[PATCH v5] Coverage support

[PATCH v5] Coverage support

[Frediano Ziglio]

Updated set of patches for coverage.

Changes:
- separate construction handling, this is not strictly related to coverage.
  Support it even on ARM.
- Rewrite blob format to allow portable definition of structures used and
  without compiler extensions used.
- remove RFC from subject.

[PATCH 1/5] Call constructors during initialization

[Frediano Ziglio]

This allow modules to set initializer functions.
This is used by Gcc instrumentation code for profiling arcs and test
coverage.
---
 xen/arch/arm/setup.c   |    2 ++
 xen/arch/arm/xen.lds.S |    7 +++++++
 xen/arch/x86/setup.c   |    2 ++
 xen/arch/x86/xen.lds.S |    7 +++++++
 xen/common/lib.c       |   16 ++++++++++++++++
 xen/include/xen/lib.h  |    2 ++
 6 files changed, 36 insertions(+)

diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index e1ab7f6..4b98dd8 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -445,6 +445,8 @@ void __init start_xen(unsigned long boot_phys_offset,
        scrub_heap_pages();
     */
 
+    init_constructors();
+
     console_endboot();
 
     /* Hide UART from DOM0 if we're using it */
diff --git a/xen/arch/arm/xen.lds.S b/xen/arch/arm/xen.lds.S
index 410d7db..bc9eae9 100644
--- a/xen/arch/arm/xen.lds.S
+++ b/xen/arch/arm/xen.lds.S
@@ -84,6 +84,13 @@ SECTIONS
        *(.init.data)
        *(.init.data.rel)
        *(.init.data.rel.*)
+
+       . = ALIGN(8);
+       __CTOR_LIST__ = .;
+       QUAD((__CTOR_END__ - __CTOR_LIST__) / 8 - 2)
+       *(.ctors)
+       QUAD(0)
+       __CTOR_END__ = .;
   } :text
   . = ALIGN(32);
   .init.setup : {
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index f4d3788..a75066e 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1313,6 +1313,8 @@ void __init __start_xen(unsigned long mbi_p)
 
     init_trace_bufs();
 
+    init_constructors();
+
     console_endboot();
 
     /* Hide UART from DOM0 if we're using it */
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index d324afd..5570389 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -108,6 +108,13 @@ SECTIONS
        __trampoline_seg_start = .;
        *(.trampoline_seg)
        __trampoline_seg_stop = .;
+
+       . = ALIGN(8);
+       __CTOR_LIST__ = .;
+       QUAD((__CTOR_END__ - __CTOR_LIST__) / 8 - 2)
+       *(.ctors)
+       QUAD(0)
+       __CTOR_END__ = .;
   } :text
   . = ALIGN(32);
   .init.setup : {
diff --git a/xen/common/lib.c b/xen/common/lib.c
index 03c8b8b..715df82 100644
--- a/xen/common/lib.c
+++ b/xen/common/lib.c
@@ -2,6 +2,7 @@
 #include <xen/ctype.h>
 #include <xen/lib.h>
 #include <xen/types.h>
+#include <xen/init.h>
 #include <asm/byteorder.h>
 
 /* for ctype.h */
@@ -478,6 +479,21 @@ unsigned long long parse_size_and_unit(const char *s, const char **ps)
     return ret;
 }
 
+typedef void (*ctor_func_t)(void);
+
+extern const struct
+{
+    unsigned long count;
+    ctor_func_t funcs[1];
+} __CTOR_LIST__;
+
+void __init init_constructors(void)
+{
+    unsigned long n;
+    for ( n = 0; n < __CTOR_LIST__.count; ++n )
+        __CTOR_LIST__.funcs[n]();
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h
index f7074cf..d856ab1 100644
--- a/xen/include/xen/lib.h
+++ b/xen/include/xen/lib.h
@@ -125,4 +125,6 @@ extern void add_taint(unsigned);
 struct cpu_user_regs;
 void dump_execstate(struct cpu_user_regs *);
 
+void init_constructors(void);
+
 #endif /* __LIB_H__ */
-- 
1.7.9.5

[PATCH 2/5] Adding support for coverage information

[Frediano Ziglio]

This patch introduce coverage support to Xen.
Currently it allows to compile Xen with coverage support but there is no
way to extract them.

The declarations came from Linux source files (as you can see from file
headers).

The idea is to have some operations mainly
- get coverage information size
- read coverage information
- reset coverage counters

Linux use a file system to export these information. The information will
be a blob to handle with some tools (as usually tools require a bunch of
files but Xen does not handle files at all). I'll pack them to make things
simpler as possible.

