patches/kernel/0067-x86-fpu-Parse-clearcpuid-as-early-XSAVE-argument.patch

   1 From df469cffe07c84906be43e89d33f2a8a5312e60f Mon Sep 17 00:00:00 2001
   2 From: Andi Kleen <ak@linux.intel.com>
   3 Date: Fri, 13 Oct 2017 14:56:43 -0700
   4 Subject: [PATCH 067/233] x86/fpu: Parse clearcpuid= as early XSAVE argument
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 CVE-2017-5754
  10
  11 With a followon patch we want to make clearcpuid affect the XSAVE
  12 configuration. But xsave is currently initialized before arguments
  13 are parsed. Move the clearcpuid= parsing into the special
  14 early xsave argument parsing code.
  15
  16 Since clearcpuid= contains a = we need to keep the old __setup
  17 around as a dummy, otherwise it would end up as a environment
  18 variable in init's environment.
  19
  20 Signed-off-by: Andi Kleen <ak@linux.intel.com>
  21 Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
  22 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  23 Cc: Peter Zijlstra <peterz@infradead.org>
  24 Link: http://lkml.kernel.org/r/20171013215645.23166-4-andi@firstfloor.org
  25 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  26 (cherry picked from commit 0c2a3913d6f50503f7c59d83a6219e39508cc898)
  27 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  28 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  29 (cherry picked from commit 27deb452eb0d27c406f3817ab057201aa8767abe)
  30 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  31 ---
  32  arch/x86/kernel/cpu/common.c | 16 +++++++---------
  33  arch/x86/kernel/fpu/init.c   | 11 +++++++++++
  34  2 files changed, 18 insertions(+), 9 deletions(-)
  35
  36 diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
  37 index 4be7b209a3d6..ef7b1ba56363 100644
  38 --- a/arch/x86/kernel/cpu/common.c
  39 +++ b/arch/x86/kernel/cpu/common.c
  40 @@ -1293,18 +1293,16 @@ void print_cpu_info(struct cpuinfo_x86 *c)
  41                 pr_cont(")\n");
  42  }
  43
  44 -static __init int setup_disablecpuid(char *arg)
  45 +/*
  46 + * clearcpuid= was already parsed in fpu__init_parse_early_param.
  47 + * But we need to keep a dummy __setup around otherwise it would
  48 + * show up as an environment variable for init.
  49 + */
  50 +static __init int setup_clearcpuid(char *arg)
  51  {
  52 -       int bit;
  53 -
  54 -       if (get_option(&arg, &bit) && bit >= 0 && bit < NCAPINTS * 32)
  55 -               setup_clear_cpu_cap(bit);
  56 -       else
  57 -               return 0;
  58 -
  59         return 1;
  60  }
  61 -__setup("clearcpuid=", setup_disablecpuid);
  62 +__setup("clearcpuid=", setup_clearcpuid);
  63
  64  #ifdef CONFIG_X86_64
  65  struct desc_ptr idt_descr __ro_after_init = {
  66 diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
  67 index d5d44c452624..07f0ab877f49 100644
  68 --- a/arch/x86/kernel/fpu/init.c
  69 +++ b/arch/x86/kernel/fpu/init.c
  70 @@ -249,6 +249,10 @@ static void __init fpu__init_system_ctx_switch(void)
  71   */
  72  static void __init fpu__init_parse_early_param(void)
  73  {
  74 +       char arg[32];
  75 +       char *argptr = arg;
  76 +       int bit;
  77 +
  78         if (cmdline_find_option_bool(boot_command_line, "no387"))
  79                 setup_clear_cpu_cap(X86_FEATURE_FPU);
  80
  81 @@ -266,6 +270,13 @@ static void __init fpu__init_parse_early_param(void)
  82
  83         if (cmdline_find_option_bool(boot_command_line, "noxsaves"))
  84                 setup_clear_cpu_cap(X86_FEATURE_XSAVES);
  85 +
  86 +       if (cmdline_find_option(boot_command_line, "clearcpuid", arg,
  87 +                               sizeof(arg)) &&
  88 +           get_option(&argptr, &bit) &&
  89 +           bit >= 0 &&
  90 +           bit < NCAPINTS * 32)
  91 +               setup_clear_cpu_cap(bit);
  92  }
  93
  94  /*
  95 --
  96 2.14.2
  97