v4.19.13 snapshot.
diff --git a/kernel/extable.c b/kernel/extable.c
new file mode 100644
index 0000000..6a5b61e
--- /dev/null
+++ b/kernel/extable.c
@@ -0,0 +1,176 @@
+/* Rewritten by Rusty Russell, on the backs of many others...
+ Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+#include <linux/ftrace.h>
+#include <linux/memory.h>
+#include <linux/extable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/init.h>
+#include <linux/kprobes.h>
+#include <linux/filter.h>
+
+#include <asm/sections.h>
+#include <linux/uaccess.h>
+
+/*
+ * mutex protecting text section modification (dynamic code patching).
+ * some users need to sleep (allocating memory...) while they hold this lock.
+ *
+ * Note: Also protects SMP-alternatives modification on x86.
+ *
+ * NOT exported to modules - patching kernel text is a really delicate matter.
+ */
+DEFINE_MUTEX(text_mutex);
+
+extern struct exception_table_entry __start___ex_table[];
+extern struct exception_table_entry __stop___ex_table[];
+
+/* Cleared by build time tools if the table is already sorted. */
+u32 __initdata __visible main_extable_sort_needed = 1;
+
+/* Sort the kernel's built-in exception table */
+void __init sort_main_extable(void)
+{
+ if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) {
+ pr_notice("Sorting __ex_table...\n");
+ sort_extable(__start___ex_table, __stop___ex_table);
+ }
+}
+
+/* Given an address, look for it in the exception tables. */
+const struct exception_table_entry *search_exception_tables(unsigned long addr)
+{
+ const struct exception_table_entry *e;
+
+ e = search_extable(__start___ex_table,
+ __stop___ex_table - __start___ex_table, addr);
+ if (!e)
+ e = search_module_extables(addr);
+ return e;
+}
+
+int init_kernel_text(unsigned long addr)
+{
+ if (addr >= (unsigned long)_sinittext &&
+ addr < (unsigned long)_einittext)
+ return 1;
+ return 0;
+}
+
+int notrace core_kernel_text(unsigned long addr)
+{
+ if (addr >= (unsigned long)_stext &&
+ addr < (unsigned long)_etext)
+ return 1;
+
+ if (system_state < SYSTEM_RUNNING &&
+ init_kernel_text(addr))
+ return 1;
+ return 0;
+}
+
+/**
+ * core_kernel_data - tell if addr points to kernel data
+ * @addr: address to test
+ *
+ * Returns true if @addr passed in is from the core kernel data
+ * section.
+ *
+ * Note: On some archs it may return true for core RODATA, and false
+ * for others. But will always be true for core RW data.
+ */
+int core_kernel_data(unsigned long addr)
+{
+ if (addr >= (unsigned long)_sdata &&
+ addr < (unsigned long)_edata)
+ return 1;
+ return 0;
+}
+
+int __kernel_text_address(unsigned long addr)
+{
+ if (kernel_text_address(addr))
+ return 1;
+ /*
+ * There might be init symbols in saved stacktraces.
+ * Give those symbols a chance to be printed in
+ * backtraces (such as lockdep traces).
+ *
+ * Since we are after the module-symbols check, there's
+ * no danger of address overlap:
+ */
+ if (init_kernel_text(addr))
+ return 1;
+ return 0;
+}
+
+int kernel_text_address(unsigned long addr)
+{
+ bool no_rcu;
+ int ret = 1;
+
+ if (core_kernel_text(addr))
+ return 1;
+
+ /*
+ * If a stack dump happens while RCU is not watching, then
+ * RCU needs to be notified that it requires to start
+ * watching again. This can happen either by tracing that
+ * triggers a stack trace, or a WARN() that happens during
+ * coming back from idle, or cpu on or offlining.
+ *
+ * is_module_text_address() as well as the kprobe slots
+ * and is_bpf_text_address() require RCU to be watching.
+ */
+ no_rcu = !rcu_is_watching();
+
+ /* Treat this like an NMI as it can happen anywhere */
+ if (no_rcu)
+ rcu_nmi_enter();
+
+ if (is_module_text_address(addr))
+ goto out;
+ if (is_ftrace_trampoline(addr))
+ goto out;
+ if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))
+ goto out;
+ if (is_bpf_text_address(addr))
+ goto out;
+ ret = 0;
+out:
+ if (no_rcu)
+ rcu_nmi_exit();
+
+ return ret;
+}
+
+/*
+ * On some architectures (PPC64, IA64) function pointers
+ * are actually only tokens to some data that then holds the
+ * real function address. As a result, to find if a function
+ * pointer is part of the kernel text, we need to do some
+ * special dereferencing first.
+ */
+int func_ptr_is_kernel_text(void *ptr)
+{
+ unsigned long addr;
+ addr = (unsigned long) dereference_function_descriptor(ptr);
+ if (core_kernel_text(addr))
+ return 1;
+ return is_module_text_address(addr);
+}