[v2] linux-user: Improve host and guest page size handling

[PATCH v2 20/33] linux-user: Do early mmap placement only for reserved_va

Richard Henderson posted 33 patches 2 years, 5 months ago

Diff against v3 v4
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Maintainers: Richard Henderson <richard.henderson@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, Riku Voipio <riku.voipio@iki.fi>, Warner Losh <imp@bsdimp.com>, Kyle Evans <kevans@freebsd.org>, Eduardo Habkost <eduardo@habkost.net>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Yanan Wang <wangyanan55@huawei.com>, Stefan Berger <stefanb@linux.vnet.ibm.com>, Laurent Vivier <laurent@vivier.eu>, Juan Quintela <quintela@redhat.com>, Peter Xu <peterx@redhat.com>, Leonardo Bras <leobras@redhat.com>, David Hildenbrand <david@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Daniel Henrique Barboza <danielhb413@gmail.com>, "Cédric Le Goater" <clg@kaod.org>, David Gibson <david@gibson.dropbear.id.au>, Greg Kurz <groug@kaod.org>, Nicholas Piggin <npiggin@gmail.com>, "Alex Bennée" <alex.bennee@linaro.org>

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[PATCH v2 20/33] linux-user: Do early mmap placement only for reserved_va

Posted by Richard Henderson 2 years, 5 months ago

For reserved_va, place all non-fixed maps then proceed
as for MAP_FIXED.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 linux-user/mmap.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index caa76eb11a..7d482df06d 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -495,17 +495,19 @@ static abi_long target_mmap__locked(abi_ulong start, abi_ulong len,
     host_offset = offset & -host_page_size;
 
     /*
-     * If the user is asking for the kernel to find a location, do that
-     * before we truncate the length for mapping files below.
+     * For reserved_va, we are in full control of the allocation.
+     * Find a suitible hole and convert to MAP_FIXED.
      */
-    if (!(flags & (MAP_FIXED | MAP_FIXED_NOREPLACE))) {
+    if (reserved_va && !(flags & (MAP_FIXED | MAP_FIXED_NOREPLACE))) {
         host_len = len + offset - host_offset;
-        host_len = ROUND_UP(host_len, host_page_size);
-        start = mmap_find_vma(real_start, host_len, TARGET_PAGE_SIZE);
+        start = mmap_find_vma(real_start, host_len,
+                              MAX(host_page_size, TARGET_PAGE_SIZE));
         if (start == (abi_ulong)-1) {
             errno = ENOMEM;
             return -1;
         }
+        start += offset - host_offset;
+        flags |= MAP_FIXED;
     }
 
     /*
-- 
2.34.1