selftests/x86/mpx: Fix incorrect bounds with old _sigfault

For distributions with old userspace header files, the _sigfault
structure is different. mpx-mini-test fails with the following
error:

  [root@Purley]# mpx-mini-test_64 tabletest
  XSAVE is supported by HW & OS
  XSAVE processor supported state mask: 0x2ff
  XSAVE OS supported state mask: 0x2ff
   BNDREGS: size: 64 user: 1 supervisor: 0 aligned: 0
    BNDCSR: size: 64 user: 1 supervisor: 0 aligned: 0
  starting mpx bounds table test
  ERROR: siginfo bounds do not match shadow bounds for register 0

Fix it by using the correct offset of _lower/_upper in _sigfault.
RHEL needs this patch to work.

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave.hansen@linux.intel.com
Fixes: e754aedc26ef ("x86/mpx, selftests: Add MPX self test")
Link: http://lkml.kernel.org/r/1513586050-1641-1-git-send-email-rui.y.wang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/tools/testing/selftests/x86/mpx-mini-test.c b/tools/testing/selftests/x86/mpx-mini-test.c
index ec0f6b45ce8b4d5f303528daf6efba71258c39c6..9c0325e1ea6844f666bfdcc8204763a8614b9875 100644 (file)
--- a/tools/testing/selftests/x86/mpx-mini-test.c
+++ b/tools/testing/selftests/x86/mpx-mini-test.c
@@ -315,11 +315,39 @@ static inline void *__si_bounds_upper(siginfo_t *si)
        return si->si_upper;
 }
 #else
+
+/*
+ * This deals with old version of _sigfault in some distros:
+ *
+
+old _sigfault:
+        struct {
+            void *si_addr;
+       } _sigfault;
+
+new _sigfault:
+       struct {
+               void __user *_addr;
+               int _trapno;
+               short _addr_lsb;
+               union {
+                       struct {
+                               void __user *_lower;
+                               void __user *_upper;
+                       } _addr_bnd;
+                       __u32 _pkey;
+               };
+       } _sigfault;
+ *
+ */
+
 static inline void **__si_bounds_hack(siginfo_t *si)
 {
        void *sigfault = &si->_sifields._sigfault;
        void *end_sigfault = sigfault + sizeof(si->_sifields._sigfault);
-       void **__si_lower = end_sigfault;
+       int *trapno = (int*)end_sigfault;
+       /* skip _trapno and _addr_lsb */
+       void **__si_lower = (void**)(trapno + 2);
 
        return __si_lower;
 }
@@ -331,7 +359,7 @@ static inline void *__si_bounds_lower(siginfo_t *si)
 
 static inline void *__si_bounds_upper(siginfo_t *si)
 {
-       return (*__si_bounds_hack(si)) + sizeof(void *);
+       return *(__si_bounds_hack(si) + 1);
 }
 #endif