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[PATCH] kprobes: Temporary disarming of reentrant probe for i386

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This patch includes i386 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 ea32c65cc2
commit 417c8da651
1 changed files with 49 additions and 13 deletions
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62
arch/i386/kernel/kprobes.c
View file

@ -37,12 +37,10 @@
#include <asm/kdebug.h> #include <asm/kdebug.h>
#include <asm/desc.h> #include <asm/desc.h>
/* kprobe_status settings */
#define KPROBE_HIT_ACTIVE 0x00000001
#define KPROBE_HIT_SS 0x00000002
static struct kprobe *current_kprobe; static struct kprobe *current_kprobe;
static unsigned long kprobe_status, kprobe_old_eflags, kprobe_saved_eflags; static unsigned long kprobe_status, kprobe_old_eflags, kprobe_saved_eflags;
static struct kprobe *kprobe_prev;
static unsigned long kprobe_status_prev, kprobe_old_eflags_prev, kprobe_saved_eflags_prev;
static struct pt_regs jprobe_saved_regs; static struct pt_regs jprobe_saved_regs;
static long *jprobe_saved_esp; static long *jprobe_saved_esp;
/* copy of the kernel stack at the probe fire time */ /* copy of the kernel stack at the probe fire time */
@ -93,6 +91,31 @@ void arch_remove_kprobe(struct kprobe *p)
{ {
} }
static inline void save_previous_kprobe(void)
{
kprobe_prev = current_kprobe;
kprobe_status_prev = kprobe_status;
kprobe_old_eflags_prev = kprobe_old_eflags;
kprobe_saved_eflags_prev = kprobe_saved_eflags;
}
static inline void restore_previous_kprobe(void)
{
current_kprobe = kprobe_prev;
kprobe_status = kprobe_status_prev;
kprobe_old_eflags = kprobe_old_eflags_prev;
kprobe_saved_eflags = kprobe_saved_eflags_prev;
}
static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs)
{
current_kprobe = p;
kprobe_saved_eflags = kprobe_old_eflags
= (regs->eflags & (TF_MASK | IF_MASK));
if (is_IF_modifier(p->opcode))
kprobe_saved_eflags &= ~IF_MASK;
}
static inline void 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 |= TF_MASK;
@ -184,9 +207,18 @@ static int kprobe_handler(struct pt_regs *regs)
unlock_kprobes(); unlock_kprobes();
goto no_kprobe; goto no_kprobe;
} }
arch_disarm_kprobe(p); /* We have reentered the kprobe_handler(), since
regs->eip = (unsigned long)p->addr; * another probe was hit while within the handler.
ret = 1; * 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();
set_current_kprobe(p, regs);
p->nmissed++;
prepare_singlestep(p, regs);
kprobe_status = KPROBE_REENTER;
return 1;
} else { } else {
p = current_kprobe; p = current_kprobe;
if (p->break_handler && p->break_handler(p, regs)) { if (p->break_handler && p->break_handler(p, regs)) {
@ -221,11 +253,7 @@ static int kprobe_handler(struct pt_regs *regs)
} }
kprobe_status = KPROBE_HIT_ACTIVE; kprobe_status = KPROBE_HIT_ACTIVE;
current_kprobe = p; set_current_kprobe(p, regs);
kprobe_saved_eflags = kprobe_old_eflags
= (regs->eflags & (TF_MASK | IF_MASK));
if (is_IF_modifier(p->opcode))
kprobe_saved_eflags &= ~IF_MASK;
if (p->pre_handler && p->pre_handler(p, regs)) if (p->pre_handler && p->pre_handler(p, regs))
/* handler has already set things up, so skip ss setup */ /* handler has already set things up, so skip ss setup */
@ -370,14 +398,22 @@ static inline int post_kprobe_handler(struct pt_regs *regs)
if (!kprobe_running()) if (!kprobe_running())
return 0; 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); current_kprobe->post_handler(current_kprobe, regs, 0);
}
if (current_kprobe->post_handler != trampoline_post_handler) if (current_kprobe->post_handler != trampoline_post_handler)
resume_execution(current_kprobe, regs); resume_execution(current_kprobe, regs);
regs->eflags |= kprobe_saved_eflags; regs->eflags |= kprobe_saved_eflags;
/*Restore back the original saved kprobes variables and continue. */
if (kprobe_status == KPROBE_REENTER) {
restore_previous_kprobe();
goto out;
}
unlock_kprobes(); unlock_kprobes();
out:
preempt_enable_no_resched(); preempt_enable_no_resched();
/* /*