diff options
Diffstat (limited to 'arch/mips/kernel')
| -rw-r--r-- | arch/mips/kernel/Makefile | 1 | ||||
| -rw-r--r-- | arch/mips/kernel/kprobes.c | 557 | ||||
| -rw-r--r-- | arch/mips/kernel/traps.c | 22 |
3 files changed, 579 insertions, 1 deletions
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile index ff5ec2e0184e..06f848299785 100644 --- a/arch/mips/kernel/Makefile +++ b/arch/mips/kernel/Makefile @@ -76,6 +76,7 @@ obj-$(CONFIG_IRQ_TXX9) += irq_txx9.o obj-$(CONFIG_IRQ_GT641XX) += irq-gt641xx.o obj-$(CONFIG_IRQ_GIC) += irq-gic.o +obj-$(CONFIG_KPROBES) += kprobes.o obj-$(CONFIG_32BIT) += scall32-o32.o obj-$(CONFIG_64BIT) += scall64-64.o obj-$(CONFIG_MIPS32_COMPAT) += linux32.o ptrace32.o signal32.o diff --git a/arch/mips/kernel/kprobes.c b/arch/mips/kernel/kprobes.c new file mode 100644 index 000000000000..ee28683fc2ac --- /dev/null +++ b/arch/mips/kernel/kprobes.c @@ -0,0 +1,557 @@ +/* + * Kernel Probes (KProbes) + * arch/mips/kernel/kprobes.c + * + * Copyright 2006 Sony Corp. + * Copyright 2010 Cavium Networks + * + * Some portions copied from the powerpc version. + * + * Copyright (C) IBM Corporation, 2002, 2004 + * + * 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 of the License. + * + * 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 + */ + +#include <linux/kprobes.h> +#include <linux/preempt.h> +#include <linux/kdebug.h> +#include <linux/slab.h> + +#include <asm/ptrace.h> +#include <asm/break.h> +#include <asm/inst.h> + +static const union mips_instruction breakpoint_insn = { + .b_format = { + .opcode = spec_op, + .code = BRK_KPROBE_BP, + .func = break_op + } +}; + +static const union mips_instruction breakpoint2_insn = { + .b_format = { + .opcode = spec_op, + .code = BRK_KPROBE_SSTEPBP, + .func = break_op + } +}; + +DEFINE_PER_CPU(struct kprobe *, current_kprobe); +DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); + +static int __kprobes insn_has_delayslot(union mips_instruction insn) +{ + switch (insn.i_format.opcode) { + + /* + * This group contains: + * jr and jalr are in r_format format. + */ + case spec_op: + switch (insn.r_format.func) { + case jr_op: + case jalr_op: + break; + default: + goto insn_ok; + } + + /* + * This group contains: + * bltz_op, bgez_op, bltzl_op, bgezl_op, + * bltzal_op, bgezal_op, bltzall_op, bgezall_op. + */ + case bcond_op: + + /* + * These are unconditional and in j_format. + */ + case jal_op: + case j_op: + + /* + * These are conditional and in i_format. + */ + case beq_op: + case beql_op: + case bne_op: + case bnel_op: + case blez_op: + case blezl_op: + case bgtz_op: + case bgtzl_op: + + /* + * These are the FPA/cp1 branch instructions. + */ + case cop1_op: + +#ifdef CONFIG_CPU_CAVIUM_OCTEON + case lwc2_op: /* This is bbit0 on Octeon */ + case ldc2_op: /* This is bbit032 on Octeon */ + case swc2_op: /* This is bbit1 on Octeon */ + case sdc2_op: /* This is bbit132 on Octeon */ +#endif + return 1; + default: + break; + } +insn_ok: + return 0; +} + +int __kprobes arch_prepare_kprobe(struct kprobe *p) +{ + union mips_instruction insn; + union mips_instruction prev_insn; + int ret = 0; + + prev_insn = p->addr[-1]; + insn = p->addr[0]; + + if (insn_has_delayslot(insn) || insn_has_delayslot(prev_insn)) { + pr_notice("Kprobes for branch and jump instructions are not supported\n"); + ret = -EINVAL; + goto out; + } + + /* insn: must be on special executable page on mips. */ + p->ainsn.insn = get_insn_slot(); + if (!p->ainsn.insn) { + ret = -ENOMEM; + goto out; + } + + /* + * 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; + +out: + return ret; +} + +void __kprobes arch_arm_kprobe(struct kprobe *p) +{ + *p->addr = breakpoint_insn; + flush_insn_slot(p); +} + +void __kprobes arch_disarm_kprobe(struct kprobe *p) +{ + *p->addr = p->opcode; + flush_insn_slot(p); +} + +void __kprobes arch_remove_kprobe(struct kprobe *p) +{ + free_insn_slot(p->ainsn.insn, 0); +} + +static void save_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + kcb->prev_kprobe.kp = kprobe_running(); + kcb->prev_kprobe.status = kcb->kprobe_status; + kcb->prev_kprobe.old_SR = kcb->kprobe_old_SR; + kcb->prev_kprobe.saved_SR = kcb->kprobe_saved_SR; + kcb->prev_kprobe.saved_epc = kcb->kprobe_saved_epc; +} + +static void 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_old_SR = kcb->prev_kprobe.old_SR; + kcb->kprobe_saved_SR = kcb->prev_kprobe.saved_SR; + kcb->kprobe_saved_epc = kcb->prev_kprobe.saved_epc; +} + +static void set_current_kprobe(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + __get_cpu_var(current_kprobe) = p; + kcb->kprobe_saved_SR = kcb->kprobe_old_SR = (regs->cp0_status & ST0_IE); + kcb->kprobe_saved_epc = regs->cp0_epc; +} + +static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) +{ + regs->cp0_status &= ~ST0_IE; + + /* single step inline if the instruction is a break */ + if (p->opcode.word == breakpoint_insn.word || + p->opcode.word == breakpoint2_insn.word) + regs->cp0_epc = (unsigned long)p->addr; + else + regs->cp0_epc = (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->cp0_epc; + + /* + * 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->word == breakpoint_insn.word) { + regs->cp0_status &= ~ST0_IE; + regs->cp0_status |= kcb->kprobe_saved_SR; + 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->word != breakpoint_insn.word) { + /* + * 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 (addr->word != breakpoint_insn.word) { + /* + * 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 whose first byte has been replaced by the "break 0" + * 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. + * + * 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_epc = kcb->kprobe_saved_epc; + regs->cp0_epc = orig_epc + 4; +} + +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); + + regs->cp0_status |= kcb->kprobe_saved_SR; + + /* 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) { + resume_execution(cur, regs, kcb); + regs->cp0_status |= kcb->kprobe_old_SR; + + 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->regs[29]; + + memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp, + MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp)); + + regs->cp0_epc = (unsigned long)(jp->entry); + + return 1; +} + +/* Defined in the inline asm below. */ +void jprobe_return_end(void); + +void __kprobes jprobe_return(void) +{ + /* Assembler quirk necessitates this '0,code' business. */ + asm volatile( + "break 0,%0\n\t" + ".globl jprobe_return_end\n" + "jprobe_return_end:\n" + : : "n" (BRK_KPROBE_BP) : "memory"); +} + +int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + if (regs->cp0_epc >= (unsigned long)jprobe_return && + regs->cp0_epc <= (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( + ".set push\n\t" + /* Keep the assembler from reordering and placing JR here. */ + ".set noreorder\n\t" + "nop\n\t" + ".global kretprobe_trampoline\n" + "kretprobe_trampoline:\n\t" + "nop\n\t" + ".set pop" + : : : "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->regs[31]; + + /* Replace the return addr with trampoline addr */ + regs->regs[31] = (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 *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 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, 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); + instruction_pointer(regs) = orig_ret_address; + + 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; +} + +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) +{ + return register_kprobe(&trampoline_p); +} diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index 1515b673179d..4c6079f24958 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -25,6 +25,7 @@ #include <linux/ptrace.h> #include <linux/kgdb.h> #include <linux/kdebug.h> +#include <linux/kprobes.h> #include <linux/notifier.h> #include <linux/kdb.h> @@ -334,7 +335,7 @@ void show_regs(struct pt_regs *regs) __show_regs((struct pt_regs *)regs); } -void show_registers(const struct pt_regs *regs) +void show_registers(struct pt_regs *regs) { const int field = 2 * sizeof(unsigned long); @@ -783,6 +784,25 @@ asmlinkage void do_bp(struct pt_regs *regs) if (bcode >= (1 << 10)) bcode >>= 10; + /* + * notify the kprobe handlers, if instruction is likely to + * pertain to them. + */ + switch (bcode) { + case BRK_KPROBE_BP: + if (notify_die(DIE_BREAK, "debug", regs, bcode, 0, 0) == NOTIFY_STOP) + return; + else + break; + case BRK_KPROBE_SSTEPBP: + if (notify_die(DIE_SSTEPBP, "single_step", regs, bcode, 0, 0) == NOTIFY_STOP) + return; + else + break; + default: + break; + } + do_trap_or_bp(regs, bcode, "Break"); return; |