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[RFC][PATCH] PPC64: return address probes
- From: Ananth N Mavinakayanahalli <amavin at redhat dot com>
- To: systemtap at sources dot redhat dot com
- Date: Fri, 20 May 2005 08:15:55 -0400
- Subject: [RFC][PATCH] PPC64: return address probes
Hi,
Here is the return address probes prototype for ppc64. This patch
applies on 2.6.12-rc4-mm2 + Rusty's arch_break_inst.patch and Hien's
kprobe_flush.patch.
The stack pointer and return address are disjoint on ppc64. Hence I had
to introduce struct arch_retaddr (instead of having a #ifdef in
include/linux/kprobes.h).
This patch is tested on Power3 uni, Power4 smp. Compile tested for x86,
x86_64 and sparc64.
Comments welcome!
Ananth
Signed-off-by: Ananth N Mavinakayanahalli <amavin@redhat.com>
arch/ppc64/kernel/kprobes.c | 95 +++++++++++++++++++++++++++++++++++++++---
arch/ppc64/kernel/process.c | 7 +++
include/asm-i386/kprobes.h | 3 +
include/asm-ppc64/kprobes.h | 8 +++
include/asm-sparc64/kprobes.h | 3 +
include/asm-x86_64/kprobes.h | 3 +
include/linux/kprobes.h | 4 -
7 files changed, 116 insertions(+), 7 deletions(-)
Index: linux-2.6.12-rc4/arch/ppc64/kernel/kprobes.c
===================================================================
--- linux-2.6.12-rc4.orig/arch/ppc64/kernel/kprobes.c 2005-05-19 08:34:43.000000000 -0400
+++ linux-2.6.12-rc4/arch/ppc64/kernel/kprobes.c 2005-05-19 18:04:16.000000000 -0400
@@ -88,6 +88,45 @@ static inline void prepare_singlestep(st
regs->nip = (unsigned long)&p->ainsn.insn;
}
+struct task_struct *arch_get_kprobe_task(void *ptr)
+{
+ return ((struct thread_info *)(((unsigned long)ptr) &
+ (~(1 << THREAD_SHIFT) - 1)))->task;
+}
+
+void arch_kprobe_flush_task(struct task_struct *tk)
+{
+ struct kretprobe_instance *ri;
+
+ while ((ri = get_rp_inst_tsk(tk)) != NULL) {
+ *(ri->arch_retaddr.linkreg_ptr) = (unsigned long)ri->ret_addr;
+ recycle_rp_inst(ri);
+ }
+}
+
+void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs)
+{
+ struct kretprobe_instance *ri;
+ static void *orig_ret_addr;
+
+ /* Save the return address when this hits the first time */
+ if (regs->link != (unsigned long)kretprobe_trampoline)
+ orig_ret_addr = (void *)regs->link;
+
+ if ((ri = get_free_rp_inst(rp)) != NULL) {
+ ri->rp = rp;
+ ri->stack_addr = (void *)regs->gpr[1];
+ ri->ret_addr = orig_ret_addr;
+ ri->arch_retaddr.linkreg_ptr =
+ (kprobe_opcode_t *)®s->link;
+ add_rp_inst(ri);
+ /* Replace original return address with trampoline address */
+ regs->link = (unsigned long)kretprobe_trampoline;
+ } else {
+ rp->nmissed++;
+ }
+}
+
static inline int kprobe_handler(struct pt_regs *regs)
{
struct kprobe *p;
@@ -168,6 +207,51 @@ no_kprobe:
}
/*
+ * Function return probe trampoline:
+ * - init_kprobes() establishes a probepoint here
+ * - When the probed function returns, this probe
+ * causes the trampoline handlers to fire
+ */
+void kretprobe_trampoline_holder(void)
+{
+ asm volatile(".global kretprobe_trampoline\n"
+ "kretprobe_trampoline:\n"
+ "nop\n");
+}
+
+/*
+ * Called when the probe at kretprobe_trampoline is hit
+ */
+int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ struct task_struct *tsk;
+ struct kretprobe_instance *ri;
+ struct hlist_head *head;
