In case (last_start <= step_size), start is for sure to be 0. So, it is
save to do the round_down for all cases and set start to map_start when
start is smaller than map_start.
>From the performance point of view, this also reduces the check on each
iteration.
This patch unifies the code on round_down memory range in
memory_map_top_doown() and also removes a redundant assignment of start
which will be assigned the correct value in each iteration.
Signed-off-by: Wei Yang <richard.weiy...@gmail.com>
---
arch/x86/mm/init.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 22af912d66d2..d8ad5e825b10 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -514,7 +514,7 @@ static void __init memory_map_top_down(unsigned long
map_start,
step_size = PMD_SIZE;
max_pfn_mapped = 0; /* will get exact value next */
min_pfn_mapped = real_end >> PAGE_SHIFT;
- last_start = start = real_end;
+ last_start = real_end;
/*
* We start from the top (end of memory) and go to the bottom.
@@ -523,12 +523,10 @@ static void __init memory_map_top_down(unsigned long
map_start,
* for page table.
*/
while (last_start > map_start) {
- if (last_start > step_size) {
- start = round_down(last_start - 1, step_size);
- if (start < map_start)
- start = map_start;
- } else
+ start = round_down(last_start - 1, step_size);
+ if (start < map_start)
start = map_start;
+
mapped_ram_size += init_range_memory_mapping(start,
last_start);
last_start = start;
--
2.11.0
