tracing/kprobes: Support "string" type
authorMasami Hiramatsu <mhiramat@redhat.com>
Mon, 5 Jul 2010 18:54:45 +0000 (15:54 -0300)
committerArnaldo Carvalho de Melo <acme@redhat.com>
Mon, 5 Jul 2010 18:54:45 +0000 (15:54 -0300)
Support string type tracing and printing in kprobe-tracer.

This allows user to trace string data in kernel including __user data. Note
that sometimes __user data may not be accessed if it is paged-out (sorry, but
kprobes operation should be done in atomic, we can not wait for page-in).

Commiter note: Fixed up conflicts with b7e2ece.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100519195724.2885.18788.stgit@localhost6.localdomain6>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Documentation/trace/kprobetrace.txt
kernel/trace/trace_kprobe.c

index ec94748..5f77d94 100644 (file)
@@ -42,7 +42,7 @@ Synopsis of kprobe_events
   +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**)
   NAME=FETCHARG : Set NAME as the argument name of FETCHARG.
   FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types
-                 (u8/u16/u32/u64/s8/s16/s32/s64) are supported.
+                 (u8/u16/u32/u64/s8/s16/s32/s64) and string are supported.
 
   (*) only for return probe.
   (**) this is useful for fetching a field of data structures.
index 3b831d8..1b79d1c 100644 (file)
@@ -30,6 +30,8 @@
 #include <linux/ptrace.h>
 #include <linux/perf_event.h>
 #include <linux/stringify.h>
+#include <linux/limits.h>
+#include <linux/uaccess.h>
 #include <asm/bitsperlong.h>
 
 #include "trace.h"
@@ -38,6 +40,7 @@
 #define MAX_TRACE_ARGS 128
 #define MAX_ARGSTR_LEN 63
 #define MAX_EVENT_NAME_LEN 64
+#define MAX_STRING_SIZE PATH_MAX
 #define KPROBE_EVENT_SYSTEM "kprobes"
 
 /* Reserved field names */
@@ -58,14 +61,16 @@ const char *reserved_field_names[] = {
 };
 
 /* Printing function type */
-typedef int (*print_type_func_t)(struct trace_seq *, const char *, void *);
+typedef int (*print_type_func_t)(struct trace_seq *, const char *, void *,
+                                void *);
 #define PRINT_TYPE_FUNC_NAME(type)     print_type_##type
 #define PRINT_TYPE_FMT_NAME(type)      print_type_format_##type
 
 /* Printing  in basic type function template */
 #define DEFINE_BASIC_PRINT_TYPE_FUNC(type, fmt, cast)                  \
 static __kprobes int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s,   \
-                                               const char *name, void *data)\
+                                               const char *name,       \
+                                               void *data, void *ent)\
 {                                                                      \
        return trace_seq_printf(s, " %s=" fmt, name, (cast)*(type *)data);\
 }                                                                      \
@@ -80,6 +85,49 @@ DEFINE_BASIC_PRINT_TYPE_FUNC(s16, "%d", int)
 DEFINE_BASIC_PRINT_TYPE_FUNC(s32, "%ld", long)
 DEFINE_BASIC_PRINT_TYPE_FUNC(s64, "%lld", long long)
 
