[lttng-dev] [LTTNG-TOOLS PATCH v5] ABI with support for compat 32/64 bits

Julien Desfossez jdesfossez at efficios.com
Tue Oct 2 15:03:26 EDT 2012


The current ABI does not work for compat 32/64 bits.
This patch moves the current ABI as old-abi and provides a new ABI in
which all the structures exchanged between user and kernel-space are
packed. Also this new ABI moves the "int overwrite" member of the
struct lttng_kernel_channel to remove the alignment added by the
compiler.

A patch for lttng-modules has been developed in parallel to this one
to support the new ABI. These 2 patches have been tested in all
possible configurations (applied or not) on 64-bit and 32-bit kernels
(with CONFIG_COMPAT) and a user-space in 32 and 64-bit.

Here are the results of the tests :
k 64 compat     | u 32 compat     | OK
k 64 compat     | u 64 compat     | OK
k 64 compat     | u 32 non-compat | KO
k 64 compat     | u 64 non-compat | OK

k 64 non-compat | u 64 compat     | OK
k 64 non-compat | u 32 compat     | KO
k 64 non-compat | u 64 non-compat | OK
k 64 non-compat | u 32 non-compat | KO

k 32 compat     | u compat        | OK
k 32 compat     | u non-compat    | OK

k 32 non-compat | u compat        | OK
k 32 non-compat | u non-compat    | OK

The results are as expected :
- on 32-bit user-space and kernel, every configuration works.
- on 64-bit user-space and kernel, every configuration works.
- with 32-bit user-space on a 64-bit kernel the only configuration
  where it works is when the compat patch is applied everywhere.

Signed-off-by: Julien Desfossez <jdesfossez at efficios.com>
---
 src/bin/lttng-sessiond/trace-kernel.h |    1 +
 src/common/kernel-ctl/kernel-ctl.c    |  224 ++++++++++++++++++++++++++++++---
 src/common/kernel-ctl/kernel-ctl.h    |    1 +
 src/common/kernel-ctl/kernel-ioctl.h  |   74 +++++++----
 src/common/lttng-kernel-old.h         |  115 +++++++++++++++++
 src/common/lttng-kernel.h             |   31 +++--
 6 files changed, 397 insertions(+), 49 deletions(-)
 create mode 100644 src/common/lttng-kernel-old.h

diff --git a/src/bin/lttng-sessiond/trace-kernel.h b/src/bin/lttng-sessiond/trace-kernel.h
index f04d9e7..c86cc27 100644
--- a/src/bin/lttng-sessiond/trace-kernel.h
+++ b/src/bin/lttng-sessiond/trace-kernel.h
@@ -22,6 +22,7 @@
 
 #include <lttng/lttng.h>
 #include <common/lttng-kernel.h>
+#include <common/lttng-kernel-old.h>
 
 #include "consumer.h"
 
diff --git a/src/common/kernel-ctl/kernel-ctl.c b/src/common/kernel-ctl/kernel-ctl.c
index 1396cd9..a93d251 100644
--- a/src/common/kernel-ctl/kernel-ctl.c
+++ b/src/common/kernel-ctl/kernel-ctl.c
@@ -18,38 +18,175 @@
 
 #define __USE_LINUX_IOCTL_DEFS
 #include <sys/ioctl.h>
+#include <string.h>
 
 #include "kernel-ctl.h"
 #include "kernel-ioctl.h"
 
+/*
+ * This flag indicates which version of the kernel ABI to use. The old
+ * ABI (namespace _old) does not support a 32-bit user-space when the
+ * kernel is 64-bit. The old ABI is kept here for compatibility but is
+ * deprecated and will be removed eventually.
+ */
+static int lttng_kernel_use_old_abi = -1;
+
+/*
+ * Execute the new or old ioctl depending on the ABI version.
+ * If the ABI version is not determined yet (lttng_kernel_use_old_abi = -1),
+ * this function tests if the new ABI is available and otherwise fallbacks
+ * on the old one.
+ * This function takes the fd on which the ioctl must be executed and the old
+ * and new request codes.
+ * It returns the return value of the ioctl executed.
+ */
+static inline int compat_ioctl_no_arg(int fd, unsigned long oldname,
+		unsigned long newname)
+{
+	int ret;
+
+	if (lttng_kernel_use_old_abi == -1) {
+		ret = ioctl(fd, newname);
+		if (!ret) {
+			lttng_kernel_use_old_abi = 0;
+			goto end;
+		}
+		lttng_kernel_use_old_abi = 1;
+	}
+	if (lttng_kernel_use_old_abi) {
+		ret = ioctl(fd, oldname);
+	} else {
+		ret = ioctl(fd, newname);
+	}
+
+end:
+	return ret;
+}
+
 int kernctl_create_session(int fd)
 {
-	return ioctl(fd, LTTNG_KERNEL_SESSION);
+	return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_SESSION,
+			LTTNG_KERNEL_SESSION);
 }
 
