![Heiko Carstens](/assets/img/avatar_default.png)
With the general-instruction extension facility (z10) a couple of instructions with a pc-relative long displacement were introduced. The kprobes support for these instructions however was never implemented. In result, if anybody ever put a probe on any of these instructions the result would have been random behaviour after the instruction got executed within the insn slot. So lets add the missing handling for these instructions. Since all of the new instructions have 32 bit signed displacement the easiest solution is to allocate an insn slot that is within the same 2GB area like the original instruction and patch the displacement field. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
819 lines
22 KiB
C
819 lines
22 KiB
C
/*
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* Kernel Probes (KProbes)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright IBM Corp. 2002, 2006
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*
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* s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com>
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*/
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#include <linux/kprobes.h>
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#include <linux/ptrace.h>
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#include <linux/preempt.h>
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#include <linux/stop_machine.h>
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#include <linux/kdebug.h>
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#include <linux/uaccess.h>
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#include <asm/cacheflush.h>
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#include <asm/sections.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/hardirq.h>
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DEFINE_PER_CPU(struct kprobe *, current_kprobe);
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DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
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struct kretprobe_blackpoint kretprobe_blacklist[] = { };
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DEFINE_INSN_CACHE_OPS(dmainsn);
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static void *alloc_dmainsn_page(void)
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{
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return (void *)__get_free_page(GFP_KERNEL | GFP_DMA);
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}
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static void free_dmainsn_page(void *page)
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{
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free_page((unsigned long)page);
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}
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struct kprobe_insn_cache kprobe_dmainsn_slots = {
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.mutex = __MUTEX_INITIALIZER(kprobe_dmainsn_slots.mutex),
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.alloc = alloc_dmainsn_page,
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.free = free_dmainsn_page,
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.pages = LIST_HEAD_INIT(kprobe_dmainsn_slots.pages),
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.insn_size = MAX_INSN_SIZE,
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};
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static int __kprobes is_prohibited_opcode(kprobe_opcode_t *insn)
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{
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switch (insn[0] >> 8) {
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case 0x0c: /* bassm */
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case 0x0b: /* bsm */
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case 0x83: /* diag */
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case 0x44: /* ex */
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case 0xac: /* stnsm */
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case 0xad: /* stosm */
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return -EINVAL;
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}
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switch (insn[0]) {
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case 0x0101: /* pr */
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case 0xb25a: /* bsa */
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case 0xb240: /* bakr */
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case 0xb258: /* bsg */
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case 0xb218: /* pc */
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case 0xb228: /* pt */
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case 0xb98d: /* epsw */
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return -EINVAL;
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}
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return 0;
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}
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static int __kprobes get_fixup_type(kprobe_opcode_t *insn)
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{
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/* default fixup method */
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int fixup = FIXUP_PSW_NORMAL;
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switch (insn[0] >> 8) {
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case 0x05: /* balr */
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case 0x0d: /* basr */
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fixup = FIXUP_RETURN_REGISTER;
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/* if r2 = 0, no branch will be taken */
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if ((insn[0] & 0x0f) == 0)
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fixup |= FIXUP_BRANCH_NOT_TAKEN;
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break;
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case 0x06: /* bctr */
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case 0x07: /* bcr */
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fixup = FIXUP_BRANCH_NOT_TAKEN;
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break;
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case 0x45: /* bal */
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case 0x4d: /* bas */
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fixup = FIXUP_RETURN_REGISTER;
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break;
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case 0x47: /* bc */
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case 0x46: /* bct */
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case 0x86: /* bxh */
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case 0x87: /* bxle */
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fixup = FIXUP_BRANCH_NOT_TAKEN;
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break;
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case 0x82: /* lpsw */
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fixup = FIXUP_NOT_REQUIRED;
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break;
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case 0xb2: /* lpswe */
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if ((insn[0] & 0xff) == 0xb2)
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fixup = FIXUP_NOT_REQUIRED;
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break;
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case 0xa7: /* bras */
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if ((insn[0] & 0x0f) == 0x05)
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fixup |= FIXUP_RETURN_REGISTER;
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break;
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case 0xc0:
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if ((insn[0] & 0x0f) == 0x05) /* brasl */
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fixup |= FIXUP_RETURN_REGISTER;
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break;
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case 0xeb:
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switch (insn[2] & 0xff) {
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case 0x44: /* bxhg */
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case 0x45: /* bxleg */
