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>

1 files changed, 153 insertions, 0 deletions

diff --git a/xen/common/gcov/gcov.c b/xen/common/gcov/gcov.c
index 4de4b58d3d..01d5b1066e 100644
--- a/xen/common/gcov/gcov.c
+++ b/xen/common/gcov/gcov.c
@@ -19,6 +19,9 @@
 #include <xen/hypercall.h>
 #include <xen/gcov.h>
 #include <xen/errno.h>
+#include <xen/guest_access.h>
+#include <public/xen.h>
+#include <public/gcov.h>
 
 static struct gcov_info *info_list;
 
@@ -61,6 +64,156 @@ void __gcov_merge_delta(gcov_type *counters, unsigned int n_counters)
     /* Unused. */
 }
 
+static inline int counter_active(const struct gcov_info *info, unsigned int type)
+{
+    return (1 << type) & info->ctr_mask;
+}
+
+typedef struct write_iter_t
+{
+    XEN_GUEST_HANDLE(uint8) ptr;
+    int real;
+    uint32_t write_offset;
+} write_iter_t;
+
+static int write_raw(struct write_iter_t *iter, const void *data,
+                     size_t data_len)
+{
+    if ( iter->real &&
+        copy_to_guest_offset(iter->ptr, iter->write_offset,
+                             (const unsigned char *) data, data_len) )
+        return -EFAULT;
+
+    iter->write_offset += data_len;
+    return 0;
+}
+
+#define chk(v) do { ret=(v); if ( ret ) return ret; } while(0)
+
+static inline int write32(write_iter_t *iter, uint32_t val)
+{
+    return write_raw(iter, &val, sizeof(val));
+}
+
+static int write_string(write_iter_t *iter, const char *s)
+{
+    int ret;
+    size_t len = strlen(s);
+
+    chk(write32(iter, len));
+    return write_raw(iter, s, len);
+}
+
+static inline int next_type(const struct gcov_info *info, int *type)
+{
+    while ( ++*type < XENCOV_COUNTERS && !counter_active(info, *type) )
+        continue;
+    return *type;
+}
+
+static inline void align_iter(write_iter_t *iter)
+{
+    iter->write_offset =
+        (iter->write_offset + sizeof(uint64_t) - 1) & -sizeof(uint64_t);
+}
+
+static int write_gcov(write_iter_t *iter)
+{
+    struct gcov_info *info;
+    int ret;
+
+    /* reset offset */
+    iter->write_offset = 0;
+
+    /* dump all files */
+    for ( info = info_list ; info; info = info->next )
+    {
+        const struct gcov_ctr_info *ctr;
+        int type;
+        size_t size_fn = sizeof(struct gcov_fn_info);
+
+        align_iter(iter);
+        chk(write32(iter, XENCOV_TAG_FILE));
+        chk(write32(iter, info->version));
+        chk(write32(iter, info->stamp));
+        chk(write_string(iter, info->filename));
+
+        /* dump counters */
+        ctr = info->counts;
+        for ( type = -1; next_type(info, &type) < XENCOV_COUNTERS; ++ctr )
+        {
+            align_iter(iter);
+            chk(write32(iter, XENCOV_TAG_COUNTER(type)));
+            chk(write32(iter, ctr->num));
+            chk(write_raw(iter, ctr->values,
+                          ctr->num * sizeof(ctr->values[0])));
+
+            size_fn += sizeof(unsigned);
+        }
+
+        /* dump all functions together */
+        align_iter(iter);
+        chk(write32(iter, XENCOV_TAG_FUNC));
+        chk(write32(iter, info->n_functions));
+        chk(write_raw(iter, info->functions, info->n_functions * size_fn));
+    }
+
+    /* stop tag */
+    align_iter(iter);
+    chk(write32(iter, XENCOV_TAG_END));
+    return 0;
+}
+
+static int reset_counters(void)
+{
+    struct gcov_info *info;
+
+    for ( info = info_list ; info; info = info->next )
+    {
+        const struct gcov_ctr_info *ctr;
+        int type;
+
+        /* reset counters */
+        ctr = info->counts;
+        for ( type = -1; next_type(info, &type) < XENCOV_COUNTERS; ++ctr )
+            memset(ctr->values, 0, ctr->num * sizeof(ctr->values[0]));
+    }
+
+    return 0;
+}
+
+int sysctl_coverage_op(xen_sysctl_coverage_op_t *op)
+{
+    int ret = -EINVAL;
+    write_iter_t iter;
+
+    switch ( op->cmd )
+    {
+    case XEN_SYSCTL_COVERAGE_get_total_size:
+        iter.real = 0;
+
+        write_gcov(&iter);
+        op->u.total_size = iter.write_offset;
+        ret = 0;
+        break;
+
+    case XEN_SYSCTL_COVERAGE_read_and_reset:
+    case XEN_SYSCTL_COVERAGE_read:
+        iter.ptr = op->u.raw_info;
+        iter.real = 1;
+
+        ret = write_gcov(&iter);
+        if ( ret || op->cmd != XEN_SYSCTL_COVERAGE_read_and_reset )
+            break;
+
+        /* fall through */
+    case XEN_SYSCTL_COVERAGE_reset:
+        ret = reset_counters();
+        break;
+    }
+    return ret;
+}
+
 /*
  * Local variables:
  * mode: C