The documentation for kprobe events says that symbol offets can

take both a + and - sign to get to befor and after the symbol address.
 But in actuality, the code does not support the minus. This fixes
 that issue, and adds a few more selftests to kprobe events.
 -----BEGIN PGP SIGNATURE-----
 
 iQHIBAABCgAyFiEEPm6V/WuN2kyArTUe1a05Y9njSUkFAlq1e6IUHHJvc3RlZHRA
 Z29vZG1pcy5vcmcACgkQ1a05Y9njSUlA2gv/WJiLQC8NvZhjIuQAmhohoW2ejkf/
 rxW8AWCArcUwtqPxpeXAg+SzDIxqtkpUw2PkuivVkzugV/9cAdM+o4yogV8aV32w
 IYix77NxdaIiFNkMCrPYIBH8Bv7TubKUNEe5j+ChFGv90E98Cy2qFLXLXM8wkapq
 FMQ9PlLr9KumRwGeCSqGx1grVLv3uWlv85XY+pTHdtoeivL/maiemISgg0HE4UVc
 ovdZBMmiQBKjc727VgdRpkXWVA+sCoIhAzlkB5cSdDoYx5pHZi23qi5ZHjvlIIRz
 dD50lI41svFd4Q+WxcKxgMWqSS0NytnjQGfO4rU+3A4ZGYbjjWPtrTGxluX6Tx3C
 vOL6SYmD8FtU9c4WvgRLUsDzUrH2plDZOeL2jJSKFHwmB3USKLhYo7I4M/VYBXII
 K3kq/8ln3vq5NbyCcpQSHC5PuRW9pSKjiLUuXMEEKTlK+Aa+Jmvx7SJWp0l6gY0q
 BSMxInLOk5E+eechCkO/S9bugwlJYw2i7Oiq
 =SWSP
 -----END PGP SIGNATURE-----

Merge tag 'trace-v4.16-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull kprobe fixes from Steven Rostedt:
 "The documentation for kprobe events says that symbol offets can take
  both a + and - sign to get to befor and after the symbol address.

  But in actuality, the code does not support the minus. This fixes that
  issue, and adds a few more selftests to kprobe events"

* tag 'trace-v4.16-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  selftests: ftrace: Add a testcase for probepoint
  selftests: ftrace: Add a testcase for string type with kprobe_event
  selftests: ftrace: Add probe event argument syntax testcase
  tracing: probeevent: Fix to support minus offset from symbol
This commit is contained in:
Linus Torvalds 2018-03-23 15:34:18 -07:00
commit 99fec39e77
6 changed files with 192 additions and 8 deletions

View File

@ -659,7 +659,7 @@ static int create_trace_kprobe(int argc, char **argv)
char *symbol = NULL, *event = NULL, *group = NULL;
int maxactive = 0;
char *arg;
unsigned long offset = 0;
long offset = 0;
void *addr = NULL;
char buf[MAX_EVENT_NAME_LEN];
@ -747,7 +747,7 @@ static int create_trace_kprobe(int argc, char **argv)
symbol = argv[1];
/* TODO: support .init module functions */
ret = traceprobe_split_symbol_offset(symbol, &offset);
if (ret) {
if (ret || offset < 0 || offset > UINT_MAX) {
pr_info("Failed to parse either an address or a symbol.\n");
return ret;
}

View File

@ -320,7 +320,7 @@ static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
}
/* Split symbol and offset. */
int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)
int traceprobe_split_symbol_offset(char *symbol, long *offset)
{
char *tmp;
int ret;
@ -328,13 +328,11 @@ int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)
if (!offset)
return -EINVAL;
tmp = strchr(symbol, '+');
tmp = strpbrk(symbol, "+-");
if (tmp) {
/* skip sign because kstrtoul doesn't accept '+' */
ret = kstrtoul(tmp + 1, 0, offset);
ret = kstrtol(tmp, 0, offset);
if (ret)
return ret;
*tmp = '\0';
} else
*offset = 0;

View File

@ -365,7 +365,7 @@ extern int traceprobe_conflict_field_name(const char *name,
extern void traceprobe_update_arg(struct probe_arg *arg);
extern void traceprobe_free_probe_arg(struct probe_arg *arg);
extern int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset);
extern int traceprobe_split_symbol_offset(char *symbol, long *offset);
/* Sum up total data length for dynamic arraies (strings) */
static nokprobe_inline int

View File

@ -0,0 +1,46 @@
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
# description: Kprobe event string type argument
[ -f kprobe_events ] || exit_unsupported # this is configurable
echo 0 > events/enable
echo > kprobe_events
case `uname -m` in
x86_64)
ARG2=%si
OFFS=8
;;
i[3456]86)
ARG2=%cx
OFFS=4
;;
aarch64)
ARG2=%x1
OFFS=8
;;
arm*)
ARG2=%r1
OFFS=4
;;
*)
echo "Please implement other architecture here"
exit_untested
esac
: "Test get argument (1)"
echo "p:testprobe create_trace_kprobe arg1=+0(+0(${ARG2})):string" > kprobe_events
echo 1 > events/kprobes/testprobe/enable
! echo test >> kprobe_events
tail -n 1 trace | grep -qe "testprobe.* arg1=\"test\""
echo 0 > events/kprobes/testprobe/enable
: "Test get argument (2)"
echo "p:testprobe create_trace_kprobe arg1=+0(+0(${ARG2})):string arg2=+0(+${OFFS}(${ARG2})):string" > kprobe_events
echo 1 > events/kprobes/testprobe/enable
! echo test1 test2 >> kprobe_events
tail -n 1 trace | grep -qe "testprobe.* arg1=\"test1\" arg2=\"test2\""
echo 0 > events/enable
echo > kprobe_events

