linux-kernel - [PATCH] x86/mpx, selftests: Only check bounds-vs-shadow when we keep shadow

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Message-Id: <1491488598-27346-1-git-send-email-joro@8bytes.org>
Date:   Thu,  6 Apr 2017 16:23:18 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Shuah Khan <shuah@...nel.org>, Ingo Molnar <mingo@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>
Cc:     linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
        Joerg Roedel <jroedel@...e.de>
Subject: [PATCH] x86/mpx, selftests: Only check bounds-vs-shadow when we keep shadow

From: Joerg Roedel <jroedel@...e.de>

The check between the hardware state and our shadow of it is
checked in the signal handler for all bounds exceptions,
even for the ones where we don't keep the shadow up2date.
This is a problem because when no shadow is kept the handler
fails at this point and hides the real reason of the
exception.

Move the check into the code-path evaluating normal bounds
exceptions to prevent this.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
---
 tools/testing/selftests/x86/mpx-mini-test.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/x86/mpx-mini-test.c b/tools/testing/selftests/x86/mpx-mini-test.c
index 616ee96..a8df159 100644
--- a/tools/testing/selftests/x86/mpx-mini-test.c
+++ b/tools/testing/selftests/x86/mpx-mini-test.c
@@ -404,8 +404,6 @@ void handler(int signum, siginfo_t *si, void *vucontext)
 		dprintf2("info->si_lower: %p\n", __si_bounds_lower(si));
 		dprintf2("info->si_upper: %p\n", __si_bounds_upper(si));
 
-		check_siginfo_vs_shadow(si);
-
 		for (i = 0; i < 8; i++)
 			dprintf3("[%d]: %p\n", i, si_addr_ptr[i]);
 		switch (br_reason) {
@@ -416,6 +414,9 @@ void handler(int signum, siginfo_t *si, void *vucontext)
 			exit(5);
 		case 1: /* #BR MPX bounds exception */
 			/* these are normal and we expect to see them */
+
+			check_siginfo_vs_shadow(si);
+
 			dprintf1("bounds exception (normal): status 0x%jx at %p si_addr: %p\n",
 				status, (void *)ip, si->si_addr);
 			num_bnd_chk++;
-- 
1.9.1