linux/arch/x86
Josh Poimboeuf 8023e0e2a4 x86/unwind: Adjust last frame check for aligned function stacks
Somehow, CONFIG_PARAVIRT=n convinces gcc to change the
x86_64_start_kernel() prologue from:

  0000000000000129 <x86_64_start_kernel>:
   129:	55                   	push   %rbp
   12a:	48 89 e5             	mov    %rsp,%rbp

to:

  0000000000000124 <x86_64_start_kernel>:
   124:	4c 8d 54 24 08       	lea    0x8(%rsp),%r10
   129:	48 83 e4 f0          	and    $0xfffffffffffffff0,%rsp
   12d:	41 ff 72 f8          	pushq  -0x8(%r10)
   131:	55                   	push   %rbp
   132:	48 89 e5             	mov    %rsp,%rbp

This is an unusual pattern which aligns rsp (though in this case it's
already aligned) and saves the start_cpu() return address again on the
stack before storing the frame pointer.

The unwinder assumes the last stack frame header is at a certain offset,
but the above code breaks that assumption, resulting in the following
warning:

  WARNING: kernel stack frame pointer at ffffffff82e03f40 in swapper:0 has bad value           (null)

Fix it by checking for the last task stack frame at the aligned offset
in addition to the normal unaligned offset.

Fixes: acb4608ad1 ("x86/unwind: Create stack frames for saved syscall registers")
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/9d7b4eb8cf55a7d6002cb738f25c23e7429c99a0.1481904011.git.jpoimboe@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-12-19 11:47:05 +01:00
..
boot Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2016-12-14 11:12:25 -08:00
configs IOMMU Updates for Linux v4.9 2016-10-11 12:52:41 -07:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2016-12-14 13:31:29 -08:00
entry This release has a few updates: 2016-12-15 13:49:34 -08:00
events Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-12 14:20:14 -08:00
ia32 x86/signal: Add SA_{X32,IA32}_ABI sa_flags 2016-09-14 21:28:11 +02:00
include x86/init: Fix a couple of comment typos 2016-12-19 11:34:16 +01:00
kernel x86/unwind: Adjust last frame check for aligned function stacks 2016-12-19 11:47:05 +01:00
kvm Small release, the most interesting stuff is x86 nested virt improvements. 2016-12-13 15:47:02 -08:00
lguest x86/fpu: Remove clts() 2016-11-01 07:47:55 +01:00
lib Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-12 13:49:57 -08:00
math-emu
mm x86/mpx: Move bd_addr to mm_context_t 2016-12-17 12:29:56 +01:00
net bpf: xdp: Allow head adjustment in XDP prog 2016-12-08 14:25:13 -05:00
oprofile x86/oprofile/nmi: Convert to hotplug state machine 2016-11-22 23:34:43 +01:00
pci xen: features and fixes for 4.10 rc0 2016-12-13 16:07:55 -08:00
platform x86/init: Remove i8042_detect() from platform ops 2016-12-19 11:34:15 +01:00
power Merge branch 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-18 13:59:10 -08:00
purgatory x86/kexec: add -fno-PIE 2016-11-09 22:28:09 +01:00
ras x86/RAS: Add TSC timestamp to the injected MCE 2016-11-08 17:10:13 +01:00
realmode x86/build: Don't use $(LINUXINCLUDE) twice 2016-11-28 07:49:17 +01:00
tools Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-12 13:49:57 -08:00
um locking/core: Provide common cpu_relax_yield() definition 2016-11-17 08:17:36 +01:00
video x86/video: Don't assume all FB devices are PCI devices 2016-03-15 11:08:26 +01:00
xen Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-18 11:12:53 -08:00
.gitignore
Kbuild perf/x86: Move perf_event.c ............... => x86/events/core.c 2016-02-09 10:23:49 +01:00
Kconfig platform-drivers-x86 for 4.10-2 2016-12-18 15:45:33 -08:00
Kconfig.cpu
Kconfig.debug Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-15 09:32:27 -07:00
Makefile lib/raid6: Add AVX512 optimized gen_syndrome functions 2016-09-21 09:09:44 -07:00
Makefile_32.cpu
Makefile.um