Pull x86 asm updates from Ingo Molnar:
"Most of the changes relate to Peter Zijlstra's cleanup of ptregs
handling, in particular the i386 part is now much simplified and
standardized - no more partial ptregs stack frames via the esp/ss
oddity. This simplifies ftrace, kprobes, the unwinder, ptrace, kdump
and kgdb.
There's also a CR4 hardening enhancements by Kees Cook, to make the
generic platform functions such as native_write_cr4() less useful as
ROP gadgets that disable SMEP/SMAP. Also protect the WP bit of CR0
against similar attacks.
The rest is smaller cleanups/fixes"
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/alternatives: Add int3_emulate_call() selftest
x86/stackframe/32: Allow int3_emulate_push()
x86/stackframe/32: Provide consistent pt_regs
x86/stackframe, x86/ftrace: Add pt_regs frame annotations
x86/stackframe, x86/kprobes: Fix frame pointer annotations
x86/stackframe: Move ENCODE_FRAME_POINTER to asm/frame.h
x86/entry/32: Clean up return from interrupt preemption path
x86/asm: Pin sensitive CR0 bits
x86/asm: Pin sensitive CR4 bits
Documentation/x86: Fix path to entry_32.S
x86/asm: Remove unused TASK_TI_flags from asm-offsets.c
Currently pt_regs on x86_32 has an oddity in that kernel regs
(!user_mode(regs)) are short two entries (esp/ss). This means that any
code trying to use them (typically: regs->sp) needs to jump through
some unfortunate hoops.
Change the entry code to fix this up and create a full pt_regs frame.
This then simplifies various trampolines in ftrace and kprobes, the
stack unwinder, ptrace, kdump and kgdb.
Much thanks to Josh for help with the cleanups!
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
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>
Add SPDX license identifiers to all files which:
- Have no license information of any form
- Have EXPORT_.*_SYMBOL_GPL inside which was used in the
initial scan/conversion to ignore the file
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When the ORC unwinder is invoked for an oops caused by IP==0,
it currently has no idea what to do because there is no debug information
for the stack frame of NULL.
But if RIP is NULL, it is very likely that the last successfully executed
instruction was an indirect CALL/JMP, and it is possible to unwind out in
the same way as for the first instruction of a normal function. Hardcode
a corresponding ORC entry.
With an artificially-added NULL call in prctl_set_seccomp(), before this
patch, the trace is:
Call Trace:
? __x64_sys_prctl+0x402/0x680
? __ia32_sys_prctl+0x6e0/0x6e0
? __do_page_fault+0x457/0x620
? do_syscall_64+0x6d/0x160
? entry_SYSCALL_64_after_hwframe+0x44/0xa9
After this patch, the trace looks like this:
Call Trace:
__x64_sys_prctl+0x402/0x680
? __ia32_sys_prctl+0x6e0/0x6e0
? __do_page_fault+0x457/0x620
do_syscall_64+0x6d/0x160
entry_SYSCALL_64_after_hwframe+0x44/0xa9
prctl_set_seccomp() still doesn't show up in the trace because for some
reason, tail call optimization is only disabled in builds that use the
frame pointer unwinder.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: syzbot <syzbot+ca95b2b7aef9e7cbd6ab@syzkaller.appspotmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: linux-kbuild@vger.kernel.org
Link: https://lkml.kernel.org/r/20190301031201.7416-2-jannh@google.com
The function tracer can create a dynamically allocated trampoline that is
called by the function mcount or fentry hook that is used to call the
function callback that is registered. The problem is that the orc undwinder
will bail if it encounters one of these trampolines. This breaks the stack
trace of function callbacks, which include the stack tracer and setting the
stack trace for individual functions.
Since these dynamic trampolines are basically copies of the static ftrace
trampolines defined in ftrace_*.S, we do not need to create new orc entries
for the dynamic trampolines. Finding the return address on the stack will be
identical as the functions that were copied to create the dynamic
trampolines. When encountering a ftrace dynamic trampoline, we can just use
the orc entry of the ftrace static function that was copied for that
trampoline.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Fengguang reported a KASAN warning:
Kprobe smoke test: started
==================================================================
BUG: KASAN: stack-out-of-bounds in deref_stack_reg+0xb5/0x11a
Read of size 8 at addr ffff8800001c7cd8 by task swapper/1
CPU: 0 PID: 1 Comm: swapper Not tainted 4.14.0-rc8 #26
Call Trace:
<#DB>
...
save_trace+0xd9/0x1d3
mark_lock+0x5f7/0xdc3
__lock_acquire+0x6b4/0x38ef
lock_acquire+0x1a1/0x2aa
_raw_spin_lock_irqsave+0x46/0x55
kretprobe_table_lock+0x1a/0x42
pre_handler_kretprobe+0x3f5/0x521
kprobe_int3_handler+0x19c/0x25f
do_int3+0x61/0x142
int3+0x30/0x60
[...]
The ORC unwinder got confused by some kprobes changes, which isn't
surprising since the runtime code no longer matches vmlinux and the
stack was modified for kretprobes.
Until we have a way for generated code to register changes with the
unwinder, these types of warnings are inevitable. So just disable KASAN
checks for stack accesses in the ORC unwinder.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171108021934.zbl6unh5hpugybc5@treble
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add the new ORC unwinder which is enabled by CONFIG_ORC_UNWINDER=y.
It plugs into the existing x86 unwinder framework.
It relies on objtool to generate the needed .orc_unwind and
.orc_unwind_ip sections.
For more details on why ORC is used instead of DWARF, see
Documentation/x86/orc-unwinder.txt - but the short version is
that it's a simplified, fundamentally more robust debugninfo
data structure, which also allows up to two orders of magnitude
faster lookups than the DWARF unwinder - which matters to
profiling workloads like perf.
Thanks to Andy Lutomirski for the performance improvement ideas:
splitting the ORC unwind table into two parallel arrays and creating a
fast lookup table to search a subset of the unwind table.
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: Jiri Slaby <jslaby@suse.cz>
Cc: 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: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/0a6cbfb40f8da99b7a45a1a8302dc6aef16ec812.1500938583.git.jpoimboe@redhat.com
[ Extended the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
