[PATCH 1/9] Kprobes: rearrange preempt_disable/enable() calls
From: Ananth N Mavinakayanahalli
Date: Mon Oct 10 2005 - 09:40:08 EST
From: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Reorder preempt_disable/enable() calls in arch kprobes files in
preparation to introduce locking changes. No functional changes
introduced by this patch.
Signed-off-by: Ananth N Mavinakayahanalli <ananth@xxxxxxxxxx>
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx>
---
arch/i386/kernel/kprobes.c | 27 ++++++++++++++-------------
arch/ia64/kernel/kprobes.c | 22 ++++++++++++++--------
arch/ppc64/kernel/kprobes.c | 11 ++++++-----
arch/sparc64/kernel/kprobes.c | 25 +++++++++++++------------
arch/x86_64/kernel/kprobes.c | 28 ++++++++++++++--------------
5 files changed, 61 insertions(+), 52 deletions(-)
Index: linux-2.6.14-rc3/arch/i386/kernel/kprobes.c
===================================================================
--- linux-2.6.14-rc3.orig/arch/i386/kernel/kprobes.c 2005-09-30 17:17:35.000000000 -0400
+++ linux-2.6.14-rc3/arch/i386/kernel/kprobes.c 2005-10-05 16:07:48.000000000 -0400
@@ -158,8 +158,6 @@ static int __kprobes kprobe_handler(stru
kprobe_opcode_t *addr = NULL;
unsigned long *lp;
- /* We're in an interrupt, but this is clear and BUG()-safe. */
- preempt_disable();
/* Check if the application is using LDT entry for its code segment and
* calculate the address by reading the base address from the LDT entry.
*/
@@ -232,6 +230,11 @@ static int __kprobes kprobe_handler(stru
goto no_kprobe;
}
+ /*
+ * This preempt_disable() matches the preempt_enable_no_resched()
+ * in post_kprobe_handler()
+ */
+ preempt_disable();
kprobe_status = KPROBE_HIT_ACTIVE;
set_current_kprobe(p, regs);
@@ -245,7 +248,6 @@ ss_probe:
return 1;
no_kprobe:
- preempt_enable_no_resched();
return ret;
}
@@ -316,7 +318,7 @@ int __kprobes trampoline_probe_handler(s
/*
* By returning a non-zero value, we are telling
* kprobe_handler() that we have handled unlocking
- * and re-enabling preemption.
+ * and re-enabling preemption
*/
return 1;
}
@@ -453,29 +455,29 @@ int __kprobes kprobe_exceptions_notify(s
unsigned long val, void *data)
{
struct die_args *args = (struct die_args *)data;
+ int ret = NOTIFY_DONE;
+
+ preempt_disable();
switch (val) {
case DIE_INT3:
if (kprobe_handler(args->regs))
- return NOTIFY_STOP;
+ ret = NOTIFY_STOP;
break;
case DIE_DEBUG:
if (post_kprobe_handler(args->regs))
- return NOTIFY_STOP;
+ ret = NOTIFY_STOP;
break;
case DIE_GPF:
- if (kprobe_running() &&
- kprobe_fault_handler(args->regs, args->trapnr))
- return NOTIFY_STOP;
- break;
case DIE_PAGE_FAULT:
if (kprobe_running() &&
kprobe_fault_handler(args->regs, args->trapnr))
- return NOTIFY_STOP;
+ ret = NOTIFY_STOP;
break;
default:
break;
}
- return NOTIFY_DONE;
+ preempt_enable();
+ return ret;
}
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
@@ -502,7 +504,6 @@ int __kprobes setjmp_pre_handler(struct
void __kprobes jprobe_return(void)
{
- preempt_enable_no_resched();
asm volatile (" xchgl %%ebx,%%esp \n"
" int3 \n"
" .globl jprobe_return_end \n"
Index: linux-2.6.14-rc3/arch/ia64/kernel/kprobes.c
===================================================================
--- linux-2.6.14-rc3.orig/arch/ia64/kernel/kprobes.c 2005-09-30 17:17:35.000000000 -0400
+++ linux-2.6.14-rc3/arch/ia64/kernel/kprobes.c 2005-10-05 16:07:47.000000000 -0400
@@ -395,7 +395,7 @@ int __kprobes trampoline_probe_handler(s
/*
* By returning a non-zero value, we are telling
* kprobe_handler() that we have handled unlocking
- * and re-enabling preemption.
