tracing/probes: Add fetch{,_size} member into deref fetch method

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.

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.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>

1 files changed, 20 insertions, 2 deletions

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index a31ad478b7f6..8d7231d436da 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -184,6 +184,8 @@ __kprobes void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
 struct deref_fetch_param {
         struct fetch_param      orig;
         long                    offset;
+        fetch_func_t            fetch;
+        fetch_func_t            fetch_size;
 };
 
 #define DEFINE_FETCH_deref(type)                                        \
@@ -195,13 +197,26 @@ __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)
 {
@@ -477,6 +492,9 @@ 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, ftbl);
                         ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
                                                         is_kprobe);
                         if (ret)