diff options
Diffstat (limited to 'arch/csky/kernel/probes/kprobes.c')
-rw-r--r-- | arch/csky/kernel/probes/kprobes.c | 412 |
1 files changed, 412 insertions, 0 deletions
diff --git a/arch/csky/kernel/probes/kprobes.c b/arch/csky/kernel/probes/kprobes.c new file mode 100644 index 0000000000..3c6e5c725d --- /dev/null +++ b/arch/csky/kernel/probes/kprobes.c @@ -0,0 +1,412 @@ +// SPDX-License-Identifier: GPL-2.0+ + +#define pr_fmt(fmt) "kprobes: " fmt + +#include <linux/kprobes.h> +#include <linux/extable.h> +#include <linux/slab.h> +#include <linux/stop_machine.h> +#include <asm/ptrace.h> +#include <linux/uaccess.h> +#include <asm/sections.h> +#include <asm/cacheflush.h> + +#include "decode-insn.h" + +DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; +DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); + +static void __kprobes +post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *); + +struct csky_insn_patch { + kprobe_opcode_t *addr; + u32 opcode; + atomic_t cpu_count; +}; + +static int __kprobes patch_text_cb(void *priv) +{ + struct csky_insn_patch *param = priv; + unsigned int addr = (unsigned int)param->addr; + + if (atomic_inc_return(¶m->cpu_count) == num_online_cpus()) { + *(u16 *) addr = cpu_to_le16(param->opcode); + dcache_wb_range(addr, addr + 2); + atomic_inc(¶m->cpu_count); + } else { + while (atomic_read(¶m->cpu_count) <= num_online_cpus()) + cpu_relax(); + } + + icache_inv_range(addr, addr + 2); + + return 0; +} + +static int __kprobes patch_text(kprobe_opcode_t *addr, u32 opcode) +{ + struct csky_insn_patch param = { addr, opcode, ATOMIC_INIT(0) }; + + return stop_machine_cpuslocked(patch_text_cb, ¶m, cpu_online_mask); +} + +static void __kprobes arch_prepare_ss_slot(struct kprobe *p) +{ + unsigned long offset = is_insn32(p->opcode) ? 4 : 2; + + p->ainsn.api.restore = (unsigned long)p->addr + offset; + + patch_text(p->ainsn.api.insn, p->opcode); +} + +static void __kprobes arch_prepare_simulate(struct kprobe *p) +{ + p->ainsn.api.restore = 0; +} + +static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + if (p->ainsn.api.handler) + p->ainsn.api.handler((u32)p->opcode, (long)p->addr, regs); + + post_kprobe_handler(kcb, regs); +} + +int __kprobes arch_prepare_kprobe(struct kprobe *p) +{ + unsigned long probe_addr = (unsigned long)p->addr; + + if (probe_addr & 0x1) + return -EILSEQ; + + /* copy instruction */ + p->opcode = le32_to_cpu(*p->addr); + + /* decode instruction */ + switch (csky_probe_decode_insn(p->addr, &p->ainsn.api)) { + case INSN_REJECTED: /* insn not supported */ + return -EINVAL; + + case INSN_GOOD_NO_SLOT: /* insn need simulation */ + p->ainsn.api.insn = NULL; + break; + + case INSN_GOOD: /* instruction uses slot */ + p->ainsn.api.insn = get_insn_slot(); + if (!p->ainsn.api.insn) + return -ENOMEM; + break; + } + + /* prepare the instruction */ + if (p->ainsn.api.insn) + arch_prepare_ss_slot(p); + else + arch_prepare_simulate(p); + + return 0; +} + +/* install breakpoint in text */ +void __kprobes arch_arm_kprobe(struct kprobe *p) +{ + patch_text(p->addr, USR_BKPT); +} + +/* remove breakpoint from text */ +void __kprobes arch_disarm_kprobe(struct kprobe *p) +{ + patch_text(p->addr, p->opcode); +} + +void __kprobes arch_remove_kprobe(struct kprobe *p) +{ + if (p->ainsn.api.insn) { + free_insn_slot(p->ainsn.api.insn, 0); + p->ainsn.api.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; +} + +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 void __kprobes set_current_kprobe(struct kprobe *p) +{ + __this_cpu_write(current_kprobe, p); +} + +/* + * Interrupts need to be disabled before single-step mode is set, and not + * reenabled until after single-step mode ends. + * Without disabling interrupt on local CPU, there is a chance of + * interrupt occurrence in the period of exception return and start of + * out-of-line single-step, that result in wrongly single stepping + * into the interrupt handler. + */ +static void __kprobes kprobes_save_local_irqflag(struct kprobe_ctlblk *kcb, + struct pt_regs *regs) +{ + kcb->saved_sr = regs->sr; + regs->sr &= ~BIT(6); +} + +static void __kprobes kprobes_restore_local_irqflag(struct kprobe_ctlblk *kcb, + struct pt_regs *regs) +{ + regs->sr = kcb->saved_sr; +} + +static void __kprobes +set_ss_context(struct kprobe_ctlblk *kcb, unsigned long addr, struct kprobe *p) +{ + unsigned long offset = is_insn32(p->opcode) ? 