[PATCH] kprobes for s390 architecture

Mike Grundy
2006-06-12T17:15:57Z

Hi Folks -

This patch provides kprobes support for s390 architecture

Thanks
Mike
--

Signed-off-by: Michael Grundy <grundym@us.ibm.com>

arch/s390/Kconfig | 14
arch/s390/kernel/Makefile | 1
arch/s390/kernel/entry.S | 4
arch/s390/kernel/entry64.S | 18 +
arch/s390/kernel/kprobes.c | 648 +++++++++++++++++++++++++++++++++++++++++
arch/s390/kernel/traps.c | 42 ++
arch/s390/kernel/vmlinux.lds.S | 1
arch/s390/mm/fault.c | 8
include/asm-s390/kdebug.h | 57 +++
include/asm-s390/kprobes.h | 208 +++++++++++++
10 files changed, 995 insertions(+), 6 deletions(-)

diff -urNp linux-2.6.17-rc6/arch/s390/Kconfig linux-2.6.17-rc6-kp390/arch/s390/Kconfig
--- linux-2.6.17-rc6/arch/s390/Kconfig 2006-06-05 20:57:02.000000000 -0400
+++ linux-2.6.17-rc6-kp390/arch/s390/Kconfig 2006-06-12 05:13:05.000000000 -0400
@@ -474,8 +474,22 @@ source "drivers/net/Kconfig"

source "fs/Kconfig"

+menu "Instrumentation Support"
+ depends on EXPERIMENTAL
+
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"
diff -urNp linux-2.6.17-rc6/arch/s390/kernel/entry64.S linux-2.6.17-rc6-kp390/arch/s390/kernel/entry64.S
--- linux-2.6.17-rc6/arch/s390/kernel/entry64.S 2006-06-05 20:57:02.000000000 -0400
+++ linux-2.6.17-rc6-kp390/arch/s390/kernel/entry64.S 2006-06-12 05:13:05.000000000 -0400
@@ -478,6 +478,8 @@ pgm_per:
clc __LC_PGM_OLD_PSW(16),__LC_SVC_NEW_PSW
je pgm_svcper
# no interesting special case, ignore PER event
+ tm __LC_PGM_OLD_PSW+1(%r15),0x01 # kernel per event ?
+ jz kernel_per
lmg %r12,%r15,__LC_SAVE_AREA
lpswe __LC_PGM_OLD_PSW

@@ -497,6 +499,8 @@ pgm_no_vtime2:
#endif
lg %r9,__LC_THREAD_INFO # load pointer to thread_info struct
lg %r1,__TI_task(%r9)
+ tm __LC_PGM_OLD_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
@@ -531,6 +535,20 @@ pgm_no_vtime3:
stosm __SF_EMPTY(%r15),0x03 # reenable interrupts
j sysc_do_svc

