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SubjectRe: [PATCH 13/13] tracing/uprobes: Add support for full argument access methods
(2013/08/09 17:45), Namhyung Kim wrote:
> From: Namhyung Kim <namhyung.kim@lge.com>
>
> Enable to fetch other types of argument for the uprobes. IOW, we can
> access stack, memory, deref, bitfield and retval from uprobes now.

Could you also add more detail descriptions about what syntax
uprobe-event will accept now and what is not?
And also, you should update Documentation/trace/uprobetracer.txt
according to your effort too. :)

Thank you,

> Original-patch-by: Hyeoncheol Lee <cheol.lee@lge.com>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> Cc: Oleg Nesterov <oleg@redhat.com>
> Cc: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
> kernel/trace/trace_probe.c | 34 ++++++++++++++++++++--------------
> 1 file changed, 20 insertions(+), 14 deletions(-)
>
> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> index 70cd3bfde5a6..b68ceb7cad6e 100644
> --- a/kernel/trace/trace_probe.c
> +++ b/kernel/trace/trace_probe.c
> @@ -253,7 +253,7 @@ fail:
> }
>
> /* Special function : only accept unsigned long */
> -static __kprobes void fetch_stack_address(struct pt_regs *regs,
> +static __kprobes void fetch_kernel_stack_address(struct pt_regs *regs,
> void *dummy, void *dest, void *priv)
> {
> *(unsigned long *)dest = kernel_stack_pointer(regs);
> @@ -303,7 +303,8 @@ int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)
> #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
>
> static int parse_probe_vars(char *arg, const struct fetch_type *t,
> - struct fetch_param *f, bool is_return)
> + struct fetch_param *f, bool is_return,
> + bool is_kprobe)
> {
> int ret = 0;
> unsigned long param;
> @@ -315,13 +316,18 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
> ret = -EINVAL;
> } else if (strncmp(arg, "stack", 5) == 0) {
> if (arg[5] == '\0') {
> - if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR) == 0)
> - f->fn = fetch_stack_address;
> - else
> - ret = -EINVAL;
> + if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR))
> + return -EINVAL;
> +
> + if (is_kprobe)
> + f->fn = fetch_kernel_stack_address;
> + else {
> + f->fn = t->fetch[FETCH_MTD_stack];
> + f->data = (void *)0;
> + }
> } else if (isdigit(arg[5])) {
> ret = kstrtoul(arg + 5, 10, &param);
> - if (ret || param > PARAM_MAX_STACK)
> + if (ret || (is_kprobe && param > PARAM_MAX_STACK))
> ret = -EINVAL;
> else {
> f->fn = t->fetch[FETCH_MTD_stack];
> @@ -345,17 +351,13 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
> int ret;
> const struct fetch_type *ttbl;
>
> - ttbl = kprobes_fetch_type_table;
> + ttbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table;
>
> ret = 0;
>
> - /* Until uprobe_events supports only reg arguments */
> - if (!is_kprobe && arg[0] != '%')
> - return -EINVAL;
> -
> switch (arg[0]) {
> case '$':
> - ret = parse_probe_vars(arg + 1, t, f, is_return);
> + ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
> break;
>
> case '%': /* named register */
> @@ -376,6 +378,10 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
> f->fn = t->fetch[FETCH_MTD_memory];
> f->data = (void *)param;
> } else {
> + /* uprobes don't support symbols */
> + if (!is_kprobe)
> + return -EINVAL;
> +
> ret = traceprobe_split_symbol_offset(arg + 1, &offset);
> if (ret)
> break;
> @@ -482,7 +488,7 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
> int ret;
> const struct fetch_type *ttbl;
>
> - ttbl = kprobes_fetch_type_table;
> + ttbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table;
>
> if (strlen(arg) > MAX_ARGSTR_LEN) {
> pr_info("Argument is too long.: %s\n", arg);
>


--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com




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