+/* data_rloc: data relative location, compatible with u32 */
+#define make_data_rloc(len, roffs)     \
+       (((u32)(len) << 16) | ((u32)(roffs) & 0xffff))
+#define get_rloc_len(dl)       ((u32)(dl) >> 16)
+#define get_rloc_offs(dl)      ((u32)(dl) & 0xffff)
+
+static inline void *get_rloc_data(u32 *dl)
+{
+       return (u8 *)dl + get_rloc_offs(*dl);
+}
+
+/* For data_loc conversion */
+static inline void *get_loc_data(u32 *dl, void *ent)
+{
+       return (u8 *)ent + get_rloc_offs(*dl);
+}
+
+/*
+ * Convert data_rloc to data_loc:
+ *  data_rloc stores the offset from data_rloc itself, but data_loc
+ *  stores the offset from event entry.
+ */
+#define convert_rloc_to_loc(dl, offs)  ((u32)(dl) + (offs))
+
+/* For defining macros, define string/string_size types */
+typedef u32 string;
+typedef u32 string_size;
+
+/* Print type function for string type */
+static __kprobes int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s,
+                                                 const char *name,
+                                                 void *data, void *ent)
+{
+       int len = *(u32 *)data >> 16;
+
+       if (!len)
+               return trace_seq_printf(s, " %s=(fault)", name);
+       else
+               return trace_seq_printf(s, " %s=\"%s\"", name,
+                                       (const char *)get_loc_data(data, ent));
+}
+static const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
+
 /* Data fetch function type */
 typedef        void (*fetch_func_t)(struct pt_regs *, void *, void *);
 
@@ -94,32 +142,38 @@ static __kprobes void call_fetch(struct fetch_param *fprm,
        return fprm->fn(regs, fprm->data, dest);
 }
 
-#define FETCH_FUNC_NAME(kind, type)    fetch_##kind##_##type
+#define FETCH_FUNC_NAME(method, type)  fetch_##method##_##type
 /*
  * Define macro for basic types - we don't need to define s* types, because
  * we have to care only about bitwidth at recording time.
  */
-#define DEFINE_BASIC_FETCH_FUNCS(kind)  \
-DEFINE_FETCH_##kind(u8)                        \
-DEFINE_FETCH_##kind(u16)               \
-DEFINE_FETCH_##kind(u32)               \
-DEFINE_FETCH_##kind(u64)
-
-#define CHECK_BASIC_FETCH_FUNCS(kind, fn)      \
-       ((FETCH_FUNC_NAME(kind, u8) == fn) ||   \
-        (FETCH_FUNC_NAME(kind, u16) == fn) ||  \
-        (FETCH_FUNC_NAME(kind, u32) == fn) ||  \
-        (FETCH_FUNC_NAME(kind, u64) == fn))
+#define DEFINE_BASIC_FETCH_FUNCS(method) \
+DEFINE_FETCH_##method(u8)              \
+DEFINE_FETCH_##method(u16)             \
+DEFINE_FETCH_##method(u32)             \
+DEFINE_FETCH_##method(u64)
+
+#define CHECK_FETCH_FUNCS(method, fn)                  \
+       (((FETCH_FUNC_NAME(method, u8) == fn) ||        \
+         (FETCH_FUNC_NAME(method, u16) == fn) ||       \
+         (FETCH_FUNC_NAME(method, u32) == fn) ||       \
+         (FETCH_FUNC_NAME(method, u64) == fn) ||       \
+         (FETCH_FUNC_NAME(method, string) == fn) ||    \
+         (FETCH_FUNC_NAME(method, string_size) == fn)) \
+        && (fn != NULL))
 
 /* Data fetch function templates */
 #define DEFINE_FETCH_reg(type)                                         \
 static __kprobes void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs, \
-                                         void *offset, void *dest)     \
+                                       void *offset, void *dest)       \
 {                                                                      \
        *(type *)dest = (type)regs_get_register(regs,                   \
                                (unsigned int)((unsigned long)offset)); \
 }
 DEFINE_BASIC_FETCH_FUNCS(reg)
+/* No string on the register */
+#define fetch_reg_string NULL
+#define fetch_reg_string_size NULL
 
 #define DEFINE_FETCH_stack(type)                                       \
 static __kprobes void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,\
@@ -129,6 +183,9 @@ static __kprobes void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,\
                                (unsigned int)((unsigned long)offset)); \
 }
 DEFINE_BASIC_FETCH_FUNCS(stack)
+/* No string on the stack entry */
+#define fetch_stack_string NULL
+#define fetch_stack_string_size NULL
 