These information cannot be put in a specific section (allowing a safe
mapping) as gcc use .rodata, .data, .text and .ctors sections.

I added code to handle constructors used in this case to initialize a
linked list of files.

I excluded %.init.o files as they are used before Xen start and should
not have section like .text or .data.

I used a "coverage" configuration option to mimic the "debug" one.

Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
---
 .gitignore               |    2 ++
 .hgignore                |    2 ++
 Config.mk                |    3 ++
 xen/Rules.mk             |    2 ++
 xen/common/Makefile      |    2 ++
 xen/common/gcov/Makefile |    2 ++
 xen/common/gcov/gcov.c   |   74 ++++++++++++++++++++++++++++++++++++++++
 xen/include/xen/gcov.h   |   84 ++++++++++++++++++++++++++++++++++++++++++++++
 8 files changed, 171 insertions(+)
 create mode 100644 xen/common/gcov/Makefile
 create mode 100644 xen/common/gcov/gcov.c
 create mode 100644 xen/include/xen/gcov.h

diff --git a/.gitignore b/.gitignore
index 462e291..af48492 100644
--- a/.gitignore
+++ b/.gitignore
@@ -13,6 +13,8 @@
 *.tmp
 *.spot
 *.spit
+*.gcno
+*.gcda
 TAGS
 GTAGS
 GRTAGS
diff --git a/.hgignore b/.hgignore
index 3024ef1..146d8d4 100644
--- a/.hgignore
+++ b/.hgignore
@@ -17,6 +17,8 @@
 .*\.rej$
 .*\.spot$
 .*\.spit$
+.*\.gcno$
+.*\.gcda$
 .*/a\.out$
 .*/Modules\.symvers$
 .*/cscope\..*$
diff --git a/Config.mk b/Config.mk
index 64541c8..8e60f5e 100644
--- a/Config.mk
+++ b/Config.mk
@@ -13,6 +13,9 @@ realpath = $(wildcard $(foreach file,$(1),$(shell cd -P $(dir $(file)) && echo "
 debug ?= y
 debug_symbols ?= $(debug)
 
+# Test coverage support
+coverage ?= n
+
 XEN_COMPILE_ARCH    ?= $(shell uname -m | sed -e s/i.86/x86_32/ \
                          -e s/i86pc/x86_32/ -e s/amd64/x86_64/ \
                          -e s/armv7.*/arm32/)
diff --git a/xen/Rules.mk b/xen/Rules.mk
index c2db449..3f0b262 100644
--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -103,6 +103,8 @@ subdir-all := $(subdir-y) $(subdir-n)
 
 $(filter %.init.o,$(obj-y) $(obj-bin-y)): CFLAGS += -DINIT_SECTIONS_ONLY
 
+$(obj-$(coverage)): CFLAGS += -fprofile-arcs -ftest-coverage -DTEST_COVERAGE
+
 ifeq ($(lto),y)
 # Would like to handle all object files as bitcode, but objects made from
 # pure asm are in a different format and have to be collected separately.
diff --git a/xen/common/Makefile b/xen/common/Makefile
index 1677342..8a0c506 100644
--- a/xen/common/Makefile
+++ b/xen/common/Makefile
@@ -59,5 +59,7 @@ subdir-$(CONFIG_COMPAT) += compat
 
