Set x86 TLS limit to 0xfffff, not PAGE_SIZE.
Not least because we set limit_in_pages to 1. PAGE_SIZE pages was never
anyone's intention.
Change-Id: Ide867f44a2fb20d4d5d0cd67ced468e8665a0193
diff --git a/libc/arch-x86/bionic/__set_tls.cpp b/libc/arch-x86/bionic/__set_tls.cpp
new file mode 100644
index 0000000..b26fd56
--- /dev/null
+++ b/libc/arch-x86/bionic/__set_tls.cpp
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in
+ * the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <limits.h>
+#include <pthread.h>
+#include <stdbool.h>
+
+#include <asm/ldt.h>
+
+extern "C" int __set_thread_area(struct user_desc*);
+
+__LIBC_HIDDEN__ void __init_user_desc(struct user_desc* result, bool allocate, void* base_addr) {
+ if (allocate) {
+ // Let the kernel choose.
+ result->entry_number = -1;
+ } else {
+ // Get the existing entry number from %gs.
+ uint32_t gs;
+ __asm__ __volatile__("movw %%gs, %w0" : "=q"(gs) /*output*/);
+ result->entry_number = (gs & 0xffff) >> 3;
+ }
+
+ result->base_addr = reinterpret_cast<uintptr_t>(base_addr);
+
+ result->limit = 0xfffff;
+
+ result->seg_32bit = 1;
+ result->contents = MODIFY_LDT_CONTENTS_DATA;
+ result->read_exec_only = 0;
+ result->limit_in_pages = 1;
+ result->seg_not_present = 0;
+ result->useable = 1;
+}
+
+extern "C" __LIBC_HIDDEN__ int __set_tls(void* ptr) {
+ struct user_desc tls_descriptor;
+ __init_user_desc(&tls_descriptor, true, ptr);
+
+ int rc = __set_thread_area(&tls_descriptor);
+ if (rc != -1) {
+ // Change %gs to be new GDT entry.
+ uint16_t table_indicator = 0; // GDT
+ uint16_t rpl = 3; // Requested privilege level
+ uint16_t selector = (tls_descriptor.entry_number << 3) | table_indicator | rpl;
+ __asm__ __volatile__("movw %w0, %%gs" : /*output*/ : "q"(selector) /*input*/ : /*clobber*/);
+ }
+
+ return rc;
+}