cregit-Linux how code gets into the kernel

Release 4.14 arch/mn10300/kernel/kprobes.c

/* MN10300 Kernel probes implementation
 *
 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
 * Written by Mark Salter (msalter@redhat.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public Licence as published by
 * the Free Software Foundation; either version 2 of the Licence, or
 * (at your option) any later version.
 *
 * 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 Licence for more details.
 *
 * You should have received a copy of the GNU General Public Licence
 * 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/ptrace.h>
#include <linux/spinlock.h>
#include <linux/preempt.h>
#include <linux/kdebug.h>
#include <asm/cacheflush.h>


struct kretprobe_blackpoint kretprobe_blacklist[] = { { NULL, NULL } };

const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist);

/* kprobe_status settings */

#define KPROBE_HIT_ACTIVE	0x00000001

#define KPROBE_HIT_SS		0x00000002


static struct kprobe *cur_kprobe;

static unsigned long cur_kprobe_orig_pc;

static unsigned long cur_kprobe_next_pc;

static int cur_kprobe_ss_flags;

static unsigned long kprobe_status;

static kprobe_opcode_t cur_kprobe_ss_buf[MAX_INSN_SIZE + 2];

static unsigned long cur_kprobe_bp_addr;

DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;


/* singlestep flag bits */

#define SINGLESTEP_BRANCH 1

#define SINGLESTEP_PCREL  2


#define READ_BYTE(p, valp) \
	do { *(u8 *)(valp) = *(u8 *)(p); } while (0)


#define READ_WORD16(p, valp)					\
	do {                                                    \
                READ_BYTE((p), (valp));                         \
                READ_BYTE((u8 *)(p) + 1, (u8 *)(valp) + 1);     \
        } while (0)


#define READ_WORD32(p, valp)					\
	do {                                                    \
                READ_BYTE((p), (valp));                         \
                READ_BYTE((u8 *)(p) + 1, (u8 *)(valp) + 1);     \
                READ_BYTE((u8 *)(p) + 2, (u8 *)(valp) + 2);     \
                READ_BYTE((u8 *)(p) + 3, (u8 *)(valp) + 3);     \
        } while (0)



static const u8 mn10300_insn_sizes[256] =
{
	/* 1  2  3  4  5  6  7  8  9  a  b  c  d  e  f */
	1, 3, 3, 3, 1, 3, 3, 3, 1, 3, 3, 3, 1, 3, 3, 3,	/* 0 */
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 1 */
	2, 2, 2, 2, 3, 3, 3, 3, 2, 2, 2, 2, 3, 3, 3, 3, /* 2 */
	3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 1, 1, 1, 1, /* 3 */
	1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, /* 4 */
	1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, /* 5 */
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 6 */
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 7 */
	2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* 8 */
	2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* 9 */
	2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* a */
	2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* b */
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 2, 2, /* c */
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* d */
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* e */
	0, 2, 2, 2, 2, 2, 2, 4, 0, 3, 0, 4, 0, 6, 7, 1  /* f */
};


#define LT (1 << 0)

#define GT (1 << 1)

#define GE (1 << 2)

#define LE (1 << 3)

#define CS (1 << 4)

#define HI (1 << 5)

#define CC (1 << 6)

#define LS (1 << 7)

#define EQ (1 << 8)

#define NE (1 << 9)

#define RA (1 << 10)

#define VC (1 << 11)

#define VS (1 << 12)

#define NC (1 << 13)

#define NS (1 << 14)


static const u16 cond_table[] = {
	/*  V  C  N  Z  */
	/*  0  0  0  0  */ (NE | NC | CC | VC | GE | GT | HI),
	/*  0  0  0  1  */ (EQ | NC | CC | VC | GE | LE | LS),
	/*  0  0  1  0  */ (NE | NS | CC | VC | LT | LE | HI),
	/*  0  0  1  1  */ (EQ | NS | CC | VC | LT | LE | LS),
	/*  0  1  0  0  */ (NE | NC | CS | VC | GE | GT | LS),
	/*  0  1  0  1  */ (EQ | NC | CS | VC | GE | LE | LS),
	/*  0  1  1  0  */ (NE | NS | CS | VC | LT | LE | LS),
	/*  0  1  1  1  */ (EQ | NS | CS | VC | LT | LE | LS),
	/*  1  0  0  0  */ (NE | NC | CC | VS | LT | LE | HI),
	/*  1  0  0  1  */ (EQ | NC | CC | VS | LT | LE | LS),
	/*  1  0  1  0  */ (NE | NS | CC | VS | GE | GT | HI),
	/*  1  0  1  1  */ (EQ | NS | CC | VS | GE | LE | LS),
	/*  1  1  0  0  */ (NE | NC | CS | VS | LT | LE | LS),
	/*  1  1  0  1  */ (EQ | NC | CS | VS | LT | LE | LS),
	/*  1  1  1  0  */ (NE | NS | CS | VS | GE | GT | LS),
	/*  1  1  1  1  */ (EQ | NS | CS | VS | GE | LE | LS),
};

