s390: add support for runtime instrumentation
authorJan Glauber <jang@linux.vnet.ibm.com>
Tue, 31 Jul 2012 08:52:05 +0000 (10:52 +0200)
committerMartin Schwidefsky <schwidefsky@de.ibm.com>
Wed, 26 Sep 2012 13:45:02 +0000 (15:45 +0200)
commite4b8b3f33fcaa0ed6e6b5482a606091d8cd20beb
tree7f1e47eafd75cb11bed5b91c2c13813eb6204fc8
parent0d804b20735d974534abb422f723d404b779433a
s390: add support for runtime instrumentation

Allow user-space threads to use runtime instrumentation (RI). To enable RI
for a thread there is a new s390 specific system call, sys_s390_runtime_instr,
that takes as parameter a realtime signal number. If the RI facility is
available the system call sets up a control block for the calling thread with
the appropriate permissions for the thread to modify the control block.

The user-space thread can then use the store and modify RI instructions to
alter the control block and start/stop the instrumentation via RION/RIOFF.

If the user specified program buffer runs full RI triggers an external
interrupt. The external interrupt is translated to a real-time signal that
is delivered to the thread that enabled RI on that CPU. The number of
the real-time signal is the number specified in the RI system call. So,
user-space can select any available real-time signal number in case the
application itself uses real-time signals for other purposes.

The kernel saves the RI control blocks on task switch only if the running
thread was enabled for RI. Therefore, the performance impact on task switch
should be negligible if RI is not used.

RI is only enabled for user-space mode and is disabled for the supervisor
state.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
14 files changed:
arch/s390/include/asm/cpu_mf.h
arch/s390/include/asm/irq.h
arch/s390/include/asm/processor.h
arch/s390/include/asm/ptrace.h
arch/s390/include/asm/runtime_instr.h [new file with mode: 0644]
arch/s390/include/asm/switch_to.h
arch/s390/include/asm/unistd.h
arch/s390/kernel/Makefile
arch/s390/kernel/compat_wrapper.S
arch/s390/kernel/dis.c
arch/s390/kernel/irq.c
arch/s390/kernel/process.c
arch/s390/kernel/runtime_instr.c [new file with mode: 0644]
arch/s390/kernel/syscalls.S