Bug 1733535

Summary:	aarch64 syscall arguments are incorrect
Product:	Red Hat Enterprise Linux 8	Reporter:	Martin Cermak <mcermak>
Component:	systemtap	Assignee:	Frank Ch. Eigler <fche>
systemtap sub component:	gcc-toolset-9	QA Contact:	Martin Cermak <mcermak>
Status:	CLOSED ERRATA	Docs Contact:
Severity:	medium
Priority:	unspecified	CC:	fche, jwboyer, lberk, mcermak, mjw, qe-baseos-tools-bugs, wcohen
Version:	8.1	Flags:	pm-rhel: mirror+
Target Milestone:	rc
Target Release:	8.0
Hardware:	aarch64
OS:	Linux
Whiteboard:
Fixed In Version:	gcc-toolset-9-systemtap-4.1-4.el8	Doc Type:	No Doc Update
Doc Text:		Story Points:	---
Clone Of:	1732173	Environment:
Last Closed:	2019-11-05 21:17:22 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Martin Cermak 2019-07-26 12:19:13 UTC

+++ This bug was initially created as a clone of Bug #1732173 +++

Description of problem:

Systemtap does not obtain the correct arguments for systemcalls


Version-Release number of selected component (if applicable):

kernel-4.18.0-107.el8.aarch64
systemtap-4.1-3.el8.aarch64

How reproducible:

every time


Steps to Reproduce:
1. sudo dnf install systemtap*
2. sudo stap -e 'probe syscall.close { printf("%x\n", fd) ; print_regs(); exit()}' 


Actual results:

ffff0000163afec0
pc : [<ffff2f7809fed910>] lr : [<ffff2f7809d74a10>] pstate: 80000005
sp : ffff0000163afe90
x29: ffff0000163afe90 x28: ffff99698660dd00 
x27: 0000ffffd8574c68 x26: 0000ffffd85754a0 
x25: 0000000056000000 x24: 0000000000000015 
x23: 0000000020000000 x22: 0000000000000000 
x21: 0000000000000039 x20: 0000000000000039 
x19: ffff0000163afec0 x18: 000000000000034f 
x17: 0000ffff97542c60 x16: 0000ffff97b8e930 
x15: 00007c6051c87fa2 x14: 0000000000000026 
x13: 0065636976726573 x12: 2e646c616e72756f 
x11: 6a2d646d65747379 x10: 732f6563696c732e 
x9 : 732e646c616e7275 x8 : 0000000000000039 
x7 : 7f7f7f7f7f7f7f7f x6 : 0000000000000000 
x5 : 0000000000000000 x4 : 0000ffff96790630 
x3 : 0000ffff96790e30 x2 : ffff99698660dd00 
x1 : ffff2f7809fed910 x0 : ffff0000163afec0 



Expected results:

The number printed out before the register dump should be a small hex number, not the same value as x0.  x0 is a pointer to a pt_regs struct.


Additional info:

What is occurring is the tapsets set CONTEXT->sregs for the various kernel.kprobe("*") syscall functions.  However, only the x86_64 register.stp is using that value.  The tapset/arm64/register.stp is not using the value in CONTEXT->sregs, so the registers from kprobe trigger are being used rather than the pt_regs argument passed into the syscalls.

Note that other non-x86 processors that use syscall wrappers look like they will suffer from the same problem.

Comment 1 Martin Cermak 2019-10-01 15:13:15 UTC

Verified with gcc-toolset-9-systemtap-4.1-4.el8.aarch64.

Comment 3 errata-xmlrpc 2019-11-05 21:17:22 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2019:3454