From 375cae3dd6151ef33cae8f243f6a2c2da6c0c356 Mon Sep 17 00:00:00 2001
From: Richard Purdie <richard.purdie@linuxfoundation.org>
Date: Fri, 8 Jan 2021 17:27:06 +0000
Subject: [PATCH 06/12] qemu: Add some user space mmap tweaks to address musl
 32 bit

When using qemu-i386 to build qemux86 webkitgtk on musl, it sits in an
infinite loop of mremap calls of ever decreasing/increasing addresses.

I suspect something in the musl memory allocation code loops indefinitely
if it only sees ENOMEM and only exits when it hits EFAULT.

According to the docs, trying to mremap outside the address space
can/should return EFAULT and changing this allows the build to succeed.

A better return value for the other cases of invalid addresses is EINVAL
rather than ENOMEM so adjust the other part of the test to this.

Upstream-Status: Submitted [https://lists.gnu.org/archive/html/qemu-devel/2021-01/msg01355.html]
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org

---
 linux-user/mmap.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

Index: qemu-8.0.0/linux-user/mmap.c
===================================================================
--- qemu-8.0.0.orig/linux-user/mmap.c
+++ qemu-8.0.0/linux-user/mmap.c
@@ -776,12 +776,16 @@ abi_long target_mremap(abi_ulong old_add
     int prot;
     void *host_addr;
 
-    if (!guest_range_valid_untagged(old_addr, old_size) ||
-        ((flags & MREMAP_FIXED) &&
+    if (!guest_range_valid_untagged(old_addr, old_size)) {
+        errno = EFAULT;
+        return -1;
+    }
+    
+    if (((flags & MREMAP_FIXED) &&
          !guest_range_valid_untagged(new_addr, new_size)) ||
         ((flags & MREMAP_MAYMOVE) == 0 &&
          !guest_range_valid_untagged(old_addr, new_size))) {
-        errno = ENOMEM;
+        errno = EINVAL;
         return -1;
     }