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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v3 5/7] 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@xxxxxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Tim Deegan <tim@xxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
Note that the file that contains the helpers is under a BSD 2-clause
license. This is done so it can be shared with other OSes that use the
llvm/clang compiler.
---
Changes since v1:
- Include private coverage.h header.
- Define LLVM_PROFILE_MAGIC based on the bitness of the arch.
- Add a comment regarding __llvm_profile_runtime.
- Constify data/names extern symbols.
- Use defines instead of variables to store the addresses of the
external symbols.
- Parenthesize size in APPEND_TO_BUFFER.
- Use >= for minor version check.
- Use sizeof(header).
---
xen/common/coverage/Makefile | 2 +
xen/common/coverage/llvm.c | 154 +++++++++++++++++++++++++++++++++++++++++++
xen/include/public/sysctl.h | 6 ++
3 files changed, 162 insertions(+)
create mode 100644 xen/common/coverage/llvm.c
diff --git a/xen/common/coverage/Makefile b/xen/common/coverage/Makefile
index 1039a160c4..46c78d1086 100644
--- 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
index 0000000000..889699a9a0
--- /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 ef10368d79..cfc7b11de8 100644
--- 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 */
--
2.15.1
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