queue-4.4/powerpc-64s-wire-up-cpu_show_spectre_v2.patch

   1 From foo@baz Mon 29 Apr 2019 11:38:37 AM CEST
   2 From: Michael Ellerman <mpe@ellerman.id.au>
   3 Date: Mon, 22 Apr 2019 00:20:04 +1000
   4 Subject: powerpc/64s: Wire up cpu_show_spectre_v2()
   5 To: stable@vger.kernel.org, gregkh@linuxfoundation.org
   6 Cc: linuxppc-dev@ozlabs.org, diana.craciun@nxp.com, msuchanek@suse.de, npiggin@gmail.com, christophe.leroy@c-s.fr
   7 Message-ID: <20190421142037.21881-20-mpe@ellerman.id.au>
   8
   9 From: Michael Ellerman <mpe@ellerman.id.au>
  10
  11 commit d6fbe1c55c55c6937cbea3531af7da84ab7473c3 upstream.
  12
  13 Add a definition for cpu_show_spectre_v2() to override the generic
  14 version. This has several permuations, though in practice some may not
  15 occur we cater for any combination.
  16
  17 The most verbose is:
  18
  19   Mitigation: Indirect branch serialisation (kernel only), Indirect
  20   branch cache disabled, ori31 speculation barrier enabled
  21
  22 We don't treat the ori31 speculation barrier as a mitigation on its
  23 own, because it has to be *used* by code in order to be a mitigation
  24 and we don't know if userspace is doing that. So if that's all we see
  25 we say:
  26
  27   Vulnerable, ori31 speculation barrier enabled
  28
  29 Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
  30 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  31 ---
  32  arch/powerpc/kernel/security.c |   33 +++++++++++++++++++++++++++++++++
  33  1 file changed, 33 insertions(+)
  34
  35 --- a/arch/powerpc/kernel/security.c
  36 +++ b/arch/powerpc/kernel/security.c
  37 @@ -58,3 +58,36 @@ ssize_t cpu_show_spectre_v1(struct devic
  38
  39         return sprintf(buf, "Vulnerable\n");
  40  }
  41 +
  42 +ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
  43 +{
  44 +       bool bcs, ccd, ori;
  45 +       struct seq_buf s;
  46 +
  47 +       seq_buf_init(&s, buf, PAGE_SIZE - 1);
  48 +
  49 +       bcs = security_ftr_enabled(SEC_FTR_BCCTRL_SERIALISED);
  50 +       ccd = security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED);
  51 +       ori = security_ftr_enabled(SEC_FTR_SPEC_BAR_ORI31);
  52 +
  53 +       if (bcs || ccd) {
  54 +               seq_buf_printf(&s, "Mitigation: ");
  55 +
  56 +               if (bcs)
  57 +                       seq_buf_printf(&s, "Indirect branch serialisation (kernel only)");
  58 +
  59 +               if (bcs && ccd)
  60 +                       seq_buf_printf(&s, ", ");
  61 +
  62 +               if (ccd)
  63 +                       seq_buf_printf(&s, "Indirect branch cache disabled");
  64 +       } else
  65 +               seq_buf_printf(&s, "Vulnerable");
  66 +
  67 +       if (ori)
  68 +               seq_buf_printf(&s, ", ori31 speculation barrier enabled");
  69 +
  70 +       seq_buf_printf(&s, "\n");
  71 +
  72 +       return s.len;
  73 +}