[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes
I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Ananth N Mavinakayanahalli
Linus Torvalds
Родитель
e65845235c
Коммит
9a0e3a8683
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@ -37,16 +37,11 @@
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#include <asm/kdebug.h>
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#include <asm/desc.h>
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static struct kprobe *current_kprobe;
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static unsigned long kprobe_status, kprobe_old_eflags, kprobe_saved_eflags;
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static struct kprobe *kprobe_prev;
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static unsigned long kprobe_status_prev, kprobe_old_eflags_prev, kprobe_saved_eflags_prev;
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static struct pt_regs jprobe_saved_regs;
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static long *jprobe_saved_esp;
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/* copy of the kernel stack at the probe fire time */
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static kprobe_opcode_t jprobes_stack[MAX_STACK_SIZE];
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void jprobe_return_end(void);
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DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
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DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
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/*
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* returns non-zero if opcode modifies the interrupt flag.
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*/
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@ -91,29 +86,30 @@ void __kprobes arch_remove_kprobe(struct kprobe *p)
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{
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}
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static inline void save_previous_kprobe(void)
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static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
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{
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kprobe_prev = current_kprobe;
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kprobe_status_prev = kprobe_status;
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kprobe_old_eflags_prev = kprobe_old_eflags;
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kprobe_saved_eflags_prev = kprobe_saved_eflags;
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kcb->prev_kprobe.kp = kprobe_running();
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kcb->prev_kprobe.status = kcb->kprobe_status;
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kcb->prev_kprobe.old_eflags = kcb->kprobe_old_eflags;
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kcb->prev_kprobe.saved_eflags = kcb->kprobe_saved_eflags;
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}
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static inline void restore_previous_kprobe(void)
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static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
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{
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current_kprobe = kprobe_prev;
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kprobe_status = kprobe_status_prev;
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kprobe_old_eflags = kprobe_old_eflags_prev;
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kprobe_saved_eflags = kprobe_saved_eflags_prev;
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__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
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kcb->kprobe_status = kcb->prev_kprobe.status;
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kcb->kprobe_old_eflags = kcb->prev_kprobe.old_eflags;
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kcb->kprobe_saved_eflags = kcb->prev_kprobe.saved_eflags;
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}
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static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs)
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static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
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struct kprobe_ctlblk *kcb)
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{
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current_kprobe = p;
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kprobe_saved_eflags = kprobe_old_eflags
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__get_cpu_var(current_kprobe) = p;
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kcb->kprobe_saved_eflags = kcb->kprobe_old_eflags
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= (regs->eflags & (TF_MASK | IF_MASK));
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if (is_IF_modifier(p->opcode))
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kprobe_saved_eflags &= ~IF_MASK;
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kcb->kprobe_saved_eflags &= ~IF_MASK;
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}
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static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
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@ -157,6 +153,7 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
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int ret = 0;
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kprobe_opcode_t *addr = NULL;
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unsigned long *lp;
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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/* Check if the application is using LDT entry for its code segment and
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* calculate the address by reading the base address from the LDT entry.
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@ -175,10 +172,10 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
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Disarm the probe we just hit, and ignore it. */
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p = get_kprobe(addr);
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if (p) {
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if (kprobe_status == KPROBE_HIT_SS &&
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if (kcb->kprobe_status == KPROBE_HIT_SS &&
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*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
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regs->eflags &= ~TF_MASK;
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regs->eflags |= kprobe_saved_eflags;
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regs->eflags |= kcb->kprobe_saved_eflags;
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unlock_kprobes();
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goto no_kprobe;
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}
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@ -188,14 +185,14 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
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* just single step on the instruction of the new probe
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* without calling any user handlers.
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*/
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save_previous_kprobe();
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set_current_kprobe(p, regs);
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save_previous_kprobe(kcb);
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set_current_kprobe(p, regs, kcb);
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p->nmissed++;
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prepare_singlestep(p, regs);
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kprobe_status = KPROBE_REENTER;
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kcb->kprobe_status = KPROBE_REENTER;
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return 1;
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} else {
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p = current_kprobe;
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p = __get_cpu_var(current_kprobe);
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if (p->break_handler && p->break_handler(p, regs)) {
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goto ss_probe;
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}
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@ -235,8 +232,8 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
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* in post_kprobe_handler()
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*/
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preempt_disable();
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kprobe_status = KPROBE_HIT_ACTIVE;
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set_current_kprobe(p, regs);
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set_current_kprobe(p, regs, kcb);
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kcb->kprobe_status = KPROBE_HIT_ACTIVE;
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if (p->pre_handler && p->pre_handler(p, regs))
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/* handler has already set things up, so skip ss setup */
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@ -244,7 +241,7 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
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ss_probe:
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prepare_singlestep(p, regs);
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kprobe_status = KPROBE_HIT_SS;
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kcb->kprobe_status = KPROBE_HIT_SS;
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return 1;
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no_kprobe:
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@ -312,6 +309,7 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
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BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
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regs->eip = orig_ret_address;
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reset_current_kprobe();
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unlock_kprobes();
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preempt_enable_no_resched();
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@ -345,7 +343,8 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
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* that is atop the stack is the address following the copied instruction.
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* We need to make it the address following the original instruction.