 #define DEFINE_FETCH_retval(type)                                      \
 static __kprobes void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs,\
@@ -137,6 +194,9 @@ static __kprobes void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs,\
        *(type *)dest = (type)regs_return_value(regs);                  \
 }
 DEFINE_BASIC_FETCH_FUNCS(retval)
+/* No string on the retval */
+#define fetch_retval_string NULL
+#define fetch_retval_string_size NULL
 
 #define DEFINE_FETCH_memory(type)                                      \
 static __kprobes void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,\
@@ -149,6 +209,62 @@ static __kprobes void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,\
                *(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)
+{
+       int ret, len = 0;
+       u8 c;
+       mm_segment_t 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;
+}
 
 /* Memory fetching by symbol */
 struct symbol_cache {
@@ -203,6 +319,8 @@ static __kprobes void FETCH_FUNC_NAME(symbol, type)(struct pt_regs *regs,\
                *(type *)dest = 0;                                      \
 }
 DEFINE_BASIC_FETCH_FUNCS(symbol)
+DEFINE_FETCH_symbol(string)
+DEFINE_FETCH_symbol(string_size)
 
 /* Dereference memory access function */
 struct deref_fetch_param {
@@ -224,12 +342,14 @@ static __kprobes void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs,\
                *(type *)dest = 0;                                      \
 }
 DEFINE_BASIC_FETCH_FUNCS(deref)
+DEFINE_FETCH_deref(string)
+DEFINE_FETCH_deref(string_size)
 
 static __kprobes void free_deref_fetch_param(struct deref_fetch_param *data)
 {
-       if (CHECK_BASIC_FETCH_FUNCS(deref, data->orig.fn))
+       if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
                free_deref_fetch_param(data->orig.data);
-       else if (CHECK_BASIC_FETCH_FUNCS(symbol, data->orig.fn))
+       else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
                free_symbol_cache(data->orig.data);
        kfree(data);
 }
@@ -240,23 +360,43 @@ static __kprobes void free_deref_fetch_param(struct deref_fetch_param *data)
 #define DEFAULT_FETCH_TYPE _DEFAULT_FETCH_TYPE(BITS_PER_LONG)
 #define DEFAULT_FETCH_TYPE_STR __stringify(DEFAULT_FETCH_TYPE)
 
-#define ASSIGN_FETCH_FUNC(kind, type)  \
-       .kind = FETCH_FUNC_NAME(kind, type)
-
-#define ASSIGN_FETCH_TYPE(ptype, ftype, sign)  \
-       {.name = #ptype,                        \
-        .size = sizeof(ftype),                 \
-        .is_signed = sign,                     \
-        .print = PRINT_TYPE_FUNC_NAME(ptype),  \
-        .fmt = PRINT_TYPE_FMT_NAME(ptype),     \
-ASSIGN_FETCH_FUNC(reg, ftype),                 \
-ASSIGN_FETCH_FUNC(stack, ftype),               \
-ASSIGN_FETCH_FUNC(retval, ftype),              \
-ASSIGN_FETCH_FUNC(memory, ftype),              \
-ASSIGN_FETCH_FUNC(symbol, ftype),              \
-ASSIGN_FETCH_FUNC(deref, ftype),               \
+/* Fetch types */
+enum {
+       FETCH_MTD_reg = 0,
+       FETCH_MTD_stack,
+       FETCH_MTD_retval,
+       FETCH_MTD_memory,
+       FETCH_MTD_symbol,
+       FETCH_MTD_deref,
+       FETCH_MTD_END,
+};
+
+#define ASSIGN_FETCH_FUNC(method, type)        \
+       [FETCH_MTD_##method] = FETCH_FUNC_NAME(method, type)
+
+#define __ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, _fmttype)        \
+       {.name = _name,                         \
+        .size = _size,                                 \
+        .is_signed = sign,                             \
+        .print = PRINT_TYPE_FUNC_NAME(ptype),          \
+        .fmt = PRINT_TYPE_FMT_NAME(ptype),             \
+        .fmttype = _fmttype,                           \
+        .fetch = {                                     \
+ASSIGN_FETCH_FUNC(reg, ftype),                         \
+ASSIGN_FETCH_FUNC(stack, ftype),                       \
+ASSIGN_FETCH_FUNC(retval, ftype),                      \
+ASSIGN_FETCH_FUNC(memory, ftype),                      \
+ASSIGN_FETCH_FUNC(symbol, ftype),                      \
+ASSIGN_FETCH_FUNC(deref, ftype),                       \
+         }                                             \
        }
 
