diff options
Diffstat (limited to 'arch/sh/kernel/kprobes.c')
| -rw-r--r-- | arch/sh/kernel/kprobes.c | 584 |
1 files changed, 584 insertions, 0 deletions
diff --git a/arch/sh/kernel/kprobes.c b/arch/sh/kernel/kprobes.c new file mode 100644 index 00000000000..c96850b061f --- /dev/null +++ b/arch/sh/kernel/kprobes.c @@ -0,0 +1,584 @@ +/* + * Kernel probes (kprobes) for SuperH + * + * Copyright (C) 2007 Chris Smith <chris.smith@st.com> + * Copyright (C) 2006 Lineo Solutions, Inc. + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + */ +#include <linux/kprobes.h> +#include <linux/module.h> +#include <linux/ptrace.h> +#include <linux/preempt.h> +#include <linux/kdebug.h> +#include <asm/cacheflush.h> +#include <asm/uaccess.h> + +DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; +DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); + +static struct kprobe saved_current_opcode; +static struct kprobe saved_next_opcode; +static struct kprobe saved_next_opcode2; + +#define OPCODE_JMP(x) (((x) & 0xF0FF) == 0x402b) +#define OPCODE_JSR(x) (((x) & 0xF0FF) == 0x400b) +#define OPCODE_BRA(x) (((x) & 0xF000) == 0xa000) +#define OPCODE_BRAF(x) (((x) & 0xF0FF) == 0x0023) +#define OPCODE_BSR(x) (((x) & 0xF000) == 0xb000) +#define OPCODE_BSRF(x) (((x) & 0xF0FF) == 0x0003) + +#define OPCODE_BF_S(x) (((x) & 0xFF00) == 0x8f00) +#define OPCODE_BT_S(x) (((x) & 0xFF00) == 0x8d00) + +#define OPCODE_BF(x) (((x) & 0xFF00) == 0x8b00) +#define OPCODE_BT(x) (((x) & 0xFF00) == 0x8900) + +#define OPCODE_RTS(x) (((x) & 0x000F) == 0x000b) +#define OPCODE_RTE(x) (((x) & 0xFFFF) == 0x002b) + +int __kprobes arch_prepare_kprobe(struct kprobe *p) +{ + kprobe_opcode_t opcode = *(kprobe_opcode_t *) (p->addr); + + if (OPCODE_RTE(opcode)) + return -EFAULT; /* Bad breakpoint */ + + p->opcode = opcode; + + return 0; +} + +void __kprobes arch_copy_kprobe(struct kprobe *p) +{ + memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); + p->opcode = *p->addr; +} + +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)); +} + +void __kprobes arch_disarm_kprobe(struct kprobe *p) +{ + *p->addr = p->opcode; + flush_icache_range((unsigned long)p->addr, + (unsigned long)p->addr + sizeof(kprobe_opcode_t)); +} + +int __kprobes arch_trampoline_kprobe(struct kprobe *p) +{ + if (*p->addr == BREAKPOINT_INSTRUCTION) + return 1; + + return 0; +} + +/** + * If an illegal slot instruction exception occurs for an address + * containing a kprobe, remove the probe. + * + * Returns 0 if the exception was handled successfully, 1 otherwise. + */ +int __kprobes kprobe_handle_illslot(unsigned long pc) +{ + struct kprobe *p = get_kprobe((kprobe_opcode_t *) pc + 1); + + if (p != NULL) { + printk("Warning: removing kprobe from delay slot: 0x%.8x\n", + (unsigned int)pc + 2); + unregister_kprobe(p); + return 0; + } + + return 1; +} + +void __kprobes arch_remove_kprobe(struct kprobe *p) +{ + if (saved_next_opcode.addr != 0x0) { + arch_disarm_kprobe(p); + arch_disarm_kprobe(&saved_next_opcode); + saved_next_opcode.addr = 0x0; + saved_next_opcode.opcode = 0x0; + + if (saved_next_opcode2.addr != 0x0) { + arch_disarm_kprobe(&saved_next_opcode2); + saved_next_opcode2.addr = 0x0; + saved_next_opcode2.opcode = 0x0; + } + } +} + +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) +{ + __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; + kcb->kprobe_status = kcb->prev_kprobe.status; +} + +static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + __get_cpu_var(current_kprobe) = p; +} + +/* + * Singlestep is implemented by disabling the current kprobe and setting one + * on the next instruction, following branches. Two probes are set if the + * branch is conditional. + */ +static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) +{ + kprobe_opcode_t *addr = NULL; + saved_current_opcode.addr = (kprobe_opcode_t *) (regs->pc); + addr = saved_current_opcode.addr; + + if (p != NULL) { + arch_disarm_kprobe(p); + + if (OPCODE_JSR(p->opcode) || OPCODE_JMP(p->opcode)) { + unsigned int reg_nr = ((p->opcode >> 8) & 0x000F); + saved_next_opcode.addr = + (kprobe_opcode_t *) regs->regs[reg_nr]; + } else if (OPCODE_BRA(p->opcode) || OPCODE_BSR(p->opcode)) { + unsigned long disp = (p->opcode & 0x0FFF); + saved_next_opcode.addr = + (kprobe_opcode_t *) (regs->pc + 4 + disp * 2); + + } else if (OPCODE_BRAF(p->opcode) || OPCODE_BSRF(p->opcode)) { + unsigned int reg_nr = ((p->opcode >> 8) & 0x000F); + saved_next_opcode.addr = + (kprobe_opcode_t *) (regs->pc + 4 + + regs->regs[reg_nr]); + + } else if (OPCODE_RTS(p->opcode)) { + saved_next_opcode.addr = (kprobe_opcode_t *) regs->pr; + + } else if (OPCODE_BF(p->opcode) || OPCODE_BT(p->opcode)) { + unsigned long disp = (p->opcode & 0x00FF); + /* case 1 */ + saved_next_opcode.addr = p->addr + 1; + /* case 2 */ + saved_next_opcode2.addr = + (kprobe_opcode_t *) (regs->pc + 4 + disp * 2); + saved_next_opcode2.opcode = *(saved_next_opcode2.addr); + arch_arm_kprobe(&saved_next_opcode2); + + } else if (OPCODE_BF_S(p->opcode) || OPCODE_BT_S(p->opcode)) { + unsigned long disp = (p->opcode & 0x00FF); + /* case 1 */ + saved_next_opcode.addr = p->addr + 2; + /* case 2 */ + saved_next_opcode2.addr = + (kprobe_opcode_t *) (regs->pc + 4 + disp * 2); + saved_next_opcode2.opcode = *(saved_next_opcode2.addr); + arch_arm_kprobe(&saved_next_opcode2); + + } else { + saved_next_opcode.addr = p->addr + 1; + } + + saved_next_opcode.opcode = *(saved_next_opcode.addr); + arch_arm_kprobe(&saved_next_opcode); + } +} + +/* Called with kretprobe_lock held */ +void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, + struct pt_regs *regs) +{ + ri->ret_addr = (kprobe_opcode_t *) regs->pr; + + /* Replace the return addr with trampoline addr */ + regs->pr = (unsigned long)kretprobe_trampoline; +} + +static int __kprobes kprobe_handler(struct pt_regs *regs) +{ + struct kprobe *p; + int ret = 0; + kprobe_opcode_t *addr = NULL; + struct kprobe_ctlblk *kcb; + + /* + * We don't want to be preempted for the entire + * duration of kprobe processing + */ + preempt_disable(); + kcb = get_kprobe_ctlblk(); + + addr = (kprobe_opcode_t *) (regs->pc); + + /* 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 == BREAKPOINT_INSTRUCTION) { + 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 { + 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) { + /* Not one of ours: let kernel handle it */ + if (*(kprobe_opcode_t *)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; + } + + 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; +} + +/* + * For function-return probes, init_kprobes() establishes a probepoint + * here. When a retprobed function returns, this probe is hit and + * trampoline_probe_handler() runs, calling the kretprobe's handler. + */ +static void __used kretprobe_trampoline_holder(void) +{ + asm volatile (".globl kretprobe_trampoline\n" + "kretprobe_trampoline:\n\t" + "nop\n"); +} + +/* + * Called when we hit the probe point at kretprobe_trampoline + */ +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 then 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) { + __get_cpu_var(current_kprobe) = &ri->rp->kp; + ri->rp->handler(ri, regs); + __get_cpu_var(current_kprobe) = NULL; + } + + 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); + + regs->pc = orig_ret_address; + 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); + } + + return orig_ret_address; +} + +static int __kprobes post_kprobe_handler(struct pt_regs *regs) +{ + struct kprobe *cur = kprobe_running(); + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + kprobe_opcode_t *addr = NULL; + struct kprobe *p = NULL; + + 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); + } + + if (saved_next_opcode.addr != 0x0) { + arch_disarm_kprobe(&saved_next_opcode); + saved_next_opcode.addr = 0x0; + saved_next_opcode.opcode = 0x0; + + addr = saved_current_opcode.addr; + saved_current_opcode.addr = 0x0; + + p = get_kprobe(addr); + arch_arm_kprobe(p); + + if (saved_next_opcode2.addr != 0x0) { + arch_disarm_kprobe(&saved_next_opcode2); + saved_next_opcode2.addr = 0x0; + saved_next_opcode2.opcode = 0x0; + } + } + + /* 