From dbbba45fa37da85ac213fbbe1f7eab3e1de74b41 Mon Sep 17 00:00:00 2001 From: Luke Shumaker 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 --- 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