+#define ASSIGN_FETCH_TYPE(ptype, ftype, sign)                  \
+       __ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, #ptype)
+
+#define FETCH_TYPE_STRING 0
+#define FETCH_TYPE_STRSIZE 1
+
 /* Fetch type information table */
 static const struct fetch_type {
        const char      *name;          /* Name of type */
@@ -264,14 +404,16 @@ static const struct fetch_type {
        int             is_signed;      /* Signed flag */
        print_type_func_t       print;  /* Print functions */
        const char      *fmt;           /* Fromat string */
+       const char      *fmttype;       /* Name in format file */
        /* Fetch functions */
-       fetch_func_t    reg;
-       fetch_func_t    stack;
-       fetch_func_t    retval;
-       fetch_func_t    memory;
-       fetch_func_t    symbol;
-       fetch_func_t    deref;
+       fetch_func_t    fetch[FETCH_MTD_END];
 } fetch_type_table[] = {
+       /* Special types */
+       [FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
+                                       sizeof(u32), 1, "__data_loc char[]"),
+       [FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
+                                       string_size, sizeof(u32), 0, "u32"),
+       /* Basic types */
        ASSIGN_FETCH_TYPE(u8,  u8,  0),
        ASSIGN_FETCH_TYPE(u16, u16, 0),
        ASSIGN_FETCH_TYPE(u32, u32, 0),
@@ -302,12 +444,28 @@ static __kprobes void fetch_stack_address(struct pt_regs *regs,
        *(unsigned long *)dest = kernel_stack_pointer(regs);
 }
 
+static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
+                                           fetch_func_t orig_fn)
+{
+       int i;
+
+       if (type != &fetch_type_table[FETCH_TYPE_STRING])
+               return NULL;    /* Only string type needs size function */
+       for (i = 0; i < FETCH_MTD_END; i++)
+               if (type->fetch[i] == orig_fn)
+                       return fetch_type_table[FETCH_TYPE_STRSIZE].fetch[i];
+
+       WARN_ON(1);     /* This should not happen */
+       return NULL;
+}
+
 /**
  * Kprobe event core functions
  */
 
 struct probe_arg {
        struct fetch_param      fetch;
+       struct fetch_param      fetch_size;
        unsigned int            offset; /* Offset from argument entry */
        const char              *name;  /* Name of this argument */
        const char              *comm;  /* Command of this argument */
@@ -429,9 +587,9 @@ error:
 
 static void free_probe_arg(struct probe_arg *arg)
 {
-       if (CHECK_BASIC_FETCH_FUNCS(deref, arg->fetch.fn))
+       if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
                free_deref_fetch_param(arg->fetch.data);
-       else if (CHECK_BASIC_FETCH_FUNCS(symbol, arg->fetch.fn))
+       else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
                free_symbol_cache(arg->fetch.data);
        kfree(arg->name);
        kfree(arg->comm);
@@ -548,7 +706,7 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
 
