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tracing: probeevent: Return consumed bytes of dynamic area

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Cleanup string fetching routine so that returns the consumed
bytes of dynamic area and store the string information as
data_loc format instead of data_rloc.
This simplifies the fetcharg loop.

Link: http://lkml.kernel.org/r/152465874163.26224.12125143907501289031.stgit@devbox

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu 2018-04-25 21:19:01 +09:00 committed by Steven Rostedt (VMware)
parent f451bc89d8
commit 9178412ddf
4 changed files with 88 additions and 110 deletions
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57
kernel/trace/trace_kprobe.c
View File

@ -853,8 +853,8 @@ static const struct file_operations kprobe_profile_ops = {
/* Kprobe specific fetch functions */
/* Return the length of string -- including null terminal byte */
static nokprobe_inline void
fetch_store_strlen(unsigned long addr, void *dest)
static nokprobe_inline int
fetch_store_strlen(unsigned long addr)
{
mm_segment_t old_fs;
int ret, len = 0;
@ -872,47 +872,40 @@ fetch_store_strlen(unsigned long addr, void *dest)
pagefault_enable();
set_fs(old_fs);
if (ret < 0) /* Failed to check the length */
*(u32 *)dest = 0;
else
*(u32 *)dest = len;
return (ret < 0) ? ret : len;
}
/*
* Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
* length and relative data location.
*/
static nokprobe_inline void
fetch_store_string(unsigned long addr, void *dest)
static nokprobe_inline int
fetch_store_string(unsigned long addr, void *dest, void *base)
{
int maxlen = get_rloc_len(*(u32 *)dest);
u8 *dst = get_rloc_data(dest);
int maxlen = get_loc_len(*(u32 *)dest);
u8 *dst = get_loc_data(dest, base);
long ret;
if (!maxlen)
return;
if (unlikely(!maxlen))
return -ENOMEM;
/*
* Try to get string again, since the string can be changed while
* probing.
*/
ret = strncpy_from_unsafe(dst, (void *)addr, maxlen);
if (ret < 0) { /* Failed to fetch string */
dst[0] = '\0';
*(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
} else {
*(u32 *)dest = make_data_rloc(ret, get_rloc_offs(*(u32 *)dest));
}
if (ret >= 0)
*(u32 *)dest = make_data_loc(ret, (void *)dst - base);
return ret;
}
/* Note that we don't verify it, since the code does not come from user space */
static int
process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
bool pre)
void *base)
{
unsigned long val;
int ret;
int ret = 0;
/* 1st stage: get value from context */
switch (code->op) {
@ -949,6 +942,13 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
}
/* 3rd stage: store value to buffer */
if (unlikely(!dest)) {
if (code->op == FETCH_OP_ST_STRING)
return fetch_store_strlen(val + code->offset);
else
return -EILSEQ;
}
switch (code->op) {
case FETCH_OP_ST_RAW:
fetch_store_raw(val, code, dest);
@ -957,10 +957,7 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
probe_kernel_read(dest, (void *)val + code->offset, code->size);
break;
case FETCH_OP_ST_STRING:
if (pre)
fetch_store_strlen(val + code->offset, dest);
else
fetch_store_string(val + code->offset, dest);
ret = fetch_store_string(val + code->offset, dest, base);
break;
default:
return -EILSEQ;
@ -973,7 +970,7 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
code++;
}
return code->op == FETCH_OP_END ? 0 : -EILSEQ;
return code->op == FETCH_OP_END ? ret : -EILSEQ;
}
NOKPROBE_SYMBOL(process_fetch_insn)
@ -1008,7 +1005,7 @@ __kprobe_trace_func(struct trace_kprobe *tk, struct pt_regs *regs,
entry = ring_buffer_event_data(event);
entry->ip = (unsigned long)tk->rp.kp.addr;
store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
store_trace_args(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
event_trigger_unlock_commit_regs(trace_file, buffer, event,
entry, irq_flags, pc, regs);
@ -1057,7 +1054,7 @@ __kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
entry = ring_buffer_event_data(event);
entry->func = (unsigned long)tk->rp.kp.addr;
entry->ret_ip = (unsigned long)ri->ret_addr;
store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
store_trace_args(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
event_trigger_unlock_commit_regs(trace_file, buffer, event,
entry, irq_flags, pc, regs);
@ -1203,7 +1200,7 @@ kprobe_perf_func(struct trace_kprobe *tk, struct pt_regs *regs)
entry->ip = (unsigned long)tk->rp.kp.addr;
memset(&entry[1], 0, dsize);
store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
store_trace_args(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
head, NULL);
return 0;
@ -1239,7 +1236,7 @@ kretprobe_perf_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
entry->func = (unsigned long)tk->rp.kp.addr;
entry->ret_ip = (unsigned long)ri->ret_addr;
store_trace_args(sizeof(*entry), &tk->tp, regs, (u8 *)&entry[1], dsize);
store_trace_args(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
head, NULL);
}

