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tracing/probes: Implement 'memory' fetch method for uprobes
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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>
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Namhyung Kim authored and Steven Rostedt committed Jan 2, 2014
1 parent 3925f4a commit 5baaa59
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Showing 4 changed files with 129 additions and 81 deletions.
77 changes: 77 additions & 0 deletions kernel/trace/trace_kprobe.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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) \
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77 changes: 0 additions & 77 deletions kernel/trace/trace_probe.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
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4 changes: 0 additions & 4 deletions kernel/trace/trace_probe.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
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52 changes: 52 additions & 0 deletions kernel/trace/trace_uprobe.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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
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