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Date: Mon, 05 Aug 2013 17:19:50 +0900
From: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Steven Rostedt <rostedt@...dmis.org>,
Namhyung Kim <namhyung.kim@....com>,
Hyeoncheol Lee <cheol.lee@....com>,
LKML <linux-kernel@...r.kernel.org>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
Oleg Nesterov <oleg@...hat.com>,
"zhangwei(Jovi)" <jovi.zhangwei@...wei.com>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Subject: Re: [PATCH 02/13] tracing/kprobes: Add fetch{,_size} member into
symbol and deref fetch method
(2013/07/31 18:03), Namhyung Kim wrote:
> From: Hyeoncheol Lee <cheol.lee@....com>
>
> Those symbol and deref fetch methods access a memory region but they
> assume it's a kernel memory since uprobes does not support them.
>
> Add ->fetch and ->fetch_size member in order to provide a proper
> access method for supporting uprobes.
It looks symbol cache is not used by uprobes. I think it it enough to
add fetch/fetch_size to only deref, isn't it?
Thank you,
>
> 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: Hyeoncheol Lee <cheol.lee@....com>
> [namhyung@...nel.org: Split original patch into pieces as requested]
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
> kernel/trace/trace_probe.c | 48 ++++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 42 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> index c58c25d81591..c123a890c5b1 100644
> --- a/kernel/trace/trace_probe.c
> +++ b/kernel/trace/trace_probe.c
> @@ -93,6 +93,8 @@ struct symbol_cache {
> char *symbol;
> long offset;
> unsigned long addr;
> + fetch_func_t fetch;
> + fetch_func_t fetch_size;
> };
>
> static unsigned long update_symbol_cache(struct symbol_cache *sc)
> @@ -139,18 +141,29 @@ __kprobes void FETCH_FUNC_NAME(symbol, type)(struct pt_regs *regs, \
> { \
> struct symbol_cache *sc = data; \
> if (sc->addr) \
> - fetch_memory_##type(regs, (void *)sc->addr, dest); \
> + sc->fetch(regs, (void *)sc->addr, dest); \
> else \
> *(type *)dest = 0; \
> }
> DEFINE_BASIC_FETCH_FUNCS(symbol)
> DEFINE_FETCH_symbol(string)
> -DEFINE_FETCH_symbol(string_size)
> +
> +__kprobes void FETCH_FUNC_NAME(symbol, string_size)(struct pt_regs *regs,
> + void *data, void *dest)
> +{
> + struct symbol_cache *sc = data;
> + if (sc->addr && sc->fetch_size)
> + sc->fetch_size(regs, (void *)sc->addr, dest);
> + else
> + *(string_size *)dest = 0;
> +}
>
> /* Dereference memory access function */
> struct deref_fetch_param {
> struct fetch_param orig;
> long offset;
> + fetch_func_t fetch;
> + fetch_func_t fetch_size;
> };
>
> #define DEFINE_FETCH_deref(type) \
> @@ -162,13 +175,26 @@ __kprobes void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs, \
> call_fetch(&dprm->orig, regs, &addr); \
> if (addr) { \
> addr += dprm->offset; \
> - fetch_memory_##type(regs, (void *)addr, dest); \
> + dprm->fetch(regs, (void *)addr, dest); \
> } else \
> *(type *)dest = 0; \
> }
> DEFINE_BASIC_FETCH_FUNCS(deref)
> DEFINE_FETCH_deref(string)
> -DEFINE_FETCH_deref(string_size)
> +
> +__kprobes void FETCH_FUNC_NAME(deref, string_size)(struct pt_regs *regs,
> + void *data, void *dest)
> +{
> + struct deref_fetch_param *dprm = data;
> + unsigned long addr;
> +
> + call_fetch(&dprm->orig, regs, &addr);
> + if (addr && dprm->fetch_size) {
> + addr += dprm->offset;
> + dprm->fetch_size(regs, (void *)addr, dest);
> + } else
> + *(string_size *)dest = 0;
> +}
>
> static __kprobes void update_deref_fetch_param(struct deref_fetch_param *data)
> {
> @@ -410,13 +436,20 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
> f->fn = t->fetch[FETCH_MTD_memory];
> f->data = (void *)param;
> } else {
> + struct symbol_cache *sc;
> +
> ret = traceprobe_split_symbol_offset(arg + 1, &offset);
> if (ret)
> break;
>
> - f->data = alloc_symbol_cache(arg + 1, offset);
> - if (f->data)
> + sc = alloc_symbol_cache(arg + 1, offset);
> + if (sc) {
> f->fn = t->fetch[FETCH_MTD_symbol];
> + sc->fetch = t->fetch[FETCH_MTD_memory];
> + sc->fetch_size = get_fetch_size_function(t,
> + sc->fetch, ttbl);
> + f->data = sc;
> + }
> }
> break;
>
> @@ -448,6 +481,9 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
> return -ENOMEM;
>
> dprm->offset = offset;
> + dprm->fetch = t->fetch[FETCH_MTD_memory];
> + dprm->fetch_size = get_fetch_size_function(t,
> + dprm->fetch, ttbl);
> ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
> is_kprobe);
> if (ret)
>
--
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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