tracing/kprobes: Have uname use __get_str() in print_fmt
commit20279420ae
upstream. Thomas Richter reported: > Test case 66 'Use vfs_getname probe to get syscall args filenames' > is broken on s390, but works on x86. The test case fails with: > > [root@m35lp76 perf]# perf test -F 66 > 66: Use vfs_getname probe to get syscall args filenames > :Recording open file: > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 0.004 MB /tmp/__perf_test.perf.data.TCdYj\ > (20 samples) ] > Looking at perf.data file for vfs_getname records for the file we touched: > FAILED! > [root@m35lp76 perf]# The root cause was the print_fmt of the kprobe event that referenced the "ustring" > Setting up the kprobe event using perf command: > > # ./perf probe "vfs_getname=getname_flags:72 pathname=filename:ustring" > > generates this format file: > [root@m35lp76 perf]# cat /sys/kernel/debug/tracing/events/probe/\ > vfs_getname/format > name: vfs_getname > ID: 1172 > format: > field:unsigned short common_type; offset:0; size:2; signed:0; > field:unsigned char common_flags; offset:2; size:1; signed:0; > field:unsigned char common_preempt_count; offset:3; size:1; signed:0; > field:int common_pid; offset:4; size:4; signed:1; > > field:unsigned long __probe_ip; offset:8; size:8; signed:0; > field:__data_loc char[] pathname; offset:16; size:4; signed:1; > > print fmt: "(%lx) pathname=\"%s\"", REC->__probe_ip, REC->pathname Instead of using "__get_str(pathname)" it referenced it directly. Link: http://lkml.kernel.org/r/20200124100742.4050c15e@gandalf.local.home Cc: stable@vger.kernel.org Fixes:88903c4643
("tracing/probe: Add ustring type for user-space string") Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Reported-by: Thomas Richter <tmricht@linux.ibm.com> Tested-by: Thomas Richter <tmricht@linux.ibm.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -876,7 +876,8 @@ static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
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for (i = 0; i < tp->nr_args; i++) {
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parg = tp->args + i;
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if (parg->count) {
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if (strcmp(parg->type->name, "string") == 0)
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if ((strcmp(parg->type->name, "string") == 0) ||
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(strcmp(parg->type->name, "ustring") == 0))
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fmt = ", __get_str(%s[%d])";
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else
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fmt = ", REC->%s[%d]";
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@ -884,7 +885,8 @@ static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
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pos += snprintf(buf + pos, LEN_OR_ZERO,
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fmt, parg->name, j);
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} else {
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if (strcmp(parg->type->name, "string") == 0)
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if ((strcmp(parg->type->name, "string") == 0) ||
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(strcmp(parg->type->name, "ustring") == 0))
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fmt = ", __get_str(%s)";
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else
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fmt = ", REC->%s";
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