[lttng-dev] [lttng-tools PATCH] Add support for kernel uprobes
Mathieu Desnoyers
mathieu.desnoyers at efficios.com
Wed Jan 16 10:52:38 EST 2013
* Yannick Brosseau (yannick.brosseau at gmail.com) wrote:
> Inspired by the k*probe support.
>
> It add a new option to enable-event --uprobe which require a path name
> and an offset in the specified file.
>
> (The file Documentation/trace/uprobetracer.txt in the kernel source provides
> and example on how to extract the offset for a symbol in a program)
Asking Masami and looking at perf might help us add support for lookup
by file/lineno (using dwarf info). I think in terms of usability this is
really important, and should appear in tools at the same time as the
basic feature based on file/offset (or at least appear in the same
LTTng release).
We should keep in mind that liblttng-ctl is LGPLv2.1, so we cannot use
perf code as-is without asking for the author's permission first.
Nothing prevents us from writing this support ourself if need be though.
Thanks,
Mathieu
>
> Signed-off-by: Yannick Brosseau <yannick.brosseau at gmail.com>
> ---
> include/lttng/lttng.h | 15 +++++++++
> src/bin/lttng-sessiond/cmd.c | 5 +++
> src/bin/lttng-sessiond/modprobe.c | 1 +
> src/bin/lttng-sessiond/trace-kernel.c | 7 ++++
> src/bin/lttng/commands/enable_events.c | 55 ++++++++++++++++++++++++++++++++
> src/bin/lttng/commands/list.c | 8 +++++
> src/common/lttng-kernel.h | 7 ++++
> 7 files changed, 98 insertions(+)
>
> diff --git a/include/lttng/lttng.h b/include/lttng/lttng.h
> index e21b479..c790e7b 100644
> --- a/include/lttng/lttng.h
> +++ b/include/lttng/lttng.h
> @@ -72,6 +72,7 @@ enum lttng_event_type {
> LTTNG_EVENT_FUNCTION_ENTRY = 3,
> LTTNG_EVENT_NOOP = 4,
> LTTNG_EVENT_SYSCALL = 5,
> + LTTNG_EVENT_UPROBE = 6,
> };
>
> /*
> @@ -219,6 +220,19 @@ struct lttng_event_function_attr {
> };
>
> /*
> + * Event uprobe.
> + *
> + * The structures should be initialized to zero before use.
> + */
> +#define LTTNG_EVENT_UPROBE_PADDING1 24
> +struct lttng_event_uprobe_attr {
> + char path[LTTNG_SYMBOL_NAME_LEN];
> + uint64_t offset;
> +
> + char padding[LTTNG_EVENT_UPROBE_PADDING1];
> +};
> +
> +/*
> * Generic lttng event
> *
> * The structures should be initialized to zero before use.
> @@ -242,6 +256,7 @@ struct lttng_event {
> union {
> struct lttng_event_probe_attr probe;
> struct lttng_event_function_attr ftrace;
> + struct lttng_event_uprobe_attr uprobe;
>
> char padding[LTTNG_EVENT_PADDING2];
> } attr;
> diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
> index 491acde..d7fee70 100644
> --- a/src/bin/lttng-sessiond/cmd.c
> +++ b/src/bin/lttng-sessiond/cmd.c
> @@ -315,6 +315,11 @@ static int list_lttng_kernel_events(char *channel_name,
> memcpy(&((*events)[i].attr.ftrace), &event->event->u.ftrace,
> sizeof(struct lttng_kernel_function));
> break;
> + case LTTNG_KERNEL_UPROBE:
> + (*events)[i].type = LTTNG_EVENT_UPROBE;
> + memcpy(&(*events)[i].attr.uprobe, &event->event->u.uprobe,
> + sizeof(struct lttng_kernel_uprobe));
> + break;
> case LTTNG_KERNEL_NOOP:
> (*events)[i].type = LTTNG_EVENT_NOOP;
> break;
> diff --git a/src/bin/lttng-sessiond/modprobe.c b/src/bin/lttng-sessiond/modprobe.c
