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[PATCH] kprobes: Temporary disarming of reentrant probe for x86_64

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This patch includes x86_64 architecture specific changes to support temporary
disarming on reentrancy of probes.

Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Prasanna S Panchamukhi 2005-06-23 00:09:37 -07:00 committed by Linus Torvalds
parent 417c8da651
commit aa3d7e3d78
1 changed files with 62 additions and 14 deletions
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76
arch/x86_64/kernel/kprobes.c
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@ -45,12 +45,10 @@
static DECLARE_MUTEX(kprobe_mutex);
/* kprobe_status settings */
#define KPROBE_HIT_ACTIVE 0x00000001
#define KPROBE_HIT_SS 0x00000002
static struct kprobe *current_kprobe;
static unsigned long kprobe_status, kprobe_old_rflags, kprobe_saved_rflags;
static struct kprobe *kprobe_prev;
static unsigned long kprobe_status_prev, kprobe_old_rflags_prev, kprobe_saved_rflags_prev;
static struct pt_regs jprobe_saved_regs;
static long *jprobe_saved_rsp;
static kprobe_opcode_t *get_insn_slot(void);
@ -240,6 +238,31 @@ void arch_remove_kprobe(struct kprobe *p)
down(&kprobe_mutex);
}
static inline void save_previous_kprobe(void)
{
kprobe_prev = current_kprobe;
kprobe_status_prev = kprobe_status;
kprobe_old_rflags_prev = kprobe_old_rflags;
kprobe_saved_rflags_prev = kprobe_saved_rflags;
}
static inline void restore_previous_kprobe(void)
{
current_kprobe = kprobe_prev;
kprobe_status = kprobe_status_prev;
kprobe_old_rflags = kprobe_old_rflags_prev;
kprobe_saved_rflags = kprobe_saved_rflags_prev;
}
static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs)
{
current_kprobe = p;
kprobe_saved_rflags = kprobe_old_rflags
= (regs->eflags & (TF_MASK | IF_MASK));
if (is_IF_modifier(p->ainsn.insn))
kprobe_saved_rflags &= ~IF_MASK;
}
static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
{
regs->eflags |= TF_MASK;
@ -319,10 +342,30 @@ int kprobe_handler(struct pt_regs *regs)
regs->eflags |= kprobe_saved_rflags;
unlock_kprobes();
goto no_kprobe;
} else if (kprobe_status == KPROBE_HIT_SSDONE) {
/* TODO: Provide re-entrancy from
* post_kprobes_handler() and avoid exception
* stack corruption while single-stepping on
* the instruction of the new probe.
*/
arch_disarm_kprobe(p);
regs->rip = (unsigned long)p->addr;
ret = 1;
} else {
/* We have reentered the kprobe_handler(), since
* another probe was hit while within the
* handler. We here save the original kprobe
* variables and just single step on instruction
* of the new probe without calling any user
* handlers.
*/
save_previous_kprobe();
set_current_kprobe(p, regs);
p->nmissed++;
prepare_singlestep(p, regs);
kprobe_status = KPROBE_REENTER;
return 1;
}
arch_disarm_kprobe(p);
regs->rip = (unsigned long)p->addr;
ret = 1;
} else {
p = current_kprobe;
if (p->break_handler && p->break_handler(p, regs)) {
@ -352,11 +395,7 @@ int kprobe_handler(struct pt_regs *regs)
}
kprobe_status = KPROBE_HIT_ACTIVE;
current_kprobe = p;
kprobe_saved_rflags = kprobe_old_rflags
= (regs->eflags & (TF_MASK | IF_MASK));
if (is_IF_modifier(p->ainsn.insn))
kprobe_saved_rflags &= ~IF_MASK;
set_current_kprobe(p, regs);
if (p->pre_handler && p->pre_handler(p, regs))
/* handler has already set things up, so skip ss setup */
@ -506,14 +545,23 @@ int post_kprobe_handler(struct pt_regs *regs)
if (!kprobe_running())
return 0;
if (current_kprobe->post_handler)
if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
kprobe_status = KPROBE_HIT_SSDONE;
current_kprobe->post_handler(current_kprobe, regs, 0);
}
if (current_kprobe->post_handler != trampoline_post_handler)
resume_execution(current_kprobe, regs);
regs->eflags |= kprobe_saved_rflags;
unlock_kprobes();
/* Restore the original saved kprobes variables and continue. */
if (kprobe_status == KPROBE_REENTER) {
restore_previous_kprobe();
goto out;
} else {
unlock_kprobes();
}
out:
preempt_enable_no_resched();
/*