+#
+# per was called from kernel, must be kprobes
+#
+kernel_per:
+ lgf %r3,__LC_PGM_ILC # load program interruption code
+ lghi %r8,0x7f
+ ngr %r8,%r3 # clear per-event-bit and ilc
+ j sysc_singlestep
+ 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
+ brcl 15,do_single_step # branch to do_single_step
+
/*
* IO interrupt handler routine
*/
diff -urNp linux-2.6.17-rc6/arch/s390/kernel/entry.S linux-2.6.17-rc6-kp390/arch/s390/kernel/entry.S
--- linux-2.6.17-rc6/arch/s390/kernel/entry.S 2006-06-05 20:57:02.000000000 -0400
+++ linux-2.6.17-rc6-kp390/arch/s390/kernel/entry.S 2006-06-12 05:13:05.000000000 -0400
@@ -456,6 +456,8 @@ pgm_per:
# ok its one of the special cases, now we need to find out which one
clc __LC_PGM_OLD_PSW(8),__LC_SVC_NEW_PSW
be BASED(pgm_svcper)
+ tm __LC_PGM_OLD_PSW+1(%r15),0x01 # kernel per event ?
+ bz BASED(sysc_singlestep)
# no interesting special case, ignore PER event
lm %r12,%r15,__LC_SAVE_AREA
lpsw 0x28
@@ -480,6 +482,8 @@ 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 __LC_PGM_OLD_PSW+1(%r15),0x01 # kernel per event ?
+ bz BASED(sysc_singlestep)
l %r3,__LC_PGM_ILC # load program interruption code
la %r8,0x7f
nr %r8,%r3 # clear per-event-bit and ilc
diff -urNp linux-2.6.17-rc6/arch/s390/kernel/kprobes.c linux-2.6.17-rc6-kp390/arch/s390/kernel/kprobes.c
--- linux-2.6.17-rc6/arch/s390/kernel/kprobes.c 1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6.17-rc6-kp390/arch/s390/kernel/kprobes.c 2006-06-12 08:27:27.000000000 -0400
@@ -0,0 +1,648 @@
+/*
+ * Kernel Probes (KProbes)
+ * arch/s390/kernel/kprobes.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2002, 2006
+ *
+ * s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com>
+ */
+
+#include <linux/config.h>
+#include <linux/kprobes.h>
+#include <linux/ptrace.h>
+#include <linux/preempt.h>
+#include <asm/cacheflush.h>
+#include <asm/kdebug.h>
+#include <asm/sections.h>
+
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+ int ret = 0;
+
+ /* Make sure the probe isn't going on a difficult instruction */
+ if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))
+ ret = -EINVAL;
+
+ /* Use the get_insn_slot() facility for correctness */
+ if (!ret) {
+ p->ainsn.insn = get_insn_slot();
+ if (!p->ainsn.insn) {
+ ret = -ENOMEM;
+ } else {
+ /* this should only happen if you got the slot */
+ memcpy(p->ainsn.insn, p->addr,
+ MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
+ p->ainsn.inst_type =
+ get_instruction_type(p->ainsn.insn);
+ }
+ }
+ p->opcode = *p->addr;
+ return ret;
+}
+
+int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction)
+{
+ __u8 opcode[6];
+ int ret = 0;
+
+ memcpy(opcode, instruction, 6 * sizeof(__u8));
+
+ switch (opcode[0]) {
+ case OPCODE_BASSM:
+ case OPCODE_BSM:
+ case OPCODE_DIAG:
+ case OPCODE_EX:
+ ret = -EINVAL;
+ break;
+ case OPCODE_PR:
+ if (opcode[1] == OPCODE_PR)
+ ret = -EINVAL;
+ break;
+ case 0xB2:
+ switch (opcode[1]) {
+ case OPCODE_BSA:
+ case OPCODE_BAKR:
+ case OPCODE_BSG:
+ case OPCODE_PC:
+ case OPCODE_PT:
+ ret = -EINVAL;
+ break;
+ }
+ break;
+ }
+ return ret;
+}
+
+/* get_instruction type will return 0 if only the regular offset adjustments
+ * after out of line singlestep are required. If a register needs to be fixed,
+ * bits 16-23 will contain the register number, bits 24-31 contain the length
+ * of the instruction unit. If fixup is only required when the branch is not
+ * taken, bits 0-16 will all be set.
+ */
+int __kprobes get_instruction_type(kprobe_opcode_t * instruction)
+{
+ __u8 opcode[6];
+ int ret = 0;
+
+ memcpy(opcode, instruction, 6 * sizeof(__u8));
+
+ switch (opcode[0]) {
+ /* RR Format - instruction unit length = 2
+ * ________ ____ ____
+ * |Op Code | R1 | R2 |
+ * |________|_M1_|____|
+ * 0 8 12 15
+ */
+ case BALR: /* PSW addr saved in R1, branch address in R2 */
+ ret = (opcode[1] & 0xf0) + 2;
+ /* Special non branching use of BALR */
+ if ((opcode[1] & 0x0f) == 0)
+ ret &= FIXUP_NOBRANCH;
+ break;
+ case BASR: /* PSW addr saved in R1, branch address in R2 */
+ ret = (opcode[1] & 0xf0) + 2;
+ /* Special non branching use of BASR */
+ if ((opcode[1] & 0x0f) == 0)
+ ret &= FIXUP_NOBRANCH;
+ break;
+ case BCR: /* M1 is mask val (condition), branch addr in R2 */
+ ret = FIXUP_NOBRANCH & 2;
+ break;
+ case BCTR: /* R1 is count down, R2 is branch addr until R1 = 0 */
+ ret = FIXUP_NOBRANCH & 2;
+ break;
+ /* RX Format - instruction unit length = 4
+ * ________ ____ ____ ____ ____________
+ * |Op Code | R1 | X2 | B2 | D2 |
+ * |________|_M1_|____|____|____________|
+ * 0 8 12 16 20 31
+ */
+ case BAL: /* PSW addr saved in R1, branch addr D2(X2,B2) */
+ ret = (opcode[1] & 0xf0) + 4;
+ break;
+ case BAS: /* PSW addr saved in R1, branch addr D2(X2,B2) */
+ ret = (opcode[1] & 0xf0) + 4;