/*
 * Calculate what the PC will be after executing next instruction
 */

static unsigned find_nextpc(struct pt_regs *regs, int *flags) { unsigned size; s8 x8; s16 x16; s32 x32; u8 opc, *pc, *sp, *next; next = 0; *flags = SINGLESTEP_PCREL; pc = (u8 *) regs->pc; sp = (u8 *) (regs + 1); opc = *pc; size = mn10300_insn_sizes[opc]; if (size > 0) { next = pc + size; } else { switch (opc) { /* Bxx (d8,PC) */ case 0xc0 ... 0xca: x8 = 2; if (cond_table[regs->epsw & 0xf] & (1 << (opc & 0xf))) x8 = (s8)pc[1]; next = pc + x8; *flags |= SINGLESTEP_BRANCH; break; /* JMP (d16,PC) or CALL (d16,PC) */ case 0xcc: case 0xcd: READ_WORD16(pc + 1, &x16); next = pc + x16; *flags |= SINGLESTEP_BRANCH; break; /* JMP (d32,PC) or CALL (d32,PC) */ case 0xdc: case 0xdd: READ_WORD32(pc + 1, &x32); next = pc + x32; *flags |= SINGLESTEP_BRANCH; break; /* RETF */ case 0xde: next = (u8 *)regs->mdr; *flags &= ~SINGLESTEP_PCREL; *flags |= SINGLESTEP_BRANCH; break; /* RET */ case 0xdf: sp += pc[2]; READ_WORD32(sp, &x32); next = (u8 *)x32; *flags &= ~SINGLESTEP_PCREL; *flags |= SINGLESTEP_BRANCH; break; case 0xf0: next = pc + 2; opc = pc[1]; if (opc >= 0xf0 && opc <= 0xf7) { /* JMP (An) / CALLS (An) */ switch (opc & 3) { case 0: next = (u8 *)regs->a0; break; case 1: next = (u8 *)regs->a1; break; case 2: next = (u8 *)regs->a2; break; case 3: next = (u8 *)regs->a3; break; } *flags &= ~SINGLESTEP_PCREL; *flags |= SINGLESTEP_BRANCH; } else if (opc == 0xfc) { /* RETS */ READ_WORD32(sp, &x32); next = (u8 *)x32; *flags &= ~SINGLESTEP_PCREL; *flags |= SINGLESTEP_BRANCH; } else if (opc == 0xfd) { /* RTI */ READ_WORD32(sp + 4, &x32); next = (u8 *)x32; *flags &= ~SINGLESTEP_PCREL; *flags |= SINGLESTEP_BRANCH; } break; /* potential 3-byte conditional branches */ case 0xf8: next = pc + 3; opc = pc[1]; if (opc >= 0xe8 && opc <= 0xeb && (cond_table[regs->epsw & 0xf] & (1 << ((opc & 0xf) + 3))) ) { READ_BYTE(pc+2, &x8); next = pc + x8; *flags |= SINGLESTEP_BRANCH; } break; case 0xfa: if (pc[1] == 0xff) { /* CALLS (d16,PC) */ READ_WORD16(pc + 2, &x16); next = pc + x16; } else next = pc + 4; *flags |= SINGLESTEP_BRANCH; break; case 0xfc: x32 = 6; if (pc[1] == 0xff) { /* CALLS (d32,PC) */ READ_WORD32(pc + 2, &x32); } next = pc + x32; *flags |= SINGLESTEP_BRANCH; break; /* LXX (d8,PC) */ /* SETLB - loads the next four bytes into the LIR reg */ case 0xd0 ... 0xda: case 0xdb: panic("Can't singlestep Lxx/SETLB\n"); break; } } return (unsigned)next; }