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fixup = FIXUP_BRANCH_NOT_TAKEN;
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break;
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}
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break;
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case 0xe3: /* bctg */
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if ((insn[2] & 0xff) == 0x46)
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fixup = FIXUP_BRANCH_NOT_TAKEN;
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break;
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case 0xec:
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switch (insn[2] & 0xff) {
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case 0xe5: /* clgrb */
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case 0xe6: /* cgrb */
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case 0xf6: /* crb */
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case 0xf7: /* clrb */
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case 0xfc: /* cgib */
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case 0xfd: /* cglib */
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case 0xfe: /* cib */
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case 0xff: /* clib */
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fixup = FIXUP_BRANCH_NOT_TAKEN;
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break;
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}
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break;
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}
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return fixup;
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}
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static int __kprobes is_insn_relative_long(kprobe_opcode_t *insn)
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{
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/* Check if we have a RIL-b or RIL-c format instruction which
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* we need to modify in order to avoid instruction emulation. */
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switch (insn[0] >> 8) {
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case 0xc0:
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if ((insn[0] & 0x0f) == 0x00) /* larl */
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return true;
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break;
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case 0xc4:
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switch (insn[0] & 0x0f) {
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case 0x02: /* llhrl */
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case 0x04: /* lghrl */
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case 0x05: /* lhrl */
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case 0x06: /* llghrl */
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case 0x07: /* sthrl */
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case 0x08: /* lgrl */
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case 0x0b: /* stgrl */
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case 0x0c: /* lgfrl */
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case 0x0d: /* lrl */
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case 0x0e: /* llgfrl */
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case 0x0f: /* strl */
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return true;
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}
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break;
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case 0xc6:
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switch (insn[0] & 0x0f) {
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case 0x00: /* exrl */
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case 0x02: /* pfdrl */
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case 0x04: /* cghrl */
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case 0x05: /* chrl */
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case 0x06: /* clghrl */
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case 0x07: /* clhrl */
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case 0x08: /* cgrl */
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case 0x0a: /* clgrl */
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case 0x0c: /* cgfrl */
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case 0x0d: /* crl */
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case 0x0e: /* clgfrl */
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case 0x0f: /* clrl */
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return true;
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}
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break;
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}
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return false;
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}
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static void __kprobes copy_instruction(struct kprobe *p)
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{
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s64 disp, new_disp;
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u64 addr, new_addr;
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memcpy(p->ainsn.insn, p->addr, ((p->opcode >> 14) + 3) & -2);
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if (!is_insn_relative_long(p->ainsn.insn))
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return;
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/*
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* For pc-relative instructions in RIL-b or RIL-c format patch the
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* RI2 displacement field. We have already made sure that the insn
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* slot for the patched instruction is within the same 2GB area
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* as the original instruction (either kernel image or module area).
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* Therefore the new displacement will always fit.
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*/
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disp = *(s32 *)&p->ainsn.insn[1];
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addr = (u64)(unsigned long)p->addr;
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new_addr = (u64)(unsigned long)p->ainsn.insn;
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new_disp = ((addr + (disp * 2)) - new_addr) / 2;
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*(s32 *)&p->ainsn.insn[1] = new_disp;
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}
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static inline int is_kernel_addr(void *addr)
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{
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return addr < (void *)_end;
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}
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static inline int is_module_addr(void *addr)
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{
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#ifdef CONFIG_64BIT
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BUILD_BUG_ON(MODULES_LEN > (1UL << 31));
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if (addr < (void *)MODULES_VADDR)
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return 0;
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if (addr > (void *)MODULES_END)
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return 0;
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#endif
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return 1;
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}
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static int __kprobes s390_get_insn_slot(struct kprobe *p)
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{
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/*
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* Get an insn slot that is within the same 2GB area like the original
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* instruction. That way instructions with a 32bit signed displacement
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* field can be patched and executed within the insn slot.
