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From dbbba45fa37da85ac213fbbe1f7eab3e1de74b41 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@parabola.nu>
Date: Wed, 27 Dec 2017 21:17:52 -0500
Subject: [PATCH 07/10] linux-user: init_guest_space: Clean up control flow a
bit
Instead of doing
if (check1) {
if (check2) {
success;
}
}
retry;
Do a clearer
if (!check1) {
goto try_again;
}
if (!check2) {
goto try_again;
}
success;
try_again:
retry;
Besides being clearer, this makes it easier to insert more checks that
need to trigger a retry on check failure, or rearrange them, or anything
like that.
Because some indentation is changing, "ignore space change" may be useful
for viewing this patch.
Signed-off-by: Luke Shumaker <lukeshu@parabola.nu>
---
linux-user/elfload.c | 34 +++++++++++++++++++---------------
1 file changed, 19 insertions(+), 15 deletions(-)
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index b560f5d6fe..5c0ad65611 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -1906,24 +1906,28 @@ unsigned long init_guest_space(unsigned long host_start,
}
/* Check to see if the address is valid. */
- if (!host_start || aligned_start == current_start) {
+ if (host_start && aligned_start != current_start) {
+ goto try_again;
+ }
+
#if defined(TARGET_ARM) && !defined(TARGET_AARCH64)
- /* On 32-bit ARM, we need to also be able to map the commpage. */
- int valid = init_guest_commpage(aligned_start - guest_start,
- aligned_size + guest_start);
- if (valid == 1) {
- break;
- } else if (valid == -1) {
- munmap((void *)real_start, real_size);
- return (unsigned long)-1;
- }
- /* valid == 0, so try again. */
-#else
- /* On other architectures, whatever we have here is fine. */
- break;
-#endif
+ /* On 32-bit ARM, we need to also be able to map the commpage. */
+ int valid = init_guest_commpage(aligned_start - guest_start,
+ aligned_size + guest_start);
+ if (valid == -1) {
+ munmap((void *)real_start, real_size);
+ return (unsigned long)-1;
+ } else if (valid == -1) {
+ goto try_again;
}
+#endif
+
+ /* If nothing has said `return -1` or `goto try_again` yet,
+ * then the address we have is good.
+ */
+ break;
+ try_again:
/* That address didn't work. Unmap and try a different one.
* The address the host picked because is typically right at
* the top of the host address space and leaves the guest with
--
2.15.1
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