26
kernel/trace/trace_probe.h
View File

@ -54,29 +54,15 @@
#define TP_FLAG_PROFILE 2
#define TP_FLAG_REGISTERED 4
/* data_loc: data location, compatible with u32 */
#define make_data_loc(len, offs) \
(((u32)(len) << 16) | ((u32)(offs) & 0xffff))
#define get_loc_len(dl) ((u32)(dl) >> 16)
#define get_loc_offs(dl) ((u32)(dl) & 0xffff)
/* 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)
/*
* 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))
static nokprobe_inline void *get_rloc_data(u32 *dl)
{
return (u8 *)dl + get_rloc_offs(*dl);
}
/* For data_loc conversion */
static nokprobe_inline void *get_loc_data(u32 *dl, void *ent)
{
return (u8 *)ent + get_rloc_offs(*dl);
return (u8 *)ent + get_loc_offs(*dl);
}
/* Printing function type */

54
kernel/trace/trace_probe_tmpl.h
View File

@ -48,24 +48,28 @@ fetch_apply_bitfield(struct fetch_insn *code, void *buf)
}
}
/* Define this for each callsite */
/*
* This must be defined for each callsite.
* Return consumed dynamic data size (>= 0), or error (< 0).
* If dest is NULL, don't store result and return required dynamic data size.
*/
static int
process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs,
void *dest, bool pre);
void *dest, void *base);
/* Sum up total data length for dynamic arraies (strings) */
static nokprobe_inline int
__get_data_size(struct trace_probe *tp, struct pt_regs *regs)
{
struct probe_arg *arg;
int i, ret = 0;
u32 len;
int i, len, ret = 0;
for (i = 0; i < tp->nr_args; i++) {
arg = tp->args + i;
if (unlikely(arg->dynamic)) {
process_fetch_insn(arg->code, regs, &len, true);
ret += len;
len = process_fetch_insn(arg->code, regs, NULL, NULL);
if (len > 0)
ret += len;
}
}
@ -74,34 +78,26 @@ __get_data_size(struct trace_probe *tp, struct pt_regs *regs)
/* Store the value of each argument */
static nokprobe_inline void
store_trace_args(int ent_size, struct trace_probe *tp, struct pt_regs *regs,
u8 *data, int maxlen)
store_trace_args(void *data, struct trace_probe *tp, struct pt_regs *regs,
int header_size, int maxlen)
{
struct probe_arg *arg;
u32 end = tp->size;
u32 *dl; /* Data (relative) location */
int i;
void *base = data - header_size;
void *dyndata = data + tp->size;
u32 *dl; /* Data location */
int ret, i;
for (i = 0; i < tp->nr_args; i++) {
arg = tp->args + i;
if (unlikely(arg->dynamic)) {
/*
* First, we set the relative location and
* maximum data length to *dl
*/
dl = (u32 *)(data + arg->offset);
*dl = make_data_rloc(maxlen, end - arg->offset);
/* Then try to fetch string or dynamic array data */
process_fetch_insn(arg->code, regs, dl, false);
/* 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 + arg->offset);
} else
/* Just fetching data normally */
process_fetch_insn(arg->code, regs, data + arg->offset,
false);
dl = data + arg->offset;
/* Point the dynamic data area if needed */
if (unlikely(arg->dynamic))
*dl = make_data_loc(maxlen, dyndata - base);
ret = process_fetch_insn(arg->code, regs, dl, base);
if (unlikely(ret < 0 && arg->dynamic))
*dl = make_data_loc(0, dyndata - base);
else
dyndata += ret;
}
}

