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Subject[PATCH 12/17] tracing/probes: Implement 'memory' fetch method for uprobes
Date
From: Namhyung Kim <namhyung.kim@lge.com>

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>
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: Namhyung Kim <namhyung@kernel.org>
---
kernel/trace/trace_kprobe.c | 77 +++++++++++++++++++++++++++++++++++++++++++++
kernel/trace/trace_probe.c | 77 ---------------------------------------------
kernel/trace/trace_probe.h | 4 ---
kernel/trace/trace_uprobe.c | 52 ++++++++++++++++++++++++++++++
4 files changed, 129 insertions(+), 81 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 1c38f3f47d0d..d1d3d8982345 100644
--- 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) \
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 8d7231d436da..8f7a2b6d389d 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -103,83 +103,6 @@ DEFINE_BASIC_FETCH_FUNCS(retval)
#define fetch_retval_string NULL
#define fetch_retval_string_size NULL

-#define DEFINE_FETCH_memory(type) \
-__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.
- */
-__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 */
-__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;
-}
-
/* Dereference memory access function */
struct deref_fetch_param {
struct fetch_param orig;
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 8be84550ceb3..2d5b8f5f5310 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -171,10 +171,6 @@ DECLARE_BASIC_FETCH_FUNCS(retval);
#define fetch_retval_string NULL
#define fetch_retval_string_size NULL

-DECLARE_BASIC_FETCH_FUNCS(memory);
-DECLARE_FETCH_FUNC(memory, string);
-DECLARE_FETCH_FUNC(memory, string_size);
-
DECLARE_BASIC_FETCH_FUNCS(symbol);
DECLARE_FETCH_FUNC(symbol, string);
DECLARE_FETCH_FUNC(symbol, string_size);
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index adc9ac70fd3c..7eb1b3244c94 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 don't support symbol fetch methods */
#define fetch_symbol_u8 NULL
--
1.7.11.7


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