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*/
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static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
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static void __kprobes resume_execution(struct kprobe *p,
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struct pt_regs *regs, struct kprobe_ctlblk *kcb)
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{
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unsigned long *tos = (unsigned long *)®s->esp;
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unsigned long next_eip = 0;
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@ -355,7 +354,7 @@ static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
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switch (p->ainsn.insn[0]) {
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case 0x9c: /* pushfl */
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*tos &= ~(TF_MASK | IF_MASK);
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*tos |= kprobe_old_eflags;
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*tos |= kcb->kprobe_old_eflags;
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break;
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case 0xc3: /* ret/lret */
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case 0xcb:
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@ -400,22 +399,26 @@ static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
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*/
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static inline int post_kprobe_handler(struct pt_regs *regs)
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{
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if (!kprobe_running())
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struct kprobe *cur = kprobe_running();
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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if (!cur)
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return 0;
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if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
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kprobe_status = KPROBE_HIT_SSDONE;
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current_kprobe->post_handler(current_kprobe, regs, 0);
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if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
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kcb->kprobe_status = KPROBE_HIT_SSDONE;
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cur->post_handler(cur, regs, 0);
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}
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resume_execution(current_kprobe, regs);
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regs->eflags |= kprobe_saved_eflags;
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resume_execution(cur, regs, kcb);
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regs->eflags |= kcb->kprobe_saved_eflags;
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/*Restore back the original saved kprobes variables and continue. */
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if (kprobe_status == KPROBE_REENTER) {
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restore_previous_kprobe();
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if (kcb->kprobe_status == KPROBE_REENTER) {
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restore_previous_kprobe(kcb);
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goto out;
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}
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reset_current_kprobe();
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unlock_kprobes();
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out:
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preempt_enable_no_resched();
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@ -434,14 +437,17 @@ out:
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/* Interrupts disabled, kprobe_lock held. */
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static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
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{
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if (current_kprobe->fault_handler
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&& current_kprobe->fault_handler(current_kprobe, regs, trapnr))
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struct kprobe *cur = kprobe_running();
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
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return 1;
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if (kprobe_status & KPROBE_HIT_SS) {
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resume_execution(current_kprobe, regs);
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regs->eflags |= kprobe_old_eflags;
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if (kcb->kprobe_status & KPROBE_HIT_SS) {
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resume_execution(cur, regs, kcb);
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regs->eflags |= kcb->kprobe_old_eflags;
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reset_current_kprobe();
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unlock_kprobes();
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preempt_enable_no_resched();
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}
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@ -484,10 +490,11 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
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{
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struct jprobe *jp = container_of(p, struct jprobe, kp);
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unsigned long addr;
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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jprobe_saved_regs = *regs;
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jprobe_saved_esp = ®s->esp;
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addr = (unsigned long)jprobe_saved_esp;
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kcb->jprobe_saved_regs = *regs;
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kcb->jprobe_saved_esp = ®s->esp;
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addr = (unsigned long)(kcb->jprobe_saved_esp);
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/*
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* TBD: As Linus pointed out, gcc assumes that the callee
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@ -496,7 +503,8 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
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* we also save and restore enough stack bytes to cover
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* the argument area.
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*/
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memcpy(jprobes_stack, (kprobe_opcode_t *) addr, MIN_STACK_SIZE(addr));
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memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr,
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MIN_STACK_SIZE(addr));
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regs->eflags &= ~IF_MASK;
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regs->eip = (unsigned long)(jp->entry);
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return 1;
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@ -504,34 +512,38 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
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void __kprobes jprobe_return(void)
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{
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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asm volatile (" xchgl %%ebx,%%esp \n"
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" int3 \n"
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" .globl jprobe_return_end \n"
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" jprobe_return_end: \n"
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" nop \n"::"b"
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(jprobe_saved_esp):"memory");
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(kcb->jprobe_saved_esp):"memory");
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}
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int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
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{
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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u8 *addr = (u8 *) (regs->eip - 1);
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unsigned long stack_addr = (unsigned long)jprobe_saved_esp;
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unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_esp);
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struct jprobe *jp = container_of(p, struct jprobe, kp);
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if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) {
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if (®s->esp != jprobe_saved_esp) {
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if (®s->esp != kcb->jprobe_saved_esp) {
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struct pt_regs *saved_regs =
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container_of(jprobe_saved_esp, struct pt_regs, esp);
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container_of(kcb->jprobe_saved_esp,
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struct pt_regs, esp);
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printk("current esp %p does not match saved esp %p\n",
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®s->esp, jprobe_saved_esp);
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®s->esp, kcb->jprobe_saved_esp);
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printk("Saved registers for jprobe %p\n", jp);
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show_registers(saved_regs);
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printk("Current registers\n");
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show_registers(regs);
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BUG();
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}
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*regs = jprobe_saved_regs;
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memcpy((kprobe_opcode_t *) stack_addr, jprobes_stack,
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*regs = kcb->jprobe_saved_regs;
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memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
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MIN_STACK_SIZE(stack_addr));
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return 1;
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}
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@ -49,6 +49,23 @@ struct arch_specific_insn {
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kprobe_opcode_t insn[MAX_INSN_SIZE];
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};
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struct prev_kprobe {
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struct kprobe *kp;
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unsigned long status;
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unsigned long old_eflags;
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unsigned long saved_eflags;
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};
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/* per-cpu kprobe control block */
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struct kprobe_ctlblk {
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unsigned long kprobe_status;
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unsigned long kprobe_old_eflags;
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unsigned long kprobe_saved_eflags;
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long *jprobe_saved_esp;
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struct pt_regs jprobe_saved_regs;
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kprobe_opcode_t jprobes_stack[MAX_STACK_SIZE];
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struct prev_kprobe prev_kprobe;
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};
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/* trap3/1 are intr gates for kprobes. So, restore the status of IF,
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* if necessary, before executing the original int3/1 (trap) handler.
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