174 строки
4.4 KiB
C
174 строки
4.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/* Rewritten by Rusty Russell, on the backs of many others...
|
|
Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.
|
|
|
|
*/
|
|
#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 kernel exception table */
|
|
const
|
|
struct exception_table_entry *search_kernel_exception_table(unsigned long addr)
|
|
{
|
|
return search_extable(__start___ex_table,
|
|
__stop___ex_table - __start___ex_table, addr);
|
|
}
|
|
|
|
/* 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_kernel_exception_table(addr);
|
|
if (!e)
|
|
e = search_module_extables(addr);
|
|
if (!e)
|
|
e = search_bpf_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);
|
|
}
|