[PATCH 5/9] Kprobes: Track kprobe on a per_cpu basis - ppc64 changes

From: Ananth N Mavinakayanahalli
Date: Mon Oct 10 2005 - 09:44:24 EST

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From: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>

PPC64 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@xxxxxxxxxx>
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx>
---

arch/ppc64/kernel/kprobes.c | 94 +++++++++++++++++++++++++-------------------
include/asm-ppc64/kprobes.h | 15 +++++++
2 files changed, 69 insertions(+), 40 deletions(-)

Index: linux-2.6.14-rc3/arch/ppc64/kernel/kprobes.c
===================================================================
--- linux-2.6.14-rc3.orig/arch/ppc64/kernel/kprobes.c 2005-10-05 15:23:42.000000000 -0400
+++ linux-2.6.14-rc3/arch/ppc64/kernel/kprobes.c 2005-10-05 15:32:00.000000000 -0400
@@ -37,12 +37,8 @@
#include <asm/sstep.h>

static DECLARE_MUTEX(kprobe_mutex);
-
-static struct kprobe *current_kprobe;
-static unsigned long kprobe_status, kprobe_saved_msr;
-static struct kprobe *kprobe_prev;
-static unsigned long kprobe_status_prev, kprobe_saved_msr_prev;
-static struct pt_regs jprobe_saved_regs;
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);

int __kprobes arch_prepare_kprobe(struct kprobe *p)
{
@@ -108,18 +104,25 @@ static inline void prepare_singlestep(st
regs->nip = (unsigned long)p->ainsn.insn;
}

-static inline void save_previous_kprobe(void)
+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_msr = kcb->kprobe_saved_msr;
+}
+
+static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
{
- kprobe_prev = current_kprobe;
- kprobe_status_prev = kprobe_status;
- kprobe_saved_msr_prev = kprobe_saved_msr;
+ __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+ kcb->kprobe_status = kcb->prev_kprobe.status;
+ kcb->kprobe_saved_msr = kcb->prev_kprobe.saved_msr;
}

-static inline void restore_previous_kprobe(void)
+static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
{
- current_kprobe = kprobe_prev;
- kprobe_status = kprobe_status_prev;
- kprobe_saved_msr = kprobe_saved_msr_prev;
+ __get_cpu_var(current_kprobe) = p;
+ kcb->kprobe_saved_msr = regs->msr;
}

void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
@@ -145,6 +148,7 @@ static inline int kprobe_handler(struct
struct kprobe *p;
int ret = 0;
unsigned int *addr = (unsigned int *)regs->nip;
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

/* Check we're not actually recursing */
if (kprobe_running()) {
@@ -153,10 +157,10 @@ static inline int kprobe_handler(struct
p = get_kprobe(addr);
if (p) {
kprobe_opcode_t insn = *p->ainsn.insn;
- if (kprobe_status == KPROBE_HIT_SS &&
+ if (kcb->kprobe_status == KPROBE_HIT_SS &&
is_trap(insn)) {
regs->msr &= ~MSR_SE;
- regs->msr |= kprobe_saved_msr;
+ regs->msr |= kcb->kprobe_saved_msr;
unlock_kprobes();
goto no_kprobe;
}
@@ -166,15 +170,15 @@ static inline int kprobe_handler(struct
* just single step on the instruction of the new probe
* without calling any user handlers.
*/
- save_previous_kprobe();
- current_kprobe = p;
- kprobe_saved_msr = regs->msr;
+ save_previous_kprobe(kcb);
+ set_current_kprobe(p, regs, kcb);
+ kcb->kprobe_saved_msr = regs->msr;
p->nmissed++;
prepare_singlestep(p, regs);
- kprobe_status = KPROBE_REENTER;
+ kcb->kprobe_status = KPROBE_REENTER;
return 1;
} else {
- p = current_kprobe;
+ p = __get_cpu_var(current_kprobe);
if (p->break_handler && p->break_handler(p, regs)) {
goto ss_probe;
}
@@ -214,16 +218,15 @@ static inline int kprobe_handler(struct
* in post_kprobe_handler().
*/
preempt_disable();
- kprobe_status = KPROBE_HIT_ACTIVE;
- current_kprobe = p;
- kprobe_saved_msr = regs->msr;
+ kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+ set_current_kprobe(p, regs, kcb);
if (p->pre_handler && p->pre_handler(p, regs))
/* handler has already set things up, so skip ss setup */
return 1;

ss_probe:
prepare_singlestep(p, regs);
- kprobe_status = KPROBE_HIT_SS;
+ kcb->kprobe_status = KPROBE_HIT_SS;
return 1;

no_kprobe:
@@ -292,6 +295,7 @@ int __kprobes trampoline_probe_handler(s
BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
regs->nip = orig_ret_address;