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*/
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p->ainsn.insn = NULL;
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if (is_kernel_addr(p->addr))
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p->ainsn.insn = get_dmainsn_slot();
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if (is_module_addr(p->addr))
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p->ainsn.insn = get_insn_slot();
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return p->ainsn.insn ? 0 : -ENOMEM;
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}
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static void __kprobes s390_free_insn_slot(struct kprobe *p)
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{
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if (!p->ainsn.insn)
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return;
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if (is_kernel_addr(p->addr))
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free_dmainsn_slot(p->ainsn.insn, 0);
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else
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free_insn_slot(p->ainsn.insn, 0);
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p->ainsn.insn = NULL;
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}
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int __kprobes arch_prepare_kprobe(struct kprobe *p)
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{
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if ((unsigned long) p->addr & 0x01)
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return -EINVAL;
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/* Make sure the probe isn't going on a difficult instruction */
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if (is_prohibited_opcode(p->addr))
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return -EINVAL;
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if (s390_get_insn_slot(p))
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return -ENOMEM;
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p->opcode = *p->addr;
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copy_instruction(p);
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return 0;
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}
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struct ins_replace_args {
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kprobe_opcode_t *ptr;
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kprobe_opcode_t opcode;
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};
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static int __kprobes swap_instruction(void *aref)
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{
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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unsigned long status = kcb->kprobe_status;
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struct ins_replace_args *args = aref;
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kcb->kprobe_status = KPROBE_SWAP_INST;
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probe_kernel_write(args->ptr, &args->opcode, sizeof(args->opcode));
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kcb->kprobe_status = status;
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return 0;
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}
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void __kprobes arch_arm_kprobe(struct kprobe *p)
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{
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struct ins_replace_args args;
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args.ptr = p->addr;
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args.opcode = BREAKPOINT_INSTRUCTION;
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stop_machine(swap_instruction, &args, NULL);
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}
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void __kprobes arch_disarm_kprobe(struct kprobe *p)
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{
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struct ins_replace_args args;
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args.ptr = p->addr;
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args.opcode = p->opcode;
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stop_machine(swap_instruction, &args, NULL);
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}
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void __kprobes arch_remove_kprobe(struct kprobe *p)
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{
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s390_free_insn_slot(p);
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}
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static void __kprobes enable_singlestep(struct kprobe_ctlblk *kcb,
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struct pt_regs *regs,
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unsigned long ip)
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{
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struct per_regs per_kprobe;
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/* Set up the PER control registers %cr9-%cr11 */
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per_kprobe.control = PER_EVENT_IFETCH;
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per_kprobe.start = ip;
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per_kprobe.end = ip;
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/* Save control regs and psw mask */
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__ctl_store(kcb->kprobe_saved_ctl, 9, 11);
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kcb->kprobe_saved_imask = regs->psw.mask &
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(PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT);
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/* Set PER control regs, turns on single step for the given address */
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__ctl_load(per_kprobe, 9, 11);
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regs->psw.mask |= PSW_MASK_PER;
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regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
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regs->psw.addr = ip | PSW_ADDR_AMODE;
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}
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static void __kprobes disable_singlestep(struct kprobe_ctlblk *kcb,
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struct pt_regs *regs,
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unsigned long ip)
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{
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/* Restore control regs and psw mask, set new psw address */
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__ctl_load(kcb->kprobe_saved_ctl, 9, 11);
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regs->psw.mask &= ~PSW_MASK_PER;
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regs->psw.mask |= kcb->kprobe_saved_imask;
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regs->psw.addr = ip | PSW_ADDR_AMODE;
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}
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/*
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* Activate a kprobe by storing its pointer to current_kprobe. The
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* previous kprobe is stored in kcb->prev_kprobe. A stack of up to
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* two kprobes can be active, see KPROBE_REENTER.
