diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/ppc64/kernel/kprobes.c | |
download | op-kernel-dev-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip op-kernel-dev-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'arch/ppc64/kernel/kprobes.c')
-rw-r--r-- | arch/ppc64/kernel/kprobes.c | 290 |
1 files changed, 290 insertions, 0 deletions
diff --git a/arch/ppc64/kernel/kprobes.c b/arch/ppc64/kernel/kprobes.c new file mode 100644 index 0000000..103daaf --- /dev/null +++ b/arch/ppc64/kernel/kprobes.c @@ -0,0 +1,290 @@ +/* + * Kernel Probes (KProbes) + * arch/ppc64/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, 2004 + * + * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel + * Probes initial implementation ( includes contributions from + * Rusty Russell). + * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes + * interface to access function arguments. + * 2004-Nov Ananth N Mavinakayanahalli <ananth@in.ibm.com> kprobes port + * for PPC64 + */ + +#include <linux/config.h> +#include <linux/kprobes.h> +#include <linux/ptrace.h> +#include <linux/spinlock.h> +#include <linux/preempt.h> +#include <asm/kdebug.h> +#include <asm/sstep.h> + +/* kprobe_status settings */ +#define KPROBE_HIT_ACTIVE 0x00000001 +#define KPROBE_HIT_SS 0x00000002 + +static struct kprobe *current_kprobe; +static unsigned long kprobe_status, kprobe_saved_msr; +static struct pt_regs jprobe_saved_regs; + +int arch_prepare_kprobe(struct kprobe *p) +{ + kprobe_opcode_t insn = *p->addr; + + if (IS_MTMSRD(insn) || IS_RFID(insn)) + /* cannot put bp on RFID/MTMSRD */ + return 1; + return 0; +} + +void arch_copy_kprobe(struct kprobe *p) +{ + memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); +} + +void arch_remove_kprobe(struct kprobe *p) +{ +} + +static inline void disarm_kprobe(struct kprobe *p, struct pt_regs *regs) +{ + *p->addr = p->opcode; + regs->nip = (unsigned long)p->addr; +} + +static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) +{ + regs->msr |= MSR_SE; + /*single step inline if it a breakpoint instruction*/ + if (p->opcode == BREAKPOINT_INSTRUCTION) + regs->nip = (unsigned long)p->addr; + else + regs->nip = (unsigned long)&p->ainsn.insn; +} + +static inline int kprobe_handler(struct pt_regs *regs) +{ + struct kprobe *p; + int ret = 0; + unsigned int *addr = (unsigned int *)regs->nip; + + /* Check we're not actually recursing */ + if (kprobe_running()) { + /* We *are* holding lock here, so this is safe. + Disarm the probe we just hit, and ignore it. */ + p = get_kprobe(addr); + if (p) { + if (kprobe_status == KPROBE_HIT_SS) { + regs->msr &= ~MSR_SE; + regs->msr |= kprobe_saved_msr; + unlock_kprobes(); + goto no_kprobe; + } + disarm_kprobe(p, regs); + ret = 1; + } else { + p = current_kprobe; + if (p->break_handler && p->break_handler(p, regs)) { + goto ss_probe; + } + } + /* If it's not ours, can't be delete race, (we hold lock). */ + goto no_kprobe; + } + + lock_kprobes(); + p = get_kprobe(addr); + if (!p) { + unlock_kprobes(); + if (*addr != BREAKPOINT_INSTRUCTION) { + /* + * PowerPC has multiple variants of the "trap" + * instruction. If the current instruction is a + * trap variant, it could belong to someone else + */ + kprobe_opcode_t cur_insn = *addr; + if (IS_TW(cur_insn) || IS_TD(cur_insn) || + IS_TWI(cur_insn) || IS_TDI(cur_insn)) + goto no_kprobe; + /* + * 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; + } + + kprobe_status = KPROBE_HIT_ACTIVE; + current_kprobe = p; + kprobe_saved_msr = regs->msr; + 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); + kprobe_status = KPROBE_HIT_SS; + /* + * This preempt_disable() matches the preempt_enable_no_resched() + * in post_kprobe_handler(). + */ + preempt_disable(); + return 1; + +no_kprobe: + return ret; +} + +/* + * 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 resume_execution(struct kprobe *p, struct pt_regs *regs) +{ + int ret; + + regs->nip = (unsigned long)p->addr; + ret = emulate_step(regs, p->ainsn.insn[0]); + if (ret == 0) + regs->nip = (unsigned long)p->addr + 4; + + regs->msr &= ~MSR_SE; +} + +static inline int post_kprobe_handler(struct pt_regs *regs) +{ + if (!kprobe_running()) + return 0; + + if (current_kprobe->post_handler) + current_kprobe->post_handler(current_kprobe, regs, 0); + + resume_execution(current_kprobe, regs); + regs->msr |= kprobe_saved_msr; + + unlock_kprobes(); + preempt_enable_no_resched(); + + /* + * if somebody else is singlestepping across a probe point, msr + * will have SE set, in which case, continue the remaining processing + * of do_debug, as if this is not a probe hit. + */ + if (regs->msr & MSR_SE) + return 0; + + return 1; +} + +/* Interrupts disabled, kprobe_lock held. */ +static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) +{ + if (current_kprobe->fault_handler + && current_kprobe->fault_handler(current_kprobe, regs, trapnr)) + return 1; + + if (kprobe_status & KPROBE_HIT_SS) { + resume_execution(current_kprobe, regs); + regs->msr |= kprobe_saved_msr; + + unlock_kprobes(); + preempt_enable_no_resched(); + } + return 0; +} + +/* + * Wrapper routine to for handling exceptions. + */ +int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, + void *data) +{ + struct die_args *args = (struct die_args *)data; + int ret = NOTIFY_DONE; + + /* + * Interrupts are not disabled here. We need to disable + * preemption, because kprobe_running() uses smp_processor_id(). + */ + preempt_disable(); + switch (val) { + case DIE_IABR_MATCH: + case DIE_DABR_MATCH: + 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_GPF: + case DIE_PAGE_FAULT: + if (kprobe_running() && + kprobe_fault_handler(args->regs, args->trapnr)) + ret = NOTIFY_STOP; + break; + default: + break; + } + preempt_enable(); + return ret; +} + +int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) +{ + struct jprobe *jp = container_of(p, struct jprobe, kp); + + memcpy(&jprobe_saved_regs, regs, sizeof(struct pt_regs)); + + /* setup return addr to the jprobe handler routine */ + regs->nip = (unsigned long)(((func_descr_t *)jp->entry)->entry); + regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc); + + return 1; +} + +void jprobe_return(void) +{ + asm volatile("trap" ::: "memory"); +} + +void jprobe_return_end(void) +{ +}; + +int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) +{ + /* + * FIXME - we should ideally be validating that we got here 'cos + * of the "trap" in jprobe_return() above, before restoring the + * saved regs... + */ + memcpy(regs, &jprobe_saved_regs, sizeof(struct pt_regs)); + return 1; +} |