+ * and re-enabling preemption
*/
return 1;
}
@@ -607,8 +607,6 @@ static int __kprobes pre_kprobes_handler
struct pt_regs *regs = args->regs;
kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
- preempt_disable();
-
/* Handle recursion cases */
if (kprobe_running()) {
p = get_kprobe(addr);
@@ -665,6 +663,11 @@ static int __kprobes pre_kprobes_handler
goto no_kprobe;
}
+ /*
+ * This preempt_disable() matches the preempt_enable_no_resched()
+ * in post_kprobes_handler()
+ */
+ preempt_disable();
kprobe_status = KPROBE_HIT_ACTIVE;
set_current_kprobe(p);
@@ -682,7 +685,6 @@ ss_probe:
return 1;
no_kprobe:
- preempt_enable_no_resched();
return ret;
}
@@ -733,22 +735,26 @@ int __kprobes kprobe_exceptions_notify(s
unsigned long val, void *data)
{
struct die_args *args = (struct die_args *)data;
+ int ret = NOTIFY_DONE;
+
+ preempt_disable();
switch(val) {
case DIE_BREAK:
if (pre_kprobes_handler(args))
- return NOTIFY_STOP;
+ ret = NOTIFY_STOP;
break;
case DIE_SS:
if (post_kprobes_handler(args->regs))
- return NOTIFY_STOP;
+ ret = NOTIFY_STOP;
break;
case DIE_PAGE_FAULT:
if (kprobes_fault_handler(args->regs, args->trapnr))
- return NOTIFY_STOP;
+ ret = NOTIFY_STOP;
default:
break;
}
- return NOTIFY_DONE;
+ preempt_enable();
+ return ret;
}
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
Index: linux-2.6.14-rc3/arch/ppc64/kernel/kprobes.c
===================================================================
--- linux-2.6.14-rc3.orig/arch/ppc64/kernel/kprobes.c 2005-09-30 17:17:35.000000000 -0400
+++ linux-2.6.14-rc3/arch/ppc64/kernel/kprobes.c 2005-10-05 16:07:45.000000000 -0400
@@ -209,6 +209,11 @@ static inline int kprobe_handler(struct
goto no_kprobe;
}
+ /*
+ * This preempt_disable() matches the preempt_enable_no_resched()
+ * in post_kprobe_handler().
+ */
+ preempt_disable();
kprobe_status = KPROBE_HIT_ACTIVE;
current_kprobe = p;
kprobe_saved_msr = regs->msr;
@@ -219,11 +224,6 @@ static inline int kprobe_handler(struct
ss_probe:
prepare_singlestep(p, regs);
kprobe_status = KPROBE_HIT_SS;
- /*
- * This preempt_disable() matches the preempt_enable_no_resched()
- * in post_kprobe_handler().
- */
- preempt_disable();
return 1;
no_kprobe:
@@ -293,6 +293,7 @@ int __kprobes trampoline_probe_handler(s
regs->nip = orig_ret_address;
unlock_kprobes();
+ preempt_enable_no_resched();
/*
* By returning a non-zero value, we are telling
Index: linux-2.6.14-rc3/arch/sparc64/kernel/kprobes.c
===================================================================
--- linux-2.6.14-rc3.orig/arch/sparc64/kernel/kprobes.c 2005-09-30 17:17:35.000000000 -0400
+++ linux-2.6.14-rc3/arch/sparc64/kernel/kprobes.c 2005-10-05 16:07:44.000000000 -0400
@@ -118,8 +118,6 @@ static int __kprobes kprobe_handler(stru
void *addr = (void *) regs->tpc;
int ret = 0;
- preempt_disable();
-
if (kprobe_running()) {
/* We *are* holding lock here, so this is safe.
* Disarm the probe we just hit, and ignore it.
