elfload: Fix alignment when unmapping excess reservation

When complying with the alignment requested in the ELF and unmapping
the excess reservation, having align_end not aligned to the guest page
causes the unmap to be rejected by the alignment check at
target_munmap and later brk adjustments hit an EEXIST.

Fix by aligning the start of region to be unmapped.

Fixes: c81d1fafa6 ("linux-user: Honor elf alignment when placing images")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1913
Signed-off-by: Fabiano Rosas <farosas@suse.de>
[rth: Align load_end as well.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20250213143558.10504-1-farosas@suse.de>

linux-user/elfload.c

@@ -3351,8 +3351,8 @@ static void load_elf_image(const char *image_name, const ImageSource *src,
 
     if (align_size != reserve_size) {
         abi_ulong align_addr = ROUND_UP(load_addr, align);
-        abi_ulong align_end = align_addr + reserve_size;
-        abi_ulong load_end = load_addr + align_size;
+        abi_ulong align_end = TARGET_PAGE_ALIGN(align_addr + reserve_size);
+        abi_ulong load_end = TARGET_PAGE_ALIGN(load_addr + align_size);
 
         if (align_addr != load_addr) {
             target_munmap(load_addr, align_addr - load_addr);