* <prasanna@in.ibm.com> added function-return probes.
*/
+#include <linux/config.h>
#include <linux/kprobes.h>
#include <linux/ptrace.h>
#include <linux/preempt.h>
#include <asm/cacheflush.h>
#include <asm/kdebug.h>
#include <asm/desc.h>
-#include <asm/uaccess.h>
void jprobe_return_end(void);
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
-/* insert a jmp code */
-static __always_inline void set_jmp_op(void *from, void *to)
-{
- struct __arch_jmp_op {
- char op;
- long raddr;
- } __attribute__((packed)) *jop;
- jop = (struct __arch_jmp_op *)from;
- jop->raddr = (long)(to) - ((long)(from) + 5);
- jop->op = RELATIVEJUMP_INSTRUCTION;
-}
-
-/*
- * returns non-zero if opcodes can be boosted.
- */
-static __always_inline int can_boost(kprobe_opcode_t *opcodes)
-{
-#define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \
- (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \
- (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \
- (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \
- (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \
- << (row % 32))
- /*
- * Undefined/reserved opcodes, conditional jump, Opcode Extension
- * Groups, and some special opcodes can not be boost.
- */
- static const unsigned long twobyte_is_boostable[256 / 32] = {
- /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
- /* ------------------------------- */
- W(0x00, 0,0,1,1,0,0,1,0,1,1,0,0,0,0,0,0)| /* 00 */
- W(0x10, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 10 */
- W(0x20, 1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0)| /* 20 */
- W(0x30, 0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 30 */
- W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 40 */
- W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 50 */
- W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,0,0,1,1)| /* 60 */
- W(0x70, 0,0,0,0,1,1,1,1,0,0,0,0,0,0,1,1), /* 70 */
- W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 80 */
- W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1), /* 90 */
- W(0xa0, 1,1,0,1,1,1,0,0,1,1,0,1,1,1,0,1)| /* a0 */
- W(0xb0, 1,1,1,1,1,1,1,1,0,0,0,1,1,1,1,1), /* b0 */
- W(0xc0, 1,1,0,0,0,0,0,0,1,1,1,1,1,1,1,1)| /* c0 */
- W(0xd0, 0,1,1,1,0,1,0,0,1,1,0,1,1,1,0,1), /* d0 */
- W(0xe0, 0,1,1,0,0,1,0,0,1,1,0,1,1,1,0,1)| /* e0 */
- W(0xf0, 0,1,1,1,0,1,0,0,1,1,1,0,1,1,1,0) /* f0 */
- /* ------------------------------- */
- /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
- };
-#undef W
- kprobe_opcode_t opcode;
- kprobe_opcode_t *orig_opcodes = opcodes;
-retry:
- if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
- return 0;
- opcode = *(opcodes++);
-
- /* 2nd-byte opcode */
- if (opcode == 0x0f) {
- if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
- return 0;
- return test_bit(*opcodes, twobyte_is_boostable);
- }
-
- switch (opcode & 0xf0) {
- case 0x60:
- if (0x63 < opcode && opcode < 0x67)
- goto retry; /* prefixes */
- /* can't boost Address-size override and bound */
- return (opcode != 0x62 && opcode != 0x67);
- case 0x70:
- return 0; /* can't boost conditional jump */
- case 0xc0:
- /* can't boost software-interruptions */
- return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf;
- case 0xd0:
- /* can boost AA* and XLAT */
- return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7);
- case 0xe0:
- /* can boost in/out and absolute jmps */
- return ((opcode & 0x04) || opcode == 0xea);
- case 0xf0:
- if ((opcode & 0x0c) == 0 && opcode != 0xf1)
- goto retry; /* lock/rep(ne) prefix */
- /* clear and set flags can be boost */
- return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));
- default:
- if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e)
- goto retry; /* prefixes */
- /* can't boost CS override and call */
- return (opcode != 0x2e && opcode != 0x9a);
- }
-}
-
/*
* returns non-zero if opcode modifies the interrupt flag.
