patches/kernel/0036-x86-kconfig-Consolidate-unwinders-into-multiple-choi.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Josh Poimboeuf <jpoimboe@redhat.com>
   3 Date: Tue, 25 Jul 2017 08:54:24 -0500
   4 Subject: [PATCH] x86/kconfig: Consolidate unwinders into multiple choice
   5  selection
   6 MIME-Version: 1.0
   7 Content-Type: text/plain; charset=UTF-8
   8 Content-Transfer-Encoding: 8bit
   9
  10 CVE-2017-5754
  11
  12 There are three mutually exclusive unwinders.  Make that more obvious by
  13 combining them into a multiple-choice selection:
  14
  15   CONFIG_FRAME_POINTER_UNWINDER
  16   CONFIG_ORC_UNWINDER
  17   CONFIG_GUESS_UNWINDER (if CONFIG_EXPERT=y)
  18
  19 Frame pointers are still the default (for now).
  20
  21 The old CONFIG_FRAME_POINTER option is still used in some
  22 arch-independent places, so keep it around, but make it
  23 invisible to the user on x86 - it's now selected by
  24 CONFIG_FRAME_POINTER_UNWINDER=y.
  25
  26 Suggested-by: Ingo Molnar <mingo@kernel.org>
  27 Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
  28 Cc: Andy Lutomirski <luto@kernel.org>
  29 Cc: Borislav Petkov <bp@alien8.de>
  30 Cc: Brian Gerst <brgerst@gmail.com>
  31 Cc: Denys Vlasenko <dvlasenk@redhat.com>
  32 Cc: H. Peter Anvin <hpa@zytor.com>
  33 Cc: Jiri Slaby <jslaby@suse.cz>
  34 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  35 Cc: Mike Galbraith <efault@gmx.de>
  36 Cc: Peter Zijlstra <peterz@infradead.org>
  37 Cc: Thomas Gleixner <tglx@linutronix.de>
  38 Cc: live-patching@vger.kernel.org
  39 Link: http://lkml.kernel.org/r/20170725135424.zukjmgpz3plf5pmt@treble
  40 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  41 (cherry picked from commit 81d387190039c14edac8de2b3ec789beb899afd9)
  42 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  43 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  44 (cherry picked from commit 26ddacc1e6333555e4a6bd63c4c935b323509f92)
  45 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  46 ---
  47  arch/x86/include/asm/unwind.h |  4 ++--
  48  arch/x86/Kconfig              |  3 +--
  49  arch/x86/Kconfig.debug        | 45 +++++++++++++++++++++++++++++++++++++------
  50  arch/x86/configs/tiny.config  |  2 ++
  51  4 files changed, 44 insertions(+), 10 deletions(-)
  52
  53 diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h
  54 index 25b8d31a007d..e9f793e2df7a 100644
  55 --- a/arch/x86/include/asm/unwind.h
  56 +++ b/arch/x86/include/asm/unwind.h
  57 @@ -16,7 +16,7 @@ struct unwind_state {
  58         bool signal, full_regs;
  59         unsigned long sp, bp, ip;
  60         struct pt_regs *regs;
  61 -#elif defined(CONFIG_FRAME_POINTER)
  62 +#elif defined(CONFIG_FRAME_POINTER_UNWINDER)
  63         bool got_irq;
  64         unsigned long *bp, *orig_sp, ip;
  65         struct pt_regs *regs;
  66 @@ -50,7 +50,7 @@ void unwind_start(struct unwind_state *state, struct task_struct *task,
  67         __unwind_start(state, task, regs, first_frame);
  68  }
  69
  70 -#if defined(CONFIG_ORC_UNWINDER) || defined(CONFIG_FRAME_POINTER)
  71 +#if defined(CONFIG_ORC_UNWINDER) || defined(CONFIG_FRAME_POINTER_UNWINDER)
  72  static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)
  73  {
  74         if (unwind_done(state))
  75 diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
  76 index d6f45f6d1054..3a0b8cb57caf 100644
  77 --- a/arch/x86/Kconfig
  78 +++ b/arch/x86/Kconfig
  79 @@ -73,7 +73,6 @@ config X86
  80         select ARCH_USE_QUEUED_RWLOCKS
  81         select ARCH_USE_QUEUED_SPINLOCKS
  82         select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
  83 -       select ARCH_WANT_FRAME_POINTERS
