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-rw-r--r--arch/um/os-Linux/elf_aux.c74
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;
+ }
+}