        if (strcmp(arg, "retval") == 0) {
                if (is_return)
-                       f->fn = t->retval;
+                       f->fn = t->fetch[FETCH_MTD_retval];
                else
                        ret = -EINVAL;
        } else if (strncmp(arg, "stack", 5) == 0) {
@@ -562,7 +720,7 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
                        if (ret || param > PARAM_MAX_STACK)
                                ret = -EINVAL;
                        else {
-                               f->fn = t->stack;
+                               f->fn = t->fetch[FETCH_MTD_stack];
                                f->data = (void *)param;
                        }
                } else
@@ -588,7 +746,7 @@ static int __parse_probe_arg(char *arg, const struct fetch_type *t,
        case '%':       /* named register */
                ret = regs_query_register_offset(arg + 1);
                if (ret >= 0) {
-                       f->fn = t->reg;
+                       f->fn = t->fetch[FETCH_MTD_reg];
                        f->data = (void *)(unsigned long)ret;
                        ret = 0;
                }
@@ -598,7 +756,7 @@ static int __parse_probe_arg(char *arg, const struct fetch_type *t,
                        ret = strict_strtoul(arg + 1, 0, &param);
                        if (ret)
                                break;
-                       f->fn = t->memory;
+                       f->fn = t->fetch[FETCH_MTD_memory];
                        f->data = (void *)param;
                } else {
                        ret = split_symbol_offset(arg + 1, &offset);
@@ -606,7 +764,7 @@ static int __parse_probe_arg(char *arg, const struct fetch_type *t,
                                break;
                        f->data = alloc_symbol_cache(arg + 1, offset);
                        if (f->data)
-                               f->fn = t->symbol;
+                               f->fn = t->fetch[FETCH_MTD_symbol];
                }
                break;
        case '+':       /* deref memory */
@@ -636,14 +794,17 @@ static int __parse_probe_arg(char *arg, const struct fetch_type *t,
                        if (ret)
                                kfree(dprm);
                        else {
-                               f->fn = t->deref;
+                               f->fn = t->fetch[FETCH_MTD_deref];
                                f->data = (void *)dprm;
                        }
                }
                break;
        }
-       if (!ret && !f->fn)
+       if (!ret && !f->fn) {   /* Parsed, but do not find fetch method */
+               pr_info("%s type has no corresponding fetch method.\n",
+                       t->name);
                ret = -EINVAL;
+       }
        return ret;
 }
 
@@ -652,6 +813,7 @@ static int parse_probe_arg(char *arg, struct trace_probe *tp,
                           struct probe_arg *parg, int is_return)
 {
        const char *t;
+       int ret;
 
        if (strlen(arg) > MAX_ARGSTR_LEN) {
                pr_info("Argument is too long.: %s\n",  arg);
@@ -674,7 +836,13 @@ static int parse_probe_arg(char *arg, struct trace_probe *tp,
        }
        parg->offset = tp->size;
        tp->size += parg->type->size;
-       return __parse_probe_arg(arg, parg->type, &parg->fetch, is_return);
+       ret = __parse_probe_arg(arg, parg->type, &parg->fetch, is_return);
+       if (ret >= 0) {
+               parg->fetch_size.fn = get_fetch_size_function(parg->type,
+                                                             parg->fetch.fn);
+               parg->fetch_size.data = parg->fetch.data;
+       }
+       return ret;
 }
 
 /* Return 1 if name is reserved or already used by another argument */
@@ -1043,6 +1211,54 @@ static const struct file_operations kprobe_profile_ops = {
        .release        = seq_release,
 };
 
+/* Sum up total data length for dynamic arraies (strings) */
+static __kprobes int __get_data_size(struct trace_probe *tp,
+                                    struct pt_regs *regs)
+{
+       int i, ret = 0;
+       u32 len;
+
+       for (i = 0; i < tp->nr_args; i++)
+               if (unlikely(tp->args[i].fetch_size.fn)) {
+                       call_fetch(&tp->args[i].fetch_size, regs, &len);
+                       ret += len;
+               }
+
+       return ret;
+}
+
+/* Store the value of each argument */
+static __kprobes void store_trace_args(int ent_size, struct trace_probe *tp,
+                                      struct pt_regs *regs,
+                                      u8 *data, int maxlen)
+{
+       int i;
+       u32 end = tp->size;
+       u32 *dl;        /* Data (relative) location */
+
+       for (i = 0; i < tp->nr_args; i++) {
+               if (unlikely(tp->args[i].fetch_size.fn)) {
+                       /*
+                        * First, we set the relative location and
+                        * maximum data length to *dl
+                        */
+                       dl = (u32 *)(data + tp->args[i].offset);
+                       *dl = make_data_rloc(maxlen, end - tp->args[i].offset);
+                       /* Then try to fetch string or dynamic array data */
+                       call_fetch(&tp->args[i].fetch, regs, dl);
+                       /* Reduce maximum length */
+                       end += get_rloc_len(*dl);
+                       maxlen -= get_rloc_len(*dl);
+                       /* Trick here, convert data_rloc to data_loc */
+                       *dl = convert_rloc_to_loc(*dl,
+                                ent_size + tp->args[i].offset);
+               } else
+                       /* Just fetching data normally */
+                       call_fetch(&tp->args[i].fetch, regs,
+                                  data + tp->args[i].offset);
+       }
+}
+
 /* Kprobe handler */
 static __kprobes void kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
 {
@@ -1050,8 +1266,7 @@ static __kprobes void kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
        struct kprobe_trace_entry_head *entry;
        struct ring_buffer_event *event;
        struct ring_buffer *buffer;
-       u8 *data;
-       int size, i, pc;
+       int size, dsize, pc;
        unsigned long irq_flags;
        struct ftrace_event_call *call = &tp->call;
 
