gcov: Implement code to read coverage informations

Operations are handled by a sysctl specific operation.

Implement 4 operations
- check if coverage is compiled in
- read size of coverage information
- read coverage information
- reset coverage counters

Information are stored in a single blob in a format specific to Xen designed
to make code that generate coverage as small as possible.

This patch add a public header with the structure of blob exported by Xen.
This avoid problems distributing header which is GPL2.

Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>

2 files changed, 153 insertions, 0 deletions

diff --git a/xen/include/public/gcov.h b/xen/include/public/gcov.h
new file mode 100644
index 0000000000..1b29b48a7a
--- /dev/null
+++ b/xen/include/public/gcov.h
@@ -0,0 +1,115 @@
+/******************************************************************************
+ * gcov.h
+ *
+ * Coverage structures exported by Xen.
+ * Structure is different from Gcc one.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Copyright (c) 2013, Citrix Systems R&D Ltd.
+ */
+
+#ifndef __XEN_PUBLIC_GCOV_H__
+#define __XEN_PUBLIC_GCOV_H__ __XEN_PUBLIC_GCOV_H__
+
+#define XENCOV_COUNTERS         5
+#define XENCOV_TAG_BASE         0x58544300u
+#define XENCOV_TAG_FILE         (XENCOV_TAG_BASE+0x46u)
+#define XENCOV_TAG_FUNC         (XENCOV_TAG_BASE+0x66u)
+#define XENCOV_TAG_COUNTER(n)   (XENCOV_TAG_BASE+0x30u+((n)&0xfu))
+#define XENCOV_TAG_END          (XENCOV_TAG_BASE+0x2eu)
+#define XENCOV_IS_TAG_COUNTER(n) \
+    ((n) >= XENCOV_TAG_COUNTER(0) && (n) < XENCOV_TAG_COUNTER(XENCOV_COUNTERS))
+#define XENCOV_COUNTER_NUM(n) ((n)-XENCOV_TAG_COUNTER(0))
+
+/*
+ * The main structure for the blob is
+ * BLOB := FILE.. END
+ * FILE := TAG_FILE VERSION STAMP FILENAME COUNTERS FUNCTIONS
+ * FILENAME := LEN characters
+ *   characters are padded to 32 bit
+ * LEN := 32 bit value
+ * COUNTERS := TAG_COUNTER(n) NUM COUNTER..
+ * NUM := 32 bit valie
+ * COUNTER := 64 bit value
+ * FUNCTIONS := TAG_FUNC NUM FUNCTION..
+ * FUNCTION := IDENT CHECKSUM NUM_COUNTERS
+ *
+ * All tagged structures are aligned to 8 bytes
+ */
+
+/**
+ * File information
+ * Prefixed with XENCOV_TAG_FILE and a string with filename
+ * Aligned to 8 bytes
+ */
+struct xencov_file
+{
+    uint32_t tag; /* XENCOV_TAG_FILE */
+    uint32_t version;
+    uint32_t stamp;
+    uint32_t fn_len;
+    char filename[1];
+};
+
+
+/**
+ * Counters information
+ * Prefixed with XENCOV_TAG_COUNTER(n) where n is 0..(XENCOV_COUNTERS-1)
+ * Aligned to 8 bytes
+ */
+struct xencov_counter
+{
+    uint32_t tag; /* XENCOV_TAG_COUNTER(n) */
+    uint32_t num;
+    uint64_t values[1];
+};
+
+/**
+ * Information for each function
+ * Number of counter is equal to the number of counter structures got before
+ */
+struct xencov_function
+{
+    uint32_t ident;
+    uint32_t checksum;
+    uint32_t num_counters[1];
+};
+
+/**
+ * Information for all functions
+ * Aligned to 8 bytes
+ */
+struct xencov_functions
+{
+    uint32_t tag; /* XENCOV_TAG_FUNC */
+    uint32_t num;
+    struct xencov_function xencov_function[1];
+};
+
+/**
+ * Terminator
+ */
+struct xencov_end
+{
+    uint32_t tag; /* XENCOV_TAG_END */
+};
+
+#endif /* __XEN_PUBLIC_GCOV_H__ */
+
diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index bd33e033e0..3ca51beb95 100644
--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -596,6 +596,42 @@ struct xen_sysctl_scheduler_op {
 typedef struct xen_sysctl_scheduler_op xen_sysctl_scheduler_op_t;
 DEFINE_XEN_GUEST_HANDLE(xen_sysctl_scheduler_op_t);
 
+/* XEN_SYSCTL_coverage_op */
+/*
+ * Get total size of information, to help allocate
+ * the buffer. The pointer points to a 32 bit value.
+ */
+#define XEN_SYSCTL_COVERAGE_get_total_size 0
+
+/*
+ * Read coverage information in a single run
+ * You must use a tool to split them.
+ */
+#define XEN_SYSCTL_COVERAGE_read           1
+
+/*
+ * Reset all the coverage counters to 0
+ * No parameters.
+ */
+#define XEN_SYSCTL_COVERAGE_reset          2
+
+/*
+ * Like XEN_SYSCTL_COVERAGE_read but reset also
+ * counters to 0 in a single call.
+ */
+#define XEN_SYSCTL_COVERAGE_read_and_reset 3
+
+struct xen_sysctl_coverage_op {
+    uint32_t cmd;        /* XEN_SYSCTL_COVERAGE_* */
+    union {
+        uint32_t total_size; /* OUT */
+        XEN_GUEST_HANDLE_64(uint8)  raw_info;   /* OUT */
+    } u;
+};
+typedef struct xen_sysctl_coverage_op xen_sysctl_coverage_op_t;
+DEFINE_XEN_GUEST_HANDLE(xen_sysctl_coverage_op_t);
+
+
 struct xen_sysctl {
     uint32_t cmd;
 #define XEN_SYSCTL_readconsole                    1
@@ -616,6 +652,7 @@ struct xen_sysctl {
 #define XEN_SYSCTL_numainfo                      17
 #define XEN_SYSCTL_cpupool_op                    18
 #define XEN_SYSCTL_scheduler_op                  19
+#define XEN_SYSCTL_coverage_op                   20
     uint32_t interface_version; /* XEN_SYSCTL_INTERFACE_VERSION */
     union {
         struct xen_sysctl_readconsole       readconsole;
@@ -636,6 +673,7 @@ struct xen_sysctl {
         struct xen_sysctl_lockprof_op       lockprof_op;
         struct xen_sysctl_cpupool_op        cpupool_op;
         struct xen_sysctl_scheduler_op      scheduler_op;
+        struct xen_sysctl_coverage_op       coverage_op;
         uint8_t                             pad[128];
     } u;
 };