releases/4.18.14/x86-vdso-fix-vdso-syscall-fallback-asm-constraint-regression.patch

   1 From 02e425668f5c9deb42787d10001a3b605993ad15 Mon Sep 17 00:00:00 2001
   2 From: Andy Lutomirski <luto@kernel.org>
   3 Date: Wed, 3 Oct 2018 16:23:49 -0700
   4 Subject: x86/vdso: Fix vDSO syscall fallback asm constraint regression
   5
   6 From: Andy Lutomirski <luto@kernel.org>
   7
   8 commit 02e425668f5c9deb42787d10001a3b605993ad15 upstream.
   9
  10 When I added the missing memory outputs, I failed to update the
  11 index of the first argument (ebx) on 32-bit builds, which broke the
  12 fallbacks.  Somehow I must have screwed up my testing or gotten
  13 lucky.
  14
  15 Add another test to cover gettimeofday() as well.
  16
  17 Signed-off-by: Andy Lutomirski <luto@kernel.org>
  18 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  19 Cc: Peter Zijlstra <peterz@infradead.org>
  20 Cc: Thomas Gleixner <tglx@linutronix.de>
  21 Cc: stable@vger.kernel.org
  22 Fixes: 715bd9d12f84 ("x86/vdso: Fix asm constraints on vDSO syscall fallbacks")
  23 Link: http://lkml.kernel.org/r/21bd45ab04b6d838278fa5bebfa9163eceffa13c.1538608971.git.luto@kernel.org
  24 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  25 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  26
  27 ---
  28  arch/x86/entry/vdso/vclock_gettime.c    |    8 +--
  29  tools/testing/selftests/x86/test_vdso.c |   73 ++++++++++++++++++++++++++++++++
  30  2 files changed, 77 insertions(+), 4 deletions(-)
  31
  32 --- a/arch/x86/entry/vdso/vclock_gettime.c
  33 +++ b/arch/x86/entry/vdso/vclock_gettime.c
  34 @@ -68,11 +68,11 @@ notrace static long vdso_fallback_gettim
  35
  36         asm (
  37                 "mov %%ebx, %%edx \n"
  38 -               "mov %2, %%ebx \n"
  39 +               "mov %[clock], %%ebx \n"
  40                 "call __kernel_vsyscall \n"
  41                 "mov %%edx, %%ebx \n"
  42                 : "=a" (ret), "=m" (*ts)
  43 -               : "0" (__NR_clock_gettime), "g" (clock), "c" (ts)
  44 +               : "0" (__NR_clock_gettime), [clock] "g" (clock), "c" (ts)
  45                 : "memory", "edx");
  46         return ret;
  47  }
  48 @@ -83,11 +83,11 @@ notrace static long vdso_fallback_gtod(s
  49
  50         asm (
  51                 "mov %%ebx, %%edx \n"
  52 -               "mov %2, %%ebx \n"
  53 +               "mov %[tv], %%ebx \n"
  54                 "call __kernel_vsyscall \n"
  55                 "mov %%edx, %%ebx \n"
  56                 : "=a" (ret), "=m" (*tv), "=m" (*tz)
  57 -               : "0" (__NR_gettimeofday), "g" (tv), "c" (tz)
  58 +               : "0" (__NR_gettimeofday), [tv] "g" (tv), "c" (tz)
  59                 : "memory", "edx");
  60         return ret;
  61  }
  62 --- a/tools/testing/selftests/x86/test_vdso.c
  63 +++ b/tools/testing/selftests/x86/test_vdso.c
  64 @@ -36,6 +36,10 @@ typedef int (*vgettime_t)(clockid_t, str
  65
  66  vgettime_t vdso_clock_gettime;
  67
  68 +typedef long (*vgtod_t)(struct timeval *tv, struct timezone *tz);
  69 +
  70 +vgtod_t vdso_gettimeofday;
  71 +
  72  typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
  73
  74  getcpu_t vgetcpu;
  75 @@ -104,6 +108,11 @@ static void fill_function_pointers()
  76         vdso_clock_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime");
  77         if (!vdso_clock_gettime)
  78                 printf("Warning: failed to find clock_gettime in vDSO\n");
  79 +