@@ -1060,7 +1275,8 @@ static __kprobes void kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
        local_save_flags(irq_flags);
        pc = preempt_count();
 
-       size = sizeof(*entry) + tp->size;
+       dsize = __get_data_size(tp, regs);
+       size = sizeof(*entry) + tp->size + dsize;
 
        event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
                                                  size, irq_flags, pc);
@@ -1069,9 +1285,7 @@ static __kprobes void kprobe_trace_func(struct kprobe *kp, struct pt_regs *regs)
 
        entry = ring_buffer_event_data(event);
        entry->ip = (unsigned long)kp->addr;
-       data = (u8 *)&entry[1];
-       for (i = 0; i < tp->nr_args; i++)
-               call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);
+       store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
 
        if (!filter_current_check_discard(buffer, call, entry, event))
                trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
@@ -1085,15 +1299,15 @@ static __kprobes void kretprobe_trace_func(struct kretprobe_instance *ri,
        struct kretprobe_trace_entry_head *entry;
        struct ring_buffer_event *event;
        struct ring_buffer *buffer;
-       u8 *data;
-       int size, i, pc;
+       int size, pc, dsize;
        unsigned long irq_flags;
        struct ftrace_event_call *call = &tp->call;
 
        local_save_flags(irq_flags);
        pc = preempt_count();
 
-       size = sizeof(*entry) + tp->size;
+       dsize = __get_data_size(tp, regs);
+       size = sizeof(*entry) + tp->size + dsize;
 
        event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
                                                  size, irq_flags, pc);
@@ -1103,9 +1317,7 @@ static __kprobes void kretprobe_trace_func(struct kretprobe_instance *ri,
        entry = ring_buffer_event_data(event);
        entry->func = (unsigned long)tp->rp.kp.addr;
        entry->ret_ip = (unsigned long)ri->ret_addr;
-       data = (u8 *)&entry[1];
-       for (i = 0; i < tp->nr_args; i++)
-               call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);
+       store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
 
        if (!filter_current_check_discard(buffer, call, entry, event))
                trace_nowake_buffer_unlock_commit(buffer, event, irq_flags, pc);
@@ -1137,7 +1349,7 @@ print_kprobe_event(struct trace_iterator *iter, int flags,
        data = (u8 *)&field[1];
        for (i = 0; i < tp->nr_args; i++)
                if (!tp->args[i].type->print(s, tp->args[i].name,
-                                            data + tp->args[i].offset))
+                                            data + tp->args[i].offset, field))
                        goto partial;
 
        if (!trace_seq_puts(s, "\n"))
@@ -1179,7 +1391,7 @@ print_kretprobe_event(struct trace_iterator *iter, int flags,
        data = (u8 *)&field[1];
        for (i = 0; i < tp->nr_args; i++)
                if (!tp->args[i].type->print(s, tp->args[i].name,
-                                            data + tp->args[i].offset))
+                                            data + tp->args[i].offset, field))
                        goto partial;
 