 /* open the metadata global channel */
 int kernctl_open_metadata(int fd, struct lttng_channel_attr *chops)
 {
-	return ioctl(fd, LTTNG_KERNEL_METADATA, chops);
+	struct lttng_kernel_old_channel old_channel;
+	struct lttng_kernel_channel channel;
+
+	if (lttng_kernel_use_old_abi) {
+		old_channel.overwrite = chops->overwrite;
+		old_channel.subbuf_size = chops->subbuf_size;
+		old_channel.num_subbuf = chops->num_subbuf;
+		old_channel.switch_timer_interval = chops->switch_timer_interval;
+		old_channel.read_timer_interval = chops->read_timer_interval;
+		old_channel.output = chops->output;
+		memcpy(old_channel.padding, chops->padding, sizeof(old_channel.padding));
+
+		return ioctl(fd, LTTNG_KERNEL_OLD_METADATA, &old_channel);
+	}
+
+	channel.overwrite = chops->overwrite;
+	channel.subbuf_size = chops->subbuf_size;
+	channel.num_subbuf = chops->num_subbuf;
+	channel.switch_timer_interval = chops->switch_timer_interval;
+	channel.read_timer_interval = chops->read_timer_interval;
+	channel.output = chops->output;
+	memcpy(channel.padding, chops->padding, sizeof(channel.padding));
+
+	return ioctl(fd, LTTNG_KERNEL_METADATA, &channel);
 }
 
 int kernctl_create_channel(int fd, struct lttng_channel_attr *chops)
 {
-	return ioctl(fd, LTTNG_KERNEL_CHANNEL, chops);
+	struct lttng_kernel_channel channel;
+
+	if (lttng_kernel_use_old_abi) {
+		struct lttng_kernel_old_channel old_channel;
+
+		old_channel.overwrite = chops->overwrite;
+		old_channel.subbuf_size = chops->subbuf_size;
+		old_channel.num_subbuf = chops->num_subbuf;
+		old_channel.switch_timer_interval = chops->switch_timer_interval;
+		old_channel.read_timer_interval = chops->read_timer_interval;
+		old_channel.output = chops->output;
+		memcpy(old_channel.padding, chops->padding, sizeof(old_channel.padding));
+
+		return ioctl(fd, LTTNG_KERNEL_OLD_CHANNEL, &old_channel);
+	}
+
+	channel.overwrite = chops->overwrite;
+	channel.subbuf_size = chops->subbuf_size;
+	channel.num_subbuf = chops->num_subbuf;
+	channel.switch_timer_interval = chops->switch_timer_interval;
+	channel.read_timer_interval = chops->read_timer_interval;
+	channel.output = chops->output;
+	memcpy(channel.padding, chops->padding, sizeof(channel.padding));
+
+	return ioctl(fd, LTTNG_KERNEL_CHANNEL, &channel);
 }
 
 int kernctl_create_stream(int fd)
 {
-	return ioctl(fd, LTTNG_KERNEL_STREAM);
+	return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_STREAM,
+			LTTNG_KERNEL_STREAM);
 }
 
