Bug 109426

Summary:	ppc: false positive in rt_sigaction
Product:	[Developer tools] valgrind	Reporter:	Craig Chaney <cwchaney>
Component:	general	Assignee:	Julian Seward <jseward>
Status:	REPORTED ---
Severity:	normal	CC:	cel, will_schmidt
Priority:	NOR
Version First Reported In:	3.0.0
Target Milestone:	---
Platform:	Compiled Sources
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	sys_rt_sigaction patch (adopted from Paul's 2.4 ppc port)

Description Craig Chaney 2005-07-21 18:35:47 UTC

On ppc, Valgrind reports spurious errors in rt_sigaction.  For example:

$ valgrind /bin/ls
==12019== Memcheck, a memory error detector.
==12019== Copyright (C) 2002-2005, and GNU GPL'd, by Julian Seward et al.
<snip>
==12019== Syscall param rt_sigaction(act) points to uninitialised byte(s)
==12019==    at 0x11A87D7C: __libc_sigaction (in /lib/tls/libpthread.so.0)
==12019==    by 0x11A7E940: __pthread_initialize_minimal (in
/lib/tls/libpthread.so.0)
==12019==    by 0x11A7E72C: (within /lib/tls/libpthread.so.0)
==12019==    by 0x1187BEE4: call_init (in /lib/ld-2.3.3.so)
==12019==    by 0x1187C018: _dl_init (in /lib/ld-2.3.3.so)
==12019==    by 0x118804B4: _start (in /lib/ld-2.3.3.so)
==12019==  Address 0x349FDD58 is on thread 1's stack
<snip>

The ppc implementation of sigaction doesn't ever read or write to the
sa_restorer field, so Valgrind is flagging it as an error.  See below for a
patch adopted from Paul's 2.4 port.

Comment 1 Craig Chaney 2005-07-21 18:39:14 UTC

Created attachment 11868 [details]
sys_rt_sigaction patch (adopted from Paul's 2.4 ppc port)

This patch makes the PRE & POST functions for sys_rt_sigaction platform
specific, so they are removed from syswrap-generic.c and added to the amd64,
ppc, and x86 version.  The ppc version is modified so that bogus values in the
sa_restorer fields in the parameters are not flagged as errors.

The patch also adds PRE and POST functions for sys_sigaction on ppc, and avoids
flagging bogus sa_restorer values there as well.

Tested on ppc and x86.