*/
-static int __kprobes is_IF_modifier(kprobe_opcode_t opcode)
+static inline int is_IF_modifier(kprobe_opcode_t opcode)
{
switch (opcode) {
case 0xfa: /* cli */
memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
p->opcode = *p->addr;
- if (can_boost(p->addr)) {
- p->ainsn.boostable = 0;
- } else {
- p->ainsn.boostable = -1;
- }
return 0;
}
void __kprobes arch_remove_kprobe(struct kprobe *p)
{
- mutex_lock(&kprobe_mutex);
+ down(&kprobe_mutex);
free_insn_slot(p->ainsn.insn);
- mutex_unlock(&kprobe_mutex);
+ up(&kprobe_mutex);
}
-static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
+static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
{
kcb->prev_kprobe.kp = kprobe_running();
kcb->prev_kprobe.status = kcb->kprobe_status;
kcb->prev_kprobe.saved_eflags = kcb->kprobe_saved_eflags;
}
-static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
+static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
{
__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
kcb->kprobe_status = kcb->prev_kprobe.status;
kcb->kprobe_saved_eflags = kcb->prev_kprobe.saved_eflags;
}
-static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
struct kprobe_ctlblk *kcb)
{
__get_cpu_var(current_kprobe) = p;
kcb->kprobe_saved_eflags &= ~IF_MASK;
}
-static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
{
regs->eflags |= TF_MASK;
regs->eflags &= ~IF_MASK;
{
struct kprobe *p;
int ret = 0;
- kprobe_opcode_t *addr;
+ kprobe_opcode_t *addr = NULL;
+ unsigned long *lp;
struct kprobe_ctlblk *kcb;
- addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
-
/*
* We don't want to be preempted for the entire
* duration of kprobe processing
preempt_disable();
kcb = get_kprobe_ctlblk();
+ /* Check if the application is using LDT entry for its code segment and
+ * calculate the address by reading the base address from the LDT entry.
+ */
+ if ((regs->xcs & 4) && (current->mm)) {
+ lp = (unsigned long *) ((unsigned long)((regs->xcs >> 3) * 8)
+ + (char *) current->mm->context.ldt);
+ addr = (kprobe_opcode_t *) (get_desc_base(lp) + regs->eip -
+ sizeof(kprobe_opcode_t));
+ } else {
+ addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
+ }
/* Check we're not actually recursing */
if (kprobe_running()) {
p = get_kprobe(addr);
kcb->kprobe_status = KPROBE_REENTER;
return 1;
} else {
+ if (regs->eflags & VM_MASK) {
+ /* We are in virtual-8086 mode. Return 0 */
+ goto no_kprobe;
+ }
if (*addr != BREAKPOINT_INSTRUCTION) {
/* The breakpoint instruction was removed by
* another cpu right after we hit, no further
p = get_kprobe(addr);
if (!p) {
+ if (regs->eflags & VM_MASK) {
+ /* We are in virtual-8086 mode. Return 0 */
+ goto no_kprobe;
+ }
+
if (*addr != BREAKPOINT_INSTRUCTION) {
/*
* The breakpoint instruction was removed right
return 1;
ss_probe:
-#ifndef CONFIG_PREEMPT
- if (p->ainsn.boostable == 1 && !p->post_handler){
- /* Boost up -- we can execute copied instructions directly */
- reset_current_kprobe();
- regs->eip = (unsigned long)p->ainsn.insn;
- preempt_enable_no_resched();
- return 1;
- }
-#endif
prepare_singlestep(p, regs);
kcb->kprobe_status = KPROBE_HIT_SS;
return 1;
* here. When a retprobed function returns, this probe is hit and
* trampoline_probe_handler() runs, calling the kretprobe's handler.
*/
- void __kprobes kretprobe_trampoline_holder(void)
+ void kretprobe_trampoline_holder(void)
{
- asm volatile ( ".global kretprobe_trampoline\n"
+ asm volatile ( ".global kretprobe_trampoline\n"
"kretprobe_trampoline: \n"
- " pushf\n"
- /* skip cs, eip, orig_eax, es, ds */
- " subl $20, %esp\n"
- " pushl %eax\n"
- " pushl %ebp\n"
- " pushl %edi\n"
- " pushl %esi\n"
- " pushl %edx\n"
- " pushl %ecx\n"
- " pushl %ebx\n"
- " movl %esp, %eax\n"
- " call trampoline_handler\n"
- /* move eflags to cs */
- " movl 48(%esp), %edx\n"
- " movl %edx, 44(%esp)\n"
- /* save true return address on eflags */
- " movl %eax, 48(%esp)\n"
- " popl %ebx\n"
- " popl %ecx\n"
- " popl %edx\n"
- " popl %esi\n"
- " popl %edi\n"
- " popl %ebp\n"
- " popl %eax\n"
- /* skip eip, orig_eax, es, ds */
- " addl $16, %esp\n"
- " popf\n"
- " ret\n");
-}
+ "nop\n");
+ }
/*
- * Called from kretprobe_trampoline
+ * Called when we hit the probe point at kretprobe_trampoline
*/
-fastcall void *__kprobes trampoline_handler(struct pt_regs *regs)
+int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
{
struct kretprobe_instance *ri = NULL;
struct hlist_head *head;
/* another task is sharing our hash bucket */
continue;
- if (ri->rp && ri->rp->handler){
- __get_cpu_var(current_kprobe) = &ri->rp->kp;
+ if (ri->rp && ri->rp->handler)
ri->rp->handler(ri, regs);
- __get_cpu_var(current_kprobe) = NULL;
- }
orig_ret_address = (unsigned long)ri->ret_addr;
recycle_rp_inst(ri);
}
BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
+ regs->eip = orig_ret_address;
+ reset_current_kprobe();
spin_unlock_irqrestore(&kretprobe_lock, flags);
+ preempt_enable_no_resched();
- return (void*)orig_ret_address;
+ /*
+ * 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;
}
/*
* 2) If the single-stepped instruction was a call, the return address
* that is atop the stack is the address following the copied instruction.