+ struct hlist_node *node;
+
+ tsk = arch_get_kprobe_task((void *)regs->gpr[1]);
+ head = kretprobe_inst_table_head(tsk);
+ hlist_for_each_entry(ri, node, head, hlist) {
+ if ((ri->stack_addr == (void *)regs->gpr[1]) && ri->rp) {
+ if (ri->rp->handler)
+ ri->rp->handler(ri, regs);
+ }
+ }
+ return 0;
+}
+
+void trampoline_post_handler(struct kprobe *p, struct pt_regs *regs,
+ unsigned long flags)
+{
+ struct kretprobe_instance *ri;
+
+ while ((ri = get_rp_inst((void *)regs->gpr[1]))) {
+ regs->nip = (unsigned long)ri->ret_addr;
+ recycle_rp_inst(ri);
+ }
+}
+
+/*
* Called after single-stepping. p->addr is the address of the
* instruction whose first byte has been replaced by the "breakpoint"
* instruction. To avoid the SMP problems that can occur when we
@@ -183,8 +267,6 @@ static void resume_execution(struct kpro
ret = emulate_step(regs, p->ainsn.insn[0]);
if (ret == 0)
regs->nip = (unsigned long)p->addr + 4;
-
- regs->msr &= ~MSR_SE;
}
static inline int post_kprobe_handler(struct pt_regs *regs)
@@ -195,9 +277,10 @@ static inline int post_kprobe_handler(st
if (current_kprobe->post_handler)
current_kprobe->post_handler(current_kprobe, regs, 0);
- resume_execution(current_kprobe, regs);
- regs->msr |= kprobe_saved_msr;
+ if (current_kprobe->post_handler != trampoline_post_handler)
+ resume_execution(current_kprobe, regs);
+ regs->msr |= kprobe_saved_msr;
unlock_kprobes();
preempt_enable_no_resched();
@@ -212,7 +295,7 @@ static inline int post_kprobe_handler(st
return 1;
}
-/* Interrupts disabled, kprobe_lock held. */
+/* kprobe_lock held. */
static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
{
if (current_kprobe->fault_handler
@@ -221,6 +304,7 @@ static inline int kprobe_fault_handler(s
if (kprobe_status & KPROBE_HIT_SS) {
resume_execution(current_kprobe, regs);
+ regs->msr &= ~MSR_SE;
regs->msr |= kprobe_saved_msr;
unlock_kprobes();
Index: linux-2.6.12-rc4/arch/ppc64/kernel/process.c
===================================================================
--- linux-2.6.12-rc4.orig/arch/ppc64/kernel/process.c 2005-05-19 08:34:23.000000000 -0400
+++ linux-2.6.12-rc4/arch/ppc64/kernel/process.c 2005-05-19 08:42:03.000000000 -0400
@@ -310,6 +310,10 @@ void show_regs(struct pt_regs * regs)
void exit_thread(void)
{
+ struct task_struct *tsk = current;
+
+ kprobe_flush_task(tsk);
+
#ifndef CONFIG_SMP
if (last_task_used_math == current)
last_task_used_math = NULL;
@@ -324,6 +328,9 @@ void exit_thread(void)
void flush_thread(void)
{
struct thread_info *t = current_thread_info();
+ struct task_struct *tsk = current;
+
+ kprobe_flush_task(tsk);
if (t->flags & _TIF_ABI_PENDING)
t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);
Index: linux-2.6.12-rc4/include/asm-i386/kprobes.h
===================================================================
--- linux-2.6.12-rc4.orig/include/asm-i386/kprobes.h 2005-05-19 08:34:36.000000000 -0400
+++ linux-2.6.12-rc4/include/asm-i386/kprobes.h 2005-05-19 08:42:03.000000000 -0400
@@ -49,6 +49,9 @@ struct arch_specific_insn {
kprobe_opcode_t insn[MAX_INSN_SIZE];
};
+struct arch_retaddr {
+};
+
/* trap3/1 are intr gates for kprobes. So, restore the status of IF,
* if necessary, before executing the original int3/1 (trap) handler.
