Commit 4ba069b8 authored by Michael Grundy's avatar Michael Grundy Committed by Martin Schwidefsky
Browse files

[S390] add kprobes support.


Signed-off-by: default avatarMichael Grundy <grundym@us.ibm.com>
Signed-off-by: default avatarDavid Wilder <dwilder@us.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 5432114b
......@@ -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"
......
......@@ -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
......
......@@ -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
*/
......
......@@ -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
*/
......
/*
* 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
*
* 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 <linux/stop_machine.h>
#include <asm/cacheflush.h>
#include <asm/kdebug.h>
#include <asm/sections.h>
#include <asm/uaccess.h>
#include <linux/module.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)
{
/* Make sure the probe isn't going on a difficult instruction */
if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))
return -EINVAL;
if ((unsigned long)p->addr & 0x01) {
printk("Attempt to register kprobe at an unaligned address\n");
return -EINVAL;
}
/* Use the get_insn_slot() facility for correctness */
if (!(p->ainsn.insn = get_insn_slot()))
return -ENOMEM;
memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
get_instruction_type(&p->ainsn);
p->opcode = *p->addr;
return 0;
}
int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction)
{
switch (*(__u8 *) instruction) {
case 0x0c: /* bassm */
case 0x0b: /* bsm */
case 0x83: /* diag */
case 0x44: /* ex */
return -EINVAL;
}
switch (*(__u16 *) instruction) {
case 0x0101: /* pr */
case 0xb25a: /* bsa */
case 0xb240: /* bakr */
case 0xb258: /* bsg */
case 0xb218: /* pc */
case 0xb228: /* pt */
return -EINVAL;
}
return 0;
}
void __kprobes get_instruction_type(struct arch_specific_insn *ainsn)
{
/* default fixup method */
ainsn->fixup = FIXUP_PSW_NORMAL;
/* save r1 operand */
ainsn->reg = (*ainsn->insn & 0xf0) >> 4;
/* save the instruction length (pop 5-5) in bytes */
switch (*(__u8 *) (ainsn->insn) >> 4) {
case 0:
ainsn->ilen = 2;
break;
case 1:
case 2:
ainsn->ilen = 4;
break;
case 3:
ainsn->ilen = 6;
break;
}
switch (*(__u8 *) ainsn->insn) {
case 0x05: /* balr */
case 0x0d: /* basr */
ainsn->fixup = FIXUP_RETURN_REGISTER;
/* if r2 = 0, no branch will be taken */
if ((*ainsn->insn & 0x0f) == 0)
ainsn->fixup |= FIXUP_BRANCH_NOT_TAKEN;
break;
case 0x06: /* bctr */
case 0x07: /* bcr */
ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
break;
case 0x45: /* bal */
case 0x4d: /* bas */
ainsn->fixup = FIXUP_RETURN_REGISTER;
break;
case 0x47: /* bc */
case 0x46: /* bct */
case 0x86: /* bxh */
case 0x87: /* bxle */
ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
break;
case 0x82: /* lpsw */
ainsn->fixup = FIXUP_NOT_REQUIRED;
break;
case 0xb2: /* lpswe */
if (*(((__u8 *) ainsn->insn) + 1) == 0xb2) {
ainsn->fixup = FIXUP_NOT_REQUIRED;
}
break;
case 0xa7: /* bras */
if ((*ainsn->insn & 0x0f) == 0x05) {
ainsn->fixup |= FIXUP_RETURN_REGISTER;
}
break;
case 0xc0:
if ((*ainsn->insn & 0x0f) == 0x00 /* larl */
|| (*ainsn->insn & 0x0f) == 0x05) /* brasl */
ainsn->fixup |= FIXUP_RETURN_REGISTER;
break;
case 0xeb:
if (*(((__u8 *) ainsn->insn) + 5 ) == 0x44 || /* bxhg */
*(((__u8 *) ainsn->insn) + 5) == 0x45) {/* bxleg */
ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
}
break;
case 0xe3: /* bctg */
if (*(((__u8 *) ainsn->insn) + 5) == 0x46) {
ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
}
break;
}
}
static int __kprobes swap_instruction(void *aref)
{
struct ins_replace_args *args = aref;
int err = -EFAULT;
asm volatile(
"0: mvc 0(2,%2),0(%3)\n"
"1: la %0,0\n"
"2:\n"
EX_TABLE(0b,2b)
: "+d" (err), "=m" (*args->ptr)
: "a" (args->ptr), "a" (&args->new), "m" (args->new));
return err;
}
void __kprobes arch_arm_kprobe(struct kprobe *p)
{
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
unsigned long status = kcb->kprobe_status;
struct ins_replace_args args;
args.ptr = p->addr;
args.old = p->opcode;
args.new = BREAKPOINT_INSTRUCTION;
kcb->kprobe_status = KPROBE_SWAP_INST;
stop_machine_run(swap_instruction, &args, NR_CPUS);
kcb->kprobe_status = status;
}
void __kprobes arch_disarm_kprobe(struct kprobe *p)
{
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
unsigned long status = kcb->kprobe_status;
struct ins_replace_args args;
args.ptr = p->addr;
args.old = BREAKPOINT_INSTRUCTION;
args.new = p->opcode;
kcb->kprobe_status = KPROBE_SWAP_INST;
stop_machine_run(swap_instruction, &args, NR_CPUS);
kcb->kprobe_status = status;
}
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 | 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 = (unsigned long)p->ainsn.insn;
kprobe_per_regs[0].ending_addr = (unsigned long)p->ainsn.insn + 1;
/* 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 __kprobes kretprobe_trampoline_holder(void)
{
asm volatile(".global kretprobe_trampoline\n"
"kretprobe_trampoline: 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)
{
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
regs->psw.addr &= PSW_ADDR_INSN;
if (p->ainsn.fixup & FIXUP_PSW_NORMAL)
regs->psw.addr = (unsigned long)p->addr +
((unsigned long)regs->psw.addr -
(unsigned long)p->ainsn.insn);
if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN)
if ((unsigned long)regs->psw.addr -
(unsigned long)p->ainsn.insn == p->ainsn.ilen)
regs->psw.addr = (unsigned long)p->addr + p->ainsn.ilen;
if (p->ainsn.fixup & FIXUP_RETURN_REGISTER)
regs->gprs[p->ainsn.reg] = ((unsigned long)p->addr +
(regs->gprs[p->ainsn.reg] -
(unsigned long)p->ainsn.insn))
| PSW_ADDR_AMODE;
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;
}
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();
const struct exception_table_entry *entry;
switch(kcb->kprobe_status) {
case KPROBE_SWAP_INST:
/* We are here because the instruction replacement failed */
return 0;
case KPROBE_HIT_SS:
case KPROBE_REENTER:
/*
* We are here because the instruction being single
* stepped caused a page fault. We reset the current
* kprobe and the nip points back to the probe address
* and allow the page fault handler to continue as a
* normal page fault.
*/
regs->psw.addr = (unsigned long)cur->addr | PSW_ADDR_AMODE;
regs->psw.mask &= ~PSW_MASK_PER;