Roger Pau Monne via llvm-dev
2017-Oct-26 09:19 UTC
[llvm-dev] [PATCH for-next 7/9] coverage: introduce support for llvm profiling
Introduce the functionality in order to fill the hooks of the
cov_sysctl_ops struct.
Signed-off-by: Roger Pau Monné <roger.pau at citrix.com>
---
Cc: Andrew Cooper <andrew.cooper3 at citrix.com>
Cc: George Dunlap <George.Dunlap at eu.citrix.com>
Cc: Ian Jackson <ian.jackson at eu.citrix.com>
Cc: Jan Beulich <jbeulich at suse.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Cc: Stefano Stabellini <sstabellini at kernel.org>
Cc: Tim Deegan <tim at xen.org>
Cc: Wei Liu <wei.liu2 at citrix.com>
Cc: llvm-dev at lists.llvm.org
---
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.
---
xen/common/coverage/Makefile | 2 +-
xen/common/coverage/llvm.c | 148 +++++++++++++++++++++++++++++++++++++++++++
xen/include/public/sysctl.h | 6 ++
3 files changed, 155 insertions(+), 1 deletion(-)
create mode 100644 xen/common/coverage/llvm.c
diff --git a/xen/common/coverage/Makefile b/xen/common/coverage/Makefile
index e4541a1233..f2ffb2b8de 100644
--- a/xen/common/coverage/Makefile
+++ b/xen/common/coverage/Makefile
@@ -11,5 +11,5 @@ obj-$(CONFIG_GCOV_FORMAT_AUTODETECT) += $(call
cc-ifversion,lt,0x040700, \
gcc_4_9.o, $(call cc-ifversion,lt,0x070000, \
gcc_5.o, gcc_7.o))))
else
-obj-y += coverage.o
+obj-y += llvm.o coverage.o
endif
diff --git a/xen/common/coverage/llvm.c b/xen/common/coverage/llvm.c
new file mode 100644
index 0000000000..c8905070a3
--- /dev/null
+++ b/xen/common/coverage/llvm.c
@@ -0,0 +1,148 @@
+/*
+ * 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 <xen/coverage.h>
+
+#ifndef __clang__
+#error "LLVM coverage selected without clang compiler"
+#endif
+
+#define LLVM_PROFILE_MAGIC_64 (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
+#define LLVM_PROFILE_MAGIC_32 (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
+
+#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;
+};
+
+int __llvm_profile_runtime;
+
+extern struct llvm_profile_data __start___llvm_prf_data;
+extern struct llvm_profile_data __stop___llvm_prf_data;
+extern uint64_t __start___llvm_prf_cnts;
+extern uint64_t __stop___llvm_prf_cnts;
+extern char __start___llvm_prf_names;
+extern char __stop___llvm_prf_names;
+
+static void *start_data = &__start___llvm_prf_data;
+static void *end_data = &__stop___llvm_prf_data;
+static void *start_counters = &__start___llvm_prf_cnts;
+static void *end_counters = &__stop___llvm_prf_cnts;
+static void *start_names = &__start___llvm_prf_names;
+static void *end_names = &__stop___llvm_prf_names;
+
+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 = {
+#if BITS_PER_LONG == 64
+ .magic = LLVM_PROFILE_MAGIC_64,
+#else
+ .magic = LLVM_PROFILE_MAGIC_32,
+#endif
+ .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, src, size); \
+ off += size; \
+})
+ APPEND_TO_BUFFER((char *)&header, sizeof(struct llvm_profile_header));
+ APPEND_TO_BUFFER((char *)start_data, end_data - start_data);
+ APPEND_TO_BUFFER((char *)start_counters, end_counters - start_counters);
+ APPEND_TO_BUFFER((char *)start_names, end_names - start_names);
+#undef APPEND_TO_BUFFER
+
+ clear_guest_offset(buffer, off, *buf_size - off);
+
+ return 0;
+}
+
+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 654b37cdce..62824b18f2 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_COV_get_size 0 /* Get total size of output data */
#define XEN_SYSCTL_COV_read 1 /* Read output data */
#define XEN_SYSCTL_COV_reset 2 /* Reset all counters */
--
2.13.5 (Apple Git-94)
Roger Pau Monné via llvm-dev
2017-Nov-08 08:56 UTC
[llvm-dev] [PATCH for-next 7/9] coverage: introduce support for llvm profiling
On Wed, Nov 08, 2017 at 01:38:59AM -0700, Jan Beulich wrote:> >>> On 26.10.17 at 11:19, <roger.pau at citrix.com> wrote: > > --- /dev/null > > +++ b/xen/common/coverage/llvm.c > > +#define LLVM_PROFILE_MAGIC_64 (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 > > +#define LLVM_PROFILE_MAGIC_32 (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 > > Judging by the file having Xen style, I imply this isn't intended to > very closely match some other original. With that, parentheses > should be added around all the shift operations above. > > > +#if __clang_major__ >= 4 || (__clang_major__ == 3 && __clang_minor__ == 9) > > Is it certain that there's never going to be a 3.10? Otherwise > >= might be more suitable for the minor version check.No, there's not going to be a clang 3.10.> > +int __llvm_profile_runtime; > > This isn't used anywhere - please add a brief comment explaining > the need for it (the more that its type being plain int is also > suspicious).This is an internal symbol that must be present because Xen is not linked against the run-time coverage library. It's described as an int here: https://clang.llvm.org/docs/SourceBasedCodeCoverage.html#using-the-profiling-runtime-without-static-initializers Without this symbol linkage fails.> > +extern struct llvm_profile_data __start___llvm_prf_data; > > +extern struct llvm_profile_data __stop___llvm_prf_data; > > +extern uint64_t __start___llvm_prf_cnts; > > +extern uint64_t __stop___llvm_prf_cnts; > > +extern char __start___llvm_prf_names; > > +extern char __stop___llvm_prf_names; > > I guess all of these really want to have [] added, making ... > > > +static void *start_data = &__start___llvm_prf_data; > > +static void *end_data = &__stop___llvm_prf_data; > > +static void *start_counters = &__start___llvm_prf_cnts; > > +static void *end_counters = &__stop___llvm_prf_cnts; > > +static void *start_names = &__start___llvm_prf_names; > > +static void *end_names = &__stop___llvm_prf_names; > > ... the &s here unnecessary. But then - do these really need to > be statics (rather than #define-s)? > > I would also guess that at least the names ones could be const.Could make them defines indeed.> > + APPEND_TO_BUFFER((char *)start_data, end_data - start_data); > > + APPEND_TO_BUFFER((char *)start_counters, end_counters - start_counters); > > + APPEND_TO_BUFFER((char *)start_names, end_names - start_names); > > The casts should all be to const char*, and perhaps that would > better be done inside the macro anyway.Seems better indeed.> > --- 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 */ > > Hmm, shouldn't the private magic #define-s actually be put here > (in which case you'd indeed need to retain both 32- and 64-bit > variants)?I don't think so, here XEN_GCOV_FORMAT_MAGIC is a Xen specific gcov magic number. OTOH LLVM_PROFILE_MAGIC_{64/32} is an llvm defined magic number, that's not under our control. Hence I don't think it should be exported in Xen public headers. Roger.