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

[~andy/linux] / kernel / trace / trace_kprobe.c

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index d2a4fd2fd8c19c76a437538b735102463a2527bd..f94a56915e698348de8621dd0d897fa6532fad1c 100644 (file)
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -148,6 +148,83 @@ 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;                                                    \
+       if (probe_kernel_address(addr, retval))                         \
+               *(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;
+       int maxlen = get_rloc_len(*(u32 *)dest);
+       u8 *dst = get_rloc_data(dest);
+       u8 *src = addr;
+       mm_segment_t old_fs = get_fs();
+
+       if (!maxlen)
+               return;
+
+       /*
+        * Try to get string again, since the string can be changed while
+        * probing.
+        */
+       set_fs(KERNEL_DS);
+       pagefault_disable();
+
+       do
+               ret = __copy_from_user_inatomic(dst++, src++, 1);
+       while (dst[-1] && ret == 0 && src - (u8 *)addr < maxlen);
+
+       dst[-1] = '\0';
+       pagefault_enable();
+       set_fs(old_fs);
+
+       if (ret < 0) {  /* Failed to fetch string */
+               ((u8 *)get_rloc_data(dest))[0] = '\0';
+               *(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
+       } else {
+               *(u32 *)dest = make_data_rloc(src - (u8 *)addr,
+                                             get_rloc_offs(*(u32 *)dest));
+       }
+}
+
+/* Return the length of string -- including null terminal byte */
+static __kprobes void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
+                                                       void *addr, void *dest)
+{
+       mm_segment_t old_fs;
+       int ret, len = 0;
+       u8 c;
+
+       old_fs = get_fs();
+       set_fs(KERNEL_DS);
+       pagefault_disable();
+
+       do {
+               ret = __copy_from_user_inatomic(&c, (u8 *)addr + len, 1);
+               len++;
+       } while (c && ret == 0 && len < MAX_STRING_SIZE);
+
+       pagefault_enable();
+       set_fs(old_fs);
+
+       if (ret < 0)    /* Failed to check the length */
+               *(u32 *)dest = 0;
+       else
+               *(u32 *)dest = len;
+}
+
 #define DEFINE_FETCH_symbol(type)                                      \
 __kprobes void FETCH_FUNC_NAME(symbol, type)(struct pt_regs *regs,     \
                                          void *data, void *dest)       \