+ break;
+ case BC: /* M1 is mask val (condition), branch addr D2(X2,B2) */
+ ret = FIXUP_NOBRANCH & 4;
+ break;
+ case BCT: /* R1 is count down, D2(X2,B2) is branch addr */
+ ret = FIXUP_NOBRANCH & 4;
+ break;
+ /* RI Format - instruction unit length = 4
+ * ________ ____ ____ _________________
+ * |Op Code | R1 |OpCd| I2 |
+ * |________|____|____|_________________|
+ * 0 8 12 16 31
+ */
+ case 0xA7: /* first byte (multiple ops have same 1st byte) */
+ if ((opcode[1] & 0x0f) == BRAS) {
+ ret = (opcode[1] & 0xf0) + 4;
+ }
+ break;
+ /* RS Format - instruction unit length = 4
+ * ________ ____ ____ ____ ____________
+ * |Op Code | R1 | R3 | B2 | D2 |
+ * |________|____|_M3_|____|____________|
+ * 0 8 12 16 20 31
+ */
+ case BXH:
+ ret = FIXUP_NOBRANCH & 4;
+ break;
+ case BXLE:
+ ret = FIXUP_NOBRANCH & 4;
+ break;
+ /* RIL Format - instruction unit length = 6
+ * ________ ____ ____ _____________/______________
+ * |Op Code | R1 |OpCd| I2 |
+ * |________|_M1_|____|_____________/______________|
+ * 0 8 12 16 47
+ */
+ case 0xC0:
+ if ((opcode[1] & 0x0f) == BRASL) {
+ ret = (opcode[1] & 0xf0) + 6;
+ } else if ((opcode[1] & 0x0f) == BRCL) {
+ ret = FIXUP_NOBRANCH & 6;
+ }
+ break;
+ /* RSY Format - instruction unit length = 6
+ * ________ ____ ____ ____ __/__ ________ ________
+ * |Op Code | R1 | R3 | B2 | DL2 | DH2 |Op Code |
+ * |________|____|_M3_|____|__/__|________|________|
+ * 0 8 12 16 20 32 40 47
+ */
+ case 0xEB:
+ if (opcode[5] == BXHG || opcode[5] == BXLEG) {
+ ret = FIXUP_NOBRANCH & 6;
+ }
+ break;
+ /* RXY Format - instruction unit length = 6
+ * ________ ____ ____ ____ __/__ ________ ________
+ * |Op Code | R1 | X2 | B2 | DL2 | DH2 |Op Code |
+ * |________|____|____|____|__/__|________|________|
+ * 0 8 12 16 20 32 40 47
+ */
+ case 0xE3:
+ if (opcode[5] == BCTG) {
+ ret = FIXUP_NOBRANCH & 6;
+ }
+ break;
+ default:
+ break;
+ }
+ return ret;
+}
+
+void __kprobes arch_arm_kprobe(struct kprobe *p)
+{
+ *p->addr = BREAKPOINT_INSTRUCTION;
+}
+
+void __kprobes arch_disarm_kprobe(struct kprobe *p)
+{
+ *p->addr = p->opcode;
+}
+
+void __kprobes arch_remove_kprobe(struct kprobe *p)
+{
+ mutex_lock(&kprobe_mutex);
+ free_insn_slot(p->ainsn.insn);
+ mutex_unlock(&kprobe_mutex);
+}
+
+static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+{
+ per_cr_bits kprobe_per_regs[1];
+
+ memset(kprobe_per_regs, 0, sizeof(per_cr_bits));
+ regs->psw.addr = (unsigned long)p->ainsn.insn;
+
+ /* Just make sure this gets done */
+ regs->psw.addr |= PSW_ADDR_AMODE;
+
+ /* Set up the per control reg info, will pass to lctl */
+ kprobe_per_regs[0].em_instruction_fetch = 1;
+ kprobe_per_regs[0].starting_addr = regs->psw.addr;
+ kprobe_per_regs[0].ending_addr = regs->psw.addr + 4;
+
+ /* Set the PER control regs, turns on single step for this address */
+ __ctl_load(kprobe_per_regs, 9, 11);
+ regs->psw.mask |= PSW_MASK_PER;
+ regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
+}
+
+static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+ kcb->prev_kprobe.kp = kprobe_running();
+ kcb->prev_kprobe.status = kcb->kprobe_status;
+ kcb->prev_kprobe.kprobe_saved_imask = kcb->kprobe_saved_imask;
+ memcpy(kcb->prev_kprobe.kprobe_saved_ctl, kcb->kprobe_saved_ctl,
+ sizeof(kcb->kprobe_saved_ctl));
+}
+
+static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+ __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+ kcb->kprobe_status = kcb->prev_kprobe.status;
+ kcb->kprobe_saved_imask = kcb->prev_kprobe.kprobe_saved_imask;
+ memcpy(kcb->kprobe_saved_ctl, kcb->prev_kprobe.kprobe_saved_ctl,
+ sizeof(kcb->kprobe_saved_ctl));
+}
+
+static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
+{
+ __get_cpu_var(current_kprobe) = p;
+ /* Save the interrupt and per flags */
+ kcb->kprobe_saved_imask = regs->psw.mask &
+ (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
+ /* Save the control regs that govern PER */
+ __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
+}
+
+/* Called with kretprobe_lock held */
+void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
+ struct pt_regs *regs)
+{
+ struct kretprobe_instance *ri;
+
+ if ((ri = get_free_rp_inst(rp)) != NULL) {
+ ri->rp = rp;
+ ri->task = current;
+ ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
+
+ /* Replace the return addr with trampoline addr */
+ regs->gprs[14] = (unsigned long)&kretprobe_trampoline;
+
+ add_rp_inst(ri);
+ } else {
+ rp->nmissed++;
+ }
+}
+
+static int __kprobes kprobe_handler(struct pt_regs *regs)
+{
+ struct kprobe *p;
+ int ret = 0;
+ unsigned long *addr = (unsigned long *)
+ ((regs->psw.addr & PSW_ADDR_INSN) - 2);
+ struct kprobe_ctlblk *kcb;
+
+ /*
+ * We don't want to be preempted for the entire
+ * duration of kprobe processing
+ */
+ preempt_disable();
+ kcb = get_kprobe_ctlblk();