View File

@ -0,0 +1,97 @@
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
# description: Kprobe event argument syntax
[ -f kprobe_events ] || exit_unsupported # this is configurable
grep "x8/16/32/64" README > /dev/null || exit_unsupported # version issue
echo 0 > events/enable
echo > kprobe_events
PROBEFUNC="vfs_read"
GOODREG=
BADREG=
GOODSYM="_sdata"
if ! grep -qw ${GOODSYM} /proc/kallsyms ; then
GOODSYM=$PROBEFUNC
fi
BADSYM="deaqswdefr"
SYMADDR=0x`grep -w ${GOODSYM} /proc/kallsyms | cut -f 1 -d " "`
GOODTYPE="x16"
BADTYPE="y16"
case `uname -m` in
x86_64|i[3456]86)
GOODREG=%ax
BADREG=%ex
;;
aarch64)
GOODREG=%x0
BADREG=%ax
;;
arm*)
GOODREG=%r0
BADREG=%ax
;;
esac
test_goodarg() # Good-args
{
while [ "$1" ]; do
echo "p ${PROBEFUNC} $1" > kprobe_events
shift 1
done;
}
test_badarg() # Bad-args
{
while [ "$1" ]; do
! echo "p ${PROBEFUNC} $1" > kprobe_events
shift 1
done;
}
echo > kprobe_events
: "Register access"
test_goodarg ${GOODREG}
test_badarg ${BADREG}
: "Symbol access"
test_goodarg "@${GOODSYM}" "@${SYMADDR}" "@${GOODSYM}+10" "@${GOODSYM}-10"
test_badarg "@" "@${BADSYM}" "@${GOODSYM}*10" "@${GOODSYM}/10" \
"@${GOODSYM}%10" "@${GOODSYM}&10" "@${GOODSYM}|10"
: "Stack access"
test_goodarg "\$stack" "\$stack0" "\$stack1"
test_badarg "\$stackp" "\$stack0+10" "\$stack1-10"
: "Retval access"
echo "r ${PROBEFUNC} \$retval" > kprobe_events
! echo "p ${PROBEFUNC} \$retval" > kprobe_events
: "Comm access"
test_goodarg "\$comm"
: "Indirect memory access"
test_goodarg "+0(${GOODREG})" "-0(${GOODREG})" "+10(\$stack)" \
"+0(\$stack1)" "+10(@${GOODSYM}-10)" "+0(+10(+20(\$stack)))"
test_badarg "+(${GOODREG})" "(${GOODREG}+10)" "-(${GOODREG})" "(${GOODREG})" \
"+10(\$comm)" "+0(${GOODREG})+10"
: "Name assignment"
test_goodarg "varname=${GOODREG}"
test_badarg "varname=varname2=${GOODREG}"
: "Type syntax"
test_goodarg "${GOODREG}:${GOODTYPE}"
test_badarg "${GOODREG}::${GOODTYPE}" "${GOODREG}:${BADTYPE}" \
"${GOODTYPE}:${GOODREG}"
: "Combination check"
test_goodarg "\$comm:string" "+0(\$stack):string"
test_badarg "\$comm:x64" "\$stack:string" "${GOODREG}:string"
echo > kprobe_events

View File

@ -0,0 +1,43 @@
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
# description: Kprobe events - probe points
[ -f kprobe_events ] || exit_unsupported # this is configurable
TARGET_FUNC=create_trace_kprobe
dec_addr() { # hexaddr
printf "%d" "0x"`echo $1 | tail -c 8`
}
set_offs() { # prev target next
A1=`dec_addr $1`
A2=`dec_addr $2`
A3=`dec_addr $3`
TARGET="0x$2" # an address
PREV=`expr $A1 - $A2` # offset to previous symbol
NEXT=+`expr $A3 - $A2` # offset to next symbol
OVERFLOW=+`printf "0x%x" ${PREV}` # overflow offset to previous symbol
}
# We have to decode symbol addresses to get correct offsets.
# If the offset is not an instruction boundary, it cause -EILSEQ.
set_offs `grep -A1 -B1 ${TARGET_FUNC} /proc/kallsyms | cut -f 1 -d " " | xargs`
UINT_TEST=no
# printf "%x" -1 returns (unsigned long)-1.
if [ `printf "%x" -1 | wc -c` != 9 ]; then
UINT_TEST=yes
fi
echo 0 > events/enable
echo > kprobe_events
echo "p:testprobe ${TARGET_FUNC}" > kprobe_events
echo "p:testprobe ${TARGET}" > kprobe_events
echo "p:testprobe ${TARGET_FUNC}${NEXT}" > kprobe_events
! echo "p:testprobe ${TARGET_FUNC}${PREV}" > kprobe_events
if [ "${UINT_TEST}" = yes ]; then
! echo "p:testprobe ${TARGET_FUNC}${OVERFLOW}" > kprobe_events
fi
echo > kprobe_events
clear_trace