 subdir-$(x86_64) += hvm
 
+subdir-$(coverage) += gcov
+
 subdir-y += libelf
 subdir-$(HAS_DEVICE_TREE) += libfdt
diff --git a/xen/common/gcov/Makefile b/xen/common/gcov/Makefile
new file mode 100644
index 0000000..c9efe6c
--- /dev/null
+++ b/xen/common/gcov/Makefile
@@ -0,0 +1,2 @@
+obj-y += gcov.o
+
diff --git a/xen/common/gcov/gcov.c b/xen/common/gcov/gcov.c
new file mode 100644
index 0000000..733d020
--- /dev/null
+++ b/xen/common/gcov/gcov.c
@@ -0,0 +1,74 @@
+/*
+ *  This code maintains a list of active profiling data structures.
+ *
+ *    Copyright IBM Corp. 2009
+ *    Author(s): Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
+ *
+ *    Uses gcc-internal data definitions.
+ *    Based on the gcov-kernel patch by:
+ *       Hubertus Franke <frankeh@us.ibm.com>
+ *       Nigel Hinds <nhinds@us.ibm.com>
+ *       Rajan Ravindran <rajancr@us.ibm.com>
+ *       Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
+ *       Paul Larson
+ */
+
+#include <xen/config.h>
+#include <xen/init.h>
+#include <xen/lib.h>
+#include <xen/hypercall.h>
+#include <xen/gcov.h>
+#include <xen/errno.h>
+
+static struct gcov_info *info_list;
+static unsigned num_info = 0;
+
+/*
+ * __gcov_init is called by gcc-generated constructor code for each object
+ * file compiled with -fprofile-arcs.
+ *
+ * Although this function is called only during initialization is called from
+ * a .text section which is still present after initialization so not declare
+ * as __init.
+ */
+void __gcov_init(struct gcov_info *info)
+{
+    /* add new profiling data structure to list */
+    info->next = info_list;
+    info_list = info;
+    ++num_info;
+}
+
+/*
+ * These functions may be referenced by gcc-generated profiling code but serve
+ * no function for Xen.
+ */
+void __gcov_flush(void)
+{
+    /* Unused. */
+}
+
+void __gcov_merge_add(gcov_type *counters, unsigned int n_counters)
+{
+    /* Unused. */
+}
+
+void __gcov_merge_single(gcov_type *counters, unsigned int n_counters)
+{
+    /* Unused. */
+}
+
+void __gcov_merge_delta(gcov_type *counters, unsigned int n_counters)
+{
+    /* Unused. */
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-set-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/xen/gcov.h b/xen/include/xen/gcov.h
new file mode 100644
index 0000000..d695919
--- /dev/null
+++ b/xen/include/xen/gcov.h
@@ -0,0 +1,84 @@
+/*
+ *  Profiling infrastructure declarations.
+ *
+ *  This file is based on gcc-internal definitions. Data structures are
+ *  defined to be compatible with gcc counterparts. For a better
+ *  understanding, refer to gcc source: gcc/gcov-io.h.
+ *
+ *    Copyright IBM Corp. 2009
+ *    Author(s): Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
+ *
+ *    Uses gcc-internal data definitions.
+ */
+
+#ifndef __XEN_GCOV_H__
+#define __XEN_GCOV_H__ __XEN_GCOV_H__
+
+/*
+ * Profiling data types used for gcc 3.4 and above - these are defined by
+ * gcc and need to be kept as close to the original definition as possible to
+ * remain compatible.
+ */
+
+typedef uint64_t gcov_type;
+
+/**
+ * struct gcov_fn_info - profiling meta data per function
+ * @ident: object file-unique function identifier
+ * @checksum: function checksum
+ * @n_ctrs: number of values per counter type belonging to this function
+ *
+ * This data is generated by gcc during compilation and doesn't change
+ * at run-time.
+ */
+struct gcov_fn_info
+{
+    unsigned int ident;
+    unsigned int checksum;
+    unsigned int n_ctrs[0];
+};
+
+/**
+ * struct gcov_ctr_info - profiling data per counter type
+ * @num: number of counter values for this type
+ * @values: array of counter values for this type
+ * @merge: merge function for counter values of this type (unused)
+ *
+ * This data is generated by gcc during compilation and doesn't change
+ * at run-time with the exception of the values array.
+ */
+struct gcov_ctr_info
+{
+    unsigned int num;
+    gcov_type *values;
+    void (*merge)(gcov_type *, unsigned int);
+};
+
+/**
+ * struct gcov_info - profiling data per object file
+ * @version: gcov version magic indicating the gcc version used for compilation
+ * @next: list head for a singly-linked list
+ * @stamp: time stamp
+ * @filename: name of the associated gcov data file
+ * @n_functions: number of instrumented functions
+ * @functions: function data
+ * @ctr_mask: mask specifying which counter types are active
+ * @counts: counter data per counter type
+ *
+ * This data is generated by gcc during compilation and doesn't change
+ * at run-time with the exception of the next pointer.
+ */
+struct gcov_info
+{
+    unsigned int              version;
+    struct gcov_info          *next;
+    unsigned int              stamp;
+    const char                *filename;
+    unsigned int              n_functions;
+    const struct gcov_fn_info *functions;
+    unsigned int              ctr_mask;
+    struct gcov_ctr_info      counts[0];
+};
+
+
+#endif /* __XEN_GCOV_H__ */
-- 
1.7.9.5

[PATCH 3/5] Implement code to read coverage informations

[Frediano Ziglio]

