Commit f3b92176 authored by Lorenzo Stoakes's avatar Lorenzo Stoakes Committed by Andrew Morton
Browse files

tools/selftests: add guard region test for /proc/$pid/pagemap 

Add a test to the guard region self tests to assert that the
/proc/$pid/pagemap information now made availabile to the user correctly
identifies and reports guard regions.

As a part of this change, update vm_util.h to add the new bit (note there
is no header file in the kernel where this is exposed, the user is
expected to provide their own mask) and utilise the helper functions there
for pagemap functionality.

[lorenzo.stoakes@oracle.com: fixup define name]
  Link: https://lkml.kernel.org/r/32e83941-e6f5-42ee-9292-a44c16463cf1@lucifer.local
Link: https://lkml.kernel.org/r/164feb0a43ae72650e6b20c3910213f469566311.1740139449.git.lorenzo.stoakes@oracle.com


Signed-off-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 8e2f2aeb

tools/testing/selftests/mm/guard-regions.c

+47 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include <sys/syscall.h>

#include <sys/uio.h>

#include <unistd.h>

#include "vm_util.h"



/*

 * Ignore the checkpatch warning, as per the C99 standard, section 7.14.1.1:
@@ -2032,4 +2033,50 @@ TEST_F(guard_regions, anon_zeropage) 
	ASSERT_EQ(munmap(ptr, 10 * page_size), 0);

}



/*

 * Assert that /proc/$pid/pagemap correctly identifies guard region ranges.

 */

TEST_F(guard_regions, pagemap)

{

	const unsigned long page_size = self->page_size;

	int proc_fd;

	char *ptr;

	int i;



	proc_fd = open("/proc/self/pagemap", O_RDONLY);

	ASSERT_NE(proc_fd, -1);



	ptr = mmap_(self, variant, NULL, 10 * page_size,

		    PROT_READ | PROT_WRITE, 0, 0);

	ASSERT_NE(ptr, MAP_FAILED);



	/* Read from pagemap, and assert no guard regions are detected. */

	for (i = 0; i < 10; i++) {

		char *ptr_p = &ptr[i * page_size];

		unsigned long entry = pagemap_get_entry(proc_fd, ptr_p);

		unsigned long masked = entry & PM_GUARD_REGION;



		ASSERT_EQ(masked, 0);

	}



	/* Install a guard region in every other page. */

	for (i = 0; i < 10; i += 2) {

		char *ptr_p = &ptr[i * page_size];



		ASSERT_EQ(madvise(ptr_p, page_size, MADV_GUARD_INSTALL), 0);

	}



	/* Re-read from pagemap, and assert guard regions are detected. */

	for (i = 0; i < 10; i++) {

		char *ptr_p = &ptr[i * page_size];

		unsigned long entry = pagemap_get_entry(proc_fd, ptr_p);

		unsigned long masked = entry & PM_GUARD_REGION;



		ASSERT_EQ(masked, i % 2 == 0 ? PM_GUARD_REGION : 0);

	}



	ASSERT_EQ(close(proc_fd), 0);

	ASSERT_EQ(munmap(ptr, 10 * page_size), 0);

}



TEST_HARNESS_MAIN

tools/testing/selftests/mm/vm_util.h

+1 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#define PM_SOFT_DIRTY                 BIT_ULL(55)

#define PM_MMAP_EXCLUSIVE             BIT_ULL(56)

#define PM_UFFD_WP                    BIT_ULL(57)

#define PM_GUARD_REGION               BIT_ULL(58)

#define PM_FILE                       BIT_ULL(61)

#define PM_SWAP                       BIT_ULL(62)

#define PM_PRESENT                    BIT_ULL(63)