.c | 38 +++++++++++++++++++++++++++++++-------
1 file changed, 31 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 1141075e4d53..09adca90c57a 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -217,18 +217,25 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max)
free_area_init(max_zone_pfns);
}
+#ifdef CONFIG_SPARSEMEM
int pfn_valid(unsigned long pfn)
{
- phys_addr_t addr = pfn << PAGE_SHIFT;
+ struct mem_section *ms = __pfn_to_section(pfn);
+ phys_addr_t addr = __pfn_to_phys(pfn);
I'd just use PFN_PHYS() here, which is more frequently used in the kernel.
- if ((addr >> PAGE_SHIFT) != pfn)
+ /*
+ * Ensure the upper PAGE_SHIFT bits are clear in the
+ * pfn. Else it might lead to false positives when
+ * some of the upper bits are set, but the lower bits
+ * match a valid pfn.
+ */
+ if (__phys_to_pfn(addr) != pfn)
and here PHYS_PFN(). Comment is helpful. :)
return 0;
-#ifdef CONFIG_SPARSEMEM
if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
return 0;
- if (!valid_section(__pfn_to_section(pfn)))
+ if (!valid_section(ms))
return 0;
/*
@@ -240,11 +247,28 @@ int pfn_valid(unsigned long pfn)
* memory sections covering all of hotplug memory including
* both normal and ZONE_DEVICE based.
*/
- if (!early_section(__pfn_to_section(pfn)))
- return pfn_section_valid(__pfn_to_section(pfn), pfn);
-#endif
+ if (!early_section(ms))
+ return pfn_section_valid(ms, pfn);
+
return memblock_is_map_memory(addr);
}
+#else
+int pfn_valid(unsigned long pfn)
+{
+ phys_addr_t addr = __pfn_to_phys(pfn);
+
+ /*
+ * Ensure the upper PAGE_SHIFT bits are clear in the
+ * pfn. Else it might lead to false positives when
+ * some of the upper bits are set, but the lower bits
+ * match a valid pfn.
+ */
+ if (__phys_to_pfn(addr) != pfn)
+ return 0;
+
+ return memblock_is_map_memory(addr);
+}
I think you can avoid duplicating the code by doing something like:
phys_addr_t addr = PFN_PHYS(pfn);
if (PHYS_PFN(addr) != pfn)
return 0;
#ifdef CONFIG_SPARSEMEM
{
struct mem_section *ms = __pfn_to_section(pfn);
if (!valid_section(ms))
return 0;
if (!early_section(ms))
return pfn_section_valid(ms, pfn);
}
#endif
return memblock_is_map_memory(addr);
--
Thanks,
David / dhildenb