+
+ /* Check we're not actually recursing */
+ if (kprobe_running()) {
+ p = get_kprobe(addr);
+ if (p) {
+ if (kcb->kprobe_status == KPROBE_HIT_SS &&
+ *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
+ regs->psw.mask &= ~PSW_MASK_PER;
+ regs->psw.mask |= kcb->kprobe_saved_imask;
+ goto no_kprobe;
+ }
+ /* We have reentered the kprobe_handler(), since
+ * another probe was hit while within the handler.
+ * We here save the original kprobes variables and
+ * just single step on the instruction of the new probe
+ * without calling any user handlers.
+ */
+ save_previous_kprobe(kcb);
+ set_current_kprobe(p, regs, kcb);
+ kprobes_inc_nmissed_count(p);
+ prepare_singlestep(p, regs);
+ kcb->kprobe_status = KPROBE_REENTER;
+ return 1;
+ } else {
+ p = __get_cpu_var(current_kprobe);
+ if (p->break_handler && p->break_handler(p, regs)) {
+ goto ss_probe;
+ }
+ }
+ goto no_kprobe;
+ }
+
+ p = get_kprobe(addr);
+ if (!p) {
+ if (*addr != BREAKPOINT_INSTRUCTION) {
+ /*
+ * The breakpoint instruction was removed right
+ * after we hit it. Another cpu has removed
+ * either a probepoint or a debugger breakpoint
+ * at this address. In either case, no further
+ * handling of this interrupt is appropriate.
+ *
+ */
+ ret = 1;
+ }
+ /* Not one of ours: let kernel handle it */
+ goto no_kprobe;
+ }
+
+ kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+ set_current_kprobe(p, regs, kcb);
+ if (p->pre_handler && p->pre_handler(p, regs))
+ /* handler has already set things up, so skip ss setup */
+ return 1;
+
+ ss_probe:
+ prepare_singlestep(p, regs);
+ kcb->kprobe_status = KPROBE_HIT_SS;
+ return 1;
+
+ no_kprobe:
+ preempt_enable_no_resched();
+ return ret;
+}
+
+/*
+ * Function return probe trampoline:
+ * - init_kprobes() establishes a probepoint here
+ * - When the probed function returns, this probe
+ * causes the handlers to fire
+ */
+void kretprobe_trampoline_holder(void)
+{
+ asm volatile (".global kretprobe_trampoline\n"
+ "kretprobe_trampoline:\n" "bcr 0,0\n");
+}
+
+/*
+ * Called when the probe at kretprobe trampoline is hit
+ */
+int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ struct kretprobe_instance *ri = NULL;
+ struct hlist_head *head;
+ struct hlist_node *node, *tmp;
+ unsigned long flags, orig_ret_address = 0;
+ unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
+
+ spin_lock_irqsave(&kretprobe_lock, flags);
+ head = kretprobe_inst_table_head(current);
+
+ /*
+ * It is possible to have multiple instances associated with a given
+ * task either because an multiple functions in the call path
+ * have a return probe installed on them, and/or more then one return
+ * return probe was registered for a target function.
+ *
+ * We can handle this because:
+ * - instances are always inserted at the head of the list
+ * - when multiple return probes are registered for the same
+ * function, the first instance's ret_addr will point to the
+ * real return address, and all the rest will point to
+ * kretprobe_trampoline
+ */
+ hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
+ if (ri->task != current)
+ /* another task is sharing our hash bucket */
+ continue;
+
+ if (ri->rp && ri->rp->handler)
+ ri->rp->handler(ri, regs);
+
+ orig_ret_address = (unsigned long)ri->ret_addr;
+ recycle_rp_inst(ri);
+
+ if (orig_ret_address != trampoline_address) {
+ /*
+ * This is the real return address. Any other
+ * instances associated with this task are for
+ * other calls deeper on the call stack
+ */
+ break;
+ }
+ }
+ BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
+ regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE;
+
+ reset_current_kprobe();
+ spin_unlock_irqrestore(&kretprobe_lock, flags);
+ preempt_enable_no_resched();
+
+ /*
+ * By returning a non-zero value, we are telling
+ * kprobe_handler() that we don't want the post_handler
+ * to run (and have re-enabled preemption)
+ */
+ return 1;
+}
+
+/*
+ * Called after single-stepping. p->addr is the address of the
+ * instruction whose first byte has been replaced by the "breakpoint"
+ * instruction. To avoid the SMP problems that can occur when we
+ * temporarily put back the original opcode to single-step, we
+ * single-stepped a copy of the instruction. The address of this
+ * copy is p->ainsn.insn.
+ */
+static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
+{
+ int ilen, reg;
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ /* regular fixup, just apply the offset */
+ if (p->ainsn.inst_type == 0)
+ regs->psw.addr = fix_offset((unsigned long)p->addr,
+ (unsigned long)p->ainsn.insn,
+ (unsigned long)regs->psw.addr);
+ /* only apply the offset if the branch wasn't taken */
+ else if (p->ainsn.inst_type < 0) {
+ ilen = p->ainsn.inst_type & 0x0f;
+ reg = (p->ainsn.inst_type & 0xf0) >> 4;
