[S390] add kprobes support.

Signed-off-by: Michael Grundy <[email protected]>
Signed-off-by: David Wilder <[email protected]>
Signed-off-by: Martin Schwidefsky <[email protected]>

Author: Michael Grundy

arch/s390/Kconfig

@@ -487,8 +487,22 @@ source "drivers/net/Kconfig"
 
 source "fs/Kconfig"
 
+menu "Instrumentation Support"
+
 source "arch/s390/oprofile/Kconfig"
 
+config KPROBES
+	bool "Kprobes (EXPERIMENTAL)"
+	depends on EXPERIMENTAL && MODULES
+	help
+	  Kprobes allows you to trap at almost any kernel address and
+	  execute a callback function.	register_kprobe() establishes
+	  a probepoint and specifies the callback.  Kprobes is useful
+	  for kernel debugging, non-intrusive instrumentation and testing.
+	  If in doubt, say "N".
+
+endmenu
+
 source "arch/s390/Kconfig.debug"
 
 source "security/Kconfig"

arch/s390/kernel/Makefile

@@ -24,6 +24,7 @@ obj-$(CONFIG_COMPAT)		+= compat_linux.o compat_signal.o \
 
 obj-$(CONFIG_VIRT_TIMER)	+= vtime.o
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
+obj-$(CONFIG_KPROBES)		+= kprobes.o
 
 # Kexec part
 S390_KEXEC_OBJS := machine_kexec.o crash.o

arch/s390/kernel/entry.S

@@ -505,6 +505,8 @@ pgm_no_vtime2:
 	mvc	__THREAD_per+__PER_address(4,%r1),__LC_PER_ADDRESS
 	mvc	__THREAD_per+__PER_access_id(1,%r1),__LC_PER_ACCESS_ID
 	oi	__TI_flags+3(%r9),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
+	tm	SP_PSW+1(%r15),0x01	# kernel per event ?
+	bz	BASED(kernel_per)
 	l	%r3,__LC_PGM_ILC	 # load program interruption code
 	la	%r8,0x7f
 	nr	%r8,%r3                  # clear per-event-bit and ilc
@@ -536,6 +538,16 @@ pgm_no_vtime3:
 	stosm	__SF_EMPTY(%r15),0x03	# reenable interrupts
 	b	BASED(sysc_do_svc)
 
+#
+# per was called from kernel, must be kprobes
+#
+kernel_per:
+	mvi	SP_TRAP+1(%r15),0x28	# set trap indication to pgm check
+	la	%r2,SP_PTREGS(%r15)	# address of register-save area
+	l	%r1,BASED(.Lhandle_per)	# load adr. of per handler
+	la	%r14,BASED(sysc_leave)	# load adr. of system return
+	br	%r1			# branch to do_single_step
+
 /*
  * IO interrupt handler routine
  */

arch/s390/kernel/entry64.S

@@ -518,6 +518,8 @@ pgm_no_vtime2:
 #endif
 	lg	%r9,__LC_THREAD_INFO	# load pointer to thread_info struct
 	lg	%r1,__TI_task(%r9)
+	tm	SP_PSW+1(%r15),0x01	# kernel per event ?
+	jz	kernel_per
 	mvc	__THREAD_per+__PER_atmid(2,%r1),__LC_PER_ATMID
 	mvc	__THREAD_per+__PER_address(8,%r1),__LC_PER_ADDRESS
 	mvc	__THREAD_per+__PER_access_id(1,%r1),__LC_PER_ACCESS_ID
@@ -553,6 +555,16 @@ pgm_no_vtime3:
 	stosm	__SF_EMPTY(%r15),0x03	# reenable interrupts
 	j	sysc_do_svc
 
+#
+# per was called from kernel, must be kprobes
+#
+kernel_per:
+	lhi	%r0,__LC_PGM_OLD_PSW
+	sth	%r0,SP_TRAP(%r15)	# set trap indication to pgm check
+	la	%r2,SP_PTREGS(%r15)	# address of register-save area
+	larl	%r14,sysc_leave		# load adr. of system ret, no work
+	jg	do_single_step		# branch to do_single_step
+
 /*
  * IO interrupt handler routine
  */