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[Bug tapsets/15961] New: nd_syscall.exp failure on i686
- From: "dsmith at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sourceware dot org
- Date: Mon, 16 Sep 2013 21:30:02 +0000
- Subject: [Bug tapsets/15961] New: nd_syscall.exp failure on i686
- Auto-submitted: auto-generated
https://sourceware.org/bugzilla/show_bug.cgi?id=15961
Bug ID: 15961
Summary: nd_syscall.exp failure on i686
Product: systemtap
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: tapsets
Assignee: systemtap at sourceware dot org
Reporter: dsmith at redhat dot com
The nd_syscall.exp testcase gets a failure on i686 RHEL6
(2.6.32-358.18.1.el6.i686) in the 'trunc' test:
FAIL: 32-bit trunc nd_syscall
This failure is because systemtap is getting the wrong value for the 'length'
convenience variable from the nd_syscall.truncate probe. Here's the source for
nd_syscall.truncate:
====
probe nd_syscall.truncate = kprobe.function("sys_truncate") ?,
kprobe.function("sys_truncate64") ?
{
name = "truncate"
// path_uaddr = $path
// path = user_string($path)
// length = $length
// argstr = sprintf("%s, %d", user_string_quoted($path), $length)
asmlinkage()
path_uaddr = pointer_arg(1)
path = user_string_quoted(path_uaddr)
if (symname(addr()) == "sys_truncate")
length = ulong_arg(2)
else
length = longlong_arg(2)
argstr = sprintf("%s, %d", user_string_quoted(path_uaddr), length)
}
====
The problem here was that a probe on "sys_truncate" was installed, but
'symname(addr())' failed, so that the wrong value was grabbed for 'length'.
'symname(addr())' shouldn't have failed, but that's a lot of work to do just to
figure out which function is being called. A call to 'ppfunc()' might be better
or breaking down the probe a bit more like the following (untested):
====
probe nd_syscall.truncate = __nd_syscall.truncate ?, __nd_syscall.truncate64 ?
{
name = "truncate"
// path_uaddr = $path
// path = user_string($path)
// length = $length
// argstr = sprintf("%s, %d", user_string_quoted($path), $length)
asmlinkage()
path_uaddr = pointer_arg(1)
path = user_string_quoted(path_uaddr)
argstr = sprintf("%s, %d", user_string_quoted(path_uaddr), length)
}
probe __nd_syscall.truncate = kprobe.function("sys_truncate")
{
asmlinkage()
length = ulong_arg(2)
}
probe __nd_syscall.truncate64 = kprobe.function("sys_truncate64")
{
asmlinkage()
length = longlong_arg(2)
}
====
Note that there are 3 other similar uses of 'symname(addr())' in the nd_syscall
tapset files.
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