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>
---
 xen/common/gcov/gcov.c      |  158 ++++++++++++++++++++++++++++++++++++++++++-
 xen/common/sysctl.c         |    5 ++
 xen/include/public/gcov.h   |  115 +++++++++++++++++++++++++++++++
 xen/include/public/sysctl.h |   38 +++++++++++
 xen/include/xen/gcov.h      |   14 ++++
 5 files changed, 328 insertions(+), 2 deletions(-)
 create mode 100644 xen/include/public/gcov.h

diff --git a/xen/common/gcov/gcov.c b/xen/common/gcov/gcov.c
index 733d020..bb85523 100644
--- a/xen/common/gcov/gcov.c
+++ b/xen/common/gcov/gcov.c
@@ -19,9 +19,11 @@
 #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;
-static unsigned num_info = 0;
 
 /*
  * __gcov_init is called by gcc-generated constructor code for each object
@@ -36,7 +38,6 @@ void __gcov_init(struct gcov_info *info)
     /* add new profiling data structure to list */
     info->next = info_list;
     info_list = info;
-    ++num_info;
 }
 
 /*
@@ -63,6 +64,159 @@ 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)
+{
+    long ret = 0;
+    write_iter_t iter;
+
+    switch ( op->cmd )
+    {
+    case XEN_SYSCTL_COVERAGE_enabled:
+        break;
+
+    case XEN_SYSCTL_COVERAGE_get_total_size:
+        iter.real = 0;
+
+        write_gcov(&iter);
+        if ( copy_to_guest(op->u.total_size, &iter.write_offset, 1) )
+            ret = -EFAULT;
+        break;
+
+    case XEN_SYSCTL_COVERAGE_read:
+        iter.ptr = op->u.raw_info;
+        iter.real = 1;
+
+        ret = write_gcov(&iter);
+        break;
+
+    case XEN_SYSCTL_COVERAGE_reset:
+        ret = reset_counters();
+        break;
+
+    default:
+        ret = -EINVAL;
+    }
+    return ret;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c
index d663ed7..fa3ef0a 100644
--- a/xen/common/sysctl.c
+++ b/xen/common/sysctl.c
@@ -26,6 +26,7 @@
 #include <xen/nodemask.h>
 #include <xsm/xsm.h>
 #include <xen/pmstat.h>
+#include <xen/gcov.h>
 
 long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) u_sysctl)
 {
@@ -249,6 +250,10 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) u_sysctl)
         ret = sched_adjust_global(&op->u.scheduler_op);
         break;
 
+    case XEN_SYSCTL_coverage_op:
+        ret = sysctl_coverage_op(&op->u.coverage_op);
+        break;
+
     default:
         ret = arch_do_sysctl(op, u_sysctl);
         copyback = 0;
diff --git a/xen/include/public/gcov.h b/xen/include/public/gcov.h
new file mode 100644
index 0000000..53a192c
--- /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, Frediano Ziglio
+ */
+
+#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 3225b2a..5e80400 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 */
+/*
+ * Check if coverage informations are available
+ * return just success or error, no parameters
+ */
+#define XEN_SYSCTL_COVERAGE_enabled        0
+
+/*
+ * 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 1
+
+/*
+ * Read coverage information in a single run
+ * You must use a tool to split them
+ */
+#define XEN_SYSCTL_COVERAGE_read           2
+
+/*
+ * Reset all the coverage counters to 0
+ * No parameters.
+ */
+#define XEN_SYSCTL_COVERAGE_reset          3
+
+struct xen_sysctl_coverage_op {
+    uint32_t cmd;        /* XEN_SYSCTL_COVERAGE_* */
+    union {
+        XEN_GUEST_HANDLE_64(uint32) 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;
 };
diff --git a/xen/include/xen/gcov.h b/xen/include/xen/gcov.h
index d695919..ad5cd9d 100644
--- a/xen/include/xen/gcov.h
+++ b/xen/include/xen/gcov.h
@@ -14,6 +14,8 @@
 #ifndef __XEN_GCOV_H__
 #define __XEN_GCOV_H__ __XEN_GCOV_H__
 
+#include <public/sysctl.h>
+
 /*
  * Profiling data types used for gcc 3.4 and above - these are defined by
  * gcc and need to be kept as close to the original definition as possible to
@@ -81,4 +83,16 @@ struct gcov_info
 };
 
 
+/**
+ * Sysctl operations for coverage
+ */
+#ifdef TEST_COVERAGE
+int sysctl_coverage_op(xen_sysctl_coverage_op_t *op);
+#else
+static inline int sysctl_coverage_op(xen_sysctl_coverage_op_t *op)
+{
+    return -ENOSYS;
+}
+#endif
+
 #endif /* __XEN_GCOV_H__ */
-- 
1.7.9.5

[PATCH 4/5] Check no constructor section

[Frediano Ziglio]

Safety check for initialization objects.
Constructors are not used so check some module does not use them.

Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
---
 xen/Rules.mk |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/Rules.mk b/xen/Rules.mk
index 3f0b262..ae35a08 100644
--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -166,7 +166,7 @@ SPECIAL_DATA_SECTIONS := rodata $(foreach n,1 2 4 8,rodata.str1.$(n)) \
 $(filter %.init.o,$(obj-y) $(obj-bin-y) $(extra-y)): %.init.o: %.o Makefile
 	$(OBJDUMP) -h $< | sed -n '/[0-9]/{s,00*,0,g;p}' | while read idx name sz rest; do \
 		case "$$name" in \
-		.text|.text.*|.data|.data.*|.bss) \
+		.text|.text.*|.data|.data.*|.bss|.ctors) \
 			test $$sz != 0 || continue; \
 			echo "Error: size of $<:$$name is 0x$$sz" >&2; \
 			exit $$(expr $$idx + 1);; \
-- 
1.7.9.5

[PATCH 5/5] Add small utility to deal with test coverage information from Xen

[Frediano Ziglio]

Currently the utility can read and reset coverage informations.

Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
---
 .gitignore          |    1 +
 .hgignore           |    1 +
 tools/misc/Makefile |    8 ++-
 tools/misc/xencov.c |  141 +++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 149 insertions(+), 2 deletions(-)
 create mode 100644 tools/misc/xencov.c

diff --git a/.gitignore b/.gitignore
index af48492..9e947ce 100644
--- a/.gitignore
+++ b/.gitignore
@@ -223,6 +223,7 @@ tools/misc/gtraceview
 tools/misc/gtracestat
 tools/misc/xenlockprof
 tools/misc/lowmemd
+tools/misc/xencov
 tools/pygrub/build/*
 tools/python/build/*
 tools/python/xen/util/path.py
diff --git a/.hgignore b/.hgignore
index 146d8d4..e98c3df 100644
--- a/.hgignore
+++ b/.hgignore
@@ -218,6 +218,7 @@
 ^tools/misc/gtraceview$
 ^tools/misc/gtracestat$
 ^tools/misc/xenlockprof$
+^tools/misc/xencov$
 ^tools/pygrub/build/.*$
 ^tools/python/build/.*$
 ^tools/python/xen/util/path\.py$
diff --git a/tools/misc/Makefile b/tools/misc/Makefile
index 22e60fd..eef9411 100644
--- a/tools/misc/Makefile
+++ b/tools/misc/Makefile
@@ -9,7 +9,7 @@ CFLAGS += $(CFLAGS_libxenstore)
 
 HDRS     = $(wildcard *.h)
 
-TARGETS-y := xenperf xenpm xen-tmem-list-parse gtraceview gtracestat xenlockprof xenwatchdogd
+TARGETS-y := xenperf xenpm xen-tmem-list-parse gtraceview gtracestat xenlockprof xenwatchdogd xencov
 TARGETS-$(CONFIG_X86) += xen-detect xen-hvmctx xen-hvmcrash xen-lowmemd
 TARGETS-$(CONFIG_MIGRATE) += xen-hptool
 TARGETS := $(TARGETS-y)
@@ -22,7 +22,8 @@ INSTALL_BIN-y := xencons
 INSTALL_BIN-$(CONFIG_X86) += xen-detect
 INSTALL_BIN := $(INSTALL_BIN-y)
 
-INSTALL_SBIN-y := xm xen-bugtool xen-python-path xend xenperf xsview xenpm xen-tmem-list-parse gtraceview gtracestat xenlockprof xenwatchdogd xen-ringwatch
+INSTALL_SBIN-y := xm xen-bugtool xen-python-path xend xenperf xsview xenpm xen-tmem-list-parse gtraceview \
+	gtracestat xenlockprof xenwatchdogd xen-ringwatch xencov
 INSTALL_SBIN-$(CONFIG_X86) += xen-hvmctx xen-hvmcrash xen-lowmemd
 INSTALL_SBIN-$(CONFIG_MIGRATE) += xen-hptool
 INSTALL_SBIN := $(INSTALL_SBIN-y)
@@ -85,4 +86,7 @@ xen-lowmemd: xen-lowmemd.o
 gtraceview: gtraceview.o
 	$(CC) $(LDFLAGS) -o $@ $< $(CURSES_LIBS) $(APPEND_LDFLAGS)
 
