[Bug tapsets/23160] New: 4.17 breaks syscalls tapset

["fche at redhat dot com" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=23160

            Bug ID: 23160
           Summary: 4.17 breaks syscalls tapset
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: tapsets
          Assignee: systemtap at sourceware dot org
          Reporter: fche at redhat dot com
                CC: jmoyer at redhat dot com
  Target Milestone: ---

Kindly reported by jmoyer@rh, 4.17-rc0 as in rawhide changes the syscall
wrapper functions in ways that our tapset cannot currently adapt to. 
https://lwn.net/Articles/752422/  This kills all the syscall.* probes.

One possible approach to fix is to switch our kprobes over to a new set of
per-arch wrapper functions that carry parameters inside a pt_regs* pointer. 
Coincidentally, that is the same way that the sys_enter/sys_exit tracepoints
carry individual parameters.  (The __do_sys* family of functions do carry
normal dwarf parameters, but cannot probe their .return because they're
declared inline.)


% uname -a
Linux vm-rawhide-64 4.17.0-0.rc3.git4.1.fc29.x86_64 #1 SMP Fri May 4 19:41:58
UTC 2018 x86_64 x86_64 x86_64 GNU/Linux


% stap -L 'kernel.function("__*_accept").*'     
kernel.function("__do_sys_accept@net/socket.c:1629").callee("__sys_accept4@net/socket.c:1542")
$fd:int $upeer_sockaddr:struct sockaddr* $upeer_addrlen:int* $flags:int
$err:int $fput_needed:int $address:struct __kernel_sockaddr_storage
kernel.function("__do_sys_accept@net/socket.c:1629").inline $upeer_addrlen:int*
$upeer_sockaddr:struct sockaddr* $fd:int
kernel.function("__ia32_sys_accept@net/socket.c:1629").call $regs:struct
pt_regs const*
kernel.function("__ia32_sys_accept@net/socket.c:1629").callee("__se_sys_accept@net/socket.c:1629")
$upeer_addrlen:long int $upeer_sockaddr:long int $fd:long int
kernel.function("__ia32_sys_accept@net/socket.c:1629").exported $regs:struct
pt_regs const*
kernel.function("__ia32_sys_accept@net/socket.c:1629").return $return:long int
$regs:struct pt_regs const*
kernel.function("__se_sys_accept@net/socket.c:1629").inline $upeer_addrlen:long
int $upeer_sockaddr:long int $fd:long int
kernel.function("__x64_sys_accept@net/socket.c:1629").call $regs:struct pt_regs
const*
kernel.function("__x64_sys_accept@net/socket.c:1629").callee("__se_sys_accept@net/socket.c:1629")
$upeer_addrlen:long int $upeer_sockaddr:long int $fd:long int
kernel.function("__x64_sys_accept@net/socket.c:1629").exported $regs:struct
pt_regs const*
kernel.function("__x64_sys_accept@net/socket.c:1629").return $return:long int
$regs:struct pt_regs const*

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