61
kernel/trace/trace_uprobe.c
View File

@ -111,43 +111,38 @@ probe_user_read(void *dest, void *src, size_t size)
* Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
* length and relative data location.
*/
static nokprobe_inline void
fetch_store_string(unsigned long addr, void *dest)
static nokprobe_inline int
fetch_store_string(unsigned long addr, void *dest, void *base)
{
long ret;
u32 rloc = *(u32 *)dest;
int maxlen = get_rloc_len(rloc);
u8 *dst = get_rloc_data(dest);
u32 loc = *(u32 *)dest;
int maxlen = get_loc_len(loc);
u8 *dst = get_loc_data(dest, base);
void __user *src = (void __force __user *) addr;
if (!maxlen)
return;
if (unlikely(!maxlen))
return -ENOMEM;
ret = strncpy_from_user(dst, src, maxlen);
if (ret == maxlen)
dst[--ret] = '\0';
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));
if (ret >= 0) {
if (ret == maxlen)
dst[ret - 1] = '\0';
*(u32 *)dest = make_data_loc(ret, (void *)dst - base);
}
return ret;
}
/* Return the length of string -- including null terminal byte */
static nokprobe_inline void
fetch_store_strlen(unsigned long addr, void *dest)
static nokprobe_inline int
fetch_store_strlen(unsigned long addr)
{
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;
return (len > MAX_STRING_SIZE) ? 0 : len;
}
static unsigned long translate_user_vaddr(unsigned long file_offset)
@ -164,10 +159,10 @@ static unsigned long translate_user_vaddr(unsigned long file_offset)
/* Note that we don't verify it, since the code does not come from user space */
static int
process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
bool pre)
void *base)
{
unsigned long val;
int ret;
int ret = 0;
/* 1st stage: get value from context */
switch (code->op) {
@ -204,18 +199,22 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
}
/* 3rd stage: store value to buffer */
if (unlikely(!dest)) {
if (code->op == FETCH_OP_ST_STRING)
return fetch_store_strlen(val + code->offset);
else
return -EILSEQ;
}
switch (code->op) {
case FETCH_OP_ST_RAW:
fetch_store_raw(val, code, dest);
break;
case FETCH_OP_ST_MEM:
probe_user_read(dest, (void *)val + code->offset, code->size);
probe_kernel_read(dest, (void *)val + code->offset, code->size);
break;
case FETCH_OP_ST_STRING:
if (pre)
fetch_store_strlen(val + code->offset, dest);
else
fetch_store_string(val + code->offset, dest);
ret = fetch_store_string(val + code->offset, dest, base);
break;
default:
return -EILSEQ;
@ -228,7 +227,7 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
code++;
}
return code->op == FETCH_OP_END ? 0 : -EILSEQ;
return code->op == FETCH_OP_END ? ret : -EILSEQ;
}
NOKPROBE_SYMBOL(process_fetch_insn)
@ -1300,7 +1299,7 @@ static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
ucb = uprobe_buffer_get();
store_trace_args(esize, &tu->tp, regs, ucb->buf, dsize);
store_trace_args(ucb->buf, &tu->tp, regs, esize, dsize);
if (tu->tp.flags & TP_FLAG_TRACE)
ret |= uprobe_trace_func(tu, regs, ucb, dsize);
@ -1335,7 +1334,7 @@ static int uretprobe_dispatcher(struct uprobe_consumer *con,
esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
ucb = uprobe_buffer_get();
store_trace_args(esize, &tu->tp, regs, ucb->buf, dsize);
store_trace_args(ucb->buf, &tu->tp, regs, esize, dsize);
if (tu->tp.flags & TP_FLAG_TRACE)
uretprobe_trace_func(tu, func, regs, ucb, dsize);