coverage: introduce support for llvm profiling

Introduce the functionality in order to fill the hooks of the
cov_sysctl_ops struct. Note that the functionality is still not wired
into the build system.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/common/coverage/Makefile b/xen/common/coverage/Makefile
index 1039a160c4f7b7074083d0f83298846d4f4a23df..46c78d1086d6ba4380285be2baa1946f636b02d1 100644 (file)
--- a/xen/common/coverage/Makefile
+++ b/xen/common/coverage/Makefile
@@ -6,4 +6,6 @@ obj-y += $(call cc-ifversion,lt,0x040700, \
                gcc_4_7.o, $(call cc-ifversion,lt,0x050000, \
                gcc_4_9.o, $(call cc-ifversion,lt,0x070000, \
                gcc_5.o, gcc_7.o))))
+else
+obj-y += llvm.o
 endif

diff --git a/xen/common/coverage/llvm.c b/xen/common/coverage/llvm.c
new file mode 100644 (file)
index 0000000..766c07f
--- /dev/null
+++ b/xen/common/coverage/llvm.c
@@ -0,0 +1,154 @@
+/*
+ * Copyright (C) 2017 Citrix Systems R&D
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <xen/errno.h>
+#include <xen/guest_access.h>
+#include <xen/types.h>
+
+#include "coverage.h"
+
+#ifndef __clang__
+#error "LLVM coverage selected without clang compiler"
+#endif
+
+#if BITS_PER_LONG == 64
+#define LLVM_PROFILE_MAGIC (((uint64_t)255 << 56) | ((uint64_t)'l' << 48) | \
+    ((uint64_t)'p' << 40) | ((uint64_t)'r' << 32) | ((uint64_t)'o' << 24) | \
+    ((uint64_t)'f' << 16) | ((uint64_t)'r' << 8)  | ((uint64_t)129))
+#else
+#define LLVM_PROFILE_MAGIC (((uint64_t)255 << 56) | ((uint64_t)'l' << 48) | \
+    ((uint64_t)'p' << 40) | ((uint64_t)'r' << 32) | ((uint64_t)'o' << 24) | \
+    ((uint64_t)'f' << 16) | ((uint64_t)'R' << 8)  | ((uint64_t)129)
+#endif
+
+#if __clang_major__ >= 4 || (__clang_major__ == 3 && __clang_minor__ >= 9)
+#define LLVM_PROFILE_VERSION    4
+#define LLVM_PROFILE_NUM_KINDS  2
+#else
+#error "clang version not supported with coverage"
+#endif
+
+struct llvm_profile_data {
+    uint64_t name_ref;
+    uint64_t function_hash;
+    void *counter;
+    void *function;
+    void *values;
+    uint32_t nr_counters;
+    uint16_t nr_value_sites[LLVM_PROFILE_NUM_KINDS];
+};
+
+struct llvm_profile_header {
+    uint64_t magic;
+    uint64_t version;
+    uint64_t data_size;
+    uint64_t counters_size;
+    uint64_t names_size;
+    uint64_t counters_delta;
+    uint64_t names_delta;
+    uint64_t value_kind_last;
+};
+
+/*
+ * Since Xen uses the llvm code coverage support without the run time library
+ * __llvm_profile_runtime must be defined according to the docs at:
+ *
+ * https://clang.llvm.org/docs/SourceBasedCodeCoverage.html 
+ */
+int __llvm_profile_runtime;
+
+extern const struct llvm_profile_data __start___llvm_prf_data[];
+extern const struct llvm_profile_data __stop___llvm_prf_data[];
+extern const char __start___llvm_prf_names[];
+extern const char __stop___llvm_prf_names[];
+extern uint64_t __start___llvm_prf_cnts[];
+extern uint64_t __stop___llvm_prf_cnts[];
+
+#define START_DATA      ((const void *)__start___llvm_prf_data)
+#define END_DATA        ((const void *)__stop___llvm_prf_data)
+#define START_NAMES     ((const void *)__start___llvm_prf_names)
+#define END_NAMES       ((const void *)__stop___llvm_prf_names)
+#define START_COUNTERS  ((void *)__start___llvm_prf_cnts)
+#define END_COUNTERS    ((void *)__stop___llvm_prf_cnts)
+
+static void reset_counters(void)
+{
+    memset(START_COUNTERS, 0, END_COUNTERS - START_COUNTERS);
+}
+
+static uint32_t get_size(void)
+{
+    return ROUNDUP(sizeof(struct llvm_profile_header) + END_DATA - START_DATA +
+                   END_COUNTERS - START_COUNTERS + END_NAMES - START_NAMES, 8);
+}
+
+static int dump(XEN_GUEST_HANDLE_PARAM(char) buffer, uint32_t *buf_size)
+{
+    struct llvm_profile_header header = {
+        .magic = LLVM_PROFILE_MAGIC,
+        .version = LLVM_PROFILE_VERSION,
+        .data_size = (END_DATA - START_DATA) / sizeof(struct llvm_profile_data),
+        .counters_size = (END_COUNTERS - START_COUNTERS) / sizeof(uint64_t),
+        .names_size = END_NAMES - START_NAMES,
+        .counters_delta = (uintptr_t)START_COUNTERS,
+        .names_delta = (uintptr_t)START_NAMES,
+        .value_kind_last = LLVM_PROFILE_NUM_KINDS - 1,
+    };
+    unsigned int off = 0;
+
+#define APPEND_TO_BUFFER(src, size)                             \
+({                                                              \
+    if ( off + (size) > *buf_size )                             \
+        return -ENOMEM;                                         \
+    copy_to_guest_offset(buffer, off, (const char *)src, size); \
+    off += (size);                                              \
+})
+    APPEND_TO_BUFFER(&header, sizeof(header));
+    APPEND_TO_BUFFER(START_DATA, END_DATA - START_DATA);
+    APPEND_TO_BUFFER(START_COUNTERS, END_COUNTERS - START_COUNTERS);
+    APPEND_TO_BUFFER(START_NAMES, END_NAMES - START_NAMES);
+#undef APPEND_TO_BUFFER
+
+    clear_guest_offset(buffer, off, *buf_size - off);
+
+    return 0;
+}
+
+const struct cov_sysctl_ops cov_ops = {
+    .get_size = get_size,
+    .reset_counters = reset_counters,
+    .dump = dump,
+};
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */

diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index ef10368d79af8ec69539700c245a33903823d89c..cfc7b11de84cbf5be7689a2dfc2f22a6d7bfa943 100644 (file)
--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -646,6 +646,12 @@ struct xen_sysctl_scheduler_op {
 
 #define XEN_GCOV_FORMAT_MAGIC    0x58434f56 /* XCOV */
 
+/*
+ * Ouput format of LLVM coverage data is just a raw stream, as would be
+ * written by the compiler_rt run time library into a .profraw file. There
+ * are no special Xen tags or delimiters because none are needed.
+ */
+
 #define XEN_SYSCTL_COVERAGE_get_size 0 /* Get total size of output data */
 #define XEN_SYSCTL_COVERAGE_read     1 /* Read output data */
 #define XEN_SYSCTL_COVERAGE_reset    2 /* Reset all counters */