+ reset_current_kprobe();
unlock_kprobes();
preempt_enable_no_resched();

@@ -324,22 +328,26 @@ static void __kprobes resume_execution(s

static inline int post_kprobe_handler(struct pt_regs *regs)
{
- if (!kprobe_running())
+ struct kprobe *cur = kprobe_running();
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ if (!cur)
return 0;

- if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
- kprobe_status = KPROBE_HIT_SSDONE;
- current_kprobe->post_handler(current_kprobe, regs, 0);
+ if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
+ kcb->kprobe_status = KPROBE_HIT_SSDONE;
+ cur->post_handler(cur, regs, 0);
}

- resume_execution(current_kprobe, regs);
- regs->msr |= kprobe_saved_msr;
+ resume_execution(cur, regs);
+ regs->msr |= kcb->kprobe_saved_msr;

/*Restore back the original saved kprobes variables and continue. */
- if (kprobe_status == KPROBE_REENTER) {
- restore_previous_kprobe();
+ if (kcb->kprobe_status == KPROBE_REENTER) {
+ restore_previous_kprobe(kcb);
goto out;
}
+ reset_current_kprobe();
unlock_kprobes();
out:
preempt_enable_no_resched();
@@ -358,15 +366,18 @@ out:
/* Interrupts disabled, kprobe_lock held. */
static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
{
- if (current_kprobe->fault_handler
- && current_kprobe->fault_handler(current_kprobe, regs, trapnr))
+ struct kprobe *cur = kprobe_running();
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
return 1;

- if (kprobe_status & KPROBE_HIT_SS) {
- resume_execution(current_kprobe, regs);
+ if (kcb->kprobe_status & KPROBE_HIT_SS) {
+ resume_execution(cur, regs);
regs->msr &= ~MSR_SE;
- regs->msr |= kprobe_saved_msr;
+ regs->msr |= kcb->kprobe_saved_msr;

+ reset_current_kprobe();
unlock_kprobes();
preempt_enable_no_resched();
}
@@ -412,8 +423,9 @@ int __kprobes kprobe_exceptions_notify(s
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
struct jprobe *jp = container_of(p, struct jprobe, kp);
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

- memcpy(&jprobe_saved_regs, regs, sizeof(struct pt_regs));
+ memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));

/* setup return addr to the jprobe handler routine */
regs->nip = (unsigned long)(((func_descr_t *)jp->entry)->entry);
@@ -433,12 +445,14 @@ void __kprobes jprobe_return_end(void)

int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
{
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
/*
* FIXME - we should ideally be validating that we got here 'cos
* of the "trap" in jprobe_return() above, before restoring the
* saved regs...
*/
- memcpy(regs, &jprobe_saved_regs, sizeof(struct pt_regs));
+ memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
return 1;
}

Index: linux-2.6.14-rc3/include/asm-ppc64/kprobes.h
===================================================================
--- linux-2.6.14-rc3.orig/include/asm-ppc64/kprobes.h 2005-09-30 17:17:35.000000000 -0400
+++ linux-2.6.14-rc3/include/asm-ppc64/kprobes.h 2005-10-05 15:31:15.000000000 -0400
@@ -28,6 +28,7 @@
*/
#include <linux/types.h>
#include <linux/ptrace.h>
+#include <linux/percpu.h>

struct pt_regs;

@@ -54,6 +55,20 @@ struct arch_specific_insn {
kprobe_opcode_t *insn;
};

+struct prev_kprobe {
+ struct kprobe *kp;
+ unsigned long status;
+ unsigned long saved_msr;
+};
+
+/* per-cpu kprobe control block */
+struct kprobe_ctlblk {
+ unsigned long kprobe_status;
+ unsigned long kprobe_saved_msr;
+ struct pt_regs jprobe_saved_regs;
+ struct prev_kprobe prev_kprobe;
+};
+
#ifdef CONFIG_KPROBES
extern int kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data);
-
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Next message: Ananth N Mavinakayanahalli: "[PATCH 6/9] Kprobes: Track kprobe on a per_cpu basis - sparc64 changes"
Previous message: Ananth N Mavinakayanahalli: "[PATCH 4/9] Kprobes: Track kprobe on a per_cpu basis - ia64 changes"
In reply to: Ananth N Mavinakayanahalli: "[PATCH 4/9] Kprobes: Track kprobe on a per_cpu basis - ia64 changes"
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