* We need to make it the address following the original instruction.
- *
- * This function also checks instruction size for preparing direct execution.
*/
static void __kprobes resume_execution(struct kprobe *p,
struct pt_regs *regs, struct kprobe_ctlblk *kcb)
{
unsigned long *tos = (unsigned long *)®s->esp;
+ unsigned long next_eip = 0;
unsigned long copy_eip = (unsigned long)p->ainsn.insn;
unsigned long orig_eip = (unsigned long)p->addr;
- regs->eflags &= ~TF_MASK;
switch (p->ainsn.insn[0]) {
case 0x9c: /* pushfl */
*tos &= ~(TF_MASK | IF_MASK);
*tos |= kcb->kprobe_old_eflags;
break;
- case 0xc2: /* iret/ret/lret */
- case 0xc3:
- case 0xca:
+ case 0xc3: /* ret/lret */
case 0xcb:
- case 0xcf:
- case 0xea: /* jmp absolute -- eip is correct */
- /* eip is already adjusted, no more changes required */
- p->ainsn.boostable = 1;
- goto no_change;
+ case 0xc2:
+ case 0xca:
+ regs->eflags &= ~TF_MASK;
+ /* eip is already adjusted, no more changes required*/
+ return;
case 0xe8: /* call relative - Fix return addr */
*tos = orig_eip + (*tos - copy_eip);
break;
- case 0x9a: /* call absolute -- same as call absolute, indirect */
- *tos = orig_eip + (*tos - copy_eip);
- goto no_change;
case 0xff:
if ((p->ainsn.insn[1] & 0x30) == 0x10) {
- /*
- * call absolute, indirect
- * Fix return addr; eip is correct.
- * But this is not boostable
- */
+ /* call absolute, indirect */
+ /* Fix return addr; eip is correct. */
+ next_eip = regs->eip;
*tos = orig_eip + (*tos - copy_eip);
- goto no_change;
} else if (((p->ainsn.insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */
((p->ainsn.insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */
- /* eip is correct. And this is boostable */
- p->ainsn.boostable = 1;
- goto no_change;
+ /* eip is correct. */
+ next_eip = regs->eip;
}
+ break;
+ case 0xea: /* jmp absolute -- eip is correct */
+ next_eip = regs->eip;
+ break;
default:
break;
}
- if (p->ainsn.boostable == 0) {
- if ((regs->eip > copy_eip) &&
- (regs->eip - copy_eip) + 5 < MAX_INSN_SIZE) {
- /*
- * These instructions can be executed directly if it
- * jumps back to correct address.
- */
- set_jmp_op((void *)regs->eip,
- (void *)orig_eip + (regs->eip - copy_eip));
- p->ainsn.boostable = 1;
- } else {
- p->ainsn.boostable = -1;
- }
+ regs->eflags &= ~TF_MASK;
+ if (next_eip) {
+ regs->eip = next_eip;
+ } else {
+ regs->eip = orig_eip + (regs->eip - copy_eip);
}
-
- regs->eip = orig_eip + (regs->eip - copy_eip);
-
-no_change:
- return;
}
/*
* Interrupts are disabled on entry as trap1 is an interrupt gate and they
* remain disabled thoroughout this function.
*/
-static int __kprobes post_kprobe_handler(struct pt_regs *regs)
+static inline int post_kprobe_handler(struct pt_regs *regs)
{
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
return 1;
}
-static int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+static inline int kprobe_fault_handler(struct pt_regs *regs, 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 eip points back to the probe address
- * and allow the page fault handler to continue as a
- * normal page fault.
- */
- regs->eip = (unsigned long)cur->addr;
- regs->eflags |= kcb->kprobe_old_eflags;
- 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 accouting
- * 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;
+ 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 (fixup_exception(regs))
- return 1;
+ if (kcb->kprobe_status & KPROBE_HIT_SS) {
+ resume_execution(cur, regs, kcb);
+ regs->eflags |= kcb->kprobe_old_eflags;
- /*
- * fixup_exception() could not handle it,
- * Let do_page_fault() fix it.
- */
- break;
- default:
- break;
+ reset_current_kprobe();
+ preempt_enable_no_resched();
}
return 0;
}
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
- if (args->regs && user_mode_vm(args->regs))
- return ret;
-
switch (val) {
case DIE_INT3:
if (kprobe_handler(args->regs))
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 0;
+ return register_kprobe(&trampoline_p);
}
git://git.onelab.eu / linux-2.6.git / blobdiff