[PATCH v2 3/3] selftests/proc: add /proc/pid/smaps tearing tests

[Suren Baghdasaryan <surenb@google.com>]

Add tearing tests for /proc/pid/smaps file. New tests reuse the same
logic as with maps file but skipping all the data except for the VMA
addresses, which are the only part relevant for the tearing tests.
Skip PROCMAP_QUERY parts of the tests because smaps does not implement
that ioctl.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Liam R. Howlett <liam@infradead.org>
---
 tools/testing/selftests/proc/proc-maps-race.c | 178 +++++++++++++-----
 1 file changed, 133 insertions(+), 45 deletions(-)

diff --git a/tools/testing/selftests/proc/proc-maps-race.c b/tools/testing/selftests/proc/proc-maps-race.c
index 5eb350c23da4..1026d8c400e1 100644
--- a/tools/testing/selftests/proc/proc-maps-race.c
+++ b/tools/testing/selftests/proc/proc-maps-race.c
@@ -17,8 +17,8 @@
  */
 /*
  * Fork a child that concurrently modifies address space while the main
- * process is reading /proc/$PID/maps and verifying the results. Address
- * space modifications include:
+ * process is reading /proc/$PID/maps and /proc/$PID/smaps, verifying the
+ * results. Address space modifications include:
  *     VMA splitting and merging
  *
  */
@@ -73,6 +73,11 @@ enum test_state {
 	TEST_DONE,
 };
 
+enum maps_file {
+	MAPS,
+	SMAPS,
+};
+
 struct vma_modifier_info;
 
 FIXTURE(proc_maps_race)
@@ -83,6 +88,7 @@ FIXTURE(proc_maps_race)
 	struct line_content last_line;
 	struct line_content first_line;
 	unsigned long duration_sec;
+	enum maps_file maps_file;
 	int shared_mem_size;
 	int skip_pages;
 	int page_size;
@@ -92,6 +98,19 @@ FIXTURE(proc_maps_race)
 	pid_t pid;
 };
 
+FIXTURE_VARIANT(proc_maps_race)
+{
+	const enum maps_file maps_file;
+};
+
+FIXTURE_VARIANT_ADD(proc_maps_race, maps) {
+	.maps_file = MAPS,
+};
+
+FIXTURE_VARIANT_ADD(proc_maps_race, smaps) {
+	.maps_file = SMAPS,
+};
+
 typedef bool (*vma_modifier_op)(FIXTURE_DATA(proc_maps_race) *self);
 typedef bool (*vma_mod_result_check_op)(struct line_content *mod_last_line,
 					struct line_content *mod_first_line,
@@ -222,6 +241,57 @@ static void copy_last_line(struct page_content *page, char *last_line,
 	copy_line(pos, end, last_line, line_size);
 }
 
+static bool copy_first_entry(struct page_content *page, char *first_line,
+			     size_t line_size)
+{
+	char *start_pos = page->data;
+
+	while (start_pos < page->data + page->size) {
+		unsigned long start_addr;
+		unsigned long end_addr;
+		char *end_pos;
+
+		end_pos = strchr(start_pos, '\n');
+		if (!end_pos)
+			break;
+
+		if (parse_vma_line(start_pos, end_pos, &start_addr, &end_addr)) {
+			copy_line(start_pos, end_pos, first_line, line_size);
+			return true;
+		}
+
+		start_pos = end_pos + 1;
+	}
+
+	return false;
+}
+
+static bool copy_last_entry(struct page_content *page, char *last_line,
+			    size_t line_size)
+{
+	char *end_pos = page->data + page->size - 1;
+	char *start_pos;
+
+	while (end_pos > page->data) {
+		unsigned long start_addr;
+		unsigned long end_addr;
+
+		/* skip last newline */
+		start_pos = end_pos - 1;
+		/* search previous newline */
+		while (start_pos > page->data && start_pos[-1] != '\n')
+			start_pos--;
+		if (parse_vma_line(start_pos, end_pos, &start_addr, &end_addr)) {
+			copy_line(start_pos, end_pos, last_line, line_size);
+			return true;
+		}
+
+		end_pos = start_pos - 1;
+	}
+
+	return false;
+}
+
 /* Read the last line of the first page and the first line of the second page */
 static bool read_boundary_lines(FIXTURE_DATA(proc_maps_race) *self,
 				struct line_content *last_line,
@@ -230,8 +300,16 @@ static bool read_boundary_lines(FIXTURE_DATA(proc_maps_race) *self,
 	if (!read_two_pages(self))
 		return false;
 
