From 2adf2164918e2dc74fef2cdd0257917aff488640 Mon Sep 17 00:00:00 2001 From: Gerd Hoffmann Date: Tue, 1 Jun 2021 15:24:02 +0200 Subject: [PATCH] qemu-trace-stap: changing SYSTEMTAP_TAPSET considered harmful. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Setting SYSTEMTAP_TAPSET to some value other than /usr/share/systemtap/tapsets results in systemtap not finding the standard tapset library any more, which in turn breaks tracing because pid() and other standard systemtap functions are not available any more. So using SYSTEMTAP_TAPSET to point systemtap to the qemu probes will only work for the prefix=/usr installs because both qemu and system tapsets in the same directory then. All other prefixes are broken. Fix that by using the "-I $tapsetdir" command line switch instead. Signed-off-by: Gerd Hoffmann Reviewed-by: Stefan Hajnoczi Reviewed-by: Daniel P. Berrangé Message-id: 20210601132414.432430-2-kraxel@redhat.com Signed-off-by: Stefan Hajnoczi --- scripts/qemu-trace-stap | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) diff --git a/scripts/qemu-trace-stap b/scripts/qemu-trace-stap index 90527eb974..eb6e951ff2 100755 --- a/scripts/qemu-trace-stap +++ b/scripts/qemu-trace-stap @@ -55,11 +55,6 @@ def tapset_dir(binary): return os.path.realpath(tapset) -def tapset_env(tapset_dir): - tenv = copy.copy(os.environ) - tenv["SYSTEMTAP_TAPSET"] = tapset_dir - return tenv - def cmd_run(args): prefix = probe_prefix(args.binary) tapsets = tapset_dir(args.binary) @@ -81,11 +76,11 @@ def cmd_run(args): # We request an 8MB buffer, since the stap default 1MB buffer # can be easily overflowed by frequently firing QEMU traces - stapargs = ["stap", "-s", "8"] + stapargs = ["stap", "-s", "8", "-I", tapsets ] if args.pid is not None: stapargs.extend(["-x", args.pid]) stapargs.extend(["-e", script]) - subprocess.call(stapargs, env=tapset_env(tapsets)) + subprocess.call(stapargs) def cmd_list(args): @@ -101,10 +96,9 @@ def cmd_list(args): if verbose: print("Listing probes with name '%s'" % script) - proc = subprocess.Popen(["stap", "-l", script], + proc = subprocess.Popen(["stap", "-I", tapsets, "-l", script], stdout=subprocess.PIPE, - universal_newlines=True, - env=tapset_env(tapsets)) + universal_newlines=True) out, err = proc.communicate() if proc.returncode != 0: print("No probes found, are the tapsets installed in %s" % tapset_dir(args.binary))