diff options
Diffstat (limited to 'arch/sparc/kernel/kprobes.c')
| -rw-r--r-- | arch/sparc/kernel/kprobes.c | 593 |
1 files changed, 593 insertions, 0 deletions
diff --git a/arch/sparc/kernel/kprobes.c b/arch/sparc/kernel/kprobes.c new file mode 100644 index 000000000000..201a6e547e4a --- /dev/null +++ b/arch/sparc/kernel/kprobes.c @@ -0,0 +1,593 @@ +/* arch/sparc64/kernel/kprobes.c + * + * Copyright (C) 2004 David S. Miller <davem@davemloft.net> + */ + +#include <linux/kernel.h> +#include <linux/kprobes.h> +#include <linux/module.h> +#include <linux/kdebug.h> +#include <asm/signal.h> +#include <asm/cacheflush.h> +#include <asm/uaccess.h> + +/* We do not have hardware single-stepping on sparc64. + * So we implement software single-stepping with breakpoint + * traps. The top-level scheme is similar to that used + * in the x86 kprobes implementation. + * + * In the kprobe->ainsn.insn[] array we store the original + * instruction at index zero and a break instruction at + * index one. + * + * When we hit a kprobe we: + * - Run the pre-handler + * - Remember "regs->tnpc" and interrupt level stored in + * "regs->tstate" so we can restore them later + * - Disable PIL interrupts + * - Set regs->tpc to point to kprobe->ainsn.insn[0] + * - Set regs->tnpc to point to kprobe->ainsn.insn[1] + * - Mark that we are actively in a kprobe + * + * At this point we wait for the second breakpoint at + * kprobe->ainsn.insn[1] to hit. When it does we: + * - Run the post-handler + * - Set regs->tpc to "remembered" regs->tnpc stored above, + * restore the PIL interrupt level in "regs->tstate" as well + * - Make any adjustments necessary to regs->tnpc in order + * to handle relative branches correctly. See below. + * - Mark that we are no longer actively in a kprobe. + */ + +DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; +DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); + +struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}}; + +int __kprobes arch_prepare_kprobe(struct kprobe *p) +{ + p->ainsn.insn[0] = *p->addr; + flushi(&p->ainsn.insn[0]); + + p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2; + flushi(&p->ainsn.insn[1]); + + p->opcode = *p->addr; + return 0; +} + +void __kprobes arch_arm_kprobe(struct kprobe *p) +{ + *p->addr = BREAKPOINT_INSTRUCTION; + flushi(p->addr); +} + +void __kprobes arch_disarm_kprobe(struct kprobe *p) +{ + *p->addr = p->opcode; + flushi(p->addr); +} + +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.orig_tnpc = kcb->kprobe_orig_tnpc; + kcb->prev_kprobe.orig_tstate_pil = kcb->kprobe_orig_tstate_pil; +} + +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_orig_tnpc = kcb->prev_kprobe.orig_tnpc; + kcb->kprobe_orig_tstate_pil = kcb->prev_kprobe.orig_tstate_pil; +} + +static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + __get_cpu_var(current_kprobe) = p; + kcb->kprobe_orig_tnpc = regs->tnpc; + kcb->kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL); +} + +static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + regs->tstate |= TSTATE_PIL; + + /*single step inline, if it a breakpoint instruction*/ + if (p->opcode == BREAKPOINT_INSTRUCTION) { + regs->tpc = (unsigned long) p->addr; + regs->tnpc = kcb->kprobe_orig_tnpc; + } else { + regs->tpc = (unsigned long) &p->ainsn.insn[0]; + regs->tnpc = (unsigned long) &p->ainsn.insn[1]; + } +} + +static int __kprobes kprobe_handler(struct pt_regs *regs) +{ + struct kprobe *p; + void *addr = (void *) regs->tpc; + int ret = 0; + struct kprobe_ctlblk *kcb; + + /* + * We don't want to be preempted for the entire + * duration of kprobe processing + */ + preempt_disable(); + kcb = get_kprobe_ctlblk(); + + if (kprobe_running()) { + p = get_kprobe(addr); + if (p) { + if (kcb->kprobe_status == KPROBE_HIT_SS) { + regs->tstate = ((regs->tstate & ~TSTATE_PIL) | + kcb->kprobe_orig_tstate_pil); + 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); + kcb->kprobe_status = KPROBE_REENTER; + prepare_singlestep(p, regs, kcb); + return 1; + } else { + if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) { + /* The breakpoint instruction