From 8f7543e4500cc71d20505265c11652509688d3ab Mon Sep 17 00:00:00 2001
From: Yiwei Zhang <zzyiwei@chromium.org>
Date: Mon, 27 Oct 2025 20:39:15 -0700
Subject: [PATCH] util: add os_map_memory_fd_placed for placed mapping support

This completes the opaque fd api coverage, and is needed by lavapipe for
sparse binding support with opaque fd external memory.

Reviewed-by: Christian Gmeiner <cgmeiner@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38074>
---
 src/util/os_memory_fd.c | 19 +++++++++++++++++++
 src/util/os_memory_fd.h |  6 ++++++
 2 files changed, 25 insertions(+)

diff --git a/src/util/os_memory_fd.c b/src/util/os_memory_fd.c
index eaf31bd45c4..fb45105d9c2 100644
--- a/src/util/os_memory_fd.c
+++ b/src/util/os_memory_fd.c
@@ -105,6 +105,25 @@ os_import_memory_fd(int fd, void **ptr, uint64_t *size, char const *driver_id)
    return true;
 }
 
+/**
+ * Map memory from a file descriptor at placed address
+ */
+bool
+os_map_memory_fd_placed(int fd, void *addr, uint64_t size, uint64_t offset,
+                        char const *driver_id)
+{
+   struct memory_header header;
+
+   if (!get_fd_header(fd, &header, driver_id))
+      return false;
+
+   if (header.size - header.offset < size + offset)
+      return false;
+
+   return mmap(addr, size, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, fd,
+               offset + header.offset) != MAP_FAILED;
+}
+
 /**
  * Return memory on given byte alignment
  */
diff --git a/src/util/os_memory_fd.h b/src/util/os_memory_fd.h
index 936e3911bbd..05be18c350c 100644
--- a/src/util/os_memory_fd.h
+++ b/src/util/os_memory_fd.h
@@ -40,6 +40,12 @@
 bool
 os_import_memory_fd(int fd, void **ptr, uint64_t *size, char const *driver_id);
 
+/**
+ * Map memory from a file descriptor at placed address
+ */
+bool
+os_map_memory_fd_placed(int fd, void *addr, uint64_t size, uint64_t offset, char const *driver_id);
+
 /**
  * Return memory on given byte alignment
  */