 int kernctl_create_event(int fd, struct lttng_kernel_event *ev)
 {
+	if (lttng_kernel_use_old_abi) {
+		struct lttng_kernel_old_event old_event;
+
+		memcpy(old_event.name, ev->name, sizeof(old_event.name));
+		old_event.instrumentation = ev->instrumentation;
+		switch (ev->instrumentation) {
+		case LTTNG_KERNEL_KPROBE:
+			old_event.u.kprobe.addr = ev->u.kprobe.addr;
+			old_event.u.kprobe.offset = ev->u.kprobe.offset;
+			memcpy(old_event.u.kprobe.symbol_name,
+				ev->u.kprobe.symbol_name,
+				sizeof(old_event.u.kprobe.symbol_name));
+			break;
+		case LTTNG_KERNEL_KRETPROBE:
+			old_event.u.kretprobe.addr = ev->u.kretprobe.addr;
+			old_event.u.kretprobe.offset = ev->u.kretprobe.offset;
+			memcpy(old_event.u.kretprobe.symbol_name,
+				ev->u.kretprobe.symbol_name,
+				sizeof(old_event.u.kretprobe.symbol_name));
+			break;
+		case LTTNG_KERNEL_FUNCTION:
+			memcpy(old_event.u.ftrace.symbol_name,
+					ev->u.ftrace.symbol_name,
+					sizeof(old_event.u.ftrace.symbol_name));
+			break;
+		default:
+			break;
+		}
+
+		return ioctl(fd, LTTNG_KERNEL_OLD_EVENT, &old_event);
+	}
 	return ioctl(fd, LTTNG_KERNEL_EVENT, ev);
 }
 
 int kernctl_add_context(int fd, struct lttng_kernel_context *ctx)
 {
+	if (lttng_kernel_use_old_abi) {
+		struct lttng_kernel_old_context old_ctx;
+
+		old_ctx.ctx = ctx->ctx;
+		/* only type that uses the union */
+		if (ctx->ctx == LTTNG_KERNEL_CONTEXT_PERF_COUNTER) {
+			old_ctx.u.perf_counter.type =
+				ctx->u.perf_counter.type;
+			old_ctx.u.perf_counter.config =
+				ctx->u.perf_counter.config;
+			memcpy(old_ctx.u.perf_counter.name,
+				ctx->u.perf_counter.name,
+				sizeof(old_ctx.u.perf_counter.name));
+		}
+		return ioctl(fd, LTTNG_KERNEL_OLD_CONTEXT, &old_ctx);
+	}
 	return ioctl(fd, LTTNG_KERNEL_CONTEXT, ctx);
 }
 
@@ -57,44 +194,98 @@ int kernctl_add_context(int fd, struct lttng_kernel_context *ctx)
 /* Enable event, channel and session ioctl */
 int kernctl_enable(int fd)
 {
-	return ioctl(fd, LTTNG_KERNEL_ENABLE);
+	return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_ENABLE,
+			LTTNG_KERNEL_ENABLE);
 }
 
 /* Disable event, channel and session ioctl */
 int kernctl_disable(int fd)
 {
-	return ioctl(fd, LTTNG_KERNEL_DISABLE);
+	return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_DISABLE,
+			LTTNG_KERNEL_DISABLE);
 }
 
 int kernctl_start_session(int fd)
 {
-	return ioctl(fd, LTTNG_KERNEL_SESSION_START);
+	return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_SESSION_START,
+			LTTNG_KERNEL_SESSION_START);
 }
 
 int kernctl_stop_session(int fd)
 {
-	return ioctl(fd, LTTNG_KERNEL_SESSION_STOP);
+	return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_SESSION_STOP,
+			LTTNG_KERNEL_SESSION_STOP);
 }
 
-
 int kernctl_tracepoint_list(int fd)
 {
-	return ioctl(fd, LTTNG_KERNEL_TRACEPOINT_LIST);
+	return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_TRACEPOINT_LIST,
+			LTTNG_KERNEL_TRACEPOINT_LIST);
 }
 
 int kernctl_tracer_version(int fd, struct lttng_kernel_tracer_version *v)
 {
-	return ioctl(fd, LTTNG_KERNEL_TRACER_VERSION, v);
+	int ret;
+
+	if (lttng_kernel_use_old_abi == -1) {
+		ret = ioctl(fd, LTTNG_KERNEL_TRACER_VERSION, v);
+		if (!ret) {
+			lttng_kernel_use_old_abi = 0;
+			goto end;
+		}
+		lttng_kernel_use_old_abi = 1;
+	}
+	if (lttng_kernel_use_old_abi) {
+		struct lttng_kernel_old_tracer_version old_v;
+
+		ret = ioctl(fd, LTTNG_KERNEL_OLD_TRACER_VERSION, &old_v);
+		if (ret) {
+			goto end;
+		}
+		v->major = old_v.major;
+		v->minor = old_v.minor;
+		v->patchlevel = old_v.patchlevel;
+	} else {
+		ret = ioctl(fd, LTTNG_KERNEL_TRACER_VERSION, v);
+	}
+
+end:
+	return ret;
 }
 