        if (!trace_seq_puts(s, "\n"))
@@ -1234,7 +1446,7 @@ static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
        DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
        /* Set argument names as fields */
        for (i = 0; i < tp->nr_args; i++) {
-               ret = trace_define_field(event_call, tp->args[i].type->name,
+               ret = trace_define_field(event_call, tp->args[i].type->fmttype,
                                         tp->args[i].name,
                                         sizeof(field) + tp->args[i].offset,
                                         tp->args[i].type->size,
@@ -1256,7 +1468,7 @@ static int kretprobe_event_define_fields(struct ftrace_event_call *event_call)
        DEFINE_FIELD(unsigned long, ret_ip, FIELD_STRING_RETIP, 0);
        /* Set argument names as fields */
        for (i = 0; i < tp->nr_args; i++) {
-               ret = trace_define_field(event_call, tp->args[i].type->name,
+               ret = trace_define_field(event_call, tp->args[i].type->fmttype,
                                         tp->args[i].name,
                                         sizeof(field) + tp->args[i].offset,
                                         tp->args[i].type->size,
@@ -1296,8 +1508,13 @@ static int __set_print_fmt(struct trace_probe *tp, char *buf, int len)
        pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
 
        for (i = 0; i < tp->nr_args; i++) {
-               pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
-                               tp->args[i].name);
+               if (strcmp(tp->args[i].type->name, "string") == 0)
+                       pos += snprintf(buf + pos, LEN_OR_ZERO,
+                                       ", __get_str(%s)",
+                                       tp->args[i].name);
+               else
+                       pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
+                                       tp->args[i].name);
        }
 
 #undef LEN_OR_ZERO
@@ -1334,11 +1551,11 @@ static __kprobes void kprobe_perf_func(struct kprobe *kp,
        struct ftrace_event_call *call = &tp->call;
        struct kprobe_trace_entry_head *entry;
        struct hlist_head *head;
-       u8 *data;
-       int size, __size, i;
+       int size, __size, dsize;
        int rctx;
 
-       __size = sizeof(*entry) + tp->size;
+       dsize = __get_data_size(tp, regs);
+       __size = sizeof(*entry) + tp->size + dsize;
        size = ALIGN(__size + sizeof(u32), sizeof(u64));
        size -= sizeof(u32);
        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
@@ -1350,9 +1567,8 @@ static __kprobes void kprobe_perf_func(struct kprobe *kp,
                return;
 
        entry->ip = (unsigned long)kp->addr;
-       data = (u8 *)&entry[1];
-       for (i = 0; i < tp->nr_args; i++)
-               call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);
+       memset(&entry[1], 0, dsize);
+       store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
 
        head = this_cpu_ptr(call->perf_events);
        perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, head);
@@ -1366,11 +1582,11 @@ static __kprobes void kretprobe_perf_func(struct kretprobe_instance *ri,
        struct ftrace_event_call *call = &tp->call;
        struct kretprobe_trace_entry_head *entry;
        struct hlist_head *head;
-       u8 *data;
-       int size, __size, i;
+       int size, __size, dsize;
        int rctx;
 
-       __size = sizeof(*entry) + tp->size;
+       dsize = __get_data_size(tp, regs);
+       __size = sizeof(*entry) + tp->size + dsize;
        size = ALIGN(__size + sizeof(u32), sizeof(u64));
        size -= sizeof(u32);
        if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
@@ -1383,9 +1599,7 @@ static __kprobes void kretprobe_perf_func(struct kretprobe_instance *ri,
 
        entry->func = (unsigned long)tp->rp.kp.addr;
        entry->ret_ip = (unsigned long)ri->ret_addr;
-       data = (u8 *)&entry[1];
-       for (i = 0; i < tp->nr_args; i++)
-               call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);
+       store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
 
        head = this_cpu_ptr(call->perf_events);
        perf_trace_buf_submit(entry, size, rctx, entry->ret_ip, 1, regs, head);