1 files changed, 74 insertions, 0 deletions
diff --git a/arch/um/os-Linux/elf_aux.c b/arch/um/os-Linux/elf_aux.c
new file mode 100644
index 000000000..77a932137
--- /dev/null
+++ b/arch/um/os-Linux/elf_aux.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  arch/um/kernel/elf_aux.c
+ *
+ *  Scan the Elf auxiliary vector provided by the host to extract
+ *  information about vsyscall-page, etc.
+ *
+ *  Copyright (C) 2004 Fujitsu Siemens Computers GmbH
+ *  Author: Bodo Stroesser (bodo.stroesser@fujitsu-siemens.com)
+ */
+#include <elf.h>
+#include <stddef.h>
+#include <init.h>
+#include <elf_user.h>
+#include <mem_user.h>
+
+typedef Elf32_auxv_t elf_auxv_t;
+
+/* These are initialized very early in boot and never changed */
+char * elf_aux_platform;
+extern long elf_aux_hwcap;
+unsigned long vsyscall_ehdr;
+unsigned long vsyscall_end;
+unsigned long __kernel_vsyscall;
+
+__init void scan_elf_aux( char **envp)
+{
+	long page_size = 0;
+	elf_auxv_t * auxv;
+
+	while ( *envp++ != NULL) ;
+
+	for ( auxv = (elf_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) {
+		switch ( auxv->a_type ) {
+			case AT_SYSINFO:
+				__kernel_vsyscall = auxv->a_un.a_val;
+				/* See if the page is under TASK_SIZE */
+				if (__kernel_vsyscall < (unsigned long) envp)
+					__kernel_vsyscall = 0;
+				break;
+			case AT_SYSINFO_EHDR:
+				vsyscall_ehdr = auxv->a_un.a_val;
+				/* See if the page is under TASK_SIZE */
+				if (vsyscall_ehdr < (unsigned long) envp)
+					vsyscall_ehdr = 0;
+				break;
+			case AT_HWCAP:
+				elf_aux_hwcap = auxv->a_un.a_val;
+				break;
+			case AT_PLATFORM:
+                                /* elf.h removed the pointer elements from
+                                 * a_un, so we have to use a_val, which is
+                                 * all that's left.
+                                 */
+				elf_aux_platform =
+					(char *) (long) auxv->a_un.a_val;
+				break;
+			case AT_PAGESZ:
+				page_size = auxv->a_un.a_val;
+				break;
+		}
+	}
+	if ( ! __kernel_vsyscall || ! vsyscall_ehdr ||
+	     ! elf_aux_hwcap || ! elf_aux_platform ||
+	     ! page_size || (vsyscall_ehdr % page_size) ) {
+		__kernel_vsyscall = 0;
+		vsyscall_ehdr = 0;
+		elf_aux_hwcap = 0;
+		elf_aux_platform = "i586";
+	}
+	else {
+		vsyscall_end = vsyscall_ehdr + page_size;
+	}
+}