+ if ((unsigned long)regs->psw.addr -
+ (unsigned long)p->ainsn.insn == ilen) {
+ /* reg slot is only nonzero here on basr
+ * and balr special cases, fixup reg too
+ */
+ if (reg != 0)
+ regs->gprs[reg] = (unsigned long)p->addr + ilen;
+ regs->psw.addr = (unsigned long)p->addr + ilen;
+ }
+ } else {
+ ilen = p->ainsn.inst_type & 0x0f;
+ reg = (p->ainsn.inst_type & 0xf0) >> 4;
+ regs->gprs[reg] = (unsigned long)p->addr + ilen;
+
+ regs->psw.addr = fix_offset((unsigned long)p->addr,
+ (unsigned long)p->ainsn.insn,
+ (unsigned long)regs->psw.addr);
+ }
+
+ /* set amode for 31bit */
+ regs->psw.addr |= PSW_ADDR_AMODE;
+ /* turn off PER mode */
+ regs->psw.mask &= ~PSW_MASK_PER;
+ /* Restore the original per control regs */
+ __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
+ regs->psw.mask |= kcb->kprobe_saved_imask;
+}
+
+/* if this isn't getting any more complicated, turn into macro? */
+unsigned long __kprobes fix_offset(unsigned long orig_addr,
+ unsigned long offset_start, unsigned long offset)
+{
+ return (orig_addr + (offset - offset_start));
+}
+static int __kprobes post_kprobe_handler(struct pt_regs *regs)
+{
+ struct kprobe *cur = kprobe_running();
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ if (!cur)
+ return 0;
+
+ if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
+ kcb->kprobe_status = KPROBE_HIT_SSDONE;
+ cur->post_handler(cur, regs, 0);
+ }
+
+ resume_execution(cur, regs);
+
+ /*Restore back the original saved kprobes variables and continue. */
+ if (kcb->kprobe_status == KPROBE_REENTER) {
+ restore_previous_kprobe(kcb);
+ goto out;
+ }
+ reset_current_kprobe();
+ out:
+ preempt_enable_no_resched();
+
+ /*
+ * if somebody else is singlestepping across a probe point, psw mask
+ * will have PER set, in which case, continue the remaining processing
+ * of do_single_step, as if this is not a probe hit.
+ */
+ if (regs->psw.mask & PSW_MASK_PER) {
+ return 0;
+ }
+
+ return 1;
+}
+
+static int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+{
+ struct kprobe *cur = kprobe_running();
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
+ return 1;
+
+ if (kcb->kprobe_status & KPROBE_HIT_SS) {
+ resume_execution(cur, regs);
+ regs->psw.mask |= kcb->kprobe_saved_imask;
+
+ reset_current_kprobe();
+ preempt_enable_no_resched();
+ }
+ return 0;
+}
+
+/*
+ * Wrapper routine to for handling exceptions.
+ */
+int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
+ unsigned long val, void *data)
+{
+ struct die_args *args = (struct die_args *)data;
+ int ret = NOTIFY_DONE;
+
+ switch (val) {
+ case DIE_BPT:
+ if (kprobe_handler(args->regs))
+ ret = NOTIFY_STOP;
+ break;
+ case DIE_SSTEP:
+ if (post_kprobe_handler(args->regs))
+ ret = NOTIFY_STOP;
+ break;
+ case DIE_PAGE_FAULT:
+ /* kprobe_running() needs smp_processor_id() */
+ preempt_disable();
+ if (kprobe_running() &&
+ kprobe_fault_handler(args->regs, args->trapnr))
+ ret = NOTIFY_STOP;
+ preempt_enable();
+ break;
+ default:
+ break;
+ }
+ return ret;
+}
+
+int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ struct jprobe *jp = container_of(p, struct jprobe, kp);
+ unsigned long addr;
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));
+
+ /* setup return addr to the jprobe handler routine */
+ regs->psw.addr = (unsigned long)(jp->entry) | PSW_ADDR_AMODE;
+
+ /* r14 is the function return address */
+ kcb->jprobe_saved_r14 = (unsigned long)regs->gprs[14];
+ /* r15 is the stack pointer */
+ kcb->jprobe_saved_r15 = (unsigned long)regs->gprs[15];
+ addr = (unsigned long)kcb->jprobe_saved_r15;
+
+ memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr,
+ MIN_STACK_SIZE(addr));
+ return 1;
+}
+
+void __kprobes jprobe_return(void)
+{
+ asm volatile (".long 0x00020000");
+}
+
+void __kprobes jprobe_return_end(void)
+{
+ asm volatile ("bcr 0,0");
+};
+
+int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_r15);
+
+ /* Put the regs back */
+ memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
+ /* put the stack back */
+ memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
+ MIN_STACK_SIZE(stack_addr));
+ preempt_enable_no_resched();
+ return 1;
+}
+
+static struct kprobe trampoline_p = {
+ .addr = (kprobe_opcode_t *) & kretprobe_trampoline,
+ .pre_handler = trampoline_probe_handler
+};
+
+int __init arch_init_kprobes(void)
+{
+ return register_kprobe(&trampoline_p);
+}
diff -urNp linux-2.6.17-rc6/arch/s390/kernel/Makefile linux-2.6.17-rc6-kp390/arch/s390/kernel/Makefile
--- linux-2.6.17-rc6/arch/s390/kernel/Makefile 2006-06-05 20:57:02.000000000 -0400
+++ linux-2.6.17-rc6-kp390/arch/s390/kernel/Makefile 2006-06-12 05:13:05.000000000 -0400
@@ -21,6 +21,7 @@ obj-$(CONFIG_COMPAT) += compat_linux.o
obj-$(CONFIG_BINFMT_ELF32) += binfmt_elf32.o

