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From: Dave Hansen <dave.hansen@linux.intel.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, Dave Hansen <dave.hansen@linux.intel.com>,
	linuxram@us.ibm.com, tglx@linutronix.de, dave.hansen@intel.com,
	mpe@ellerman.id.au, mingo@kernel.org, akpm@linux-foundation.org,
	shuah@kernel.org
Subject: [PATCH 3/9] x86, pkeys, selftests: add a test for pkey 0
Date: Fri, 23 Mar 2018 11:09:09 -0700	[thread overview]
Message-ID: <20180323180909.17B06F8C@viggo.jf.intel.com> (raw)
In-Reply-To: <20180323180903.33B17168@viggo.jf.intel.com>


From: Dave Hansen <dave.hansen@linux.intel.com>

Protection key 0 is the default key for all memory and will
not normally come back from pkey_alloc().  But, you might
still want pass it to mprotect_pkey().

This check ensures that you can use pkey 0.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Michael Ellermen <mpe@ellerman.id.au>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Shuah Khan <shuah@kernel.org>
---

 b/tools/testing/selftests/x86/protection_keys.c |   30 ++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff -puN tools/testing/selftests/x86/protection_keys.c~pkeys-update-selftests-with-pkey-0-test tools/testing/selftests/x86/protection_keys.c
--- a/tools/testing/selftests/x86/protection_keys.c~pkeys-update-selftests-with-pkey-0-test	2018-03-21 15:47:49.273198924 -0700
+++ b/tools/testing/selftests/x86/protection_keys.c	2018-03-21 15:47:49.277198924 -0700
@@ -1169,6 +1169,35 @@ void test_pkey_alloc_exhaust(int *ptr, u
 	}
 }
 
+/*
+ * pkey 0 is special.  It is allocated by default, so you do not
+ * have to call pkey_alloc() to use it first.  Make sure that it
+ * is usable.
+ */
+void test_mprotect_with_pkey_0(int *ptr, u16 pkey)
+{
+	long size;
+	int prot;
+
+	assert(pkey_last_malloc_record);
+	size = pkey_last_malloc_record->size;
+	/*
+	 * This is a bit of a hack.  But mprotect() requires
+	 * huge-page-aligned sizes when operating on hugetlbfs.
+	 * So, make sure that we use something that's a multiple
+	 * of a huge page when we can.
+	 */
+	if (size >= HPAGE_SIZE)
+		size = HPAGE_SIZE;
+	prot = pkey_last_malloc_record->prot;
+
+	/* Use pkey 0 */
+	mprotect_pkey(ptr, size, prot, 0);
+
+	/* Make sure that we can set it back to the original pkey. */
+	mprotect_pkey(ptr, size, prot, pkey);
+}
+
 void test_ptrace_of_child(int *ptr, u16 pkey)
 {
 	__attribute__((__unused__)) int peek_result;
@@ -1306,6 +1335,7 @@ void (*pkey_tests[])(int *ptr, u16 pkey)
 	test_kernel_gup_of_access_disabled_region,
 	test_kernel_gup_write_to_write_disabled_region,
 	test_executing_on_unreadable_memory,
+	test_mprotect_with_pkey_0,
 	test_ptrace_of_child,
 	test_pkey_syscalls_on_non_allocated_pkey,
 	test_pkey_syscalls_bad_args,
_

  parent reply	other threads:[~2018-03-23 18:11 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-23 18:09 [PATCH 0/9] x86, pkeys: two protection keys bug fixes Dave Hansen
2018-03-23 18:09 ` [PATCH 1/9] x86, pkeys: do not special case protection key 0 Dave Hansen
2018-03-26 17:35   ` Ram Pai
2018-03-26 17:39     ` Dave Hansen
2018-03-27  2:27   ` Ram Pai
2018-03-27  4:11     ` Dave Hansen
2018-03-23 18:09 ` [PATCH 2/9] x86, pkeys, selftests: save off 'prot' for allocations Dave Hansen
2018-03-23 18:09 ` Dave Hansen [this message]
2018-03-23 18:09 ` [PATCH 4/9] x86, pkeys: override pkey when moving away from PROT_EXEC Dave Hansen
2018-03-23 19:15   ` Shakeel Butt
2018-03-23 19:23     ` Dave Hansen
2018-03-23 19:27       ` Shakeel Butt
2018-03-23 19:29         ` Dave Hansen
2018-03-23 19:38       ` Thomas Gleixner
2018-03-23 19:45         ` Thomas Gleixner
2018-03-23 19:48           ` Dave Hansen
2018-03-23 18:09 ` [PATCH 5/9] x86, pkeys, selftests: fix pointer math Dave Hansen
2018-03-23 18:09 ` [PATCH 6/9] x86, pkeys, selftests: fix pkey exhaustion test off-by-one Dave Hansen
2018-03-23 18:09 ` [PATCH 7/9] x86, pkeys, selftests: factor out "instruction page" Dave Hansen
2018-03-23 18:09 ` [PATCH 8/9] x86, pkeys, selftests: add allow faults on unknown keys Dave Hansen
2018-03-23 18:09 ` [PATCH 9/9] x86, pkeys, selftests: add PROT_EXEC test Dave Hansen
2018-03-26 17:27 [PATCH 0/9] [v2] x86, pkeys: two protection keys bug fixes Dave Hansen
2018-03-26 17:27 ` [PATCH 3/9] x86, pkeys, selftests: add a test for pkey 0 Dave Hansen
2018-04-27 17:45 [PATCH 0/9] [v3] x86, pkeys: two protection keys bug fixes Dave Hansen
2018-04-27 17:45 ` [PATCH 3/9] x86, pkeys, selftests: add a test for pkey 0 Dave Hansen

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