aec0be2d6e
Stack traces that happen from function tracing check if the address on the stack is a __kernel_text_address(). That is, is the address kernel code. This calls core_kernel_text() which returns true if the address is part of the builtin kernel code. It also calls is_module_text_address() which returns true if the address belongs to module code. But what is missing is ftrace dynamically allocated trampolines. These trampolines are allocated for individual ftrace_ops that call the ftrace_ops callback functions directly. But if they do a stack trace, the code checking the stack wont detect them as they are neither core kernel code nor module address space. Adding another field to ftrace_ops that also stores the size of the trampoline assigned to it we can create a new function called is_ftrace_trampoline() that returns true if the address is a dynamically allocate ftrace trampoline. Note, it ignores trampolines that are not dynamically allocated as they will return true with the core_kernel_text() function. Link: http://lkml.kernel.org/r/20141119034829.497125839@goodmis.org Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
145 lines
4 KiB
C
145 lines
4 KiB
C
/* 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/module.h>
|
|
#include <linux/ftrace.h>
|
|
#include <linux/mutex.h>
|
|
#include <linux/init.h>
|
|
|
|
#include <asm/sections.h>
|
|
#include <asm/uaccess.h>
|
|
|
|
/*
|
|
* mutex protecting text section modification (dynamic code patching).
|
|
* some users need to sleep (allocating memory...) while they hold this lock.
|
|
*
|
|
* 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-1, addr);
|
|
if (!e)
|
|
e = search_module_extables(addr);
|
|
return e;
|
|
}
|
|
|
|
static inline int init_kernel_text(unsigned long addr)
|
|
{
|
|
if (addr >= (unsigned long)_sinittext &&
|
|
addr < (unsigned long)_einittext)
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
int core_kernel_text(unsigned long addr)
|
|
{
|
|
if (addr >= (unsigned long)_stext &&
|
|
addr < (unsigned long)_etext)
|
|
return 1;
|
|
|
|
if (system_state == SYSTEM_BOOTING &&
|
|
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 (core_kernel_text(addr))
|
|
return 1;
|
|
if (is_module_text_address(addr))
|
|
return 1;
|
|
if (is_ftrace_trampoline(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)
|
|
{
|
|
if (core_kernel_text(addr))
|
|
return 1;
|
|
if (is_module_text_address(addr))
|
|
return 1;
|
|
return is_ftrace_trampoline(addr);
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|