obj-$(CONFIG_VIRT_TIMER) += vtime.o
+obj-$(CONFIG_KPROBES) += kprobes.o

# Kexec part
S390_KEXEC_OBJS := machine_kexec.o crash.o
diff -urNp linux-2.6.17-rc6/arch/s390/kernel/traps.c linux-2.6.17-rc6-kp390/arch/s390/kernel/traps.c
--- linux-2.6.17-rc6/arch/s390/kernel/traps.c 2006-06-05 20:57:02.000000000 -0400
+++ linux-2.6.17-rc6-kp390/arch/s390/kernel/traps.c 2006-06-12 06:30:24.000000000 -0400
@@ -30,6 +30,7 @@
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/reboot.h>
+#include <linux/kprobes.h>

#include <asm/system.h>
#include <asm/uaccess.h>
@@ -40,6 +41,7 @@
#include <asm/s390_ext.h>
#include <asm/lowcore.h>
#include <asm/debug.h>
+#include <asm/kdebug.h>

/* Called from entry.S only */
extern void handle_per_exception(struct pt_regs *regs);
@@ -75,6 +77,20 @@ static int kstack_depth_to_print = 12;
static int kstack_depth_to_print = 20;
#endif /* CONFIG_64BIT */

+ATOMIC_NOTIFIER_HEAD(s390die_chain);
+
+int register_die_notifier(struct notifier_block *nb)
+{
+ return atomic_notifier_chain_register(&s390die_chain, nb);
+}
+EXPORT_SYMBOL(register_die_notifier);
+
+int unregister_die_notifier(struct notifier_block *nb)
+{
+ return atomic_notifier_chain_unregister(&s390die_chain, nb);
+}
+EXPORT_SYMBOL(unregister_die_notifier);
+
/*
* For show_trace we have tree different stack to consider:
* - the panic stack which is used if the kernel stack has overflown
@@ -308,8 +324,9 @@ report_user_fault(long interruption_code
#endif
}

-static void inline do_trap(long interruption_code, int signr, char *str,
- struct pt_regs *regs, siginfo_t *info)
+static void __kprobes inline do_trap(long interruption_code, int signr,
+ char *str, struct pt_regs *regs,
+ siginfo_t *info)
{
/*
* We got all needed information from the lowcore and can
@@ -318,6 +335,10 @@ static void inline do_trap(long interrup
if (regs->psw.mask & PSW_MASK_PSTATE)
local_irq_enable();

+ if (notify_die(DIE_TRAP, str, regs, interruption_code,
+ interruption_code, signr) == NOTIFY_STOP)
+ return;
+
if (regs->psw.mask & PSW_MASK_PSTATE) {
struct task_struct *tsk = current;

@@ -339,8 +360,12 @@ static inline void *get_check_address(st
return (void *)((regs->psw.addr-S390_lowcore.pgm_ilc) & PSW_ADDR_INSN);
}

-void do_single_step(struct pt_regs *regs)
+void __kprobes do_single_step(struct pt_regs *regs)
{
+ if (notify_die(DIE_SSTEP, "sstep", regs, 0, 0,
+ SIGTRAP) == NOTIFY_STOP){
+ return;
+ }
if ((current->ptrace & PT_PTRACED) != 0)
force_sig(SIGTRAP, current);
}
@@ -466,8 +491,15 @@ asmlinkage void illegal_op(struct pt_reg
#endif
} else
signal = SIGILL;
- } else
- signal = SIGILL;
+ } else {
+ /*
+ * If we get an illegal op in kernel mode, send it through the
+ * kprobes notifier. If kprobes doesn't pick it up, SIGILL
+ */
+ if (notify_die(DIE_BPT, "bpt", regs, interruption_code,
+ 3, SIGTRAP) != NOTIFY_STOP)
+ signal = SIGILL;
+ }

#ifdef CONFIG_MATHEMU
if (signal == SIGFPE)
diff -urNp linux-2.6.17-rc6/arch/s390/kernel/vmlinux.lds.S linux-2.6.17-rc6-kp390/arch/s390/kernel/vmlinux.lds.S
--- linux-2.6.17-rc6/arch/s390/kernel/vmlinux.lds.S 2006-06-05 20:57:02.000000000 -0400
+++ linux-2.6.17-rc6-kp390/arch/s390/kernel/vmlinux.lds.S 2006-06-12 05:13:05.000000000 -0400
@@ -25,6 +25,7 @@ SECTIONS
*(.text)
SCHED_TEXT
LOCK_TEXT
+ KPROBES_TEXT
*(.fixup)
*(.gnu.warning)
} = 0x0700
diff -urNp linux-2.6.17-rc6/arch/s390/mm/fault.c linux-2.6.17-rc6-kp390/arch/s390/mm/fault.c
--- linux-2.6.17-rc6/arch/s390/mm/fault.c 2006-06-05 20:57:02.000000000 -0400
+++ linux-2.6.17-rc6-kp390/arch/s390/mm/fault.c 2006-06-12 05:13:05.000000000 -0400
@@ -26,10 +26,12 @@
#include <linux/console.h>
#include <linux/module.h>
#include <linux/hardirq.h>
+#include <linux/kprobes.h>

