We are going to split <linux/sched/debug.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/debug.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
For mostly historical reasons, the x86 oops dump shows the raw stack
values:
...
[registers]
Stack:
ffff880079af7350 ffff880079905400 0000000000000000 ffffc900008f3ae0
ffffffffa0196610 0000000000000001 00010000ffffffff 0000000087654321
0000000000000002 0000000000000000 0000000000000000 0000000000000000
Call Trace:
...
This seems to be an artifact from long ago, and probably isn't needed
anymore. It generally just adds noise to the dump, and it can be
actively harmful because it leaks kernel addresses.
Linus says:
"The stack dump actually goes back to forever, and it used to be
useful back in 1992 or so. But it used to be useful mainly because
stacks were simpler and we didn't have very good call traces anyway. I
definitely remember having used them - I just do not remember having
used them in the last ten+ years.
Of course, it's still true that if you can trigger an oops, you've
likely already lost the security game, but since the stack dump is so
useless, let's aim to just remove it and make games like the above
harder."
This also removes the related 'kstack=' cmdline option and the
'kstack_depth_to_print' sysctl.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/e83bd50df52d8fe88e94d2566426ae40d813bf8f.1477405374.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Convert show_trace_log_lvl() to use the new unwinder. dump_trace() has
been deprecated.
show_trace_log_lvl() is special compared to other users of the unwinder.
It's the only place where both reliable *and* unreliable addresses are
needed. With frame pointers enabled, most callers of the unwinder don't
want to know about unreliable addresses. But in this case, when we're
dumping the stack to the console because something presumably went
wrong, the unreliable addresses are useful:
- They show stale data on the stack which can provide useful clues.
- If something goes wrong with the unwinder, or if frame pointers are
corrupt or missing, all the stack addresses still get shown.
So in order to show all addresses on the stack, and at the same time
figure out which addresses are reliable, we have to do the scanning and
the unwinding in parallel.
The scanning is done with the help of get_stack_info() to traverse the
stacks. The unwinding is done separately by the new unwinder.
In theory we could simplify show_trace_log_lvl() by instead pushing some
of this logic into the unwind code. But then we would need some kind of
"fake" frame logic in the unwinder which would add a lot of complexity
and wouldn't be worth it in order to support only one user.
Another benefit of this approach is that once we have a DWARF unwinder,
we should be able to just plug it in with minimal impact to this code.
Another change here is that callers of show_trace_log_lvl() don't need
to provide the 'bp' argument. The unwinder already finds the relevant
frame pointer by unwinding until it reaches the first frame after the
provided stack pointer.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/703b5998604c712a1f801874b43f35d6dac52ede.1474045023.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
show_stack_log_lvl() and friends allow a NULL pointer for the
task_struct to indicate the current task. This creates confusion and
can cause sneaky bugs.
Instead require the caller to pass 'current' directly.
This only changes the internal workings of the dumpstack code. The
dump_trace() and show_stack() interfaces still allow a NULL task
pointer. Those interfaces should also probably be fixed as well.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86 header cleanups from Ingo Molnar:
"This tree is a cleanup of the x86 tree reducing spurious uses of
module.h - which should improve build performance a bit"
* 'x86-headers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, crypto: Restore MODULE_LICENSE() to glue_helper.c so it loads
x86/apic: Remove duplicated include from probe_64.c
x86/ce4100: Remove duplicated include from ce4100.c
x86/headers: Include spinlock_types.h in x8664_ksyms_64.c for missing spinlock_t
x86/platform: Delete extraneous MODULE_* tags fromm ts5500
x86: Audit and remove any remaining unnecessary uses of module.h
x86/kvm: Audit and remove any unnecessary uses of module.h
x86/xen: Audit and remove any unnecessary uses of module.h
x86/platform: Audit and remove any unnecessary uses of module.h
x86/lib: Audit and remove any unnecessary uses of module.h
x86/kernel: Audit and remove any unnecessary uses of module.h
x86/mm: Audit and remove any unnecessary uses of module.h
x86: Don't use module.h just for AUTHOR / LICENSE tags
Historically a lot of these existed because we did not have
a distinction between what was modular code and what was providing
support to modules via EXPORT_SYMBOL and friends. That changed
when we forked out support for the latter into the export.h file.
This means we should be able to reduce the usage of module.h
in code that is obj-y Makefile or bool Kconfig. The advantage
in doing so is that module.h itself sources about 15 other headers;
adding significantly to what we feed cpp, and it can obscure what
headers we are effectively using.
Since module.h was the source for init.h (for __init) and for
export.h (for EXPORT_SYMBOL) we consider each obj-y/bool instance
for the presence of either and replace as needed. Build testing
revealed some implicit header usage that was fixed up accordingly.
