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.
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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

kernel/trace/trace_kprobe.c

@@ -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;
 		}

kernel/trace/trace_probe.c

@@ -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;

kernel/trace/trace_probe.h

@@ -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

tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_string.tc

@@ -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

tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_syntax.tc

@@ -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

tools/testing/selftests/ftrace/test.d/kprobe/probepoint.tc

@@ -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