 int kernctl_wait_quiescent(int fd)
 {
-	return ioctl(fd, LTTNG_KERNEL_WAIT_QUIESCENT);
+	return compat_ioctl_no_arg(fd, LTTNG_KERNEL_OLD_WAIT_QUIESCENT,
+			LTTNG_KERNEL_WAIT_QUIESCENT);
 }
 
 int kernctl_calibrate(int fd, struct lttng_kernel_calibrate *calibrate)
 {
-	return ioctl(fd, LTTNG_KERNEL_CALIBRATE, calibrate);
+	int ret;
+
+	if (lttng_kernel_use_old_abi == -1) {
+		ret = ioctl(fd, LTTNG_KERNEL_CALIBRATE, calibrate);
+		if (!ret) {
+			lttng_kernel_use_old_abi = 0;
+			goto end;
+		}
+		lttng_kernel_use_old_abi = 1;
+	}
+	if (lttng_kernel_use_old_abi) {
+		struct lttng_kernel_old_calibrate old_calibrate;
+
+		old_calibrate.type = calibrate->type;
+		ret = ioctl(fd, LTTNG_KERNEL_OLD_CALIBRATE, &old_calibrate);
+		if (ret) {
+			goto end;
+		}
+		calibrate->type = old_calibrate.type;
+	} else {
+		ret = ioctl(fd, LTTNG_KERNEL_CALIBRATE, calibrate);
+	}
+
+end:
+	return ret;
 }
 
 
@@ -193,10 +384,3 @@ int kernctl_set_stream_id(int fd, unsigned long *stream_id)
 {
 	return ioctl(fd, RING_BUFFER_SET_STREAM_ID, stream_id);
 }
-
-/* Get the offset of the stream_id in the packet header */
-int kernctl_get_net_stream_id_offset(int fd, unsigned long *offset)
-{
-	return ioctl(fd, LTTNG_KERNEL_STREAM_ID_OFFSET, offset);
-
-}
diff --git a/src/common/kernel-ctl/kernel-ctl.h b/src/common/kernel-ctl/kernel-ctl.h
index 18712d9..85a3a18 100644
--- a/src/common/kernel-ctl/kernel-ctl.h
+++ b/src/common/kernel-ctl/kernel-ctl.h
@@ -21,6 +21,7 @@
 
 #include <lttng/lttng.h>
 #include <common/lttng-kernel.h>
+#include <common/lttng-kernel-old.h>
 
 int kernctl_create_session(int fd);
 int kernctl_open_metadata(int fd, struct lttng_channel_attr *chops);
diff --git a/src/common/kernel-ctl/kernel-ioctl.h b/src/common/kernel-ctl/kernel-ioctl.h
index 35942be..8e22632 100644
--- a/src/common/kernel-ctl/kernel-ioctl.h
+++ b/src/common/kernel-ctl/kernel-ioctl.h
@@ -49,37 +49,69 @@
 /* map stream to stream id for network streaming */
 #define RING_BUFFER_SET_STREAM_ID           _IOW(0xF6, 0x0D, unsigned long)
 
