zephyr: test: Test get_panic_data_write()

Test the get_panic_data_write() implementation used in device builds

Also remove an unreachable `else` statement from the function (The jump
data version cannot be anything other than 1, 2, or 3 since we check
that a few lines above)

BRANCH=None
BUG=None
TEST=./twister

Signed-off-by: Tristan Honscheid <honscheid@google.com>

Change-Id: Ie83cf3c655662498ef6a487d51d39c65d790de2d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/4052122
Commit-Queue: Tristan Honscheid <honscheid@google.com>
Code-Coverage: Zoss <zoss-cl-coverage@prod.google.com>
Tested-by: Tristan Honscheid <honscheid@google.com>
Reviewed-by: Tomasz Michalec <tmichalec@google.com>

3 files changed, 215 insertions, 4 deletions

diff --git a/common/panic_output.c b/common/panic_output.c
index 066eb05d6f..87b83043f3 100644
--- a/common/panic_output.c
+++ b/common/panic_output.c
@@ -256,16 +256,13 @@ test_mockable struct panic_data *get_panic_data_write(void)
 		return pdata_ptr;
 	}
 
+	move_size = 0;
 	if (jdata_ptr->version == 1)
 		move_size = JUMP_DATA_SIZE_V1;
 	else if (jdata_ptr->version == 2)
 		move_size = JUMP_DATA_SIZE_V2 + jdata_ptr->jump_tag_total;
 	else if (jdata_ptr->version == 3)
 		move_size = jdata_ptr->struct_size + jdata_ptr->jump_tag_total;
-	else {
-		/* Unknown jump data version - set move size to 0 */
-		move_size = 0;
-	}
 
 	/* Check if there's enough space for jump tags after move */
 	if (data_begin - move_size < JUMP_DATA_MIN_ADDRESS) {
@@ -273,8 +270,12 @@ test_mockable struct panic_data *get_panic_data_write(void)
 		 * TODO(b/251190975): This failure should be reported
 		 * in the panic data structure for more visibility.
 		 */
+		/* LCOV_EXCL_START - JUMP_DATA_MIN_ADDRESS is 0 in test builds
+		 * and we cannot go negative by subtracting unsigned ints.
+		 */
 		move_size -= jdata_ptr->jump_tag_total;
 		jdata_ptr->jump_tag_total = 0;
+		/* LCOV_EXCL_STOP */
 	}
 
