[Qemu-devel] [PATCH 5/6] hypertrace: Add guest-side user-level library

["Lluís Vilanova" <vilanova@ac.upc.edu>]

Provides guest library "libqemu-hypertrace-guest.a" to abstract access
to the hypertrace channel.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
---
 Makefile                                |    6 +
 configure                               |    2 
 hypertrace/guest/user/Makefile          |   28 ++++
 hypertrace/guest/user/common.c          |  221 +++++++++++++++++++++++++++++++
 hypertrace/guest/user/qemu-hypertrace.h |   77 +++++++++++
 5 files changed, 333 insertions(+), 1 deletion(-)
 create mode 100644 hypertrace/guest/user/Makefile
 create mode 100644 hypertrace/guest/user/common.c
 create mode 100644 hypertrace/guest/user/qemu-hypertrace.h

diff --git a/Makefile b/Makefile
index 0d7647f..bebd6e6 100644
--- a/Makefile
+++ b/Makefile
@@ -459,9 +459,13 @@ ifneq (,$(findstring qemu-ga,$(TOOLS)))
 endif
 endif
 
+install-hypertrace:
+	$(INSTALL_DIR) "$(DESTDIR)$(includedir)"
+	$(INSTALL_DATA) "$(SRC_PATH)/hypertrace/guest/user/qemu-hypertrace.h" "$(DESTDIR)$(includedir)/"
+
 
 install: all $(if $(BUILD_DOCS),install-doc) \
-install-datadir install-localstatedir
+install-datadir install-localstatedir install-hypertrace
 ifneq ($(TOOLS),)
 	$(call install-prog,$(subst qemu-ga,qemu-ga$(EXESUF),$(TOOLS)),$(DESTDIR)$(bindir))
 endif
diff --git a/configure b/configure
index e80fde4..076eb8b 100755
--- a/configure
+++ b/configure
@@ -5780,6 +5780,8 @@ if [ "$TARGET_BASE_ARCH" = "" ]; then
 fi
 
 symlink "$source_path/Makefile.target" "$target_dir/Makefile"
+mkdir -p $target_dir/hypertrace/guest/user
+symlink $source_path/hypertrace/guest/user/Makefile $target_dir/hypertrace/guest/user/Makefile
 