+/* Old ABI (without support for 32/64 bits compat) */
+/* LTTng file descriptor ioctl */
+#define LTTNG_KERNEL_OLD_SESSION                _IO(0xF6, 0x40)
+#define LTTNG_KERNEL_OLD_TRACER_VERSION         \
+		_IOR(0xF6, 0x41, struct lttng_kernel_old_tracer_version)
+#define LTTNG_KERNEL_OLD_TRACEPOINT_LIST        _IO(0xF6, 0x42)
+#define LTTNG_KERNEL_OLD_WAIT_QUIESCENT         _IO(0xF6, 0x43)
+#define LTTNG_KERNEL_OLD_CALIBRATE		\
+	_IOWR(0xF6, 0x44, struct lttng_kernel_old_calibrate)
+
+/* Session FD ioctl */
+#define LTTNG_KERNEL_OLD_METADATA               \
+		_IOW(0xF6, 0x50, struct lttng_kernel_old_channel)
+#define LTTNG_KERNEL_OLD_CHANNEL                \
+		_IOW(0xF6, 0x51, struct lttng_kernel_old_channel)
+#define LTTNG_KERNEL_OLD_SESSION_START          _IO(0xF6, 0x52)
+#define LTTNG_KERNEL_OLD_SESSION_STOP           _IO(0xF6, 0x53)
+
+/* Channel FD ioctl */
+#define LTTNG_KERNEL_OLD_STREAM                 _IO(0xF6, 0x60)
+#define LTTNG_KERNEL_OLD_EVENT                  \
+		_IOW(0xF6, 0x61, struct lttng_kernel_old_event)
+#define LTTNG_KERNEL_OLD_STREAM_ID_OFFSET       \
+		_IOR(0xF6, 0x62, unsigned long)
 
+/* Event and Channel FD ioctl */
+#define LTTNG_KERNEL_OLD_CONTEXT                \
+		_IOW(0xF6, 0x70, struct lttng_kernel_old_context)
+
+/* Event, Channel and Session ioctl */
+#define LTTNG_KERNEL_OLD_ENABLE                 _IO(0xF6, 0x80)
+#define LTTNG_KERNEL_OLD_DISABLE                _IO(0xF6, 0x81)
+
+
+/* Current ABI (with suport for 32/64 bits compat) */
 /* LTTng file descriptor ioctl */
-#define LTTNG_KERNEL_SESSION                _IO(0xF6, 0x40)
-#define LTTNG_KERNEL_TRACER_VERSION         \
-		_IOR(0xF6, 0x41, struct lttng_kernel_tracer_version)
-#define LTTNG_KERNEL_TRACEPOINT_LIST        _IO(0xF6, 0x42)
-#define LTTNG_KERNEL_WAIT_QUIESCENT         _IO(0xF6, 0x43)
+#define LTTNG_KERNEL_SESSION			_IO(0xF6, 0x45)
+#define LTTNG_KERNEL_TRACER_VERSION		\
+	_IOR(0xF6, 0x46, struct lttng_kernel_tracer_version)
+#define LTTNG_KERNEL_TRACEPOINT_LIST		_IO(0xF6, 0x47)
+#define LTTNG_KERNEL_WAIT_QUIESCENT		_IO(0xF6, 0x48)
 #define LTTNG_KERNEL_CALIBRATE			\
-	_IOWR(0xF6, 0x44, struct lttng_kernel_calibrate)
+	_IOWR(0xF6, 0x49, struct lttng_kernel_calibrate)
 
 /* Session FD ioctl */
-#define LTTNG_KERNEL_METADATA               \
-		_IOW(0xF6, 0x50, struct lttng_channel_attr)
-#define LTTNG_KERNEL_CHANNEL                \
-		_IOW(0xF6, 0x51, struct lttng_channel_attr)
-#define LTTNG_KERNEL_SESSION_START          _IO(0xF6, 0x52)
-#define LTTNG_KERNEL_SESSION_STOP           _IO(0xF6, 0x53)
+#define LTTNG_KERNEL_METADATA			\
+	_IOW(0xF6, 0x54, struct lttng_kernel_channel)
+#define LTTNG_KERNEL_CHANNEL			\
+	_IOW(0xF6, 0x55, struct lttng_kernel_channel)
+#define LTTNG_KERNEL_SESSION_START		_IO(0xF6, 0x56)
+#define LTTNG_KERNEL_SESSION_STOP		_IO(0xF6, 0x57)
 
 /* Channel FD ioctl */
-#define LTTNG_KERNEL_STREAM                 _IO(0xF6, 0x60)
-#define LTTNG_KERNEL_EVENT                  \
-		_IOW(0xF6, 0x61, struct lttng_kernel_event)
-#define LTTNG_KERNEL_STREAM_ID_OFFSET       \
-		_IOR(0xF6, 0x62, unsigned long)
+#define LTTNG_KERNEL_STREAM			_IO(0xF6, 0x62)
+#define LTTNG_KERNEL_EVENT			\
+	_IOW(0xF6, 0x63, struct lttng_kernel_event)
 
