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4a44bac1f9
Impact: fix incomplete stacktraces
I noticed such weird stacktrace entries in lockdep dumps:
[ 0.285956] {HARDIRQ-ON-W} state was registered at:
[ 0.285956] [<ffffffff802bce90>] mark_irqflags+0xbe/0x125
[ 0.285956] [<ffffffff802bf2fd>] __lock_acquire+0x674/0x82d
[ 0.285956] [<ffffffff802bf5b2>] lock_acquire+0xfc/0x128
[ 0.285956] [<ffffffff8135b636>] rt_spin_lock+0xc8/0xd0
[ 0.285956] [<ffffffffffffffff>] 0xffffffffffffffff
The stacktrace entry is cut off after rt_spin_lock.
After much debugging i found out that stacktrace entries that
belong to init symbols dont get printed out, due to commit:
a2da405: module: Don't report discarded init pages as kernel text.
The reason is this check added to core_kernel_text():
- if (addr >= (unsigned long)_sinittext &&
+ if (system_state == SYSTEM_BOOTING &&
+ addr >= (unsigned long)_sinittext &&
addr <= (unsigned long)_einittext)
return 1;
This will discard inittext symbols even though their symbol table
is still present and even though stacktraces done while the system
was booting up might still be relevant.
To not reintroduce the (not well-specified) bug addressed in that
commit, first do a module symbols lookup, then a final init-symbols
lookup.
This will work fine on architectures that have separate address
spaces for modules (such as x86) - and should not crash any other
architectures either.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
LKML-Reference: <new-discussion>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
105 lines
3.0 KiB
C
105 lines
3.0 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/module.h>
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#include <linux/init.h>
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#include <linux/ftrace.h>
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#include <asm/uaccess.h>
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#include <asm/sections.h>
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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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__notrace_funcgraph 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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__notrace_funcgraph 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 (__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 module_text_address(addr) != NULL;
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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 module_text_address(addr) != NULL;
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}
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