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/* * set up out of place singlestep of some branching instructions */
static unsigned __kprobes singlestep_branch_setup(struct pt_regs *regs) { u8 opc, *pc, *sp, *next; next = NULL; pc = (u8 *) regs->pc; sp = (u8 *) (regs + 1); switch (pc[0]) { case 0xc0 ... 0xca: /* Bxx (d8,PC) */ case 0xcc: /* JMP (d16,PC) */ case 0xdc: /* JMP (d32,PC) */ case 0xf8: /* Bxx (d8,PC) 3-byte version */ /* don't really need to do anything except cause trap */ next = pc; break; case 0xcd: /* CALL (d16,PC) */ pc[1] = 5; pc[2] = 0; next = pc + 5; break; case 0xdd: /* CALL (d32,PC) */ pc[1] = 7; pc[2] = 0; pc[3] = 0; pc[4] = 0; next = pc + 7; break; case 0xde: /* RETF */ next = pc + 3; regs->mdr = (unsigned) next; break; case 0xdf: /* RET */ sp += pc[2]; next = pc + 3; *(unsigned *)sp = (unsigned) next; break; case 0xf0: next = pc + 2; opc = pc[1]; if (opc >= 0xf0 && opc <= 0xf3) { /* CALLS (An) */ /* use CALLS (d16,PC) to avoid mucking with An */ pc[0] = 0xfa; pc[1] = 0xff; pc[2] = 4; pc[3] = 0; next = pc + 4; } else if (opc >= 0xf4 && opc <= 0xf7) { /* JMP (An) */ next = pc; } else if (opc == 0xfc) { /* RETS */ next = pc + 2; *(unsigned *) sp = (unsigned) next; } else if (opc == 0xfd) { /* RTI */ next = pc + 2; *(unsigned *)(sp + 4) = (unsigned) next; } break; case 0xfa: /* CALLS (d16,PC) */ pc[2] = 4; pc[3] = 0; next = pc + 4; break; case 0xfc: /* CALLS (d32,PC) */ pc[2] = 6; pc[3] = 0; pc[4] = 0; pc[5] = 0; next = pc + 6; break; case 0xd0 ... 0xda: /* LXX (d8,PC) */ case 0xdb: /* SETLB */ panic("Can't singlestep Lxx/SETLB\n"); } return (unsigned) next; }

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int __kprobes arch_prepare_kprobe(struct kprobe *p) { return 0; }

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void __kprobes arch_copy_kprobe(struct kprobe *p) { memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE); }

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void __kprobes arch_arm_kprobe(struct kprobe *p) { *p->addr = BREAKPOINT_INSTRUCTION; flush_icache_range((unsigned long) p->addr, (unsigned long) p->addr + sizeof(kprobe_opcode_t)); }

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void __kprobes arch_disarm_kprobe(struct kprobe *p) { #ifndef CONFIG_MN10300_CACHE_SNOOP mn10300_dcache_flush(); mn10300_icache_inv(); #endif }

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void arch_remove_kprobe(struct kprobe *p) { }

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static inline void __kprobes disarm_kprobe(struct kprobe *p, struct pt_regs *regs) { *p->addr = p->opcode; regs->pc = (unsigned long) p->addr; #ifndef CONFIG_MN10300_CACHE_SNOOP mn10300_dcache_flush(); mn10300_icache_inv(); #endif }

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static inline void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) { unsigned long nextpc; cur_kprobe_orig_pc = regs->pc; memcpy(cur_kprobe_ss_buf, &p->ainsn.insn[0], MAX_INSN_SIZE); regs->pc = (unsigned long) cur_kprobe_ss_buf; nextpc = find_nextpc(regs, &cur_kprobe_ss_flags); if (cur_kprobe_ss_flags & SINGLESTEP_PCREL) cur_kprobe_next_pc = cur_kprobe_orig_pc + (nextpc - regs->pc); else cur_kprobe_next_pc = nextpc; /* branching instructions need special handling */ if (cur_kprobe_ss_flags & SINGLESTEP_BRANCH) nextpc = singlestep_branch_setup(regs); cur_kprobe_bp_addr = nextpc; *(u8 *) nextpc = BREAKPOINT_INSTRUCTION; mn10300_dcache_flush_range2((unsigned) cur_kprobe_ss_buf, sizeof(cur_kprobe_ss_buf)); mn10300_icache_inv(); }

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static inline int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; unsigned int *addr = (unsigned int *) regs->pc; /* We're in an interrupt, but this is clear and BUG()-safe. */ preempt_disable(); /* Check we're not actually recursing */ if (kprobe_running()) { /* We *are* holding lock here, so this is safe. Disarm the probe we just hit, and ignore it. */ p = get_kprobe(addr); if (p) { disarm_kprobe(p, regs); ret = 1; } else { p = cur_kprobe; if (p->break_handler && p->break_handler(p, regs)) goto ss_probe; } /* If it's not ours, can't be delete race, (we hold lock). */ goto no_kprobe; } p = get_kprobe(addr); if (!p) { if (*addr != BREAKPOINT_INSTRUCTION) { /* 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; } kprobe_status = KPROBE_HIT_ACTIVE; cur_kprobe = p; if (p->pre_handler(p, regs)) { /* handler has already set things up, so skip ss setup */ return 1; } ss_probe: prepare_singlestep(p, regs); kprobe_status = KPROBE_HIT_SS; return 1; no_kprobe: preempt_enable_no_resched(); return ret; }