was removed by + * another cpu right after we hit, no further + * handling of this interrupt is appropriate + */ + ret = 1; + goto no_kprobe; + } + 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 (*(u32 *)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; + } + + set_current_kprobe(p, regs, kcb); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + if (p->pre_handler && p->pre_handler(p, regs)) + return 1; + +ss_probe: + prepare_singlestep(p, regs, kcb); + kcb->kprobe_status = KPROBE_HIT_SS; + return 1; + +no_kprobe: + preempt_enable_no_resched(); + return ret; +} + +/* If INSN is a relative control transfer instruction, + * return the corrected branch destination value. + * + * regs->tpc and regs->tnpc still hold the values of the + * program counters at the time of trap due to the execution + * of the BREAKPOINT_INSTRUCTION_2 at p->ainsn.insn[1] + * + */ +static unsigned long __kprobes relbranch_fixup(u32 insn, struct kprobe *p, + struct pt_regs *regs) +{ + unsigned long real_pc = (unsigned long) p->addr; + + /* Branch not taken, no mods necessary. */ + if (regs->tnpc == regs->tpc + 0x4UL) + return real_pc + 0x8UL; + + /* The three cases are call, branch w/prediction, + * and traditional branch. + */ + if ((insn & 0xc0000000) == 0x40000000 || + (insn & 0xc1c00000) == 0x00400000 || + (insn & 0xc1c00000) == 0x00800000) { + unsigned long ainsn_addr; + + ainsn_addr = (unsigned long) &p->ainsn.insn[0]; + + /* The instruction did all the work for us + * already, just apply the offset to the correct + * instruction location. + */ + return (real_pc + (regs->tnpc - ainsn_addr)); + } + + /* It is jmpl or some other absolute PC modification instruction, + * leave NPC as-is. + */ + return regs->tnpc; +} + +/* If INSN is an instruction which writes it's PC location + * into a destination register, fix that up. + */ +static void __kprobes retpc_fixup(struct pt_regs *regs, u32 insn, + unsigned long real_pc) +{ + unsigned long *slot = NULL; + + /* Simplest case is 'call', which always uses %o7 */ + if ((insn & 0xc0000000) == 0x40000000) { + slot = ®s->u_regs[UREG_I7]; + } + + /* 'jmpl' encodes the register inside of the opcode */ + if ((insn & 0xc1f80000) == 0x81c00000) { + unsigned long rd = ((insn >> 25) & 0x1f); + + if (rd <= 15) { + slot = ®s->u_regs[rd]; + } else { + /* Hard case, it goes onto the stack. */ + flushw_all(); + + rd -= 16; + slot = (unsigned long *) + (regs->u_regs[UREG_FP] + STACK_BIAS); + slot += rd; + } + } + if (slot != NULL) + *slot = real_pc; +} + +/* + * Called after single-stepping. p->addr is the address of the + * instruction which 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[0]. + * + * This function prepares to return from the post-single-step + * breakpoint trap. + */ +static void __kprobes resume_execution(struct kprobe *p, + struct pt_regs *regs, struct kprobe_ctlblk *kcb) +{ + u32 insn = p->ainsn.insn[0]; + + regs->tnpc = relbranch_fixup(insn, p, regs); + + /* This assignment must occur after relbranch_fixup() */ + regs->tpc = kcb->kprobe_orig_tnpc; + + retpc_fixup(regs, insn, (unsigned long) p->addr); + + regs->tstate = ((regs->tstate & ~TSTATE_PIL) | + kcb->kprobe_orig_tstate_pil); +} + +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, kcb); + + /*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(); + + return 1; +} + +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_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 tpc points back to the probe address + * and allow the page fault handler to continue as a + * normal page fault. + */ + regs->tpc = (unsigned long)cur->addr; + regs->tnpc = kcb->kprobe_orig_tnpc; + regs->tstate = ((regs->tstate & ~TSTATE_PIL) | + kcb->kprobe_orig_tstate_pil); + if (kcb->kprobe_status == KPROBE_REENTER) + restore_previous_kprobe(kcb); + else + reset_current_kprobe(); + 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(cur); + + /* + * 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 (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) + return 1; + + /* + * In case the user-specified fault handler returned + * zero, try to fix up. + */ + + entry = search_exception_tables(regs->tpc); + if (entry) { + regs->tpc = entry->fixup; + regs->tnpc = regs->tpc + 4; + return 1; + } + + /* + * fixup_exception() could not handle it, + * Let do_page_fault() fix it. + */ + break; + default: + break; + } + + 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; + + if (args->regs && user_mode(args->regs)) + return ret; + + switch (val) { + case DIE_DEBUG: + if (kprobe_handler(args->regs)) + ret = NOTIFY_STOP; + break; + case DIE_DEBUG_2: + if (post_kprobe_handler(args->regs)) + ret = NOTIFY_STOP; + break; + default: + break; + } + return ret; +} + +asmlinkage void __kprobes kprobe_trap(unsigned long trap_level, + struct pt_regs *regs) +{ + BUG_ON(trap_level != 0x170 && trap_level != 0x171); + + if (user_mode(regs)) { + local_irq_enable(); + bad_trap(regs, trap_level); + return; + } + + /* trap_level == 0x170 --> ta 0x70 + * trap_level == 0x171 --> ta 0x71 + */ + if (notify_die((trap_level == 0x170) ? DIE_DEBUG : DIE_DEBUG_2, + (trap_level == 0x170) ? "debug" : "debug_2", + regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP) + bad_trap(regs, trap_level); +} + +/* Jprobes support. */ +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(); + + memcpy(&(kcb->jprobe_saved_regs), regs, sizeof(*regs)); + + regs->tpc = (unsigned long) jp->entry; + regs->tnpc = ((unsigned long) jp->entry) + 0x4UL; + regs->tstate |= TSTATE_PIL; + + return 1; +} + +void __kprobes jprobe_return(void) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + register unsigned long orig_fp asm("g1"); + + orig_fp = kcb->jprobe_saved_regs.u_regs[UREG_FP]; + __asm__ __volatile__("\n" +"1: cmp %%sp, %0\n\t" + "blu,a,pt %%xcc, 1b\n\t" + " restore\n\t" + ".globl jprobe_return_trap_instruction\n" +"jprobe_return_trap_instruction:\n\t" + "ta 0x70" + : /* no outputs */ + : "r" (orig_fp)); +} + +extern void jprobe_return_trap_instruction(void); + +int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) +{ + u32 *addr = (u32 *) regs->tpc; + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + if (addr == (u32 *) jprobe_return_trap_instruction) { + memcpy(regs, &(kcb->jprobe_saved_regs), sizeof(*regs)); + preempt_enable_no_resched(); + return 1; + } + return 0; +} + +/* The value stored in the return address register is actually 2 + * instructions before where the callee will return to. + * Sequences usually look something like this + * + * call some_function <--- return register points here + * nop <--- call delay slot + * whatever <--- where callee returns to + * + * To keep trampoline_probe_handler logic simpler, we normalize the + * value kept in ri->ret_addr so we don't need to keep adjusting it + * back and forth. + */ +void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, + struct pt_regs *regs) +{ + ri->ret_addr = (kprobe_opcode_t *)(regs->u_regs[UREG_RETPC] + 8); + + /* Replace the return addr with trampoline addr */ + regs->u_regs[UREG_RETPC] = + ((unsigned long)kretprobe_trampoline) - 8; +} + +/* + * 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, empty_rp; + struct hlist_node *node, *tmp; + unsigned long flags, orig_ret_address = 0; + unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; + + 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 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, &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; + } + + kretprobe_assert(ri, orig_ret_address, trampoline_address); + regs->tpc = orig_ret_address; + regs->tnpc = orig_ret_address + 4; + + reset_current_kprobe(); + kretprobe_hash_unlock(current, &flags); + preempt_enable_no_resched(); + + hlist_for_each_entry_safe(ri, node, 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; +} + +void kretprobe_trampoline_holder(void) +{ + asm volatile(".global kretprobe_trampoline\n" + "kretprobe_trampoline:\n" + "\tnop\n" + "\tnop\n"); +} +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); +} + +int __kprobes arch_trampoline_kprobe(struct kprobe *p) +{ + if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline) + return 1; + + return 0; +} |