linux-kernel - [tip:x86/urgent] x86/pkeys/selftests: Factor out "instruction page"

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Date:   Mon, 14 May 2018 05:43:16 -0700
From:   tip-bot for Dave Hansen <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     peterz@...radead.org, mingo@...nel.org, hpa@...or.com,
        akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
        linux-kernel@...r.kernel.org, mpe@...erman.id.au,
        dave.hansen@...el.com, dave.hansen@...ux.intel.com,
        shuah@...nel.org, linuxram@...ibm.com, tglx@...utronix.de
Subject: [tip:x86/urgent] x86/pkeys/selftests: Factor out "instruction page"

Commit-ID:  3fcd2b2d928904cbf30b01e2c5e4f1dd2f9ab262
Gitweb:     https://git.kernel.org/tip/3fcd2b2d928904cbf30b01e2c5e4f1dd2f9ab262
Author:     Dave Hansen <dave.hansen@...ux.intel.com>
AuthorDate: Wed, 9 May 2018 10:13:47 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 14 May 2018 11:14:45 +0200

x86/pkeys/selftests: Factor out "instruction page"

We currently have an execute-only test, but it is for
the explicit mprotect_pkey() interface.  We will soon
add a test for the implicit mprotect(PROT_EXEC)
enterface.  We need this code in both tests.

Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Michael Ellermen <mpe@...erman.id.au>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ram Pai <linuxram@...ibm.com>
Cc: Shuah Khan <shuah@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-mm@...ck.org
Link: http://lkml.kernel.org/r/20180509171347.C64AB733@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 tools/testing/selftests/x86/protection_keys.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/x86/protection_keys.c b/tools/testing/selftests/x86/protection_keys.c
index 7d95acd2aec3..083ebd51b44e 100644
--- a/tools/testing/selftests/x86/protection_keys.c
+++ b/tools/testing/selftests/x86/protection_keys.c
@@ -1253,12 +1253,9 @@ void test_ptrace_of_child(int *ptr, u16 pkey)
 	free(plain_ptr_unaligned);
 }
 
-void test_executing_on_unreadable_memory(int *ptr, u16 pkey)
+void *get_pointer_to_instructions(void)
 {
 	void *p1;
-	int scratch;
-	int ptr_contents;
-	int ret;
 
 	p1 = ALIGN_PTR_UP(&lots_o_noops_around_write, PAGE_SIZE);
 	dprintf3("&lots_o_noops: %p\n", &lots_o_noops_around_write);
@@ -1268,7 +1265,23 @@ void test_executing_on_unreadable_memory(int *ptr, u16 pkey)
 	/* Point 'p1' at the *second* page of the function: */
 	p1 += PAGE_SIZE;
 
+	/*
+	 * Try to ensure we fault this in on next touch to ensure
+	 * we get an instruction fault as opposed to a data one
+	 */
 	madvise(p1, PAGE_SIZE, MADV_DONTNEED);
+
+	return p1;
+}
+
+void test_executing_on_unreadable_memory(int *ptr, u16 pkey)
+{
+	void *p1;
+	int scratch;
+	int ptr_contents;
+	int ret;
+
+	p1 = get_pointer_to_instructions();
 	lots_o_noops_around_write(&scratch);
 	ptr_contents = read_ptr(p1);
 	dprintf2("ptr (%p) contents@%d: %x\n", p1, __LINE__, ptr_contents);