a2d063ac21
A new utility function (core_kernel_data()) is used to determine if a passed in address is part of core kernel data or not. It may or may not return true for RO data, but this utility must work for RW data. Thus both _sdata and _edata must be defined and continuous, without .init sections that may later be freed and replaced by volatile memory (memory that can be freed). This utility function is used to determine if data is safe from ever being freed. Thus it should return true for all RW global data that is not in a module or has been allocated, or false otherwise. Also change core_kernel_data() back to the more precise _sdata condition and document the function. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Ralf Baechle <ralf@linux-mips.org> Acked-by: Hirokazu Takata <takata@linux-m32r.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: linux-m68k@lists.linux-m68k.org Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Helge Deller <deller@gmx.de> Cc: JamesE.J.Bottomley <jejb@parisc-linux.org> Link: http://lkml.kernel.org/r/1305855298.1465.19.camel@gandalf.stny.rr.com Signed-off-by: Ingo Molnar <mingo@elte.hu> ---- arch/alpha/kernel/vmlinux.lds.S | 1 + arch/m32r/kernel/vmlinux.lds.S | 1 + arch/m68k/kernel/vmlinux-std.lds | 2 ++ arch/m68k/kernel/vmlinux-sun3.lds | 1 + arch/mips/kernel/vmlinux.lds.S | 1 + arch/parisc/kernel/vmlinux.lds.S | 3 +++ kernel/extable.c | 12 +++++++++++- 7 files changed, 20 insertions(+), 1 deletion(-)
133 lines
3.7 KiB
C
133 lines
3.7 KiB
C
/* Rewritten by Rusty Russell, on the backs of many others...
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Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/ftrace.h>
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#include <linux/memory.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/init.h>
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#include <asm/sections.h>
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#include <asm/uaccess.h>
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/*
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* mutex protecting text section modification (dynamic code patching).
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* some users need to sleep (allocating memory...) while they hold this lock.
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*
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* NOT exported to modules - patching kernel text is a really delicate matter.
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*/
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DEFINE_MUTEX(text_mutex);
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extern struct exception_table_entry __start___ex_table[];
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extern struct exception_table_entry __stop___ex_table[];
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/* Sort the kernel's built-in exception table */
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void __init sort_main_extable(void)
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{
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sort_extable(__start___ex_table, __stop___ex_table);
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}
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/* Given an address, look for it in the exception tables. */
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const struct exception_table_entry *search_exception_tables(unsigned long addr)
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{
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const struct exception_table_entry *e;
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e = search_extable(__start___ex_table, __stop___ex_table-1, addr);
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if (!e)
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e = search_module_extables(addr);
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return e;
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}
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static inline int init_kernel_text(unsigned long addr)
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{
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if (addr >= (unsigned long)_sinittext &&
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addr <= (unsigned long)_einittext)
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return 1;
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return 0;
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}
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int core_kernel_text(unsigned long addr)
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{
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if (addr >= (unsigned long)_stext &&
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addr <= (unsigned long)_etext)
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return 1;
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if (system_state == SYSTEM_BOOTING &&
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init_kernel_text(addr))
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return 1;
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return 0;
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}
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/**
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* core_kernel_data - tell if addr points to kernel data
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* @addr: address to test
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*
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* Returns true if @addr passed in is from the core kernel data
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* section.
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*
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* Note: On some archs it may return true for core RODATA, and false
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* for others. But will always be true for core RW data.
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*/
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int core_kernel_data(unsigned long addr)
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{
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if (addr >= (unsigned long)_sdata &&
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addr < (unsigned long)_edata)
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return 1;
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return 0;
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}
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int __kernel_text_address(unsigned long addr)
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{
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if (core_kernel_text(addr))
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return 1;
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if (is_module_text_address(addr))
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return 1;
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/*
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* There might be init symbols in saved stacktraces.
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* Give those symbols a chance to be printed in
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* backtraces (such as lockdep traces).
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*
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* Since we are after the module-symbols check, there's
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* no danger of address overlap:
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*/
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if (init_kernel_text(addr))
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return 1;
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return 0;
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}
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int kernel_text_address(unsigned long addr)
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{
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if (core_kernel_text(addr))
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return 1;
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return is_module_text_address(addr);
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}
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/*
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* On some architectures (PPC64, IA64) function pointers
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* are actually only tokens to some data that then holds the
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* real function address. As a result, to find if a function
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* pointer is part of the kernel text, we need to do some
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* special dereferencing first.
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*/
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int func_ptr_is_kernel_text(void *ptr)
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{
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unsigned long addr;
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addr = (unsigned long) dereference_function_descriptor(ptr);
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if (core_kernel_text(addr))
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return 1;
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return is_module_text_address(addr);
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}
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