> index 1a5a1b7..805e127 100644
> --- a/src/bin/lttng-sessiond/modprobe.c
> +++ b/src/bin/lttng-sessiond/modprobe.c
> @@ -35,6 +35,7 @@ const struct kern_modules_param kern_modules_list[] = {
> { "lttng-ftrace", 0 },
> { "lttng-kprobes", 0 },
> { "lttng-kretprobes", 0 },
> + { "lttng-uprobes", 0 },
> { "lttng-lib-ring-buffer", 1 },
> { "lttng-ring-buffer-client-discard", 1 },
> { "lttng-ring-buffer-client-overwrite", 1 },
> diff --git a/src/bin/lttng-sessiond/trace-kernel.c b/src/bin/lttng-sessiond/trace-kernel.c
> index f38cf3d..24f33f9 100644
> --- a/src/bin/lttng-sessiond/trace-kernel.c
> +++ b/src/bin/lttng-sessiond/trace-kernel.c
> @@ -207,6 +207,13 @@ struct ltt_kernel_event *trace_kernel_create_event(struct lttng_event *ev)
> ev->attr.probe.symbol_name, LTTNG_KERNEL_SYM_NAME_LEN);
> attr->u.kprobe.symbol_name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
> break;
> + case LTTNG_EVENT_UPROBE:
> + attr->instrumentation = LTTNG_KERNEL_UPROBE;
> + attr->u.uprobe.offset = ev->attr.uprobe.offset;
> + strncpy(attr->u.uprobe.path,
> + ev->attr.uprobe.path, LTTNG_KERNEL_SYM_NAME_LEN);
> + attr->u.uprobe.path[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
> + break;
> case LTTNG_EVENT_FUNCTION:
> attr->instrumentation = LTTNG_KERNEL_KRETPROBE;
> attr->u.kretprobe.addr = ev->attr.probe.addr;
> diff --git a/src/bin/lttng/commands/enable_events.c b/src/bin/lttng/commands/enable_events.c
> index b6c18e1..61cb15b 100644
> --- a/src/bin/lttng/commands/enable_events.c
> +++ b/src/bin/lttng/commands/enable_events.c
> @@ -38,6 +38,7 @@ static char *opt_session_name;
> static int opt_userspace;
> static int opt_enable_all;
> static char *opt_probe;
> +static char *opt_uprobe;
> static char *opt_function;
> static char *opt_function_entry_symbol;
> static char *opt_channel_name;
> @@ -52,6 +53,7 @@ enum {
> OPT_HELP = 1,
> OPT_TRACEPOINT,
> OPT_PROBE,
> + OPT_UPROBE,
> OPT_FUNCTION,
> OPT_FUNCTION_ENTRY,
> OPT_SYSCALL,
> @@ -74,6 +76,7 @@ static struct poptOption long_options[] = {
> {"userspace", 'u', POPT_ARG_NONE, 0, OPT_USERSPACE, 0, 0},
> {"tracepoint", 0, POPT_ARG_NONE, 0, OPT_TRACEPOINT, 0, 0},
> {"probe", 0, POPT_ARG_STRING, &opt_probe, OPT_PROBE, 0, 0},
> + {"uprobe", 0, POPT_ARG_STRING, &opt_uprobe, OPT_UPROBE, 0, 0},
> {"function", 0, POPT_ARG_STRING, &opt_function, OPT_FUNCTION, 0, 0},
> #if 0
> /*
> @@ -117,6 +120,10 @@ static void usage(FILE *ofp)
> fprintf(ofp, " Dynamic probe.\n");
> fprintf(ofp, " Addr and offset can be octal (0NNN...),\n");
> fprintf(ofp, " decimal (NNN...) or hexadecimal (0xNNN...)\n");
> + fprintf(ofp, " --uprobe [path+offset]\n");
> + fprintf(ofp, " Dynamic uprobe.\n");
> + fprintf(ofp, " offset can be octal (0NNN...),\n");
> + fprintf(ofp, " decimal (NNN...) or hexadecimal (0xNNN...)\n");
> fprintf(ofp, " --function [addr | symbol | symbol+offset]\n");
> fprintf(ofp, " Dynamic function entry/return probe.\n");
> fprintf(ofp, " Addr and offset can be octal (0NNN...),\n");
> @@ -245,6 +252,42 @@ static int parse_probe_opts(struct lttng_event *ev, char *opt)
> end:
> return ret;
> }
> +/*
> + * Parse uprobe options.
