Thanks Alan, I’m tinkering with diag a0, subcode 60, a non-ibm api. And yes the virtual machine needs additional privileges to use it.
Thanks for the tip though. But whether I use diag a0 or 88 or any other privileged instruction, my problem is getting into supervisor state so it can do it. If a kernel extension is the only way, I’ll have to decide how I want to proceed. I don’t mind doing it, I just have to find the time and weigh the benefit vs possible security risk. Cheers Don On Sat, Nov 10, 2018 at 08:31 Alan Altmark <alan_altm...@us.ibm.com> wrote: > > A0? Please make sure that your usage is not outdated. The most common > usages of A0 were replaced long ago by DIAG 88. > > Regards, > Alan Altmark > IBM > > > On Nov 10, 2018, at 10:32 AM, Donald Russell <russell....@gmail.com> > wrote: > > > > Thanks Neale! > > > > In my case I’m using diag a0. Though I may want to do this for other diag > > instructions too. > > > > Getting in/out of supervisor state is my next hurdle. :-) > > > > I was going to use stidp to make sure I was actually on VM but that got > > “Illegal Instruction” when it ran. > > Maybe there’s a function I can call, or I can read /proc/cpuinfo to > verify > > A-it’s IBM/S390 and B-VM is running. I don’t like the idea of reading a > > whole “file” to provide what a single instruction can give me. > > > > I still have to figure out how to get in and out of supervisor state for > > the diag though. > > > > Thanks for tip on generating the machine code. That’s great! :-) > > > > Cheers, > > Don > > > > > > > > > >> On Sat, Nov 10, 2018 at 03:31 Neale Ferguson <ne...@sinenomine.net> > wrote: > >> > >> .byte 0x83, 0x12, 0x00, 0x08 > >> > >> == diag 1,2,8 (CP command) > >> > >> You can either load r1/r2 in the _asm_ section or tell gcc to bind the > >> variables to the registers. > >> > >> Remember, though, that diag is a privileged instruction and won't work > in > >> a userland program. > >> > >> In what particular diag are you interested? > >> > >> > >> -------- Original message -------- > >> From: Donald Russell <russell....@gmail.com> > >> Date: 11/10/18 06:00 (GMT-05:00) > >> To: LINUX-390@VM.MARIST.EDU > >> Subject: [LINUX-390] Using diagnose instruction from C on RHEL 7 > >> > >> Hello, > >> > >> I want to write a program in C and use a diagnose instruction. > >> > >> I thought I could do > >> > >> __asm___( “ diag ... “ ...); > >> > >> but that fails because diag is not a real instruction mnemonic. When I > use > >> gcc to compile and link I get an error: > >> > >> Program.c(.text+0x578): undefined reference to ‘x480a032’ > >> collect2: error: ld returned 1 exit status > >> > >> I thought I could code dc x’8312....’ and force the use of registers 1 > and > >> 2 but it complains that dc is not valid. (The doc says instructions > >> including directives are ok. But obviously not dc directives. :-) I > also > >> tried upper case just to be thorough) > >> > >> How can I coerce C into generating a diagnose instruction? > >> > >> Thanks, > >> Don > >> > >> ---------------------------------------------------------------------- > >> For LINUX-390 subscribe / signoff / archive access instructions, > >> send email to lists...@vm.marist.edu with the message: INFO LINUX-390 > or > >> visit > >> > http://www.marist.edu/htbin/wlvindex?LINUX-390 > > >> ---------------------------------------------------------------------- > >> For more information on Linux on System z, visit > >> > http://wiki.linuxvm.org/ > > >> > >> ---------------------------------------------------------------------- > >> For LINUX-390 subscribe / signoff / archive access instructions, > >> send email to lists...@vm.marist.edu with the message: INFO LINUX-390 > or > >> visit > >> > http://www.marist.edu/htbin/wlvindex?LINUX-390 > > >> ---------------------------------------------------------------------- > >> For more information on Linux on System z, visit > >> > http://wiki.linuxvm.org/ > > >> > > > > ---------------------------------------------------------------------- > > For LINUX-390 subscribe / signoff / archive access instructions, > > send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or > visit > > > http://www.marist.edu/htbin/wlvindex?LINUX-390 > > > ---------------------------------------------------------------------- > > For more information on Linux on System z, visit > > > http://wiki.linuxvm.org/ > > > > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or > visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 > ---------------------------------------------------------------------- > For more information on Linux on System z, visit > http://wiki.linuxvm.org/ > ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