 	data_begin -= move_size;
diff --git a/zephyr/test/drivers/panic_output/CMakeLists.txt b/zephyr/test/drivers/panic_output/CMakeLists.txt
index 79cf21fc5f..c9b50b0365 100644
--- a/zephyr/test/drivers/panic_output/CMakeLists.txt
+++ b/zephyr/test/drivers/panic_output/CMakeLists.txt
@@ -5,4 +5,5 @@
 # Add source files
 target_sources(app PRIVATE
   src/panic_output_crash_cmd.c
+  src/panic_output_get_panic_data_write.c
 )
diff --git a/zephyr/test/drivers/panic_output/src/panic_output_get_panic_data_write.c b/zephyr/test/drivers/panic_output/src/panic_output_get_panic_data_write.c
new file mode 100644
index 0000000000..e1f4cda84c
--- /dev/null
+++ b/zephyr/test/drivers/panic_output/src/panic_output_get_panic_data_write.c
@@ -0,0 +1,209 @@
+/* Copyright 2022 The ChromiumOS Authors
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <zephyr/ztest.h>
+#include <zephyr/ztest_assert.h>
+
+#include "panic.h"
+#include "sysjump.h"
+#include "test/drivers/test_state.h"
+
+/**
+ * @brief Returns a pointer to an object (such as a struct jump_data) of type
+ *        TYPE at the end of the mock_jump_data memory region, plus an optional,
+ *        additional offset of OFFSET bytes. OFFSET can be used to help get the
+ *        pointer after jump data has been moved by get_panic_data_write(), or
+ *        left as zero to get the pre-move location.
+ */
+#define GET_JUMP_DATA_PTR(TYPE, OFFSET)                                    \
+	((TYPE *)(mock_jump_data + sizeof(mock_jump_data) - sizeof(TYPE) + \
+		  (OFFSET)))
+
+ZTEST(panic_output_get_panic_data_write, test_existing_panic_data)
+{
+	struct panic_data *pdata_actual = test_get_panic_data_pointer();
+
+	/* Pretend panic data exists by setting the magic header and setting its
+	 * size.
+	 */
+	pdata_actual->magic = PANIC_DATA_MAGIC;
+	pdata_actual->struct_size = CONFIG_PANIC_DATA_SIZE;
+
+	/* Verify that pdata_ptr is returned */
+	zassert_equal(pdata_actual, get_panic_data_write());
+}
+
+ZTEST(panic_output_get_panic_data_write, test_no_panic_data__no_jump_data)
+{
+	struct panic_data *pdata_actual = test_get_panic_data_pointer();
+	struct panic_data pdata_expected = {
+		.magic = PANIC_DATA_MAGIC,
+		.struct_size = CONFIG_PANIC_DATA_SIZE,
+	};
+
+	/* Don't fill in any panic data, but add some fake data so we can ensure
+	 * it gets reset to zero.
+	 */
+	pdata_actual->flags = 0xFF;
+
+	/* Verify that pdata_ptr is returned */
+	zassert_equal(pdata_actual, get_panic_data_write());
+
+	/* Verify the pdata struct has correct fields filled out. */
+	zassert_mem_equal(&pdata_expected, pdata_actual,
+			  sizeof(struct panic_data));
+}
+
+/**
+ * @brief Implements the fields of a version 1 jump_data header.
+ *
+ */
+struct jump_data_v1 {
+	/** V1 Jump data header, always goes at end. See sysjump.h for info */
+
+	uint32_t reset_flags;
+	int version;
+	int magic;
+};
+
+/* Test that V1 jump data is moved correctly. */
+ZTEST(panic_output_get_panic_data_write, test_no_panic_data__jump_data_v1)
+{
+	struct panic_data *pdata_actual = test_get_panic_data_pointer();
+	struct jump_data_v1 jdata_expected = {
+		.magic = JUMP_DATA_MAGIC,
+		.version = 1,
+		.reset_flags = 0xAABBCCDD,
+	};
+
+	/* Set up some jump data. Version 1 does not have any jump tags, only
+	 * the magic, version number, and reset_flags so it is constant size.
+	 */
+	*GET_JUMP_DATA_PTR(struct jump_data_v1, 0) = jdata_expected;
+
+	/* Verify that pdata_ptr is returned */
+	zassert_equal(pdata_actual, get_panic_data_write());
+
+	/* Verify that jump data has been moved to its new location */
+	ssize_t expected_move_delta = -1 * sizeof(struct panic_data);
+	struct jump_data_v1 *jdata_moved =