  84         select ARCH_WANTS_DYNAMIC_TASK_STRUCT
  85         select ARCH_WANTS_THP_SWAP              if X86_64
  86         select BUILDTIME_EXTABLE_SORT
  87 @@ -169,7 +168,7 @@ config X86
  88         select HAVE_PERF_REGS
  89         select HAVE_PERF_USER_STACK_DUMP
  90         select HAVE_REGS_AND_STACK_ACCESS_API
  91 -       select HAVE_RELIABLE_STACKTRACE         if X86_64 && FRAME_POINTER && STACK_VALIDATION
  92 +       select HAVE_RELIABLE_STACKTRACE         if X86_64 && FRAME_POINTER_UNWINDER && STACK_VALIDATION
  93         select HAVE_STACK_VALIDATION            if X86_64
  94         select HAVE_SYSCALL_TRACEPOINTS
  95         select HAVE_UNSTABLE_SCHED_CLOCK
  96 diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
  97 index d5bca2ec8a74..c441b5d65ec8 100644
  98 --- a/arch/x86/Kconfig.debug
  99 +++ b/arch/x86/Kconfig.debug
 100 @@ -356,6 +356,29 @@ config PUNIT_ATOM_DEBUG
 101           The current power state can be read from
 102           /sys/kernel/debug/punit_atom/dev_power_state
 103
 104 +choice
 105 +       prompt "Choose kernel unwinder"
 106 +       default FRAME_POINTER_UNWINDER
 107 +       ---help---
 108 +         This determines which method will be used for unwinding kernel stack
 109 +         traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack,
 110 +         livepatch, lockdep, and more.
 111 +
 112 +config FRAME_POINTER_UNWINDER
 113 +       bool "Frame pointer unwinder"
 114 +       select FRAME_POINTER
 115 +       ---help---
 116 +         This option enables the frame pointer unwinder for unwinding kernel
 117 +         stack traces.
 118 +
 119 +         The unwinder itself is fast and it uses less RAM than the ORC
 120 +         unwinder, but the kernel text size will grow by ~3% and the kernel's
 121 +         overall performance will degrade by roughly 5-10%.
 122 +
 123 +         This option is recommended if you want to use the livepatch
 124 +         consistency model, as this is currently the only way to get a
 125 +         reliable stack trace (CONFIG_HAVE_RELIABLE_STACKTRACE).
 126 +
 127  config ORC_UNWINDER
 128         bool "ORC unwinder"
 129         depends on X86_64
 130 @@ -373,12 +396,22 @@ config ORC_UNWINDER
 131           Enabling this option will increase the kernel's runtime memory usage
 132           by roughly 2-4MB, depending on your kernel config.
 133
 134 -config FRAME_POINTER_UNWINDER
 135 -       def_bool y
 136 -       depends on !ORC_UNWINDER && FRAME_POINTER
 137 -
 138  config GUESS_UNWINDER
 139 -       def_bool y
 140 -       depends on !ORC_UNWINDER && !FRAME_POINTER
 141 +       bool "Guess unwinder"
 142 +       depends on EXPERT
 143 +       ---help---
 144 +         This option enables the "guess" unwinder for unwinding kernel stack
 145 +         traces.  It scans the stack and reports every kernel text address it
 146 +         finds.  Some of the addresses it reports may be incorrect.
 147 +
 148 +         While this option often produces false positives, it can still be
 149 +         useful in many cases.  Unlike the other unwinders, it has no runtime
 150 +         overhead.
 151 +
 152 +endchoice
 153 +
 154 +config FRAME_POINTER
 155 +       depends on !ORC_UNWINDER && !GUESS_UNWINDER
 156 +       bool
 157
 158  endmenu
 159 diff --git a/arch/x86/configs/tiny.config b/arch/x86/configs/tiny.config
 160 index 4b429df40d7a..550cd5012b73 100644
 161 --- a/arch/x86/configs/tiny.config
 162 +++ b/arch/x86/configs/tiny.config
 163 @@ -1,3 +1,5 @@
 164  CONFIG_NOHIGHMEM=y
 165  # CONFIG_HIGHMEM4G is not set
 166  # CONFIG_HIGHMEM64G is not set
 167 +CONFIG_GUESS_UNWINDER=y
 168 +# CONFIG_FRAME_POINTER_UNWINDER is not set
 169 --
 170 2.14.2
 171