diff options
Diffstat (limited to 'kernel/extable.c')
| -rw-r--r-- | kernel/extable.c | 139 |
1 files changed, 85 insertions, 54 deletions
diff --git a/kernel/extable.c b/kernel/extable.c index 67460b93b1a1..71f482581cab 100644 --- a/kernel/extable.c +++ b/kernel/extable.c @@ -1,33 +1,27 @@ +// 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. - 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/elf.h> #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 <asm/uaccess.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); @@ -36,71 +30,53 @@ 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 main_extable_sort_needed = 1; +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) { + 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_extable(__start___ex_table, __stop___ex_table-1, addr); + e = search_kernel_exception_table(addr); if (!e) e = search_module_extables(addr); + if (!e) + e = search_bpf_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) +int notrace core_kernel_text(unsigned long addr) { - if (addr >= (unsigned long)_stext && - addr <= (unsigned long)_etext) + if (is_kernel_text(addr)) 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) + if (system_state < SYSTEM_FREEING_INITMEM && + is_kernel_inittext(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)) + if (kernel_text_address(addr)) return 1; /* * There might be init symbols in saved stacktraces. @@ -110,25 +86,80 @@ int __kernel_text_address(unsigned long addr) * Since we are after the module-symbols check, there's * no danger of address overlap: */ - if (init_kernel_text(addr)) + if (is_kernel_inittext(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; - return is_module_text_address(addr); + + /* + * 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, + * is_bpf_text_address() and is_bpf_image_address require + * RCU to be watching. + */ + no_rcu = !rcu_is_watching(); + + /* Treat this like an NMI as it can happen anywhere */ + if (no_rcu) + ct_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) + ct_nmi_exit(); + + return ret; } /* - * On some architectures (PPC64, IA64) function pointers + * On some architectures (PPC64, IA64, PARISC) 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. */ +#ifdef CONFIG_HAVE_FUNCTION_DESCRIPTORS +void *dereference_function_descriptor(void *ptr) +{ + func_desc_t *desc = ptr; + void *p; + + if (!get_kernel_nofault(p, (void *)&desc->addr)) + ptr = p; + return ptr; +} +EXPORT_SYMBOL_GPL(dereference_function_descriptor); + +void *dereference_kernel_function_descriptor(void *ptr) +{ + if (ptr < (void *)__start_opd || ptr >= (void *)__end_opd) + return ptr; + + return dereference_function_descriptor(ptr); +} +#endif + int func_ptr_is_kernel_text(void *ptr) { unsigned long addr; |