From 3c479b5dc60b297a9e327ac2734475c1d68b4443 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Thomas=20Wei=C3=9Fschuh?= <thomas.weissschuh@linutronix.de>
Date: Tue, 14 Jan 2025 17:06:47 +0100
Subject: [PATCH] selftests/mm: vm_util: split up /proc/self/smaps parsing
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Upcoming changes want to reuse the /proc/self/smaps parsing logic to parse
the VmFlags field.

As that works differently from the currently parsed HugePage counters,
split up the logic so common functionality can be shared.

While reworking this code, also use the correct sscanf placeholder for the
"uint64_t thp" variable.

Link: https://lkml.kernel.org/r/20250114-virtual_address_range-tests-v4-3-6fd7269934a5@linutronix.de
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: kernel test robot <oliver.sang@intel.com>
Cc: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 tools/testing/selftests/mm/vm_util.c | 42 +++++++++++++++++++---------
 1 file changed, 29 insertions(+), 13 deletions(-)

diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index 7519c9a892f0f..b16f9d3adc69b 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -2,6 +2,7 @@
 #include <string.h>
 #include <fcntl.h>
 #include <dirent.h>
+#include <inttypes.h>
 #include <sys/ioctl.h>
 #include <linux/userfaultfd.h>
 #include <linux/fs.h>
@@ -193,13 +194,11 @@ err_out:
 	return rss_anon;
 }
 
-bool __check_huge(void *addr, char *pattern, int nr_hpages,
-		  uint64_t hpage_size)
+char *__get_smap_entry(void *addr, const char *pattern, char *buf, size_t len)
 {
-	uint64_t thp = -1;
 	int ret;
 	FILE *fp;
-	char buffer[MAX_LINE_LENGTH];
+	char *entry = NULL;
 	char addr_pattern[MAX_LINE_LENGTH];
 
 	ret = snprintf(addr_pattern, MAX_LINE_LENGTH, "%08lx-",
@@ -211,23 +210,40 @@ bool __check_huge(void *addr, char *pattern, int nr_hpages,
 	if (!fp)
 		ksft_exit_fail_msg("%s: Failed to open file %s\n", __func__, SMAP_FILE_PATH);
 
-	if (!check_for_pattern(fp, addr_pattern, buffer, sizeof(buffer)))
+	if (!check_for_pattern(fp, addr_pattern, buf, len))
 		goto err_out;
 
-	/*
-	 * Fetch the pattern in the same block and check the number of
-	 * hugepages.
-	 */
-	if (!check_for_pattern(fp, pattern, buffer, sizeof(buffer)))
+	/* Fetch the pattern in the same block */
+	if (!check_for_pattern(fp, pattern, buf, len))
 		goto err_out;
 
-	snprintf(addr_pattern, MAX_LINE_LENGTH, "%s%%9ld kB", pattern);
+	/* Trim trailing newline */
+	entry = strchr(buf, '\n');
+	if (entry)
+		*entry = '\0';
 
-	if (sscanf(buffer, addr_pattern, &thp) != 1)
-		ksft_exit_fail_msg("Reading smap error\n");
+	entry = buf + strlen(pattern);
 
 err_out:
 	fclose(fp);
+	return entry;
+}
+
+bool __check_huge(void *addr, char *pattern, int nr_hpages,
+		  uint64_t hpage_size)
+{
+	char buffer[MAX_LINE_LENGTH];
+	uint64_t thp = -1;
+	char *entry;
+
+	entry = __get_smap_entry(addr, pattern, buffer, sizeof(buffer));
+	if (!entry)
+		goto err_out;
+
+	if (sscanf(entry, "%9" SCNu64 " kB", &thp) != 1)
+		ksft_exit_fail_msg("Reading smap error\n");
+
+err_out:
 	return thp == (nr_hpages * (hpage_size >> 10));
 }
 
-- 
2.47.3