cregit-Linux how code gets into the kernel

Release 4.15 kernel/extable.c

Directory: kernel
/* 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); } }

Contributors

PersonTokensPropCommitsCommitProp
Paul Mackerras1550.00%125.00%
Borislav Petkov723.33%125.00%
Uwe Kleine-König413.33%125.00%
David Daney413.33%125.00%
Total30100.00%4100.00%

/* 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; }

Contributors

PersonTokensPropCommitsCommitProp
Rusty Russell3576.09%250.00%
Linus Torvalds1021.74%125.00%
Thomas Meyer12.17%125.00%
Total46100.00%4100.00%


static inline int init_kernel_text(unsigned long addr) { if (addr >= (unsigned long)_sinittext && addr < (unsigned long)_einittext) return 1; return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Rusty Russell2571.43%133.33%
Ingo Molnar925.71%133.33%
Helge Deller12.86%133.33%
Total35100.00%3100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar2245.83%114.29%
Andrew Morton1837.50%114.29%
Rusty Russell48.33%228.57%
Thomas Gleixner24.17%114.29%
Marcin Nowakowski12.08%114.29%
Helge Deller12.08%114.29%
Total48100.00%7100.00%

/** * 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; }

Contributors

PersonTokensPropCommitsCommitProp
Steven Rostedt33100.00%2100.00%
Total33100.00%2100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Ingo Molnar1339.39%125.00%
Rusty Russell1236.36%125.00%
Daniel Borkmann721.21%125.00%
Steven Rostedt13.03%125.00%
Total33100.00%4100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Steven Rostedt5654.37%225.00%
Rusty Russell2423.30%337.50%
Masami Hiramatsu1615.53%112.50%
Daniel Borkmann54.85%112.50%
Linus Torvalds21.94%112.50%
Total103100.00%8100.00%

/* * 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); }

Contributors

PersonTokensPropCommitsCommitProp
Arjan van de Ven3997.50%150.00%
Rusty Russell12.50%150.00%
Total40100.00%2100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
Rusty Russell10724.94%720.59%
Steven Rostedt9121.21%514.71%
Ingo Molnar5512.82%25.88%
Arjan van de Ven409.32%12.94%
Linus Torvalds286.53%38.82%
Masami Hiramatsu194.43%12.94%
Paul Mackerras184.20%12.94%
Andrew Morton184.20%12.94%
Daniel Borkmann153.50%12.94%
David Daney112.56%12.94%
Borislav Petkov71.63%12.94%
Uwe Kleine-König40.93%12.94%
Frédéric Weisbecker40.93%12.94%
Paul Gortmaker30.70%12.94%
Helge Deller20.47%12.94%
Thomas Gleixner20.47%12.94%
Andi Kleen10.23%12.94%
Thomas Meyer10.23%12.94%
Marcin Nowakowski10.23%12.94%
Zhou Chengming10.23%12.94%
Dmitri Vorobiev10.23%12.94%
Total429100.00%34100.00%
Directory: kernel
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