#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
+#include <asm/kdebug.h>

#ifndef CONFIG_64BIT
#define __FAIL_ADDR_MASK 0x7ffff000
@@ -160,7 +162,7 @@ static void do_sigsegv(struct pt_regs *r
* 11 Page translation -> Not present (nullification)
* 3b Region third trans. -> Not present (nullification)
*/
-static inline void
+static inline void __kprobes
do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection)
{
struct task_struct *tsk;
@@ -174,6 +176,10 @@ do_exception(struct pt_regs *regs, unsig
tsk = current;
mm = tsk->mm;

+ if (notify_die(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
+ SIGSEGV) == NOTIFY_STOP)
+ return;
+
/*
* Check for low-address protection. This needs to be treated
* as a special case because the translation exception code
diff -urNp linux-2.6.17-rc6/include/asm-s390/kdebug.h linux-2.6.17-rc6-kp390/include/asm-s390/kdebug.h
--- linux-2.6.17-rc6/include/asm-s390/kdebug.h 1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6.17-rc6-kp390/include/asm-s390/kdebug.h 2006-06-12 06:27:25.000000000 -0400
@@ -0,0 +1,57 @@
+#ifndef _S390_KDEBUG_H
+#define _S390_KDEBUG_H 1
+
+/*
+ * Feb 2006 Ported to s390 <grundym@us.ibm.com>
+ */
+#include <linux/notifier.h>
+
+struct pt_regs;
+
+struct die_args {
+ struct pt_regs *regs;
+ const char *str;
+ long err;
+ int trapnr;
+ int signr;
+};
+
+/* Note - you should never unregister because that can race with NMIs.
+ * If you really want to do it first unregister - then synchronize_sched
+ * - then free.
+ */
+extern int register_die_notifier(struct notifier_block *);
+extern int unregister_die_notifier(struct notifier_block *);
+extern struct atomic_notifier_head s390die_chain;
+
+
+enum die_val {
+ DIE_OOPS = 1,
+ DIE_BPT,
+ DIE_SSTEP,
+ DIE_PANIC,
+ DIE_NMI,
+ DIE_DIE,
+ DIE_NMIWATCHDOG,
+ DIE_KERNELDEBUG,
+ DIE_TRAP,
+ DIE_GPF,
+ DIE_CALL,
+ DIE_NMI_IPI,
+ DIE_PAGE_FAULT,
+};
+
+static inline int notify_die(enum die_val val, const char *str,
+ struct pt_regs *regs, long err, int trap, int sig)
+{
+ struct die_args args = {
+ .regs = regs,
+ .str = str,
+ .err = err,
+ .trapnr = trap,
+ .signr = sig
+ };
+ return atomic_notifier_call_chain(&s390die_chain, val, &args);
+}
+
+#endif
diff -urNp linux-2.6.17-rc6/include/asm-s390/kprobes.h linux-2.6.17-rc6-kp390/include/asm-s390/kprobes.h
--- linux-2.6.17-rc6/include/asm-s390/kprobes.h 1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6.17-rc6-kp390/include/asm-s390/kprobes.h 2006-06-12 08:28:13.000000000 -0400
@@ -0,0 +1,208 @@
+#ifndef _ASM_S390_KPROBES_H
+#define _ASM_S390_KPROBES_H
+/*
+ * Kernel Probes (KProbes)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2002, 2006
+ *
+ * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
+ * Probes initial implementation ( includes suggestions from
+ * Rusty Russell).
+ * 2004-Nov Modified for PPC64 by Ananth N Mavinakayanahalli
+ * <ananth@in.ibm.com>
+ * 2005-Dec Used as a template for s390 by Mike Grundy
+ * <grundym@us.ibm.com>
+ */
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/percpu.h>
+
+#define __ARCH_WANT_KPROBES_INSN_SLOT
+struct pt_regs;
+struct kprobe;
+
+typedef u16 kprobe_opcode_t;
+#define BREAKPOINT_INSTRUCTION 0x0002
+
+/* Maximum instruction size is 3 (16bit) halfwords: */
+#define MAX_INSN_SIZE 0x0003
+#define MAX_STACK_SIZE 64
+#define MIN_STACK_SIZE(ADDR) (((MAX_STACK_SIZE) < \
+ (((unsigned long)current_thread_info()) + THREAD_SIZE - (ADDR))) \
+ ? (MAX_STACK_SIZE) \
+ : (((unsigned long)current_thread_info()) + THREAD_SIZE - (ADDR)))
+
+#define FIXUP_NOBRANCH 0xFFFF0000
+
+/* These are the s390 opcodes that could be troublesome with probes */
+#define OPCODE_BASSM 0x0C
+#define OPCODE_BSM 0x0B
+#define OPCODE_DIAG 0x83
+#define OPCODE_EX 0x44
+#define OPCODE_PR 0x01
+/* These all have a first byte of 0xB2, second byte defined */
+#define OPCODE_BSA 0x5A
+#define OPCODE_BAKR 0x40
+#define OPCODE_BSG 0x58
+#define OPCODE_PC 0x18
