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D44306.1775298931.diff
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D44306.1775298931.diff

diff --git a/sys/compat/linuxkpi/common/include/linux/module.h b/sys/compat/linuxkpi/common/include/linux/module.h
--- a/sys/compat/linuxkpi/common/include/linux/module.h
+++ b/sys/compat/linuxkpi/common/include/linux/module.h
@@ -32,6 +32,8 @@
#include <sys/types.h>
#include <sys/param.h>
#include <sys/module.h>
+#include <sys/queue.h>
+#include <sys/linker.h>
#include <linux/list.h>
#include <linux/compiler.h>
@@ -51,7 +53,26 @@
#define MODULE_SUPPORTED_DEVICE(name)
#define MODULE_IMPORT_NS(_name)
+/*
+ * THIS_MODULE is used to differentiate modules on Linux. We currently
+ * completely stub out any Linux struct module usage, but THIS_MODULE is still
+ * used to populate the "owner" fields of various drivers. Even though we
+ * don't actually dereference these "owner" fields they are still used by
+ * drivers to check if devices/dmabufs/etc come from different modules. For
+ * example, during DRM GEM import some drivers check if the dmabuf's owner
+ * matches the dev's owner. If they match because they are both NULL drivers
+ * may incorrectly think two resources come from the same module.
+ *
+ * To handle this we specify an undefined symbol __this_linker_file, which
+ * will get special treatment from the linker when resolving. This will
+ * populate the usages of __this_linker_file with the linker_file_t of the
+ * module.
+ */
+#ifdef KLD_MODULE
+#define THIS_MODULE ((struct module *)&__this_linker_file)
+#else
#define THIS_MODULE ((struct module *)0)
+#endif
#define __MODULE_STRING(x) __stringify(x)
diff --git a/sys/kern/kern_linker.c b/sys/kern/kern_linker.c
--- a/sys/kern/kern_linker.c
+++ b/sys/kern/kern_linker.c
@@ -906,6 +906,20 @@
KLD_DPF(SYM, ("linker_file_lookup_symbol: file=%p, name=%s, deps=%d\n",
file, name, deps));
+ /*
+ * Treat the __this_linker_file as a special symbol. This is a
+ * global that linuxkpi uses to populate the THIS_MODULE
+ * value. In this case we can simply return the linker_file_t.
+ *
+ * Modules compiled statically into the kernel are assigned NULL.
+ */
+ if (strcmp(name, "__this_linker_file") == 0) {
+ address = (file == linker_kernel_file) ? NULL : (caddr_t)file;
+ KLD_DPF(SYM, ("linker_file_lookup_symbol: resolving special "
+ "symbol __this_linker_file to %p\n", address));
+ return (address);
+ }
+
if (LINKER_LOOKUP_SYMBOL(file, name, &sym) == 0) {
LINKER_SYMBOL_VALUES(file, sym, &symval);
if (symval.value == 0)
diff --git a/sys/sys/linker.h b/sys/sys/linker.h
--- a/sys/sys/linker.h
+++ b/sys/sys/linker.h
@@ -130,6 +130,12 @@
*/
extern linker_file_t linker_kernel_file;
+/*
+ * Special symbol which will be replaced by a reference to the linker_file_t
+ * of the module it is used in.
+ */
+extern linker_file_t __this_linker_file;
+
/*
* Obtain a reference to a module, loading it if required.
*/

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