tools/testing: add PROCMAP_QUERY helper functions in mm self tests

The PROCMAP_QUERY ioctl() is very useful - it allows for binary access to
/proc/$pid/[s]maps data and thus convenient lookup of data contained
there.

This patch exposes this for convenient use by mm self tests so the state
of VMAs can easily be queried.

Link: https://lkml.kernel.org/r/ce83d877093d1fc594762cf4b82f0c27963030ee.1744104124.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index a36734fb62f386f2d89a575011dc847f1c915a2e..1357e2d6a7b686d6694064130b960c1aafb4ec1d 100644 (file)
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <string.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <dirent.h>
 #include <inttypes.h>
@@ -424,3 +425,64 @@ bool check_vmflag_io(void *addr)
                flags += flaglen;
        }
 }
+
+/*
+ * Open an fd at /proc/$pid/maps and configure procmap_out ready for
+ * PROCMAP_QUERY query. Returns 0 on success, or an error code otherwise.
+ */
+int open_procmap(pid_t pid, struct procmap_fd *procmap_out)
+{
+       char path[256];
+       int ret = 0;
+
+       memset(procmap_out, '\0', sizeof(*procmap_out));
+       sprintf(path, "/proc/%d/maps", pid);
+       procmap_out->query.size = sizeof(procmap_out->query);
+       procmap_out->fd = open(path, O_RDONLY);
+       if (procmap_out < 0)
+               ret = -errno;
+
+       return ret;
+}
+
+/* Perform PROCMAP_QUERY. Returns 0 on success, or an error code otherwise. */
+int query_procmap(struct procmap_fd *procmap)
+{
+       int ret = 0;
+
+       if (ioctl(procmap->fd, PROCMAP_QUERY, &procmap->query) == -1)
+               ret = -errno;
+
+       return ret;
+}
+
+/*
+ * Try to find the VMA at specified address, returns true if found, false if not
+ * found, and the test is failed if any other error occurs.
+ *
+ * On success, procmap->query is populated with the results.
+ */
+bool find_vma_procmap(struct procmap_fd *procmap, void *address)
+{
+       int err;
+
+       procmap->query.query_flags = 0;
+       procmap->query.query_addr = (unsigned long)address;
+       err = query_procmap(procmap);
+       if (!err)
+               return true;
+
+       if (err != -ENOENT)
+               ksft_exit_fail_msg("%s: Error %d on ioctl(PROCMAP_QUERY)\n",
+                                  __func__, err);
+       return false;
+}
+
+/*
+ * Close fd used by PROCMAP_QUERY mechanism. Returns 0 on success, or an error
+ * code otherwise.
+ */
+int close_procmap(struct procmap_fd *procmap)
+{
+       return close(procmap->fd);
+}

diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index 6effafdc4d8a23f91f0adcb9e43d6196d651ba88..9211ba640d9cd8ce793f4222312736662f7939ab 100644 (file)
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -6,6 +6,7 @@
 #include <strings.h> /* ffsl() */
 #include <unistd.h> /* _SC_PAGESIZE */
 #include "../kselftest.h"
+#include <linux/fs.h>
 
 #define BIT_ULL(nr)                   (1ULL << (nr))
 #define PM_SOFT_DIRTY                 BIT_ULL(55)
@@ -19,6 +20,15 @@
 extern unsigned int __page_size;
 extern unsigned int __page_shift;
 
+/*
+ * Represents an open fd and PROCMAP_QUERY state for binary (via ioctl)
+ * /proc/$pid/[s]maps lookup.
+ */
+struct procmap_fd {
+       int fd;
+       struct procmap_query query;
+};
+
 static inline unsigned int psize(void)
 {
        if (!__page_size)
@@ -73,6 +83,17 @@ int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len,
                              bool miss, bool wp, bool minor, uint64_t *ioctls);
 unsigned long get_free_hugepages(void);
 bool check_vmflag_io(void *addr);
+int open_procmap(pid_t pid, struct procmap_fd *procmap_out);
+int query_procmap(struct procmap_fd *procmap);
+bool find_vma_procmap(struct procmap_fd *procmap, void *address);
+int close_procmap(struct procmap_fd *procmap);
+
+static inline int open_self_procmap(struct procmap_fd *procmap_out)
+{
+       pid_t pid = getpid();
+
+       return open_procmap(pid, procmap_out);
+}
 
 /*
  * On ppc64 this will only work with radix 2M hugepage size