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Subject[PATCH 04/13] tracing/kprobes: Add fetch{,_size} member into deref fetch method
Date
From: Hyeoncheol Lee <cheol.lee@lge.com>

The deref fetch methods access a memory region but it assumes that
it's a kernel memory since uprobes does not support them.

Add ->fetch and ->fetch_size member in order to provide a proper
access methods 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: zhangwei(Jovi) <jovi.zhangwei@huawei.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 | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 41f654d24cd9..b7b8bda02d6e 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -97,6 +97,8 @@ DEFINE_BASIC_FETCH_FUNCS(retval)
struct deref_fetch_param {
struct fetch_param orig;
long offset;
+ fetch_func_t fetch;
+ fetch_func_t fetch_size;
};

#define DEFINE_FETCH_deref(type) \
@@ -108,13 +110,26 @@ __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)
{
@@ -394,6 +409,9 @@ 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


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