+		GET_JUMP_DATA_PTR(struct jump_data_v1, expected_move_delta);
+
+	zassert_mem_equal(&jdata_expected, jdata_moved,
+			  sizeof(struct jump_data_v1));
+}
+
+/**
+ * @brief Implements a V2 jump_data header plus some extra bytes in front that
+ *        represent jump tag data. This reflects how they are stored in the EC's
+ *        memory. The jump_tag_total field in jdata stored how many bytes of
+ *        preceding jump tag data exists.
+ */
+struct jump_data_v2_plus_tags {
+	/** Arbitrary amount of jump tag data. */
+	uint8_t tag_data[8];
+	/** V2 Jump data header, always goes at end. See sysjump.h for info */
+	struct {
+		int jump_tag_total;
+		uint32_t reset_flags;
+		int version;
+		int magic;
+	} jdata;
+};
+
+/* Test that V2 jump data is moved correctly. */
+ZTEST(panic_output_get_panic_data_write, test_no_panic_data__jump_data_v2)
+{
+	struct panic_data *pdata_actual = test_get_panic_data_pointer();
+	struct jump_data_v2_plus_tags jdata_expected = {
+		/* Arbitrary jump tag data */
+		.tag_data = {1, 2, 3, 4, 5, 6, 7, 8},
+		.jdata = {
+			.magic = JUMP_DATA_MAGIC,
+			.version = 2,
+			.reset_flags = 0xAABBCCDD,
+			.jump_tag_total = sizeof(jdata_expected.tag_data),
+		},
+	};
+
+	/* Set up some jump data and preceding tags */
+	*GET_JUMP_DATA_PTR(struct jump_data_v2_plus_tags, 0) = jdata_expected;
+
+	/* Verify that pdata_ptr is returned */
+	zassert_equal(pdata_actual, get_panic_data_write());
+
+	/* Verify that jump data and tags moved to their new location */
+	ssize_t expected_move_delta = -1 * sizeof(struct panic_data);
+	struct jump_data_v2_plus_tags *jdata_moved = GET_JUMP_DATA_PTR(
+		struct jump_data_v2_plus_tags, expected_move_delta);
+
+	zassert_mem_equal(&jdata_expected, jdata_moved,
+			  sizeof(struct jump_data_v2_plus_tags));
+}
+
+/**
+ * @brief Implements a V3 jump_data header with space in front for jump tag data
+ */
+struct jump_data_v3_plus_tags {
+	/** Arbitrary amount of jump tag data. */
+	uint8_t tag_data[8];
+	/** V3 Jump data header, always goes at end. See sysjump.h for info */
+	struct {
+		uint8_t reserved0;
+		int struct_size;
+		int jump_tag_total;
+		uint32_t reset_flags;
+		int version;
+		int magic;
+	} jdata;
+};
+
+/* Test that V3 jump data is moved correctly. */
+ZTEST(panic_output_get_panic_data_write, test_no_panic_data__jump_data_v3)
+{
+	struct panic_data *pdata_actual = test_get_panic_data_pointer();
+	struct jump_data_v3_plus_tags jdata_expected = {
+		/* Arbitrary jump tag data */
+		.tag_data = {1, 2, 3, 4, 5, 6, 7, 8},
+		.jdata = {
+			.magic = JUMP_DATA_MAGIC,
+			.version = 3,
+			.reset_flags = 0xAABBCCDD,
+			.jump_tag_total = sizeof(jdata_expected.tag_data),
+			.struct_size = sizeof(jdata_expected.jdata),
+			.reserved0 = 0xFF,
+		},
+	};
+
+	/* Set up some jump data and preceding tags */
+	*GET_JUMP_DATA_PTR(struct jump_data_v3_plus_tags, 0) = jdata_expected;
+
+	/* Verify that pdata_ptr is returned */
+	zassert_equal(pdata_actual, get_panic_data_write());
+
+	/* Verify that jump data and tags moved to their new location */
+	ssize_t expected_move_delta = -1 * sizeof(struct panic_data);
+	struct jump_data_v3_plus_tags *jdata_moved = GET_JUMP_DATA_PTR(
+		struct jump_data_v3_plus_tags, expected_move_delta);
+
+	zassert_mem_equal(&jdata_expected, jdata_moved,
+			  sizeof(struct jump_data_v3_plus_tags));
+}
+
+static void reset(void *data)
+{
+	ARG_UNUSED(data);
+
+	struct panic_data *pdata = test_get_panic_data_pointer();
+
+	memset(pdata, 0, sizeof(struct panic_data));
+	memset(mock_jump_data, 0, sizeof(mock_jump_data));
+}
+
+ZTEST_SUITE(panic_output_get_panic_data_write, drivers_predicate_post_main,
+	    NULL, reset, reset, NULL);