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*/
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static void __kprobes push_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p)
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{
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kcb->prev_kprobe.kp = __get_cpu_var(current_kprobe);
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kcb->prev_kprobe.status = kcb->kprobe_status;
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__get_cpu_var(current_kprobe) = p;
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}
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/*
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* Deactivate a kprobe by backing up to the previous state. If the
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* current state is KPROBE_REENTER prev_kprobe.kp will be non-NULL,
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* for any other state prev_kprobe.kp will be NULL.
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*/
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static void __kprobes pop_kprobe(struct kprobe_ctlblk *kcb)
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{
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__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
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kcb->kprobe_status = kcb->prev_kprobe.status;
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}
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void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
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struct pt_regs *regs)
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{
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ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
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/* Replace the return addr with trampoline addr */
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regs->gprs[14] = (unsigned long) &kretprobe_trampoline;
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}
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static void __kprobes kprobe_reenter_check(struct kprobe_ctlblk *kcb,
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struct kprobe *p)
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{
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switch (kcb->kprobe_status) {
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case KPROBE_HIT_SSDONE:
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case KPROBE_HIT_ACTIVE:
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kprobes_inc_nmissed_count(p);
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break;
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case KPROBE_HIT_SS:
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case KPROBE_REENTER:
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default:
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/*
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* A kprobe on the code path to single step an instruction
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* is a BUG. The code path resides in the .kprobes.text
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* section and is executed with interrupts disabled.
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*/
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printk(KERN_EMERG "Invalid kprobe detected at %p.\n", p->addr);
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dump_kprobe(p);
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BUG();
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}
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}
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static int __kprobes kprobe_handler(struct pt_regs *regs)
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{
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struct kprobe_ctlblk *kcb;
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struct kprobe *p;
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/*
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* We want to disable preemption for the entire duration of kprobe
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* processing. That includes the calls to the pre/post handlers
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* and single stepping the kprobe instruction.
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*/
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preempt_disable();
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kcb = get_kprobe_ctlblk();
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p = get_kprobe((void *)((regs->psw.addr & PSW_ADDR_INSN) - 2));
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if (p) {
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if (kprobe_running()) {
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/*
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* We have hit a kprobe while another is still
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* active. This can happen in the pre and post
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* handler. Single step the instruction of the
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* new probe but do not call any handler function
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* of this secondary kprobe.
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* push_kprobe and pop_kprobe saves and restores
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* the currently active kprobe.
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*/
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kprobe_reenter_check(kcb, p);
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push_kprobe(kcb, p);
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kcb->kprobe_status = KPROBE_REENTER;
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} else {
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/*
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* If we have no pre-handler or it returned 0, we
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* continue with single stepping. If we have a
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* pre-handler and it returned non-zero, it prepped
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* for calling the break_handler below on re-entry
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* for jprobe processing, so get out doing nothing
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* more here.
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*/
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push_kprobe(kcb, p);
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kcb->kprobe_status = KPROBE_HIT_ACTIVE;
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if (p->pre_handler && p->pre_handler(p, regs))
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return 1;
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kcb->kprobe_status = KPROBE_HIT_SS;
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}
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enable_singlestep(kcb, regs, (unsigned long) p->ainsn.insn);
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return 1;
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} else if (kprobe_running()) {
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p = __get_cpu_var(current_kprobe);
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if (p->break_handler && p->break_handler(p, regs)) {
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/*
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* Continuation after the jprobe completed and
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* caused the jprobe_return trap. The jprobe
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* break_handler "returns" to the original
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* function that still has the kprobe breakpoint
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* installed. We continue with single stepping.
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*/
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kcb->kprobe_status = KPROBE_HIT_SS;
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enable_singlestep(kcb, regs,
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(unsigned long) p->ainsn.insn);
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return 1;
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} /* else:
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* No kprobe at this address and the current kprobe
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* has no break handler (no jprobe!). The kernel just
|
|
* exploded, let the standard trap handler pick up the
|
|
* pieces.
|
|
*/
|
|
} /* else:
|
|
* No kprobe at this address and no active kprobe. The trap has
|
|
* not been caused by a kprobe breakpoint. The race of breakpoint
|
|
* vs. kprobe remove does not exist because on s390 as we use
|
|
* stop_machine to arm/disarm the breakpoints.