+xencov: xencov.o
+	$(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) $(APPEND_LDFLAGS)
+
 -include $(DEPS)
diff --git a/tools/misc/xencov.c b/tools/misc/xencov.c
new file mode 100644
index 0000000..5e7f440
--- /dev/null
+++ b/tools/misc/xencov.c
@@ -0,0 +1,141 @@
+/*
+ * xencov: handle test coverage information from Xen.
+ *
+ * Copyright (c) 2013, Frediano Ziglio
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <xenctrl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <err.h>
+#include <sys/mman.h>
+
+static xc_interface *gcov_xch = NULL;
+
+static void gcov_init(void)
+{
+    gcov_xch = xc_interface_open(NULL, NULL, 0);
+    if ( !gcov_xch )
+        err(1, "opening interface");
+}
+
+int gcov_get_info(int op, void *ptr)
+{
+    struct xen_sysctl_coverage_op *cov;
+    struct xen_sysctl sys;
+
+    memset(&sys, 0, sizeof(sys));
+    sys.cmd = XEN_SYSCTL_coverage_op;
+
+    cov = &sys.u.coverage_op;
+    cov->cmd = op;
+    cov->u.total_size.p = ptr;
+
+    return xc_sysctl(gcov_xch, &sys);
+}
+
+static void gcov_read(const char *fn)
+{
+    unsigned page_size = sysconf(_SC_PAGESIZE);
+    uint32_t *ui, total_len;
+    uint8_t *p;
+    size_t size;
+    FILE *f;
+
+    /* allocate */
+    p = mmap(0, page_size, PROT_WRITE|PROT_READ,
+             MAP_PRIVATE|MAP_ANON|MAP_LOCKED, -1, 0);
+    if ( p == (uint8_t *) -1 )
+        err(1, "allocating memory");
+
+    /* get total length */
+    ui = (uint32_t *) p;
+    *ui = 0;
+    if ( gcov_get_info(XEN_SYSCTL_COVERAGE_get_total_size, ui) < 0 )
+        err(1, "getting total length");
+    fprintf(stderr, "returned %u bytes\n", (unsigned) *ui);
+
+    /* safe check */
+    total_len = *ui;
+    if ( total_len > 16u * 1024u * 1024u )
+        errx(1, "coverage size too big %u bytes\n", total_len);
+
+    /* reallocate */
+    munmap(p, page_size);
+    size = total_len + page_size;
+    size -= (size % page_size);
+    p = mmap(0, size, PROT_WRITE|PROT_READ,
+             MAP_PRIVATE|MAP_ANON|MAP_LOCKED, -1, 0);
+    if ( p == (uint8_t *) -1 )
+        err(1, "mapping memory for coverage");
+
+    /* get data */
+    memset(p, 0, total_len);
+    if ( gcov_get_info(XEN_SYSCTL_COVERAGE_read, p) < 0 )
+        err(1, "getting coverage information");
+
+    /* write to a file */
+    if ( strcmp(fn, "-") == 0 )
+        f = stdout;
+    else
+        f = fopen(fn, "w");
+    if ( !f )
+        err(1, "opening output file");
+    if ( fwrite(p, 1, total_len, f) != total_len )
+        err(1, "writing coverage to file");
+    if (f != stdout)
+        fclose(f);
+}
+
+static void gcov_reset(void)
+{
+    if ( gcov_get_info(XEN_SYSCTL_COVERAGE_reset, NULL) < 0 )
+        err(1, "resetting coverage information");
+}
+
+static void usage(void)
+{
+    fprintf(stderr, "xencov {reset|read} [<filename>]\n"
+        "\treset     reset information\n"
+        "\tread      read information from xen to filename\n"
+        "\tfilename  optional filename (default output)\n"
+        );
+    exit(1);
+}
+
+int main(int argc, char **argv)
+{
+    gcov_init();
+
+    /* check support */
+    if ( gcov_get_info(XEN_SYSCTL_COVERAGE_enabled, NULL) < 0 )
+        err(1, "checking coverage support");
+
+    if ( argc < 2 )
+        usage();
+    if ( strcmp(argv[1], "reset") == 0 )
+        gcov_reset();
+    else if ( strcmp(argv[1], "read") == 0 )
+        gcov_read(argc > 2 ? argv[2] : "-");
+    else
+        usage();
+
+    return 0;
+}
+
-- 
1.7.9.5

