From 3fa17c395bb0c358745fbe0c8aa039d6cdac1735 Mon Sep 17 00:00:00 2001 From: Tony Lu Date: Fri, 9 Aug 2013 15:08:57 -0400 Subject: tile: support kprobes on tilegx This change includes support for Kprobes, Jprobes and Return Probes. Reviewed-by: Masami Hiramatsu Signed-off-by: Tony Lu Signed-off-by: Chris Metcalf --- arch/tile/kernel/kprobes.c | 528 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 528 insertions(+) create mode 100644 arch/tile/kernel/kprobes.c (limited to 'arch/tile/kernel/kprobes.c') diff --git a/arch/tile/kernel/kprobes.c b/arch/tile/kernel/kprobes.c new file mode 100644 index 000000000000..27cdcacbe81d --- /dev/null +++ b/arch/tile/kernel/kprobes.c @@ -0,0 +1,528 @@ +/* + * arch/tile/kernel/kprobes.c + * Kprobes on TILE-Gx + * + * Some portions copied from the MIPS version. + * + * Copyright (C) IBM Corporation, 2002, 2004 + * Copyright 2006 Sony Corp. + * Copyright 2010 Cavium Networks + * + * Copyright 2012 Tilera Corporation. All Rights Reserved. + * + * 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, version 2. + * + * 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, GOOD TITLE or + * NON INFRINGEMENT. See the GNU General Public License for + * more details. + */ + +#include +#include +#include +#include +#include +#include + +#include + +DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; +DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); + +tile_bundle_bits breakpoint_insn = TILEGX_BPT_BUNDLE; +tile_bundle_bits breakpoint2_insn = TILEGX_BPT_BUNDLE | DIE_SSTEPBP; + +/* + * Check whether instruction is branch or jump, or if executing it + * has different results depending on where it is executed (e.g. lnk). + */ +static int __kprobes insn_has_control(kprobe_opcode_t insn) +{ + if (get_Mode(insn) != 0) { /* Y-format bundle */ + if (get_Opcode_Y1(insn) != RRR_1_OPCODE_Y1 || + get_RRROpcodeExtension_Y1(insn) != UNARY_RRR_1_OPCODE_Y1) + return 0; + + switch (get_UnaryOpcodeExtension_Y1(insn)) { + case JALRP_UNARY_OPCODE_Y1: + case JALR_UNARY_OPCODE_Y1: + case JRP_UNARY_OPCODE_Y1: + case JR_UNARY_OPCODE_Y1: + case LNK_UNARY_OPCODE_Y1: + return 1; + default: + return 0; + } + } + + switch (get_Opcode_X1(insn)) { + case BRANCH_OPCODE_X1: /* branch instructions */ + case JUMP_OPCODE_X1: /* jump instructions: j and jal */ + return 1; + + case RRR_0_OPCODE_X1: /* other jump instructions */ + if (get_RRROpcodeExtension_X1(insn) != UNARY_RRR_0_OPCODE_X1) + return 0; + switch (get_UnaryOpcodeExtension_X1(insn)) { + case JALRP_UNARY_OPCODE_X1: + case JALR_UNARY_OPCODE_X1: + case JRP_UNARY_OPCODE_X1: + case JR_UNARY_OPCODE_X1: + case LNK_UNARY_OPCODE_X1: + return 1; + default: + return 0; + } + default: + return 0; + } +} + +int __kprobes arch_prepare_kprobe(struct kprobe *p) +{ + unsigned long addr = (unsigned long)p->addr; + + if (addr & (sizeof(kprobe_opcode_t) - 1)) + return -EINVAL; + + if (insn_has_control(*p->addr)) { + pr_notice("Kprobes for control instructions are not " + "supported\n"); + return -EINVAL; + } + + /* insn: must be on special executable page on tile. */ + p->ainsn.insn = get_insn_slot(); + if (!p->ainsn.insn) + return -ENOMEM; + + /* + * In the kprobe->ainsn.insn[] array we store the original + * instruction at index zero and a break trap instruction at + * index one. + */ + memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t)); + p->ainsn.insn[1] = breakpoint2_insn; + p->opcode = *p->addr; + + return 0; +} + +void __kprobes arch_arm_kprobe(struct kprobe *p) +{ + unsigned long addr_wr; + + /* Operate on writable kernel text mapping. */ + addr_wr = (unsigned long)p->addr - MEM_SV_START + PAGE_OFFSET; + + if (probe_kernel_write((void *)addr_wr, &breakpoint_insn, + sizeof(breakpoint_insn))) + pr_err("%s: failed to enable kprobe\n", __func__); + + smp_wmb(); + flush_insn_slot(p); +} + +void __kprobes arch_disarm_kprobe(struct kprobe *kp) +{ + unsigned long addr_wr; + + /* Operate on writable kernel text mapping. */ + addr_wr = (unsigned long)kp->addr - MEM_SV_START + PAGE_OFFSET; + + if (probe_kernel_write((void *)addr_wr, &kp->opcode, + sizeof(kp->opcode))) + pr_err("%s: failed to enable kprobe\n", __func__); + + smp_wmb(); + flush_insn_slot(kp); +} + +void __kprobes arch_remove_kprobe(struct kprobe *p) +{ + if (p->ainsn.insn) { + free_insn_slot(p->ainsn.insn, 0); + p->ainsn.insn = NULL; + } +} + +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.saved_pc = kcb->kprobe_saved_pc; +} + +static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); + kcb->kprobe_status = kcb->prev_kprobe.status; + kcb->kprobe_saved_pc = kcb->prev_kprobe.saved_pc; +} + +static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + __this_cpu_write(current_kprobe, p); + kcb->kprobe_saved_pc = regs->pc; +} + +static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) +{ + /* Single step inline if the instruction is a break. */ + if (p->opcode == breakpoint_insn || + p->opcode == breakpoint2_insn) + regs->pc = (unsigned long)p->addr; + else + regs->pc = (unsigned long)&p->ainsn.insn[0]; +} + +static int __kprobes kprobe_handler(struct pt_regs *regs) +{ + struct kprobe *p; + int ret = 0; + kprobe_opcode_t *addr; + struct kprobe_ctlblk *kcb; + + addr = (kprobe_opcode_t *)regs->pc; + + /* + * 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[0] == breakpoint_insn) { + 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 { + if (*addr != breakpoint_insn) { + /* + * 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 = __this_cpu_read(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_insn) { + /* + * 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)) { + /* 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; +} + +/* + * Called after single-stepping. p->addr is the address of the + * instruction that has been replaced by the breakpoint. 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. + * + * 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) +{ + unsigned long orig_pc = kcb->kprobe_saved_pc; + regs->pc = orig_pc + 8; +} + +static inline int 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; +} + +static inline int 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) { + /* + * We are here because the instruction being single + * stepped caused a page fault. We reset the current + * kprobe and the ip points back to the probe address + * and allow the page fault handler to continue as a + * normal page fault. + */ + resume_execution(cur, regs, kcb); + reset_current_kprobe(); + preempt_enable_no_resched(); + } + return 0; +} + +/* + * Wrapper routine 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_BREAK: + if (kprobe_handler(args->regs)) + ret = NOTIFY_STOP; + break; + case DIE_SSTEPBP: + 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); + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + kcb->jprobe_saved_regs = *regs; + kcb->jprobe_saved_sp = regs->sp; + + memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp, + MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp)); + + regs->pc = (unsigned long)(jp->entry); + + return 1; +} + +/* Defined in the inline asm below. */ +void jprobe_return_end(void); + +void __kprobes jprobe_return(void) +{ + asm volatile( + "bpt\n\t" + ".globl jprobe_return_end\n" + "jprobe_return_end:\n"); +} + +int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + if (regs->pc >= (unsigned long)jprobe_return && + regs->pc <= (unsigned long)jprobe_return_end) { + *regs = kcb->jprobe_saved_regs; + memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack, + MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp)); + preempt_enable_no_resched(); + + return 1; + } + 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( + "nop\n\t" + ".global kretprobe_trampoline\n" + "kretprobe_trampoline:\n\t" + "nop\n\t" + : : : "memory"); +} + +void kretprobe_trampoline(void); + +void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, + struct pt_regs *regs) +{ + ri->ret_addr = (kprobe_opcode_t *) regs->lr; + + /* Replace the return addr with trampoline addr */ + regs->lr = (unsigned long)kretprobe_trampoline; +} + +/* + * 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 = NULL; + struct hlist_head *head, empty_rp; + struct hlist_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 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 + */ + hlist_for_each_entry_safe(ri, 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); + instruction_pointer(regs) = orig_ret_address; + + reset_current_kprobe(); + 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; +} + +int __kprobes arch_trampoline_kprobe(struct kprobe *p) +{ + if (p->addr == (kprobe_opcode_t *)kretprobe_trampoline) + return 1; + + return 0; +} + +static struct kprobe trampoline_p = { + .addr = (kprobe_opcode_t *)kretprobe_trampoline, + .pre_handler = trampoline_probe_handler +}; + +int __init arch_init_kprobes(void) +{ + register_kprobe(&trampoline_p); + return 0; +} -- cgit v1.2.3