|
|
*/
|
|
preempt_enable_no_resched();
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Function return probe trampoline:
|
|
* - init_kprobes() establishes a probepoint here
|
|
* - When the probed function returns, this probe
|
|
* causes the handlers to fire
|
|
*/
|
|
static void __used 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
|
|
*/
|
|
static int __kprobes trampoline_probe_handler(struct kprobe *p,
|
|
struct pt_regs *regs)
|
|
{
|
|
struct kretprobe_instance *ri;
|
|
struct hlist_head *head, empty_rp;
|
|
struct hlist_node *tmp;
|
|
unsigned long flags, orig_ret_address;
|
|
unsigned long trampoline_address;
|
|
kprobe_opcode_t *correct_ret_addr;
|
|
|
|
INIT_HLIST_HEAD(&empty_rp);
|
|
kretprobe_hash_lock(current, &head, &flags);
|
|
|
|
/*
|
|
* 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 than 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
|
|
*/
|
|
ri = NULL;
|
|
orig_ret_address = 0;
|
|
correct_ret_addr = NULL;
|
|
trampoline_address = (unsigned long) &kretprobe_trampoline;
|
|
hlist_for_each_entry_safe(ri, tmp, head, hlist) {
|
|
if (ri->task != current)
|
|
/* another task is sharing our hash bucket */
|
|
continue;
|
|
|
|
orig_ret_address = (unsigned long) ri->ret_addr;
|
|
|
|
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;
|
|
}
|
|
|
|
kretprobe_assert(ri, orig_ret_address, trampoline_address);
|
|
|
|
correct_ret_addr = ri->ret_addr;
|
|
hlist_for_each_entry_safe(ri, tmp, head, hlist) {
|
|
if (ri->task != current)
|
|
/* another task is sharing our hash bucket */
|
|
continue;
|
|
|
|
orig_ret_address = (unsigned long) ri->ret_addr;
|
|
|
|
if (ri->rp && ri->rp->handler) {
|
|
ri->ret_addr = correct_ret_addr;
|
|
ri->rp->handler(ri, regs);
|
|
}
|
|
|
|
recycle_rp_inst(ri, &empty_rp);
|
|
|
|
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;
|
|
}
|
|
|
|
regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE;
|
|
|
|
pop_kprobe(get_kprobe_ctlblk());
|
|
kretprobe_hash_unlock(current, &flags);
|
|
preempt_enable_no_resched();
|
|
|
|
hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
|
|
hlist_del(&ri->hlist);
|
|
kfree(ri);
|
|
}
|
|
/*
|
|
* 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();
|
|
unsigned long ip = regs->psw.addr & PSW_ADDR_INSN;
|
|
int fixup = get_fixup_type(p->ainsn.insn);
|
|
|
|
if (fixup & FIXUP_PSW_NORMAL)
|
|
ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn;
|
|
|
|
if (fixup & FIXUP_BRANCH_NOT_TAKEN) {
|
|
int ilen = ((p->ainsn.insn[0] >> 14) + 3) & -2;
|
|
if (ip - (unsigned long) p->ainsn.insn == ilen)
|
|
ip = (unsigned long) p->addr + ilen;
|
|
}
|
|
|
|
if (fixup & FIXUP_RETURN_REGISTER) {
|
|
int reg = (p->ainsn.insn[0] & 0xf0) >> 4;
|
|
regs->gprs[reg] += (unsigned long) p->addr -
|
|
(unsigned long) p->ainsn.insn;
|
|
}
|
|
|
|
disable_singlestep(kcb, regs, ip);
|
|
}
|
|
|
|
static int __kprobes post_kprobe_handler(struct pt_regs *regs)
|
|
{
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
struct kprobe *p = kprobe_running();
|
|
|
|
if (!p)
|
|
return 0;
|
|
|
|
if (kcb->kprobe_status != KPROBE_REENTER && p->post_handler) {
|
|
kcb->kprobe_status = KPROBE_HIT_SSDONE;
|
|
p->post_handler(p, regs, 0);
|
|
}
|
|
|
|
resume_execution(p, regs);
|
|
pop_kprobe(kcb);
|
|
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_trap_handler(struct pt_regs *regs, int trapnr)
|
|
{
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
struct kprobe *p = kprobe_running();
|
|
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.
