diff options
Diffstat (limited to 'arch/parisc/kernel/kprobes.c')
| -rw-r--r-- | arch/parisc/kernel/kprobes.c | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/arch/parisc/kernel/kprobes.c b/arch/parisc/kernel/kprobes.c new file mode 100644 index 000000000..6d21a515e --- /dev/null +++ b/arch/parisc/kernel/kprobes.c @@ -0,0 +1,222 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * arch/parisc/kernel/kprobes.c + * + * PA-RISC kprobes implementation + * + * Copyright (c) 2019 Sven Schnelle <svens@stackframe.org> + */ + +#include <linux/types.h> +#include <linux/kprobes.h> +#include <linux/slab.h> +#include <asm/cacheflush.h> +#include <asm/patch.h> + +DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; +DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); + +int __kprobes arch_prepare_kprobe(struct kprobe *p) +{ + if ((unsigned long)p->addr & 3UL) + return -EINVAL; + + p->ainsn.insn = get_insn_slot(); + if (!p->ainsn.insn) + return -ENOMEM; + + memcpy(p->ainsn.insn, p->addr, + MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); + p->opcode = *p->addr; + flush_insn_slot(p); + return 0; +} + +void __kprobes arch_remove_kprobe(struct kprobe *p) +{ + if (!p->ainsn.insn) + return; + + free_insn_slot(p->ainsn.insn, 0); + p->ainsn.insn = NULL; +} + +void __kprobes arch_arm_kprobe(struct kprobe *p) +{ + patch_text(p->addr, PARISC_KPROBES_BREAK_INSN); +} + +void __kprobes arch_disarm_kprobe(struct kprobe *p) +{ + patch_text(p->addr, p->opcode); +} + +static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + kcb->prev_kprobe.kp = kprobe_running(); + kcb->prev_kprobe.status = kcb->kprobe_status; +} + +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; +} + +static inline void __kprobes set_current_kprobe(struct kprobe *p) +{ + __this_cpu_write(current_kprobe, p); +} + +static void __kprobes setup_singlestep(struct kprobe *p, + struct kprobe_ctlblk *kcb, struct pt_regs *regs) +{ + kcb->iaoq[0] = regs->iaoq[0]; + kcb->iaoq[1] = regs->iaoq[1]; + regs->iaoq[0] = (unsigned long)p->ainsn.insn; + mtctl(0, 0); + regs->gr[0] |= PSW_R; +} + +int __kprobes parisc_kprobe_break_handler(struct pt_regs *regs) +{ + struct kprobe *p; + struct kprobe_ctlblk *kcb; + + preempt_disable(); + + kcb = get_kprobe_ctlblk(); + p = get_kprobe((unsigned long *)regs->iaoq[0]); + + if (!p) { + preempt_enable_no_resched(); + return 0; + } + + if (kprobe_running()) { + /* + * We have reentered the kprobe_handler, since another kprobe + * was hit while within the handler, we save the original + * kprobes and single step on the instruction of the new probe + * without calling any user handlers to avoid recursive + * kprobes. + */ + save_previous_kprobe(kcb); + set_current_kprobe(p); + kprobes_inc_nmissed_count(p); + setup_singlestep(p, kcb, regs); + kcb->kprobe_status = KPROBE_REENTER; + return 1; + } + + set_current_kprobe(p); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + + /* If we have no pre-handler or it returned 0, we continue with + * normal processing. If we have a pre-handler and it returned + * non-zero - which means user handler setup registers to exit + * to another instruction, we must skip the single stepping. + */ + + if (!p->pre_handler || !p->pre_handler(p, regs)) { + setup_singlestep(p, kcb, regs); + kcb->kprobe_status = KPROBE_HIT_SS; + } else { + reset_current_kprobe(); + preempt_enable_no_resched(); + } + return 1; +} + +int __kprobes parisc_kprobe_ss_handler(struct pt_regs *regs) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + struct kprobe *p = kprobe_running(); + + if (!p) + return 0; + + if (regs->iaoq[0] != (unsigned long)p->ainsn.insn+4) + return 0; + + /* restore back original saved kprobe variables and continue */ + if (kcb->kprobe_status == KPROBE_REENTER) { + restore_previous_kprobe(kcb); + return 1; + } + + /* for absolute branch instructions we can copy iaoq_b. for relative + * branch instructions we need to calculate the new address based on the + * difference between iaoq_f and iaoq_b. We cannot use iaoq_b without + * modificationt because it's based on our ainsn.insn address. + */ + + if (p->post_handler) + p->post_handler(p, regs, 0); + + switch (regs->iir >> 26) { + case 0x38: /* BE */ + case 0x39: /* BE,L */ + case 0x3a: /* BV */ + case 0x3b: /* BVE */ + /* for absolute branches, regs->iaoq[1] has already the right + * address + */ + regs->iaoq[0] = kcb->iaoq[1]; + break; + default: + regs->iaoq[1] = kcb->iaoq[0]; + regs->iaoq[1] += (regs->iaoq[1] - regs->iaoq[0]) + 4; + regs->iaoq[0] = kcb->iaoq[1]; + break; + } + kcb->kprobe_status = KPROBE_HIT_SSDONE; + reset_current_kprobe(); + return 1; +} + +static inline void kretprobe_trampoline(void) +{ + asm volatile("nop"); + asm volatile("nop"); +} + +static int __kprobes trampoline_probe_handler(struct kprobe *p, + struct pt_regs *regs); + +static struct kprobe trampoline_p = { + .pre_handler = trampoline_probe_handler +}; + +static int __kprobes trampoline_probe_handler(struct kprobe *p, + struct pt_regs *regs) +{ + unsigned long orig_ret_address; + + orig_ret_address = __kretprobe_trampoline_handler(regs, trampoline_p.addr, NULL); + instruction_pointer_set(regs, orig_ret_address); + + return 1; +} + +void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, + struct pt_regs *regs) +{ + ri->ret_addr = (kprobe_opcode_t *)regs->gr[2]; + ri->fp = NULL; + + /* Replace the return addr with trampoline addr. */ + regs->gr[2] = (unsigned long)trampoline_p.addr; +} + +int __kprobes arch_trampoline_kprobe(struct kprobe *p) +{ + return p->addr == trampoline_p.addr; +} + +int __init arch_init_kprobes(void) +{ + trampoline_p.addr = (kprobe_opcode_t *) + dereference_function_descriptor(kretprobe_trampoline); + return register_kprobe(&trampoline_p); +} |