  80 +       vdso_gettimeofday = (vgtod_t)dlsym(vdso, "__vdso_gettimeofday");
  81 +       if (!vdso_gettimeofday)
  82 +               printf("Warning: failed to find gettimeofday in vDSO\n");
  83 +
  84  }
  85
  86  static long sys_getcpu(unsigned * cpu, unsigned * node,
  87 @@ -117,6 +126,11 @@ static inline int sys_clock_gettime(cloc
  88         return syscall(__NR_clock_gettime, id, ts);
  89  }
  90
  91 +static inline int sys_gettimeofday(struct timeval *tv, struct timezone *tz)
  92 +{
  93 +       return syscall(__NR_gettimeofday, tv, tz);
  94 +}
  95 +
  96  static void test_getcpu(void)
  97  {
  98         printf("[RUN]\tTesting getcpu...\n");
  99 @@ -177,6 +191,14 @@ static bool ts_leq(const struct timespec
 100                 return a->tv_nsec <= b->tv_nsec;
 101  }
 102
 103 +static bool tv_leq(const struct timeval *a, const struct timeval *b)
 104 +{
 105 +       if (a->tv_sec != b->tv_sec)
 106 +               return a->tv_sec < b->tv_sec;
 107 +       else
 108 +               return a->tv_usec <= b->tv_usec;
 109 +}
 110 +
 111  static char const * const clocknames[] = {
 112         [0] = "CLOCK_REALTIME",
 113         [1] = "CLOCK_MONOTONIC",
 114 @@ -248,11 +270,62 @@ static void test_clock_gettime(void)
 115         test_one_clock_gettime(INT_MAX, "invalid");
 116  }
 117
 118 +static void test_gettimeofday(void)
 119 +{
 120 +       struct timeval start, vdso, end;
 121 +       struct timezone sys_tz, vdso_tz;
 122 +       int vdso_ret, end_ret;
 123 +
 124 +       if (!vdso_gettimeofday)
 125 +               return;
 126 +
 127 +       printf("[RUN]\tTesting gettimeofday...\n");
 128 +
 129 +       if (sys_gettimeofday(&start, &sys_tz) < 0) {
 130 +               printf("[FAIL]\tsys_gettimeofday failed (%d)\n", errno);
 131 +               nerrs++;
 132 +               return;
 133 +       }
 134 +
 135 +       vdso_ret = vdso_gettimeofday(&vdso, &vdso_tz);
 136 +       end_ret = sys_gettimeofday(&end, NULL);
 137 +
 138 +       if (vdso_ret != 0 || end_ret != 0) {
 139 +               printf("[FAIL]\tvDSO returned %d, syscall errno=%d\n",
 140 +                      vdso_ret, errno);
 141 +               nerrs++;
 142 +               return;
 143 +       }
 144 +
 145 +       printf("\t%llu.%06ld %llu.%06ld %llu.%06ld\n",
 146 +              (unsigned long long)start.tv_sec, start.tv_usec,
 147 +              (unsigned long long)vdso.tv_sec, vdso.tv_usec,
 148 +              (unsigned long long)end.tv_sec, end.tv_usec);
 149 +
 150 +       if (!tv_leq(&start, &vdso) || !tv_leq(&vdso, &end)) {
 151 +               printf("[FAIL]\tTimes are out of sequence\n");
 152 +               nerrs++;
 153 +       }
 154 +
 155 +       if (sys_tz.tz_minuteswest == vdso_tz.tz_minuteswest &&
 156 +           sys_tz.tz_dsttime == vdso_tz.tz_dsttime) {
 157 +               printf("[OK]\ttimezones match: minuteswest=%d, dsttime=%d\n",
 158 +                      sys_tz.tz_minuteswest, sys_tz.tz_dsttime);
 159 +       } else {
 160 +               printf("[FAIL]\ttimezones do not match\n");
 161 +               nerrs++;
 162 +       }
 163 +
 164 +       /* And make sure that passing NULL for tz doesn't crash. */
 165 +       vdso_gettimeofday(&vdso, NULL);
 166 +}
 167 +
 168  int main(int argc, char **argv)
 169  {
 170         fill_function_pointers();
 171
 172         test_clock_gettime();
 173 +       test_gettimeofday();
 174
 175         /*
 176          * Test getcpu() last so that, if something goes wrong setting affinity,