|
|
*/
|
|
disable_singlestep(kcb, regs, (unsigned long) p->addr);
|
|
pop_kprobe(kcb);
|
|
preempt_enable_no_resched();
|
|
break;
|
|
case KPROBE_HIT_ACTIVE:
|
|
case KPROBE_HIT_SSDONE:
|
|
/*
|
|
* We increment the nmissed count for accounting,
|
|
* we can also use npre/npostfault count for accouting
|
|
* these specific fault cases.
|
|
*/
|
|
kprobes_inc_nmissed_count(p);
|
|
|
|
/*
|
|
* We come here because instructions in the pre/post
|
|
* handler caused the page_fault, this could happen
|
|
* if handler tries to access user space by
|
|
* copy_from_user(), get_user() etc. Let the
|
|
* user-specified handler try to fix it first.
|
|
*/
|
|
if (p->fault_handler && p->fault_handler(p, regs, trapnr))
|
|
return 1;
|
|
|
|
/*
|
|
* In case the user-specified fault handler returned
|
|
* zero, try to fix up.
|
|
*/
|
|
entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
|
|
if (entry) {
|
|
regs->psw.addr = extable_fixup(entry) | PSW_ADDR_AMODE;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* fixup_exception() could not handle it,
|
|
* Let do_page_fault() fix it.
|
|
*/
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
|
|
{
|
|
int ret;
|
|
|
|
if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
|
|
local_irq_disable();
|
|
ret = kprobe_trap_handler(regs, trapnr);
|
|
if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
|
|
local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
struct pt_regs *regs = args->regs;
|
|
int ret = NOTIFY_DONE;
|
|
|
|
if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
|
|
local_irq_disable();
|
|
|
|
switch (val) {
|
|
case DIE_BPT:
|
|
if (kprobe_handler(regs))
|
|
ret = NOTIFY_STOP;
|
|
break;
|
|
case DIE_SSTEP:
|
|
if (post_kprobe_handler(regs))
|
|
ret = NOTIFY_STOP;
|
|
break;
|
|
case DIE_TRAP:
|
|
if (!preemptible() && kprobe_running() &&
|
|
kprobe_trap_handler(regs, args->trapnr))
|
|
ret = NOTIFY_STOP;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT))
|
|
local_irq_restore(regs->psw.mask & ~PSW_MASK_PER);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
struct jprobe *jp = container_of(p, struct jprobe, kp);
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
unsigned long stack;
|
|
|
|
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;
|
|
regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT);
|
|
|
|
/* r15 is the stack pointer */
|
|
stack = (unsigned long) regs->gprs[15];
|
|
|
|
memcpy(kcb->jprobes_stack, (void *) stack, MIN_STACK_SIZE(stack));
|
|
return 1;
|
|
}
|
|
|
|
void __kprobes jprobe_return(void)
|
|
{
|
|
asm volatile(".word 0x0002");
|
|
}
|
|
|
|
static void __used __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;
|
|
|
|
stack = (unsigned long) kcb->jprobe_saved_regs.gprs[15];
|
|
|
|
/* Put the regs back */
|
|
memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
|
|
/* put the stack back */
|
|
memcpy((void *) stack, kcb->jprobes_stack, MIN_STACK_SIZE(stack));
|
|
preempt_enable_no_resched();
|
|
return 1;
|
|
}
|
|
|
|
static struct kprobe trampoline = {
|
|
.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
|
|
.pre_handler = trampoline_probe_handler
|
|
};
|
|
|
|
int __init arch_init_kprobes(void)
|
|
{
|
|
return register_kprobe(&trampoline);
|
|
}
|
|
|
|
int __kprobes arch_trampoline_kprobe(struct kprobe *p)
|
|
{
|
|
return p->addr == (kprobe_opcode_t *) &kretprobe_trampoline;
|
|
}
|