Note that some bool/obj-y instances remain since module.h is
the header for some exception table entry stuff, and for things
like __init_or_module (code that is tossed when MODULES=n).
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160714001901.31603-4-paul.gortmaker@windriver.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
None of the code actually wants a thread_info, it all wants a
task_struct, and it's just converting to a thread_info pointer much too
early.
No semantic change.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull x86 debug changes from Ingo Molnar:
"Stack printing fixlets"
* 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/kernel: Use kstack_end() in dumpstack_64.c
x86/kernel: Fix output of show_stack_log_lvl()
show_stack_log_lvl() does not set the log level after a new line, the
following messages printed with pr_cont() are thus assigned to the
default log level.
This patch prepends the log level to the next message following a new
line.
print_trace_address() uses printk(log_lvl). Using printk() with just
a log level is ignored and thus has no effect on the next pr_cont().
We need to prepend the log level directly into the message.
Signed-off-by: Adrien Schildknecht <adrien+dev@schischi.me>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1424399661-20327-1-git-send-email-adrien+dev@schischi.me
Signed-off-by: Borislav Petkov <bp@suse.de>
Pull x86 threadinfo changes from Ingo Molnar:
"The main change here is the consolidation/unification of 32 and 64 bit
thread_info handling methods, from Steve Rostedt"
* 'x86-threadinfo-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, threadinfo: Redo "x86: Use inline assembler to get sp"
x86: Clean up dumpstack_64.c code
x86: Keep thread_info on thread stack in x86_32
x86: Prepare removal of previous_esp from i386 thread_info structure
x86: Nuke GET_THREAD_INFO_WITH_ESP() macro for i386
x86: Nuke the supervisor_stack field in i386 thread_info
Commit 028a690a1e "i386: Remove unneeded test of 'task' in
dump_trace()" correctly removed the unneeded 'task != NULL'
check because it would be set to current if it was NULL.
Commit 2bc5f927d4 "i386: split out dumpstack code from
traps_32.c" moved the code from traps_32.c to its own file
dump_stack.c for preparation of the i386 / x86_64 merge.
Commit 8a541665b9 "dumpstack: x86: various small unification
steps" worked to make i386 and x86_64 dump_stack logic similar.
But this actually reverted the correct change from
028a690a1e.
Commit d0caf29250 "x86/dumpstack: Remove unneeded check in
dump_trace()" removed the unneeded "task != NULL" check for
x86_64 but left that same unneeded check for i386, that was
added because x86_64 had it!
This chain of events ironically had i386 add back the unneeded
task != NULL check because x86_64 did it, and then the fix for
x86_64 was fixed by Dan. And even more ironically, it was Dan's
smatch bot that told me that a change to dump_stack_32 I made
may be wrong if current can be NULL (it can't), as there was a
check for it by assigning task to current, and then checking if
task is NULL.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Alexander van Heukelum <heukelum@fastmail.fm>
Cc: Jesper Juhl <jesper.juhl@gmail.com>
Link: http://lkml.kernel.org/r/20140307105242.79a0befd@gandalf.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>
x86_64 uses a per_cpu variable kernel_stack to always point to
the thread stack of current. This is where the thread_info is stored
and is accessed from this location even when the irq or exception stack
is in use. This removes the complexity of having to maintain the
thread info on the stack when interrupts are running and having to
copy the preempt_count and other fields to the interrupt stack.
x86_32 uses the old method of copying the thread_info from the thread
stack to the exception stack just before executing the exception.
Having the two different requires #ifdefs and also the x86_32 way
is a bit of a pain to maintain. By converting x86_32 to the same
method of x86_64, we can remove #ifdefs, clean up the x86_32 code
a little, and remove the overhead of the copy.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20110806012354.263834829@goodmis.org
Link: http://lkml.kernel.org/r/20140206144321.852942014@goodmis.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
The i386 thread_info contains a previous_esp field that is used
to daisy chain the different stacks for dump_stack()
(ie. irq, softirq, thread stacks).
The goal is to eventual make i386 handling of thread_info the same
as x86_64, which means that the thread_info will not be in the stack
but as a per_cpu variable. We will no longer depend on thread_info
being able to daisy chain different stacks as it will only exist
in one location (the thread stack).
By moving previous_esp to the end of thread_info and referencing
it as an offset instead of using a thread_info field, this becomes
a stepping stone to moving the thread_info.
The offset to get to the previous stack is rather ugly in this
patch, but this is only temporary and the prev_esp will be changed
in the next commit. This commit is more for sanity checks of the
change.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Robert Richter <rric@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20110806012353.891757693@goodmis.org
Link: http://lkml.kernel.org/r/20140206144321.608754481@goodmis.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Ingo Molnar
Josh Poimboeuf
Andy Lutomirski
Linus Torvalds
Paul Gortmaker
Adrien Schildknecht
Steven Rostedt
Steven Rostedt