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Date: Tue, 03 Dec 2013 18:32:52 +0900
From: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Oleg Nesterov <oleg@...hat.com>,
Steven Rostedt <rostedt@...dmis.org>,
Hyeoncheol Lee <cheol.lee@....com>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
"zhangwei(Jovi)" <jovi.zhangwei@...wei.com>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
Hemant Kumar <hkshaw@...ux.vnet.ibm.com>,
LKML <linux-kernel@...r.kernel.org>,
Namhyung Kim <namhyung.kim@....com>
Subject: Re: [PATCH/RFC 17/17] tracing/uprobes: Add @+file_offset fetch method
(2013/12/03 15:23), Namhyung Kim wrote:
>>> So do you want me to change to make it simpler without a fetch_param?
>>
>> Yes, yes. Assuming that you agree, of course.
>
> Okay, here goes v8 then. :)
>
> I also push it (with other changes come from Srikar) to the
> uprobe/fetch-v8 branch in my tree for your convenience. :)
This looks good for me :)
>>>From 25bc2bab14e9461f8b15e34f26d1de51f96e44e1 Mon Sep 17 00:00:00 2001
> From: Namhyung Kim <namhyung.kim@....com>
> Date: Mon, 25 Nov 2013 13:42:47 +0900
> Subject: [PATCH v8 17/17] tracing/uprobes: Add @+file_offset fetch method
>
> Enable to fetch data from a file offset. Currently it only supports
> fetching from same binary uprobe set. It'll translate the file offset
> to a proper virtual address in the process.
>
> The syntax is "@+OFFSET" as it does similar to normal memory fetching
> (@ADDR) which does no address translation.
>
> To do it, change fifth argument to receive 'void *priv' and make it
> set only for uprobes so that we can determine the arg is for kprobes
> or uprobes easily.
>
> Suggested-by: Oleg Nesterov <oleg@...hat.com>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
> Cc: Oleg Nesterov <oleg@...hat.com>
> Cc: zhangwei(Jovi) <jovi.zhangwei@...wei.com>
> Cc: Arnaldo Carvalho de Melo <acme@...stprotocols.net>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Thank you!
> ---
> Documentation/trace/uprobetracer.txt | 1 +
> kernel/trace/trace_kprobe.c | 8 ++++++++
> kernel/trace/trace_probe.c | 13 +++++++++++-
> kernel/trace/trace_probe.h | 2 ++
> kernel/trace/trace_uprobe.c | 40 ++++++++++++++++++++++++++++++++++++
> 5 files changed, 63 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/trace/uprobetracer.txt b/Documentation/trace/uprobetracer.txt
> index 6e5cff263e2b..f1cf9a34ad9d 100644
> --- a/Documentation/trace/uprobetracer.txt
> +++ b/Documentation/trace/uprobetracer.txt
> @@ -32,6 +32,7 @@ Synopsis of uprobe_tracer
> FETCHARGS : Arguments. Each probe can have up to 128 args.
> %REG : Fetch register REG
> @ADDR : Fetch memory at ADDR (ADDR should be in userspace)
> + @+OFFSET : Fetch memory at OFFSET (OFFSET from same file as PATH)
> $stackN : Fetch Nth entry of stack (N >= 0)
> $stack : Fetch stack address.