-	copy_last_line(&self->page1, last_line->text, LINE_MAX_SIZE);
-	copy_first_line(&self->page2, first_line->text, LINE_MAX_SIZE);
+	if (self->maps_file == MAPS) {
+		copy_last_line(&self->page1, last_line->text, LINE_MAX_SIZE);
+		copy_first_line(&self->page2, first_line->text, LINE_MAX_SIZE);
+	} else if (self->maps_file == SMAPS) {
+		if (!copy_last_entry(&self->page1, last_line->text, LINE_MAX_SIZE) ||
+		    !copy_first_entry(&self->page2, first_line->text, LINE_MAX_SIZE))
+			return false;
+	} else {
+		return false;
+	}
 
 	return sscanf(last_line->text, "%lx-%lx", &last_line->start_addr,
 		      &last_line->end_addr) == 2 &&
@@ -497,6 +575,7 @@ FIXTURE_SETUP(proc_maps_race)
 
 	self->page_size = (unsigned long)sysconf(_SC_PAGESIZE);
 	self->verbose = verbose && !strncmp(verbose, "1", 1);
+	self->maps_file = variant->maps_file;
 	duration_sec = duration ? atol(duration) : 0;
 	self->duration_sec = duration_sec ? duration_sec : 5UL;
 
@@ -563,7 +642,16 @@ FIXTURE_SETUP(proc_maps_race)
 		exit(0);
 	}
 
-	sprintf(fname, "/proc/%d/maps", self->pid);
+	switch (self->maps_file) {
+	case MAPS:
+		sprintf(fname, "/proc/%d/maps", self->pid);
+		break;
+	case SMAPS:
+		sprintf(fname, "/proc/%d/smaps", self->pid);
+		break;
+	default:
+		ksft_exit_fail();
+	}
 	self->maps_fd = open(fname, O_RDONLY);
 	ASSERT_NE(self->maps_fd, -1);
 
@@ -608,7 +696,6 @@ FIXTURE_SETUP(proc_maps_race)
 	ASSERT_TRUE(mod_info->addr && mod_info->next_addr);
 
