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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171// 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/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 <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 */conststruct 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 notrace core_kernel_text(unsigned long addr){ if (is_kernel_text(addr)) return 1;
if (system_state < SYSTEM_FREEING_INITMEM && is_kernel_inittext(addr)) 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 (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;
/* * 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, 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_DESCRIPTORSvoid *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; addr = (unsigned long) dereference_function_descriptor(ptr); if (core_kernel_text(addr)) return 1; return is_module_text_address(addr);}