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[Qemu-devel] [PATCH] exec.c: remove an unnecessary condition in flatview
From: |
Wei Yang |
Subject: |
[Qemu-devel] [PATCH] exec.c: remove an unnecessary condition in flatview_add_to_dispatch() |
Date: |
Mon, 4 Mar 2019 14:51:02 +0800 |
flatview_add_to_dispatch() registers page based on the condition of
*section*, which may looks like this:
|s|PPPPPPP|s|
where s stands for subpage and P for page.
The procedure of this function could be described as:
- register first subpage
- register page
- register last subpage
This means only the first offset_within_address_space could be not
TARGET_PAGE_SIZE aligned. During the wile loop, this will not happen.
This patch just removes the unnecessary condition and adds some comment
to clarify it.
Signed-off-by: Wei Yang <address@hidden>
---
exec.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/exec.c b/exec.c
index 518064530b..e6221d52ba 100644
--- a/exec.c
+++ b/exec.c
@@ -1599,12 +1599,26 @@ static void register_multipage(FlatView *fv,
phys_page_set(d, start_addr >> TARGET_PAGE_BITS, num_pages, section_index);
}
+/*
+ * The range in *section* may look like this:
+ *
+ * |s|PPPPPPP|s|
+ *
+ * where s stands for subpage and P for page.
+ *
+ * The procedure in following function could be described as:
+ *
+ * - register first subpage
+ * - register page
+ * - register last subpage
+ */
void flatview_add_to_dispatch(FlatView *fv, MemoryRegionSection *section)
{
MemoryRegionSection now = *section, remain = *section;
Int128 page_size = int128_make64(TARGET_PAGE_SIZE);
if (now.offset_within_address_space & ~TARGET_PAGE_MASK) {
+ /* register first subpage */
uint64_t left = TARGET_PAGE_ALIGN(now.offset_within_address_space)
- now.offset_within_address_space;
@@ -1619,11 +1633,10 @@ void flatview_add_to_dispatch(FlatView *fv,
MemoryRegionSection *section)
remain.offset_within_region += int128_get64(now.size);
now = remain;
if (int128_lt(remain.size, page_size)) {
- register_subpage(fv, &now);
- } else if (remain.offset_within_address_space & ~TARGET_PAGE_MASK) {
- now.size = page_size;
+ /* register last subpage */
register_subpage(fv, &now);
} else {
+ /* register page */
now.size = int128_and(now.size, int128_neg(page_size));
register_multipage(fv, &now);
}
--
2.19.1
- [Qemu-devel] [PATCH] exec.c: remove an unnecessary condition in flatview_add_to_dispatch(),
Wei Yang <=