+#define OPCODE_PT 0x28
+
+/* These are the various branch (jump) instructions available on the s390 in
+ * 32 and 64bit mode. Most of the instruction formats are pretty straight
+ * forward, but some have the opcode split in different places.
+ */
+/* RR Format
+* ________ ____ ____
+* |Op Code | R1 | R2 |
+* |________|_M1_|____|
+* 0 8 12 15
+*/
+#define BALR 0x05
+#define BASR 0x0D
+#define BCR 0x07
+#define BCTR 0x06
+/* RX Format
+* ________ ____ ____ ____ ____________
+* |Op Code | R1 | X2 | B2 | D2 |
+* |________|_M1_|____|____|____________|
+* 0 8 12 16 20 31
+*/
+#define BAL 0x45
+#define BAS 0x4D
+#define BC 0x47
+#define BCT 0x46
+/* RI Format
+* ________ ____ ____ _________________
+* |Op Code | R1 |OpCd| I2 |
+* |________|____|____|_________________|
+* 0 8 12 16 31
+*/
+/* First byte is 0xA7 */
+#define BRC 0x4
+#define BRAS 0x5
+#define BRCT 0x6
+#define BRCTG 0x7
+/* RIE Format
+* ________ ____ ____ ____/_____ ________ ________
+* |Op Code | R1 | R3 | I2 |////////|Op Code |
+* |________|____|____|____/_____|________|________|
+* 0 8 12 16 32 40 47
+*/
+/* First byte is 0xEC */
+#define BRXHG 0x44
+#define BRXLG 0x45
+/* RRE Format
+* _________________ ________ ____ ____
+* | Op Code |////////| R1 | R2 |
+* |_________________|________|____|____|
+* 0 16 24 28 31
+*/
+/* First byte is 0xB9 */
+#define BCTGR 0x46
+/* RS Format
+* ________ ____ ____ ____ ____________
+* |Op Code | R1 | R3 | B2 | D2 |
+* |________|____|_M3_|____|____________|
+* 0 8 12 16 20 31
+*/
+#define BXH 0x86
+#define BXLE 0x87
+/* RSI Format
+* ________ ____ ____ _________________
+* |Op Code | R1 | R3 | I2 |
+* |________|____|____|_________________|
+* 0 8 12 16 31
+*/
+#define BRXH 0x84
+#define BRXLE 0x85
+/* RIL Format
+* ________ ____ ____ _____________/______________
+* |Op Code | R1 |OpCd| I2 |
+* |________|_M1_|____|_____________/______________|
+* 0 8 12 16 47
+*/
+/* First byte is 0xC0 */
+#define BRASL 0x5
+#define BRCL 0x4
+/* RSY Format
+* ________ ____ ____ ____ __/__ ________ ________
+* |Op Code | R1 | R3 | B2 | DL2 | DH2 |Op Code |
+* |________|____|_M3_|____|__/__|________|________|
+* 0 8 12 16 20 32 40 47
+*/
+/* First byte is 0xEB */
+#define BXHG 0x44
+#define BXLEG 0x45
+/* RXY Format
+* ________ ____ ____ ____ __/__ ________ ________
+* |Op Code | R1 | X2 | B2 | DL2 | DH2 |Op Code |
+* |________|____|____|____|__/__|________|________|
+* 0 8 12 16 20 32 40 47
+*/
+/* First byte is 0xE3 */
+#define BCTG 0x46
+
+#define JPROBE_ENTRY(pentry) (kprobe_opcode_t *)((func_descr_t *)pentry)
+
+#define ARCH_SUPPORTS_KRETPROBES
+
+void arch_remove_kprobe(struct kprobe *p);
+void kretprobe_trampoline(void);
+int is_prohibited_opcode(kprobe_opcode_t *instruction);
+int get_instruction_type(kprobe_opcode_t *instruction);
+unsigned long fix_offset( unsigned long orig_addr,
+ unsigned long offset_start,
+ unsigned long offset);
+
+/* Architecture specific copy of original instruction */
+struct arch_specific_insn {
+ /* copy of original instruction */
+ kprobe_opcode_t *insn;
+ int inst_type;
+};
+
+struct prev_kprobe {
+ struct kprobe *kp;
+ unsigned long status;
+ unsigned long saved_psw;
+ unsigned long kprobe_saved_imask;
+ unsigned long kprobe_saved_ctl[3];
+};
+
+/* per-cpu kprobe control block */
+struct kprobe_ctlblk {
+ unsigned long kprobe_status;
+ unsigned long kprobe_saved_imask;
+ unsigned long kprobe_saved_ctl[3];
+ struct pt_regs jprobe_saved_regs;
+ unsigned long jprobe_saved_r14;
+ unsigned long jprobe_saved_r15;
+ struct prev_kprobe prev_kprobe;
+ kprobe_opcode_t jprobes_stack[MAX_STACK_SIZE];
+};
+#endif /* _ASM_S390_KPROBES_H */
+#ifdef CONFIG_KPROBES
+
+extern int kprobe_exceptions_notify(struct notifier_block *self,
+ unsigned long val, void *data);
+#else /* !CONFIG_KPROBES */
+static inline int kprobe_exceptions_notify(struct notifier_block *self,
+ unsigned long val, void *data)
+{
+ return 0;
+}
+#endif