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 __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) +{ + struct kprobe *cur = kprobe_running(); + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + const struct exception_table_entry *entry; + + 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, point the pc back to the probe address + * and allow the page fault handler to continue as a + * normal page fault. + */ + regs->pc = (unsigned long)cur->addr; + if (kcb->kprobe_status == KPROBE_REENTER) + restore_previous_kprobe(kcb); + else + reset_current_kprobe(); + preempt_enable_no_resched(); + break; + case KPROBE_HIT_ACTIVE: + case KPROBE_HIT_SSDONE: + /* + * We increment the nmissed count for accounting, + * we can also use npre/npostfault count for accounting + * these specific fault cases. + */ + kprobes_inc_nmissed_count(cur); + + /* + * We come here because instructions in the pre/post + * handler caused the page_fault, this could happen + * if handler tries to access user space by + * copy_from_user(), get_user() etc. Let the + * user-specified handler try to fix it first. + */ + if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) + return 1; + + /* + * In case the user-specified fault handler returned + * zero, try to fix up. + */ + if ((entry = search_exception_tables(regs->pc)) != NULL) { + regs->pc = entry->fixup; + return 1; + } + + /* + * fixup_exception() could not handle it, + * Let do_page_fault() fix it. + */ + break; + default: + break; + } + + return 0; +} + +/* + * Wrapper routine to for handling exceptions. + */ +int __kprobes kprobe_exceptions_notify(struct notifier_block *self, + unsigned long val, void *data) +{ + struct kprobe *p = NULL; + struct die_args *args = (struct die_args *)data; + int ret = NOTIFY_DONE; + kprobe_opcode_t *addr = NULL; + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + addr = (kprobe_opcode_t *) (args->regs->pc); + if (val == DIE_TRAP) { + if (!kprobe_running()) { + if (kprobe_handler(args->regs)) { + ret = NOTIFY_STOP; + } else { + /* Not a kprobe trap */ + ret = NOTIFY_DONE; + } + } else { + p = get_kprobe(addr); + if ((kcb->kprobe_status == KPROBE_HIT_SS) || + (kcb->kprobe_status == KPROBE_REENTER)) { + if (post_kprobe_handler(args->regs)) + ret = NOTIFY_STOP; + } else { + if (kprobe_handler(args->regs)) { + ret = NOTIFY_STOP; + } else { + p = __get_cpu_var(current_kprobe); + if (p->break_handler && + p->break_handler(p, args->regs)) + ret = NOTIFY_STOP; + } + } + } + } + + return ret; +} + +int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) +{ + struct jprobe *jp = container_of(p, struct jprobe, kp); + unsigned long addr; + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + kcb->jprobe_saved_regs = *regs; + kcb->jprobe_saved_r15 = regs->regs[15]; + addr = kcb->jprobe_saved_r15; + + /* + * TBD: As Linus pointed out, gcc assumes that the callee + * owns the argument space and could overwrite it, e.g. + * tailcall optimization. So, to be absolutely safe + * we also save and restore enough stack bytes to cover + * the argument area. + */ + memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr, + MIN_STACK_SIZE(addr)); + + regs->pc = (unsigned long)(jp->entry); + + return 1; +} + +void __kprobes jprobe_return(void) +{ + asm volatile ("trapa #0x3a\n\t" "jprobe_return_end:\n\t" "nop\n\t"); +} + +int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + unsigned long stack_addr = kcb->jprobe_saved_r15; + u8 *addr = (u8 *)regs->pc; + + if ((addr >= (u8 *)jprobe_return) && + (addr <= (u8 *)jprobe_return_end)) { + *regs = kcb->jprobe_saved_regs; + + memcpy((kprobe_opcode_t *)stack_addr, kcb->jprobes_stack, + MIN_STACK_SIZE(stack_addr)); + + kcb->kprobe_status = KPROBE_HIT_SS; + preempt_enable_no_resched(); + 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) +{ + saved_next_opcode.addr = 0x0; + saved_next_opcode.opcode = 0x0; + + saved_current_opcode.addr = 0x0; + saved_current_opcode.opcode = 0x0; + + saved_next_opcode2.addr = 0x0; + saved_next_opcode2.opcode = 0x0; + + return register_kprobe(&trampoline_p); +} |