 /* Event and Channel FD ioctl */
-#define LTTNG_KERNEL_CONTEXT                \
-		_IOW(0xF6, 0x70, struct lttng_kernel_context)
+#define LTTNG_KERNEL_CONTEXT			\
+	_IOW(0xF6, 0x71, struct lttng_kernel_context)
 
 /* Event, Channel and Session ioctl */
-#define LTTNG_KERNEL_ENABLE                 _IO(0xF6, 0x80)
-#define LTTNG_KERNEL_DISABLE                _IO(0xF6, 0x81)
+#define LTTNG_KERNEL_ENABLE			_IO(0xF6, 0x82)
+#define LTTNG_KERNEL_DISABLE			_IO(0xF6, 0x83)
 
 #endif /* _LTT_KERNEL_IOCTL_H */
diff --git a/src/common/lttng-kernel-old.h b/src/common/lttng-kernel-old.h
new file mode 100644
index 0000000..1b8999a
--- /dev/null
+++ b/src/common/lttng-kernel-old.h
@@ -0,0 +1,115 @@
+/*
+ * Copyright (C) 2011 - Julien Desfossez <julien.desfossez at polymtl.ca>
+ *                      Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
+ *                      David Goulet <david.goulet at polymtl.ca>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef _LTTNG_KERNEL_OLD_H
+#define _LTTNG_KERNEL_OLD_H
+
+#include <stdint.h>
+#include <common/lttng-kernel.h>
+
+/*
+ * LTTng DebugFS ABI structures.
+ *
+ * This is the kernel ABI copied from lttng-modules tree.
+ */
+
+/* Perf counter attributes */
+struct lttng_kernel_old_perf_counter_ctx {
+	uint32_t type;
+	uint64_t config;
+	char name[LTTNG_KERNEL_SYM_NAME_LEN];
+};
+
+/* Event/Channel context */
+#define LTTNG_KERNEL_OLD_CONTEXT_PADDING1  16
+#define LTTNG_KERNEL_OLD_CONTEXT_PADDING2  LTTNG_KERNEL_SYM_NAME_LEN + 32
+struct lttng_kernel_old_context {
+	enum lttng_kernel_context_type ctx;
+	char padding[LTTNG_KERNEL_OLD_CONTEXT_PADDING1];
+
+	union {
+		struct lttng_kernel_old_perf_counter_ctx perf_counter;
+		char padding[LTTNG_KERNEL_OLD_CONTEXT_PADDING2];
+	} u;
+};
+
+struct lttng_kernel_old_kretprobe {
+	uint64_t addr;
+
+	uint64_t offset;
+	char symbol_name[LTTNG_KERNEL_SYM_NAME_LEN];
+};
+
+/*
+ * Either addr is used, or symbol_name and offset.
+ */
+struct lttng_kernel_old_kprobe {
+	uint64_t addr;
+
+	uint64_t offset;
+	char symbol_name[LTTNG_KERNEL_SYM_NAME_LEN];
+};
+
+/* Function tracer */
+struct lttng_kernel_old_function {
+	char symbol_name[LTTNG_KERNEL_SYM_NAME_LEN];
+};
+
+#define LTTNG_KERNEL_OLD_EVENT_PADDING1    16
+#define LTTNG_KERNEL_OLD_EVENT_PADDING2    LTTNG_KERNEL_SYM_NAME_LEN + 32
+struct lttng_kernel_old_event {
+	char name[LTTNG_KERNEL_SYM_NAME_LEN];
+	enum lttng_kernel_instrumentation instrumentation;
+	char padding[LTTNG_KERNEL_OLD_EVENT_PADDING1];
+
+	/* Per instrumentation type configuration */
+	union {
+		struct lttng_kernel_old_kretprobe kretprobe;
+		struct lttng_kernel_old_kprobe kprobe;
+		struct lttng_kernel_old_function ftrace;
+		char padding[LTTNG_KERNEL_OLD_EVENT_PADDING2];
+	} u;
+};
+
+struct lttng_kernel_old_tracer_version {
+	uint32_t major;
+	uint32_t minor;
+	uint32_t patchlevel;
+};
+
+struct lttng_kernel_old_calibrate {
+	enum lttng_kernel_calibrate_type type;	/* type (input) */
+};
+
+/*
+ * kernel channel
+ */
+#define LTTNG_KERNEL_OLD_CHANNEL_PADDING1 LTTNG_SYMBOL_NAME_LEN + 32
+struct lttng_kernel_old_channel {
+	int overwrite;                      /* 1: overwrite, 0: discard */
+	uint64_t subbuf_size;               /* bytes */
+	uint64_t num_subbuf;                /* power of 2 */
+	unsigned int switch_timer_interval; /* usec */
+	unsigned int read_timer_interval;   /* usec */
+	enum lttng_event_output output;     /* splice, mmap */
+
+	char padding[LTTNG_KERNEL_OLD_CHANNEL_PADDING1];
+};
+
+#endif /* _LTTNG_KERNEL_OLD_H */
diff --git a/src/common/lttng-kernel.h b/src/common/lttng-kernel.h
index dbeb6aa..fa8ba61 100644
--- a/src/common/lttng-kernel.h
+++ b/src/common/lttng-kernel.h
@@ -59,7 +59,7 @@ struct lttng_kernel_perf_counter_ctx {
 	uint32_t type;
 	uint64_t config;
 	char name[LTTNG_KERNEL_SYM_NAME_LEN];
-};
+}__attribute__((packed));
 
