Initial commit: OpenHarmony-v4.0-ReleaseOpenHarmony-v4.0-Release

1 files changed, 518 insertions, 0 deletions

diff --git a/arch/mips/kernel/kprobes.c b/arch/mips/kernel/kprobes.c
new file mode 100644
index 000000000..54dfba8fa
--- /dev/null
+++ b/arch/mips/kernel/kprobes.c
@@ -0,0 +1,518 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  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
+ */
+
+#include <linux/kprobes.h>
+#include <linux/preempt.h>
+#include <linux/uaccess.h>
+#include <linux/kdebug.h>
+#include <linux/slab.h>
+
+#include <asm/ptrace.h>
+#include <asm/branch.h>
+#include <asm/break.h>
+
+#include "probes-common.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)
+{
+        return __insn_has_delay_slot(insn);
+}
+
+/*
+ * insn_has_ll_or_sc function checks whether instruction is ll or sc
+ * one; putting breakpoint on top of atomic ll/sc pair is bad idea;
+ * so we need to prevent it and refuse kprobes insertion for such
+ * instructions; cannot do much about breakpoint in the middle of
+ * ll/sc pair; it is upto user to avoid those places
+ */
+static int __kprobes insn_has_ll_or_sc(union mips_instruction insn)
+{
+        int ret = 0;
+
+        switch (insn.i_format.opcode) {
+        case ll_op:
+        case lld_op:
+        case sc_op:
+        case scd_op:
+                ret = 1;
+                break;
+        default:
+                break;
+        }
+        return ret;
+}
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+        union mips_instruction insn;
+        union mips_instruction prev_insn;
+        int ret = 0;
+
+        insn = p->addr[0];
+
+        if (insn_has_ll_or_sc(insn)) {
+                pr_notice("Kprobes for ll and sc instructions are not"
+                          "supported\n");
+                ret = -EINVAL;
+                goto out;
+        }
+
+        if (copy_from_kernel_nofault(&prev_insn, p->addr - 1,
+                        sizeof(mips_instruction)) == 0 &&
+            insn_has_delayslot(prev_insn)) {
+                pr_notice("Kprobes for branch delayslot are not supported\n");
+                ret = -EINVAL;
+                goto out;
+        }
+
+        if (__insn_is_compact_branch(insn)) {
+                pr_notice("Kprobes for compact branches 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.
+         *
+         * On MIPS arch if the instruction at probed address is a
+         * branch instruction, we need to execute the instruction at
+         * Branch Delayslot (BD) at the time of probe hit. As MIPS also
+         * doesn't have single stepping support, the BD instruction can
+         * not be executed in-line and it would be executed on SSOL slot
+         * using a normal breakpoint instruction in the next slot.
+         * So, read the instruction and save it for later execution.
+         */
+        if (insn_has_delayslot(insn))
+                memcpy(&p->ainsn.insn[0], p->addr + 1, sizeof(kprobe_opcode_t));
+        else
+                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)
+{
+        if (p->ainsn.insn) {
+                free_insn_slot(p->ainsn.insn, 0);
+                p->ainsn.insn = NULL;
+        }
+}
+
+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)
+{
+        __this_cpu_write(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)
+{
+        __this_cpu_write(current_kprobe, p);
+        kcb->kprobe_saved_SR = kcb->kprobe_old_SR = (regs->cp0_status & ST0_IE);
+        kcb->kprobe_saved_epc = regs->cp0_epc;
+}
+
+/**
+ * evaluate_branch_instrucion -
+ *
+ * Evaluate the branch instruction at probed address during probe hit. The
+ * result of evaluation would be the updated epc. The insturction in delayslot
+ * would actually be single stepped using a normal breakpoint) on SSOL slot.
+ *
+ * The result is also saved in the kprobe control block for later use,
+ * in case we need to execute the delayslot instruction. The latter will be
+ * false for NOP instruction in dealyslot and the branch-likely instructions
+ * when the branch is taken. And for those cases we set a flag as
+ * SKIP_DELAYSLOT in the kprobe control block
+ */
+static int evaluate_branch_instruction(struct kprobe *p, struct pt_regs *regs,
+                                        struct kprobe_ctlblk *kcb)
+{
+        union mips_instruction insn = p->opcode;
+        long epc;
+        int ret = 0;
+
+        epc = regs->cp0_epc;
+        if (epc & 3)
+                goto unaligned;
+
+        if (p->ainsn.insn->word == 0)
+                kcb->flags |= SKIP_DELAYSLOT;
+        else
+                kcb->flags &= ~SKIP_DELAYSLOT;
+
+        ret = __compute_return_epc_for_insn(regs, insn);
+        if (ret < 0)
+                return ret;
+
+        if (ret == BRANCH_LIKELY_TAKEN)
+                kcb->flags |= SKIP_DELAYSLOT;
+
+        kcb->target_epc = regs->cp0_epc;
+
+        return 0;
+
+unaligned:
+        pr_notice("%s: unaligned epc - sending SIGBUS.\n", current->comm);
+        force_sig(SIGBUS);
+        return -EFAULT;
+
+}
+
+static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
+                                                struct kprobe_ctlblk *kcb)
+{
+        int ret = 0;
+
+        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 if (insn_has_delayslot(p->opcode)) {
+                ret = evaluate_branch_instruction(p, regs, kcb);
+                if (ret < 0) {
+                        pr_notice("Kprobes: Error in evaluating branch\n");
+                        return;
+                }
+        }
+        regs->cp0_epc = (unsigned long)&p->ainsn.insn[0];
+}
+
+/*
+ * 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. In case of branch instructions, the target
+ * epc to be restored.
+ */
+static void __kprobes resume_execution(struct kprobe *p,
+                                       struct pt_regs *regs,
+                                       struct kprobe_ctlblk *kcb)
+{
+        if (insn_has_delayslot(p->opcode))
+                regs->cp0_epc = kcb->target_epc;
+        else {
+                unsigned long orig_epc = kcb->kprobe_saved_epc;
+                regs->cp0_epc = orig_epc + 4;
+        }
+}
+
+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);
+                        kcb->kprobe_status = KPROBE_REENTER;
+                        if (kcb->flags & SKIP_DELAYSLOT) {
+                                resume_execution(p, regs, kcb);
+                                restore_previous_kprobe(kcb);
+                                preempt_enable_no_resched();
+                        }
+                        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_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 */
+                reset_current_kprobe();
+                preempt_enable_no_resched();
+                return 1;
+        }
+
+        prepare_singlestep(p, regs, kcb);
+        if (kcb->flags & SKIP_DELAYSLOT) {
+                kcb->kprobe_status = KPROBE_HIT_SSDONE;
+                if (p->post_handler)
+                        p->post_handler(p, regs, 0);
+                resume_execution(p, regs, kcb);
+                preempt_enable_no_resched();
+        } else
+                kcb->kprobe_status = KPROBE_HIT_SS;
+
+        return 1;
+
+no_kprobe:
+        preempt_enable_no_resched();
+        return ret;
+
+}
+
+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;
+}
+
+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;
+}
+
+/*
+ * 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];
+        ri->fp = NULL;
+
+        /* 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)
+{
+        instruction_pointer(regs) = __kretprobe_trampoline_handler(regs,
+                                                kretprobe_trampoline, NULL);
+        /*
+         * 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);
+}