@@ -171,6 +169,11 @@ static int __kprobes kprobe_handler(stru
goto no_kprobe;
}
+ /*
+ * This preempt_disable() matches the preempt_enable_no_resched()
+ * in post_kprobes_handler()
+ */
+ preempt_disable();
set_current_kprobe(p, regs);
kprobe_status = KPROBE_HIT_ACTIVE;
if (p->pre_handler && p->pre_handler(p, regs))
@@ -182,7 +185,6 @@ ss_probe:
return 1;
no_kprobe:
- preempt_enable_no_resched();
return ret;
}
@@ -322,29 +324,29 @@ int __kprobes kprobe_exceptions_notify(s
unsigned long val, void *data)
{
struct die_args *args = (struct die_args *)data;
+ int ret = NOTIFY_DONE;
+
+ preempt_disable();
switch (val) {
case DIE_DEBUG:
if (kprobe_handler(args->regs))
- return NOTIFY_STOP;
+ ret = NOTIFY_STOP;
break;
case DIE_DEBUG_2:
if (post_kprobe_handler(args->regs))
- return NOTIFY_STOP;
+ ret = NOTIFY_STOP;
break;
case DIE_GPF:
- if (kprobe_running() &&
- kprobe_fault_handler(args->regs, args->trapnr))
- return NOTIFY_STOP;
- break;
case DIE_PAGE_FAULT:
if (kprobe_running() &&
kprobe_fault_handler(args->regs, args->trapnr))
- return NOTIFY_STOP;
+ ret = NOTIFY_STOP;
break;
default:
break;
}
- return NOTIFY_DONE;
+ preempt_enable();
+ return ret;
}
asmlinkage void __kprobes kprobe_trap(unsigned long trap_level,
@@ -396,7 +398,6 @@ int __kprobes setjmp_pre_handler(struct
void __kprobes jprobe_return(void)
{
- preempt_enable_no_resched();
__asm__ __volatile__(
".globl jprobe_return_trap_instruction\n"
"jprobe_return_trap_instruction:\n\t"
Index: linux-2.6.14-rc3/arch/x86_64/kernel/kprobes.c
===================================================================
--- linux-2.6.14-rc3.orig/arch/x86_64/kernel/kprobes.c 2005-09-30 17:17:35.000000000 -0400
+++ linux-2.6.14-rc3/arch/x86_64/kernel/kprobes.c 2005-10-05 16:08:04.000000000 -0400
@@ -302,9 +302,6 @@ int __kprobes kprobe_handler(struct pt_r
int ret = 0;
kprobe_opcode_t *addr = (kprobe_opcode_t *)(regs->rip - sizeof(kprobe_opcode_t));
- /* We're in an interrupt, but this is clear and BUG()-safe. */
- preempt_disable();
-
/* Check we're not actually recursing */
if (kprobe_running()) {
/* We *are* holding lock here, so this is safe.
@@ -372,6 +369,11 @@ int __kprobes kprobe_handler(struct pt_r
goto no_kprobe;
}
+ /*
+ * This preempt_disable() matches the preempt_enable_no_resched()
+ * in post_kprobe_handler()
+ */
+ preempt_disable();
kprobe_status = KPROBE_HIT_ACTIVE;
set_current_kprobe(p, regs);
@@ -385,7 +387,6 @@ ss_probe:
return 1;
no_kprobe:
- preempt_enable_no_resched();
return ret;
}
@@ -456,7 +457,7 @@ int __kprobes trampoline_probe_handler(s
/*
* By returning a non-zero value, we are telling
* kprobe_handler() that we have handled unlocking
- * and re-enabling preemption.
+ * and re-enabling preemption
*/
return 1;
}
@@ -599,29 +600,29 @@ int __kprobes kprobe_exceptions_notify(s
unsigned long val, void *data)
{
struct die_args *args = (struct die_args *)data;
+ int ret = NOTIFY_DONE;
+
+ preempt_disable();
switch (val) {
case DIE_INT3:
if (kprobe_handler(args->regs))
- return NOTIFY_STOP;
+ ret = NOTIFY_STOP;
break;
case DIE_DEBUG:
if (post_kprobe_handler(args->regs))
- return NOTIFY_STOP;
+ ret = NOTIFY_STOP;
break;
case DIE_GPF:
- if (kprobe_running() &&
- kprobe_fault_handler(args->regs, args->trapnr))
- return NOTIFY_STOP;
- break;
case DIE_PAGE_FAULT:
if (kprobe_running() &&
kprobe_fault_handler(args->regs, args->trapnr))
- return NOTIFY_STOP;
+ ret = NOTIFY_STOP;
break;
default:
break;
}
- return NOTIFY_DONE;
+ preempt_enable();
+ return ret;
}
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
@@ -647,7 +648,6 @@ int __kprobes setjmp_pre_handler(struct
void __kprobes jprobe_return(void)
{
- preempt_enable_no_resched();
asm volatile (" xchg %%rbx,%%rsp \n"
" int3 \n"
" .globl jprobe_return_end \n"
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/