> $retval : Fetch return value.(*)
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 8b32236ae890..1cf8f3375559 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -239,6 +239,14 @@ DEFINE_BASIC_FETCH_FUNCS(symbol)
> DEFINE_FETCH_symbol(string)
> DEFINE_FETCH_symbol(string_size)
>
> +/* kprobes don't support file_offset fetch methods */
> +#define fetch_file_offset_u8 NULL
> +#define fetch_file_offset_u16 NULL
> +#define fetch_file_offset_u32 NULL
> +#define fetch_file_offset_u64 NULL
> +#define fetch_file_offset_string NULL
> +#define fetch_file_offset_string_size NULL
> +
> /* Fetch type information table */
> const struct fetch_type kprobes_fetch_type_table[] = {
> /* Special types */
> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> index 464ec506ec08..705c06ba0a8a 100644
> --- a/kernel/trace/trace_probe.c
> +++ b/kernel/trace/trace_probe.c
> @@ -373,7 +373,7 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
> }
> break;
>
> - case '@': /* memory or symbol */
> + case '@': /* memory, file-offset or symbol */
> if (isdigit(arg[1])) {
> ret = kstrtoul(arg + 1, 0, ¶m);
> if (ret)
> @@ -381,6 +381,17 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
>
> f->fn = t->fetch[FETCH_MTD_memory];
> f->data = (void *)param;
> + } else if (arg[1] == '+') {
> + /* kprobes don't support file offsets */
> + if (is_kprobe)
> + return -EINVAL;
> +
> + ret = kstrtol(arg + 2, 0, &offset);
> + if (ret)
> + break;
> +
> + f->fn = t->fetch[FETCH_MTD_file_offset];
> + f->data = (void *)offset;
> } else {
> /* uprobes don't support symbols */
> if (!is_kprobe)
> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> index 385206bbbf8b..d9afeb580cbf 100644
> --- a/kernel/trace/trace_probe.h
> +++ b/kernel/trace/trace_probe.h
> @@ -106,6 +106,7 @@ enum {
> FETCH_MTD_symbol,
> FETCH_MTD_deref,
> FETCH_MTD_bitfield,
> + FETCH_MTD_file_offset,
> FETCH_MTD_END,
> };
>
> @@ -217,6 +218,7 @@ ASSIGN_FETCH_FUNC(memory, ftype), \
> ASSIGN_FETCH_FUNC(symbol, ftype), \
> ASSIGN_FETCH_FUNC(deref, ftype), \
> ASSIGN_FETCH_FUNC(bitfield, ftype), \
> +ASSIGN_FETCH_FUNC(file_offset, ftype), \
> } \
> }
>
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index f86a6a711de9..f5cbed7e7709 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -70,6 +70,11 @@ static int unregister_uprobe_event(struct trace_uprobe *tu);
> static DEFINE_MUTEX(uprobe_lock);
> static LIST_HEAD(uprobe_list);
>
> +struct uprobe_dispatch_data {
> + struct trace_uprobe *tu;
> + unsigned long bp_addr;
> +};
> +
> static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs);
> static int uretprobe_dispatcher(struct uprobe_consumer *con,
> unsigned long func, struct pt_regs *regs);
> @@ -175,6 +180,29 @@ static __kprobes void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
> #define fetch_symbol_string NULL
> #define fetch_symbol_string_size NULL
>
> +static unsigned long translate_user_vaddr(void *file_offset)
> +{
> + unsigned long base_addr;
> + struct uprobe_dispatch_data *udd;
> +
> + udd = (void *) current->utask->vaddr;
> +
> + base_addr = udd->bp_addr - udd->tu->offset;
> + return base_addr + (unsigned long)file_offset;
> +}
> +
> +#define DEFINE_FETCH_file_offset(type) \
> +static __kprobes void FETCH_FUNC_NAME(file_offset, type)(struct pt_regs *regs,\
> + void *offset, void *dest) \
> +{ \
> + void *vaddr = (void *)translate_user_vaddr(offset); \
> + \
> + FETCH_FUNC_NAME(memory, type)(regs, vaddr, dest); \
> +}
> +DEFINE_BASIC_FETCH_FUNCS(file_offset)
> +DEFINE_FETCH_file_offset(string)
> +DEFINE_FETCH_file_offset(string_size)
> +
> /* Fetch type information table */
> const struct fetch_type uprobes_fetch_type_table[] = {
> /* Special types */
> @@ -1104,11 +1132,17 @@ int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type,
> static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
> {
> struct trace_uprobe *tu;
> + struct uprobe_dispatch_data udd;
> int ret = 0;
>
> tu = container_of(con, struct trace_uprobe, consumer);
> tu->nhit++;
>
> + udd.tu = tu;
> + udd.bp_addr = instruction_pointer(regs);
> +
> + current->utask->vaddr = (unsigned long) &udd;
> +
> if (tu->tp.flags & TP_FLAG_TRACE)
> ret |= uprobe_trace_func(tu, regs);
>
> @@ -1123,9 +1157,15 @@ static int uretprobe_dispatcher(struct uprobe_consumer *con,
> unsigned long func, struct pt_regs *regs)
> {
> struct trace_uprobe *tu;
> + struct uprobe_dispatch_data udd;
>
> tu = container_of(con, struct trace_uprobe, consumer);
>
> + udd.tu = tu;
> + udd.bp_addr = func;
> +
> + current->utask->vaddr = (unsigned long) &udd;
> +
> if (tu->tp.flags & TP_FLAG_TRACE)
> uretprobe_trace_func(tu, func, regs);
>
>
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@...achi.com
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