Re: [PATCH 1/5] Call constructors during initialization

[Jan Beulich]

>>> On 06.02.13 at 15:32, Frediano Ziglio <frediano.ziglio@citrix.com> wrote:
> --- a/xen/arch/arm/xen.lds.S
> +++ b/xen/arch/arm/xen.lds.S
> @@ -84,6 +84,13 @@ SECTIONS
>         *(.init.data)
>         *(.init.data.rel)
>         *(.init.data.rel.*)
> +
> +       . = ALIGN(8);
> +       __CTOR_LIST__ = .;
> +       QUAD((__CTOR_END__ - __CTOR_LIST__) / 8 - 2)

Afaict this will crash if there's at least one constructor, because
the word size on (32-bit) ARM is 32 bits, i.e. the first function
pointer will be found to be NULL (the upper half of the count,
assuming ARM uses little endian, which I think it does).

> @@ -478,6 +479,21 @@ unsigned long long parse_size_and_unit(const char *s, const char **ps)
>      return ret;
>  }
>  
> +typedef void (*ctor_func_t)(void);

This typedef if being used just once, so what's the point?

Jan

Re: [PATCH 4/5] Check no constructor section

[Jan Beulich]

>>> On 06.02.13 at 15:32, Frediano Ziglio <frediano.ziglio@citrix.com> wrote:
> Safety check for initialization objects.
> Constructors are not used so check some module does not use them.

Once again - why?

And repeating earlier complaints of mine - why do you continue to
re-post without having addressed all comments on prior revisions
(verbally or by changing the patches)? This is just wasting
reviewers' time.

Jan

> Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
> ---
>  xen/Rules.mk |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/xen/Rules.mk b/xen/Rules.mk
> index 3f0b262..ae35a08 100644
> --- a/xen/Rules.mk
> +++ b/xen/Rules.mk
> @@ -166,7 +166,7 @@ SPECIAL_DATA_SECTIONS := rodata $(foreach n,1 2 4 
> 8,rodata.str1.$(n)) \
>  $(filter %.init.o,$(obj-y) $(obj-bin-y) $(extra-y)): %.init.o: %.o Makefile
>  	$(OBJDUMP) -h $< | sed -n '/[0-9]/{s,00*,0,g;p}' | while read idx name sz rest; 
> do \
>  		case "$$name" in \
> -		.text|.text.*|.data|.data.*|.bss) \
> +		.text|.text.*|.data|.data.*|.bss|.ctors) \
>  			test $$sz != 0 || continue; \
>  			echo "Error: size of $<:$$name is 0x$$sz" >&2; \
>  			exit $$(expr $$idx + 1);; \
> -- 
> 1.7.9.5

Re: [PATCH 4/5] Check no constructor section

[George Dunlap]

On 06/02/13 16:10, Frediano Ziglio wrote:
> On Wed, 2013-02-06 at 15:01 +0000, Jan Beulich wrote:
>>>>> On 06.02.13 at 15:32, Frediano Ziglio <frediano.ziglio@citrix.com> wrote:
>>> Safety check for initialization objects.
>>> Constructors are not used so check some module does not use them.
>> Once again - why?
>>
>> And repeating earlier complaints of mine - why do you continue to
>> re-post without having addressed all comments on prior revisions
>> (verbally or by changing the patches)? This is just wasting
>> reviewers' time.
>>
>> Jan
>>
> Nothing personal, I'm just a bad mail reader. In this case I checked
> mails filtering with "cover" but your reply didn't have it on the
> subject.

If that's going to be your modus operandi, then *you* need to put the 
search term in your subject line; for example, by making your one-line 
summary "cover: Check no constructor section"

  -George

Re: [PATCH 4/5] Check no constructor section

[Frediano Ziglio]

On Wed, 2013-02-06 at 15:01 +0000, Jan Beulich wrote:
> >>> On 06.02.13 at 15:32, Frediano Ziglio <frediano.ziglio@citrix.com> wrote:
> > Safety check for initialization objects.
> > Constructors are not used so check some module does not use them.
> 
> Once again - why?
> 
> And repeating earlier complaints of mine - why do you continue to
> re-post without having addressed all comments on prior revisions
> (verbally or by changing the patches)? This is just wasting
> reviewers' time.
> 
> Jan
> 

Nothing personal, I'm just a bad mail reader. In this case I checked
mails filtering with "cover" but your reply didn't have it on the
subject.