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David Howells18298.91%150.00%
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/* * Called after single-stepping. p->addr is the address of the * instruction whose first byte has been replaced by the "breakpoint" * 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. */
static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs) { /* we may need to fixup regs/stack after singlestepping a call insn */ if (cur_kprobe_ss_flags & SINGLESTEP_BRANCH) { regs->pc = cur_kprobe_orig_pc; switch (p->ainsn.insn[0]) { case 0xcd: /* CALL (d16,PC) */ *(unsigned *) regs->sp = regs->mdr = regs->pc + 5; break; case 0xdd: /* CALL (d32,PC) */ /* fixup mdr and return address on stack */ *(unsigned *) regs->sp = regs->mdr = regs->pc + 7; break; case 0xf0: if (p->ainsn.insn[1] >= 0xf0 && p->ainsn.insn[1] <= 0xf3) { /* CALLS (An) */ /* fixup MDR and return address on stack */ regs->mdr = regs->pc + 2; *(unsigned *) regs->sp = regs->mdr; } break; case 0xfa: /* CALLS (d16,PC) */ /* fixup MDR and return address on stack */ *(unsigned *) regs->sp = regs->mdr = regs->pc + 4; break; case 0xfc: /* CALLS (d32,PC) */ /* fixup MDR and return address on stack */ *(unsigned *) regs->sp = regs->mdr = regs->pc + 6; break; } } regs->pc = cur_kprobe_next_pc; cur_kprobe_bp_addr = 0; }

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static inline int __kprobes post_kprobe_handler(struct pt_regs *regs) { if (!kprobe_running()) return 0; if (cur_kprobe->post_handler) cur_kprobe->post_handler(cur_kprobe, regs, 0); resume_execution(cur_kprobe, regs); reset_current_kprobe(); preempt_enable_no_resched(); return 1; }

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/* Interrupts disabled, kprobe_lock held. */
static inline int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) { if (cur_kprobe->fault_handler && cur_kprobe->fault_handler(cur_kprobe, regs, trapnr)) return 1; if (kprobe_status & KPROBE_HIT_SS) { resume_execution(cur_kprobe, regs); reset_current_kprobe(); preempt_enable_no_resched(); } return 0; }

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/* * Wrapper routine to for handling exceptions. */
int __kprobes kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data) { struct die_args *args = data; switch (val) { case DIE_BREAKPOINT: if (cur_kprobe_bp_addr != args->regs->pc) { if (kprobe_handler(args->regs)) return NOTIFY_STOP; } else { if (post_kprobe_handler(args->regs)) return NOTIFY_STOP; } break; case DIE_GPF: if (kprobe_running() && kprobe_fault_handler(args->regs, args->trapnr)) return NOTIFY_STOP; break; default: break; } return NOTIFY_DONE; }

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David Howells10299.03%150.00%
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/* Jprobes support. */ static struct pt_regs jprobe_saved_regs; static struct pt_regs *jprobe_saved_regs_location; static kprobe_opcode_t jprobe_saved_stack[MAX_STACK_SIZE];
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) { struct jprobe *jp = container_of(p, struct jprobe, kp); jprobe_saved_regs_location = regs; memcpy(&jprobe_saved_regs, regs, sizeof(struct pt_regs)); /* Save a whole stack frame, this gets arguments * pushed onto the stack after using up all the * arg registers. */ memcpy(&jprobe_saved_stack, regs + 1, sizeof(jprobe_saved_stack)); /* setup return addr to the jprobe handler routine */ regs->pc = (unsigned long) jp->entry; return 1; }

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void __kprobes jprobe_return(void) { void *orig_sp = jprobe_saved_regs_location + 1; preempt_enable_no_resched(); asm volatile(" mov %0,sp\n" ".globl jprobe_return_bp_addr\n" "jprobe_return_bp_addr:\n\t" " .byte 0xff\n" : : "d" (orig_sp)); }

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extern void jprobe_return_bp_addr(void);
int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) { u8 *addr = (u8 *) regs->pc; if (addr == (u8 *) jprobe_return_bp_addr) { if (jprobe_saved_regs_location != regs) { printk(KERN_ERR"JPROBE:" " Current regs (%p) does not match saved regs" " (%p).\n", regs, jprobe_saved_regs_location); BUG(); } /* Restore old register state. */ memcpy(regs, &jprobe_saved_regs, sizeof(struct pt_regs)); memcpy(regs + 1, &jprobe_saved_stack, sizeof(jprobe_saved_stack)); return 1; } return 0; }

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int __init arch_init_kprobes(void) { return 0; }

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