> + */
> +static int parse_uprobe_opts(struct lttng_event *ev, char *opt)
> +{
> + int ret;
> + char s_hex[19];
> + char name[LTTNG_SYMBOL_NAME_LEN];
> +
> + if (opt == NULL) {
> + ret = -1;
> + goto end;
> + }
> +
> + /* Check for path+offset */
> + ret = sscanf(opt, "%[^'+']+%s", name, s_hex);
> + if (ret == 2) {
> + strncpy(ev->attr.uprobe.path, name, LTTNG_SYMBOL_NAME_LEN);
> + ev->attr.uprobe.path[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
> + DBG("probe path %s", ev->attr.uprobe.path);
> + if (strlen(s_hex) == 0) {
> + ERR("Invalid uprobe offset %s", s_hex);
> + ret = -1;
> + goto end;
> + }
> + ev->attr.uprobe.offset = strtoul(s_hex, NULL, 0);
> + DBG("uprobe offset %" PRIu64, ev->attr.uprobe.offset);
> + goto end;
> + }
> +
> + /* No match */
> + ret = -1;
> +
> +end:
> + return ret;
> +}
>
> /*
> * Maps loglevel from string to value
> @@ -471,6 +514,14 @@ static int enable_events(char *session_name)
> goto error;
> }
> break;
> + case LTTNG_EVENT_UPROBE:
> + ret = parse_uprobe_opts(&ev, opt_uprobe);
> + if (ret < 0) {
> + ERR("Unable to parse uprobe options");
> + ret = 0;
> + goto error;
> + }
> + break;
> case LTTNG_EVENT_FUNCTION:
> ret = parse_probe_opts(&ev, opt_function);
> if (ret < 0) {
> @@ -522,6 +573,7 @@ static int enable_events(char *session_name)
> ev.name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
> break;
> case LTTNG_EVENT_PROBE:
> + case LTTNG_EVENT_UPROBE:
> case LTTNG_EVENT_FUNCTION:
> case LTTNG_EVENT_FUNCTION_ENTRY:
> case LTTNG_EVENT_SYSCALL:
> @@ -636,6 +688,9 @@ int cmd_enable_events(int argc, const char **argv)
> case OPT_PROBE:
> opt_event_type = LTTNG_EVENT_PROBE;
> break;
> + case OPT_UPROBE:
> + opt_event_type = LTTNG_EVENT_UPROBE;
> + break;
> case OPT_FUNCTION:
> opt_event_type = LTTNG_EVENT_FUNCTION;
> break;
> diff --git a/src/bin/lttng/commands/list.c b/src/bin/lttng/commands/list.c
> index a6ea6b8..ffae239 100644
> --- a/src/bin/lttng/commands/list.c
> +++ b/src/bin/lttng/commands/list.c
> @@ -231,6 +231,14 @@ static void print_events(struct lttng_event *event)
> MSG("%ssymbol: %s", indent8, event->attr.probe.symbol_name);
> }
> break;
> + case LTTNG_EVENT_UPROBE:
> + MSG("%s%s (type: uprobe)%s%s", indent6,
> + event->name, enabled_string(event->enabled),
> + filter_string(event->filter));
> +
> + MSG("%spath: %s", indent8, event->attr.uprobe.path);
> + MSG("%soffset: 0x%" PRIx64, indent8, event->attr.uprobe.offset);
> + break;
> case LTTNG_EVENT_FUNCTION:
> case LTTNG_EVENT_FUNCTION_ENTRY:
> MSG("%s%s (type: function)%s%s", indent6,
> diff --git a/src/common/lttng-kernel.h b/src/common/lttng-kernel.h
> index fa8ba61..a43b956 100644
> --- a/src/common/lttng-kernel.h
> +++ b/src/common/lttng-kernel.h
> @@ -38,6 +38,7 @@ enum lttng_kernel_instrumentation {
> LTTNG_KERNEL_KRETPROBE = 3,
> LTTNG_KERNEL_NOOP = 4, /* not hooked */
> LTTNG_KERNEL_SYSCALL = 5,
> + LTTNG_KERNEL_UPROBE = 6,
> };
>
> enum lttng_kernel_context_type {
> @@ -96,6 +97,11 @@ struct lttng_kernel_function {
> char symbol_name[LTTNG_KERNEL_SYM_NAME_LEN];
> }__attribute__((packed));
>
> +struct lttng_kernel_uprobe {
> + char path[LTTNG_KERNEL_SYM_NAME_LEN];
> + uint64_t offset;
> +}__attribute__((packed));
> +
> #define LTTNG_KERNEL_EVENT_PADDING1 16
> #define LTTNG_KERNEL_EVENT_PADDING2 LTTNG_KERNEL_SYM_NAME_LEN + 32
> struct lttng_kernel_event {
> @@ -108,6 +114,7 @@ struct lttng_kernel_event {
> struct lttng_kernel_kretprobe kretprobe;
> struct lttng_kernel_kprobe kprobe;
> struct lttng_kernel_function ftrace;
> + struct lttng_kernel_uprobe uprobe;
> char padding[LTTNG_KERNEL_EVENT_PADDING2];
> } u;
> }__attribute__((packed));
> --
> 1.7.10.4
>
>
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> lttng-dev at lists.lttng.org
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--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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