Sometimes I search if there are courses for reading mail but strangely
there are only courses on how use use some mail products or how to write
them.

Frediano

> > Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
> > ---
> >  xen/Rules.mk |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/xen/Rules.mk b/xen/Rules.mk
> > index 3f0b262..ae35a08 100644
> > --- a/xen/Rules.mk
> > +++ b/xen/Rules.mk
> > @@ -166,7 +166,7 @@ SPECIAL_DATA_SECTIONS := rodata $(foreach n,1 2 4 
> > 8,rodata.str1.$(n)) \
> >  $(filter %.init.o,$(obj-y) $(obj-bin-y) $(extra-y)): %.init.o: %.o Makefile
> >  	$(OBJDUMP) -h $< | sed -n '/[0-9]/{s,00*,0,g;p}' | while read idx name sz rest; 
> > do \
> >  		case "$$name" in \
> > -		.text|.text.*|.data|.data.*|.bss) \
> > +		.text|.text.*|.data|.data.*|.bss|.ctors) \
> >  			test $$sz != 0 || continue; \
> >  			echo "Error: size of $<:$$name is 0x$$sz" >&2; \
> >  			exit $$(expr $$idx + 1);; \
> > -- 
> > 1.7.9.5
> 
> 
> 

Re: [PATCH 3/5] Implement code to read coverage informations

[Ian Campbell]

> diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
> index 3225b2a..5e80400 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 */
> +/*
> + * Check if coverage informations are available
> + * return just success or error, no parameters
> + */
> +#define XEN_SYSCTL_COVERAGE_enabled        0

You can detect this by getting -ENOSYS from the hypercall, which is what
you would get running the tool on an older hypervisor, so you need to
handle it anyway.

> +
> +/*
> + * 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 1
> +
> +/*
> + * Read coverage information in a single run
> + * You must use a tool to split them
> + */
> +#define XEN_SYSCTL_COVERAGE_read           2
> +
> +/*
> + * Reset all the coverage counters to 0
> + * No parameters.
> + */
> +#define XEN_SYSCTL_COVERAGE_reset          3

Any need for simultaneous read+reset?

> +struct xen_sysctl_coverage_op {
> +    uint32_t cmd;        /* XEN_SYSCTL_COVERAGE_* */
> +    union {
> +        XEN_GUEST_HANDLE_64(uint32) total_size; /* OUT */

This one can just be a uint32_t I think, no need for it to be a
pointer/handle.

> +        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;
>  };

Re: [PATCH 3/5] Implement code to read coverage informations

[Frediano Ziglio]

On Wed, 2013-02-06 at 17:12 +0000, Ian Campbell wrote:
> > diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
> > index 3225b2a..5e80400 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 */
> > +/*
> > + * Check if coverage informations are available
> > + * return just success or error, no parameters
> > + */
> > +#define XEN_SYSCTL_COVERAGE_enabled        0
> 
> You can detect this by getting -ENOSYS from the hypercall, which is what
> you would get running the tool on an older hypervisor, so you need to
> handle it anyway.
> 

Yes, I think so. I'll change it. Was here cause on the separate
hypercall was the only operation available to non privileged domains but
since sysctl already check for it there is no clue.

> > +
> > +/*
> > + * 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 1
> > +
> > +/*
> > + * Read coverage information in a single run
> > + * You must use a tool to split them
> > + */
> > +#define XEN_SYSCTL_COVERAGE_read           2
> > +
> > +/*
> > + * Reset all the coverage counters to 0
> > + * No parameters.
> > + */
> > +#define XEN_SYSCTL_COVERAGE_reset          3
> 
> Any need for simultaneous read+reset?
> 

Mmmm... possibly could help, I'll add it!

> > +struct xen_sysctl_coverage_op {
> > +    uint32_t cmd;        /* XEN_SYSCTL_COVERAGE_* */
> > +    union {
> > +        XEN_GUEST_HANDLE_64(uint32) total_size; /* OUT */
> 
> This one can just be a uint32_t I think, no need for it to be a
> pointer/handle.
> 

I could, this require to set copyback to 1 in do_sysctl. Yes, it's
probably only a single instruction. It also complicate a bit the program
that extract the information but it's not a problem. And performance are
not a problem too. So, do you prefer I change it to uint32_t directly ?

I don't like the idea to pass a pointer to copyback to
sysctl_coverage_op as this could lead to sub optimization in do_sysctl
(passing a pointer lead to a stack allocation for the variable,
currently compiler can allocate just a register).

> > +        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;
> >  };
> 
> 

Frediano