[PATCH 02/12] tracing/kprobes: Add fetch{,_size} member into symbol and deref fetch method

Namhyung Kim
2013-07-03T12:35:53Z

From: Hyeoncheol Lee <cheol.lee@lge.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.

Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: Hyeoncheol Lee <cheol.lee@lge.com>
[namhyung@kernel.org: Split original patch into pieces as requested]
Signed-off-by: Namhyung Kim <namhyung@kernel.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)
--
1.7.11.7