 upper() {
     echo "$@"| LC_ALL=C tr '[a-z]' '[A-Z]'
diff --git a/hypertrace/guest/user/Makefile b/hypertrace/guest/user/Makefile
new file mode 100644
index 0000000..bcc9dc9
--- /dev/null
+++ b/hypertrace/guest/user/Makefile
@@ -0,0 +1,28 @@
+include ../../../../config-host.mak
+include ../../../config-target.mak
+include $(SRC_PATH)/rules.mak
+
+vpath % $(SRC_PATH)/hypertrace/guest/user
+
+# do not use QEMU's per-host cflags when building guest code
+QEMU_CFLAGS  = -Werror -Wall
+
+QEMU_CFLAGS += $(GLIB_CFLAGS)
+QEMU_CFLAGS += -I$(SRC_PATH)/include
+QEMU_CFLAGS += -I../../../../linux-headers
+QEMU_CFLAGS += -I../../../../
+QEMU_CFLAGS += -I../../../
+
+ifdef CONFIG_SOFTMMU
+QEMU_CFLAGS += -DNEED_CPU_H
+QEMU_CFLAGS += -I$(SRC_PATH)/target-$(TARGET_BASE_ARCH)
+endif
+
+obj-y = common.o
+
+libqemu-hypertrace-guest.a: $(obj-y)
+
+all: libqemu-hypertrace-guest.a
+
+clean:
+	rm -f $(obj-y) libqemu-hypertrace-guest.a
diff --git a/hypertrace/guest/user/common.c b/hypertrace/guest/user/common.c
new file mode 100644
index 0000000..1429b2a
--- /dev/null
+++ b/hypertrace/guest/user/common.c
@@ -0,0 +1,221 @@
+/*
+ * Guest-side management of hypertrace.
+ *
+ * Copyright (C) 2016 Lluís Vilanova <vilanova@ac.upc.edu>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu-hypertrace.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <glob.h>
+
+#include "config-host.h"
+#include "config-target.h"
+#if defined(CONFIG_SOFTMMU)
+#include "qemu/osdep.h"
+#include "hw/pci/pci.h"
+#endif
+
+
+static char *data_path = NULL;
+static char *control_path = NULL;
+static int data_fd = -1;
+static int control_fd = -1;
+
+static uint64_t *data_addr = NULL;
+static uint64_t *control_addr = NULL;
+
+
+static int init_channel_file(const char *base, const char *suffix, size_t size,
+                             char ** path, int *fd, uint64_t **addr)
+{
+    *path = malloc(strlen(base) + strlen(suffix) + 1);
+    sprintf(*path, "%s%s", base, suffix);
+
+    *fd = open(*path, O_RDWR);
+    if (*fd == -1) {
+        return -1;
+    }
+
+    *addr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, *fd, 0);
+    if (*addr == MAP_FAILED) {
+        return -1;
+    }
+    return 0;
+}
+
+#if !defined(CONFIG_USER_ONLY) && defined(__linux__)
+static int check_device_id (const char *base, const char *name, uint64_t value)
+{
+    char tmp[1024];
+    sprintf(tmp, "%s/%s", base, name);
+
+    int fd = open(tmp, O_RDONLY);
+    if (fd < 0) {
+        return -1;
+    }
+
+    char v[1024];
+    ssize_t s = read(fd, v, sizeof(v));
+    if (s < 0) {
+        close(fd);
+        return -1;
+    }
+    v[s] = '\0';
+
+    char *end;
+    uint64_t vv = strtoull(v, &end, 16);
+    if (*end == '\n' && vv == value) {
+        return 0;
+    }
+    else {
+        return -1;
+    }
+}
+
+static char* find_device(void)
+{
+    static char tmp[1024];
+    char *res = NULL;
+
+    glob_t g;
+    if (glob("/sys/devices/pci*/*", GLOB_NOSORT, NULL, &g) != 0) {
+        return NULL;
+    }
+
+
+    int i;
+    for (i = 0; i < g.gl_pathc; i++) {
+        char *path = g.gl_pathv[i];
+
+        if (check_device_id(path, "vendor", PCI_VENDOR_ID_REDHAT_QUMRANET) < 0) {
+            continue;
+        }
+        if (check_device_id(path, "device", PCI_DEVICE_ID_HYPERTRACE) < 0) {
+            continue;
+        }
+
+        sprintf(tmp, "%s", path);
+        res = tmp;
+        break;
+    }
+
+    globfree(&g);
+
+    return res;
+}
+#endif
+
+int qemu_hypertrace_init(const char *base)
+{
+#if defined(CONFIG_USER_ONLY)
+    const char *control_suff = "-control";
+    const size_t control_size = getpagesize() * 2;
+    const char *data_suff = "-data";
+#elif defined(__linux__)
+    const char *control_suff = "/resource0";
+    const size_t control_size = getpagesize();
+    const char *data_suff = "/resource1";
+#else
+#error Unsupported OS
+#endif
+
+#if defined(CONFIG_USER_ONLY)
+    if (base == NULL) {
+        errno = ENOENT;
+        return -1;
+    }
+#elif defined(__linux__)
+    if (base == NULL) {