Index: linux-2.6.12-rc4/include/asm-ppc64/kprobes.h
===================================================================
--- linux-2.6.12-rc4.orig/include/asm-ppc64/kprobes.h 2005-05-07 01:20:31.000000000 -0400
+++ linux-2.6.12-rc4/include/asm-ppc64/kprobes.h 2005-05-19 08:42:03.000000000 -0400
@@ -41,6 +41,9 @@ typedef unsigned int kprobe_opcode_t;
#define IS_TWI(instr) (((instr) & 0xfc000000) == 0x0c000000)
#define JPROBE_ENTRY(pentry) (kprobe_opcode_t *)((func_descr_t *)pentry)
+#define ARCH_SUPPORTS_KRETPROBES
+
+void kretprobe_trampoline(void);
/* Architecture specific copy of original instruction */
struct arch_specific_insn {
@@ -48,6 +51,11 @@ struct arch_specific_insn {
kprobe_opcode_t insn[MAX_INSN_SIZE];
};
+struct arch_retaddr {
+ /* return address on ppc64 is in regs->lr not on stack */
+ kprobe_opcode_t *linkreg_ptr;
+};
+
#ifdef CONFIG_KPROBES
extern int kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data);
Index: linux-2.6.12-rc4/include/asm-sparc64/kprobes.h
===================================================================
--- linux-2.6.12-rc4.orig/include/asm-sparc64/kprobes.h 2005-05-07 01:20:31.000000000 -0400
+++ linux-2.6.12-rc4/include/asm-sparc64/kprobes.h 2005-05-19 08:42:03.000000000 -0400
@@ -18,6 +18,9 @@ struct arch_specific_insn {
kprobe_opcode_t insn[MAX_INSN_SIZE];
};
+struct arch_retaddr {
+};
+
#ifdef CONFIG_KPROBES
extern int kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data);
Index: linux-2.6.12-rc4/include/asm-x86_64/kprobes.h
===================================================================
--- linux-2.6.12-rc4.orig/include/asm-x86_64/kprobes.h 2005-05-07 01:20:31.000000000 -0400
+++ linux-2.6.12-rc4/include/asm-x86_64/kprobes.h 2005-05-19 08:42:03.000000000 -0400
@@ -45,6 +45,9 @@ struct arch_specific_insn {
kprobe_opcode_t *insn;
};
+struct arch_retaddr {
+};
+
/* trap3/1 are intr gates for kprobes. So, restore the status of IF,
* if necessary, before executing the original int3/1 (trap) handler.
*/
Index: linux-2.6.12-rc4/include/linux/kprobes.h
===================================================================
--- linux-2.6.12-rc4.orig/include/linux/kprobes.h 2005-05-19 08:34:46.000000000 -0400
+++ linux-2.6.12-rc4/include/linux/kprobes.h 2005-05-19 08:42:03.000000000 -0400
@@ -118,8 +118,7 @@ static inline void arch_prepare_kretprob
struct pt_regs *regs)
{
}
-static inline void arch_kprobe_flush_task(struct task_struct *tk,
- spinlock_t *kp_lock)
+static inline void arch_kprobe_flush_task(struct task_struct *tk)
{
}
#define arch_get_kprobe_task(ptr) ((struct task_struct *)NULL)
@@ -149,6 +148,7 @@ struct kretprobe_instance {
struct kretprobe *rp;
void *ret_addr;
void *stack_addr;
+ struct arch_retaddr arch_retaddr;
};
#ifdef CONFIG_KPROBES