tracing/probes: Implement 'memory' fetch method for uprobes

Use separate method to fetch from memory.  Move existing functions to
trace_kprobe.c and make them static.  Also add new memory fetch
implementation for 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: Namhyung Kim <namhyung@kernel.org>

1 files changed, 52 insertions, 0 deletions

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 24ef6a33d93f..bebd2f5d9ea3 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -114,6 +114,58 @@ DEFINE_BASIC_FETCH_FUNCS(stack)
 #define fetch_stack_string      NULL
 #define fetch_stack_string_size NULL
 
+#define DEFINE_FETCH_memory(type)                                       \
+static __kprobes void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,\
+                                                void *addr, void *dest) \
+{                                                                       \
+        type retval;                                                    \
+        void __user *vaddr = (void __force __user *) addr;              \
+                                                                        \
+        if (copy_from_user(&retval, vaddr, sizeof(type)))               \
+                *(type *)dest = 0;                                      \
+        else                                                            \
+                *(type *) dest = retval;                                \
+}
+DEFINE_BASIC_FETCH_FUNCS(memory)
+/*
+ * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
+ * length and relative data location.
+ */
+static __kprobes void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
+                                                      void *addr, void *dest)
+{
+        long ret;
+        u32 rloc = *(u32 *)dest;
+        int maxlen  = get_rloc_len(rloc);
+        u8 *dst = get_rloc_data(dest);
+        void __user *src = (void __force __user *) addr;
+
+        if (!maxlen)
+                return;
+
+        ret = strncpy_from_user(dst, src, maxlen);
+
+        if (ret < 0) {  /* Failed to fetch string */
+                ((u8 *)get_rloc_data(dest))[0] = '\0';
+                *(u32 *)dest = make_data_rloc(0, get_rloc_offs(rloc));
+        } else {
+                *(u32 *)dest = make_data_rloc(ret, get_rloc_offs(rloc));
+        }
+}
+
+static __kprobes void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
+                                                      void *addr, void *dest)
+{
+        int len;
+        void __user *vaddr = (void __force __user *) addr;
+
+        len = strnlen_user(vaddr, MAX_STRING_SIZE);
+
+        if (len == 0 || len > MAX_STRING_SIZE)  /* Failed to check length */
+                *(u32 *)dest = 0;
+        else
+                *(u32 *)dest = len;
+}
 
 /* uprobes do not support symbol fetch methods */
 #define fetch_symbol_u8                 NULL