+        /* try to guess the base path */
+        base = find_device();
+        if (base == NULL) {
+            errno = ENOENT;
+            return -1;
+        }
+    }
+#endif
+
+    int res;
+    res = init_channel_file(base, control_suff, control_size,
+                            &control_path, &control_fd, &control_addr);
+    if (res != 0) {
+        return res;
+    }
+
+    size_t data_size = qemu_hypertrace_num_args() * sizeof(uint64_t);
+    data_size *= qemu_hypertrace_max_offset() + 1;
+    res = init_channel_file(base, data_suff, data_size,
+                            &data_path, &data_fd, &data_addr);
+    if (res != 0) {
+        return res;
+    }
+    return 0;
+}
+
+
+static int fini_channel(int *fd, char **path)
+{
+    if (*fd != -1) {
+        if (close(*fd) == -1) {
+            return -1;
+        }
+        *fd = -1;
+    }
+    if (*path != NULL) {
+        free(*path);
+        *path =  NULL;
+    }
+    return 0;
+}
+
+int qemu_hypertrace_fini(void)
+{
+    if (fini_channel(&data_fd, &data_path) != 0) {
+        return -1;
+    }
+    if (fini_channel(&control_fd, &control_path) != 0) {
+        return -1;
+    }
+    return 0;
+}
+
+
+uint64_t qemu_hypertrace_num_args(void)
+{
+    return CONFIG_HYPERTRACE_ARGS;
+}
+
+uint64_t qemu_hypertrace_max_offset(void)
+{
+    return control_addr[0];
+}
+
+uint64_t *qemu_hypertrace_data(uint64_t data_offset)
+{
+    return &data_addr[data_offset * CONFIG_HYPERTRACE_ARGS * sizeof(uint64_t)];
+}
+
+void qemu_hypertrace (uint64_t data_offset)
+{
+    uint64_t *ctrl;
+    ctrl = control_addr;
+    ctrl[1] = data_offset;
+#if defined(CONFIG_USER_ONLY)
+    /* QEMU in 'user' mode uses two faulting pages to detect invocations */
+    ctrl = (uint64_t*)((char*)control_addr + getpagesize());
+    ctrl[1] = data_offset;
+#endif
+}
diff --git a/hypertrace/guest/user/qemu-hypertrace.h b/hypertrace/guest/user/qemu-hypertrace.h
new file mode 100644
index 0000000..ba58e49
--- /dev/null
+++ b/hypertrace/guest/user/qemu-hypertrace.h
@@ -0,0 +1,77 @@
+/*
+ * Guest-side management of hypertrace.
+ *
+ * Copyright (C) 2016 Lluís Vilanova <vilanova@ac.upc.edu>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include <stdint.h>
+#include <sys/types.h>
+
+
+/**
+ * qemu_hypertrace_init:
+ * @base: Base path to the hypertrace channel.
+ *
+ * Initialize the hypertrace channel.
+ *
+ * The base path to the hypertrace channel depends on the type of QEMU target:
+ *
+ * - User (single-application)
+ *   The base path provided when starting QEMU ("-hypertrace" commandline
+ *   option).
+ *
+ * - System (OS-dependant)
+ *   + Linux
+ *     The base path to the hypertrace channel virtual device; on a default QEMU
+ *     device setup for x86 this is "/sys/devices/pci0000:00/0000:00:04.0". If
+ *     NULL is provided, the hypertrace device will be automatically detected.
+ *
+ * Returns: Zero on success.
+ */
+int qemu_hypertrace_init(const char *base);
+
+/**
+ * qemu_hypertrace_fini:
+ *
+ * Deinitialize the hypertrace channel.
+ *
+ * Returns: Zero on success.
+ */
+int qemu_hypertrace_fini(void);
+
+/**
+ * qemu_hypertrace_num_args:
+ *
+ * Number of uint64_t values read by each call to qemu_hypertrace().
+ */
+uint64_t qemu_hypertrace_num_args(void);
+
+/**
+ * qemu_hypertrace_data_size:
+ *
+ * Maximum data offset value accepted by other calls.
+ */
+uint64_t qemu_hypertrace_max_offset(void);
+
+/**
+ * qemu_hypertrace_data:
+ * @data_offset: Offset in multiples of argument packs.
+ *
+ * Pointer to the start of the data channel.
+ */
+uint64_t *qemu_hypertrace_data(uint64_t data_offset);
+
+/**
+ * qemu_hypertrace:
+ * @data_offset: Offset in multiples of argument packs.
+ *
+ * Invoke the control channel.
+ *
+ * Each of the users (e.g., thread) of the hypertrace channel can use a
+ * different data offset to ensure they can work concurrently without using
+ * locks (i.e., each uses a different portion of the data channel).
+ */
+void qemu_hypertrace(uint64_t data_offset);