 /* Event/Channel context */
 #define LTTNG_KERNEL_CONTEXT_PADDING1  16
@@ -72,14 +72,14 @@ struct lttng_kernel_context {
 		struct lttng_kernel_perf_counter_ctx perf_counter;
 		char padding[LTTNG_KERNEL_CONTEXT_PADDING2];
 	} u;
-};
+}__attribute__((packed));
 
 struct lttng_kernel_kretprobe {
 	uint64_t addr;
 
 	uint64_t offset;
 	char symbol_name[LTTNG_KERNEL_SYM_NAME_LEN];
-};
+}__attribute__((packed));
 
 /*
  * Either addr is used, or symbol_name and offset.
@@ -89,12 +89,12 @@ struct lttng_kernel_kprobe {
 
 	uint64_t offset;
 	char symbol_name[LTTNG_KERNEL_SYM_NAME_LEN];
-};
+}__attribute__((packed));
 
 /* Function tracer */
 struct lttng_kernel_function {
 	char symbol_name[LTTNG_KERNEL_SYM_NAME_LEN];
-};
+}__attribute__((packed));
 
 #define LTTNG_KERNEL_EVENT_PADDING1    16
 #define LTTNG_KERNEL_EVENT_PADDING2    LTTNG_KERNEL_SYM_NAME_LEN + 32
@@ -110,13 +110,13 @@ struct lttng_kernel_event {
 		struct lttng_kernel_function ftrace;
 		char padding[LTTNG_KERNEL_EVENT_PADDING2];
 	} u;
-};
+}__attribute__((packed));
 
 struct lttng_kernel_tracer_version {
 	uint32_t major;
 	uint32_t minor;
 	uint32_t patchlevel;
-};
+}__attribute__((packed));
 
 enum lttng_kernel_calibrate_type {
 	LTTNG_KERNEL_CALIBRATE_KRETPROBE,
@@ -124,6 +124,21 @@ enum lttng_kernel_calibrate_type {
 
 struct lttng_kernel_calibrate {
 	enum lttng_kernel_calibrate_type type;	/* type (input) */
-};
+}__attribute__((packed));
+
+/*
+ * kernel channel
+ */
+#define LTTNG_KERNEL_CHANNEL_PADDING1 LTTNG_SYMBOL_NAME_LEN + 32
+struct lttng_kernel_channel {
+	uint64_t subbuf_size;               /* bytes */
+	uint64_t num_subbuf;                /* power of 2 */
+	unsigned int switch_timer_interval; /* usec */
+	unsigned int read_timer_interval;   /* usec */
+	enum lttng_event_output output;     /* splice, mmap */
+
+	int overwrite;                      /* 1: overwrite, 0: discard */
+	char padding[LTTNG_KERNEL_CHANNEL_PADDING1];
+}__attribute__((packed));
 
 #endif /* _LTTNG_KERNEL_H */
-- 
1.7.9.5




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