4 : 2; + + kcb->ss_ctx.ss_pending = true; + kcb->ss_ctx.match_addr = addr + offset; +} + +static void __kprobes clear_ss_context(struct kprobe_ctlblk *kcb) +{ + kcb->ss_ctx.ss_pending = false; + kcb->ss_ctx.match_addr = 0; +} + +#define TRACE_MODE_SI BIT(14) +#define TRACE_MODE_MASK ~(0x3 << 14) +#define TRACE_MODE_RUN 0 + +static void __kprobes setup_singlestep(struct kprobe *p, + struct pt_regs *regs, + struct kprobe_ctlblk *kcb, int reenter) +{ + unsigned long slot; + + if (reenter) { + save_previous_kprobe(kcb); + set_current_kprobe(p); + kcb->kprobe_status = KPROBE_REENTER; + } else { + kcb->kprobe_status = KPROBE_HIT_SS; + } + + if (p->ainsn.api.insn) { + /* prepare for single stepping */ + slot = (unsigned long)p->ainsn.api.insn; + + set_ss_context(kcb, slot, p); /* mark pending ss */ + + /* IRQs and single stepping do not mix well. */ + kprobes_save_local_irqflag(kcb, regs); + regs->sr = (regs->sr & TRACE_MODE_MASK) | TRACE_MODE_SI; + instruction_pointer_set(regs, slot); + } else { + /* insn simulation */ + arch_simulate_insn(p, regs); + } +} + +static int __kprobes reenter_kprobe(struct kprobe *p, + struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + switch (kcb->kprobe_status) { + case KPROBE_HIT_SSDONE: + case KPROBE_HIT_ACTIVE: + kprobes_inc_nmissed_count(p); + setup_singlestep(p, regs, kcb, 1); + break; + case KPROBE_HIT_SS: + case KPROBE_REENTER: + pr_warn("Failed to recover from reentered kprobes.\n"); + dump_kprobe(p); + BUG(); + break; + default: + WARN_ON(1); + return 0; + } + + return 1; +} + +static void __kprobes +post_kprobe_handler(struct kprobe_ctlblk *kcb, struct pt_regs *regs) +{ + struct kprobe *cur = kprobe_running(); + + if (!cur) + return; + + /* return addr restore if non-branching insn */ + if (cur->ainsn.api.restore != 0) + regs->pc = cur->ainsn.api.restore; + + /* restore back original saved kprobe variables and continue */ + if (kcb->kprobe_status == KPROBE_REENTER) { + restore_previous_kprobe(kcb); + return; + } + + /* call post handler */ + kcb->kprobe_status = KPROBE_HIT_SSDONE; + if (cur->post_handler) { + /* post_handler can hit breakpoint and single step + * again, so we enable D-flag for recursive exception. + */ + cur->post_handler(cur, regs, 0); + } + + reset_current_kprobe(); +} + +int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int trapnr) +{ + struct kprobe *cur = kprobe_running(); + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + 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 ip points back to the probe address + * and allow the page fault handler to continue as a + * normal page fault. + */ + regs->pc = (unsigned long) cur->addr; + BUG_ON(!instruction_pointer(regs)); + + if (kcb->kprobe_status == KPROBE_REENTER) + restore_previous_kprobe(kcb); + else + reset_current_kprobe(); + + break; + case KPROBE_HIT_ACTIVE: + case KPROBE_HIT_SSDONE: + /* + * In case the user-specified fault handler returned + * zero, try to fix up. + */ + if (fixup_exception(regs)) + return 1; + } + return 0; +} + +int __kprobes +kprobe_breakpoint_handler(struct pt_regs *regs) +{ + struct kprobe *p, *cur_kprobe; + struct kprobe_ctlblk *kcb; + unsigned long addr = instruction_pointer(regs); + + kcb = get_kprobe_ctlblk(); + cur_kprobe = kprobe_running(); + + p = get_kprobe((kprobe_opcode_t *) addr); + + if (p) { + if (cur_kprobe) { + if (reenter_kprobe(p, regs, kcb)) + return 1; + } else { + /* Probe hit */ + 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, it will + * modify the execution path and no need to single + * stepping. Let's just reset current kprobe and exit. + * + * pre_handler can hit a breakpoint and can step thru + * before return. + */ + if (!p->pre_handler || !p->pre_handler(p, regs)) + setup_singlestep(p, regs, kcb, 0); + else + reset_current_kprobe(); + } + return 1; + } + + /* + * 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. + * Return back to original instruction, and continue. + */ + return 0; +} + +int __kprobes +kprobe_single_step_handler(struct pt_regs *regs) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + if ((kcb->ss_ctx.ss_pending) + && (kcb->ss_ctx.match_addr == instruction_pointer(regs))) { + clear_ss_context(kcb); /* clear pending ss */ + + kprobes_restore_local_irqflag(kcb, regs); + regs->sr = (regs->sr & TRACE_MODE_MASK) | TRACE_MODE_RUN; + + post_kprobe_handler(kcb, regs); + return 1; + } + return 0; +} + +/* + * Provide a blacklist of symbols identifying ranges which cannot be kprobed. + * This blacklist is exposed to userspace via debugfs (kprobes/blacklist). + */ +int __init arch_populate_kprobe_blacklist(void) +{ + int ret; + + ret = kprobe_add_area_blacklist((unsigned long)__irqentry_text_start, + (unsigned long)__irqentry_text_end); + return ret; +} + +void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs) +{ + return (void *)kretprobe_trampoline_handler(regs, NULL); +} + +void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, + struct pt_regs *regs) +{ + ri->ret_addr = (kprobe_opcode_t *)regs->lr; + ri->fp = NULL; + regs->lr = (unsigned long) &__kretprobe_trampoline; +} + +int __kprobes arch_trampoline_kprobe(struct kprobe *p) +{ + return 0; +} + +int __init arch_init_kprobes(void) +{ + return 0; +} |