 	signal_state(mod_info, PARENT_READY);
-
 }
 
 FIXTURE_TEARDOWN(proc_maps_race)
@@ -698,20 +785,20 @@ TEST_F(proc_maps_race, test_maps_tearing_from_split)
 		last_line_changed = strcmp(new_last_line.text, self->last_line.text) != 0;
 		first_line_changed = strcmp(new_first_line.text, self->first_line.text) != 0;
 		ASSERT_EQ(last_line_changed, first_line_changed);
-
-		/* Check if PROCMAP_QUERY ioclt() finds the right VMA */
-		ASSERT_TRUE(query_addr_at(self->maps_fd, mod_info->addr + self->page_size,
-					  &vma_start, &vma_end));
-		/*
-		 * The vma at the split address can be either the same as
-		 * original one (if read before the split) or the same as the
-		 * first line in the second page (if read after the split).
-		 */
-		ASSERT_TRUE((vma_start == self->last_line.start_addr &&
-			     vma_end == self->last_line.end_addr) ||
-			    (vma_start == split_first_line.start_addr &&
-			     vma_end == split_first_line.end_addr));
-
+		if (self->maps_file == MAPS) {
+			/* Check if PROCMAP_QUERY ioclt() finds the right VMA */
+			ASSERT_TRUE(query_addr_at(self->maps_fd, mod_info->addr + self->page_size,
+						  &vma_start, &vma_end));
+			/*
+			 * The vma at the split address can be either the same as
+			 * original one (if read before the split) or the same as the
+			 * first line in the second page (if read after the split).
+			 */
+			ASSERT_TRUE((vma_start == self->last_line.start_addr &&
+				     vma_end == self->last_line.end_addr) ||
+				    (vma_start == split_first_line.start_addr &&
+				     vma_end == split_first_line.end_addr));
+		}
 		clock_gettime(CLOCK_MONOTONIC_COARSE, &end_ts);
 		end_test_iteration(&end_ts, self->verbose);
 	} while (end_ts.tv_sec - start_ts.tv_sec < self->duration_sec);
@@ -781,17 +868,18 @@ TEST_F(proc_maps_race, test_maps_tearing_from_resize)
 					strcmp(new_first_line.text, restored_first_line.text),
 					"Expand result invalid", self));
 		}
-
-		/* Check if PROCMAP_QUERY ioclt() finds the right VMA */
-		ASSERT_TRUE(query_addr_at(self->maps_fd, mod_info->addr, &vma_start, &vma_end));
-		/*
-		 * The vma should stay at the same address and have either the
-		 * original size of 3 pages or 1 page if read after shrinking.
-		 */
-		ASSERT_TRUE(vma_start == self->last_line.start_addr &&
-			    (vma_end - vma_start == self->page_size * 3 ||
-			     vma_end - vma_start == self->page_size));
-
+		if (self->maps_file == MAPS) {
+			/* Check if PROCMAP_QUERY ioclt() finds the right VMA */
+			ASSERT_TRUE(query_addr_at(self->maps_fd, mod_info->addr,
+						  &vma_start, &vma_end));
+			/*
+			 * The vma should stay at the same address and have either the
+			 * original size of 3 pages or 1 page if read after shrinking.
+			 */
+			ASSERT_TRUE(vma_start == self->last_line.start_addr &&
+				    (vma_end - vma_start == self->page_size * 3 ||
+				     vma_end - vma_start == self->page_size));
+		}
 		clock_gettime(CLOCK_MONOTONIC_COARSE, &end_ts);
 		end_test_iteration(&end_ts, self->verbose);
 	} while (end_ts.tv_sec - start_ts.tv_sec < self->duration_sec);
@@ -861,20 +949,20 @@ TEST_F(proc_maps_race, test_maps_tearing_from_remap)
 					strcmp(new_first_line.text, restored_first_line.text),
 					"Remap restore result invalid", self));
 		}
-
-		/* Check if PROCMAP_QUERY ioclt() finds the right VMA */
-		ASSERT_TRUE(query_addr_at(self->maps_fd, mod_info->addr + self->page_size,
-					  &vma_start, &vma_end));
-		/*
-		 * The vma should either stay at the same address and have the
-		 * original size of 3 pages or we should find the remapped vma
-		 * at the remap destination address with size of 1 page.
-		 */
-		ASSERT_TRUE((vma_start == self->last_line.start_addr &&
-			     vma_end - vma_start == self->page_size * 3) ||
-			    (vma_start == self->last_line.start_addr + self->page_size &&
-			     vma_end - vma_start == self->page_size));
-
+		if (self->maps_file == MAPS) {
+			/* Check if PROCMAP_QUERY ioclt() finds the right VMA */
+			ASSERT_TRUE(query_addr_at(self->maps_fd, mod_info->addr + self->page_size,
+						  &vma_start, &vma_end));
+			/*
+			 * The vma should either stay at the same address and have the
+			 * original size of 3 pages or we should find the remapped vma
+			 * at the remap destination address with size of 1 page.
+			 */
+			ASSERT_TRUE((vma_start == self->last_line.start_addr &&
+				     vma_end - vma_start == self->page_size * 3) ||
+				    (vma_start == self->last_line.start_addr + self->page_size &&
+				     vma_end - vma_start == self->page_size));
+		}
 		clock_gettime(CLOCK_MONOTONIC_COARSE, &end_ts);
 		end_test_iteration(&end_ts, self->verbose);
 	} while (end_ts.tv_sec - start_ts.tv_sec < self->duration_sec);
-- 
2.54.0.545.g6539524ca2-goog