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powerpc/kprobes: Invoke handlers directly

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Invoke the kprobe handlers directly rather than through notify_die(), to
reduce path taken for handling kprobes. Similar to commit 6f6343f53d
("kprobes/x86: Call exception handlers directly from do_int3/do_debug").

While at it, rename post_kprobe_handler() to kprobe_post_handler() for
more uniform naming.

Reported-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Naveen N. Rao 2016-11-21 22:36:41 +05:30 committed by Michael Ellerman
parent 82de5797a2
commit 6cc89bad60
3 changed files with 27 additions and 22 deletions
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7
arch/powerpc/include/asm/kprobes.h
View File

@ -32,6 +32,7 @@
#include <asm/probes.h>
#include <asm/code-patching.h>
#ifdef CONFIG_KPROBES
#define __ARCH_WANT_KPROBES_INSN_SLOT
struct pt_regs;
@ -127,5 +128,11 @@ struct kprobe_ctlblk {
extern int kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data);
extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr);
extern int kprobe_handler(struct pt_regs *regs);
extern int kprobe_post_handler(struct pt_regs *regs);
#else
static inline int kprobe_handler(struct pt_regs *regs) { return 0; }
static inline int kprobe_post_handler(struct pt_regs *regs) { return 0; }
#endif /* CONFIG_KPROBES */
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_KPROBES_H */

29
arch/powerpc/kernel/kprobes.c
View File

@ -140,13 +140,16 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
regs->link = (unsigned long)kretprobe_trampoline;
}
static int __kprobes kprobe_handler(struct pt_regs *regs)
int __kprobes kprobe_handler(struct pt_regs *regs)
{
struct kprobe *p;
int ret = 0;
unsigned int *addr = (unsigned int *)regs->nip;
struct kprobe_ctlblk *kcb;
if (user_mode(regs))
return 0;
/*
* We don't want to be preempted for the entire
* duration of kprobe processing
@ -359,12 +362,12 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p,
* single-stepped a copy of the instruction. The address of this
* copy is p->ainsn.insn.
*/
static int __kprobes post_kprobe_handler(struct pt_regs *regs)
int __kprobes kprobe_post_handler(struct pt_regs *regs)
{
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
if (!cur)
if (!cur || user_mode(regs))
return 0;
/* make sure we got here for instruction we have a kprobe on */
@ -470,25 +473,7 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data)
{
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
if (args->regs && user_mode(args->regs))
return ret;
switch (val) {
case DIE_BPT:
if (kprobe_handler(args->regs))
ret = NOTIFY_STOP;
break;
case DIE_SSTEP:
if (post_kprobe_handler(args->regs))
ret = NOTIFY_STOP;
break;
default:
break;
}
return ret;
return NOTIFY_DONE;
}
unsigned long arch_deref_entry_point(void *entry)

13
arch/powerpc/kernel/traps.c
View File

@ -64,6 +64,7 @@
#include <asm/asm-prototypes.h>
#include <asm/hmi.h>
#include <sysdev/fsl_pci.h>
#include <asm/kprobes.h>
#if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
int (*__debugger)(struct pt_regs *regs) __read_mostly;
@ -826,6 +827,9 @@ void single_step_exception(struct pt_regs *regs)
clear_single_step(regs);
if (kprobe_post_handler(regs))
return;
if (notify_die(DIE_SSTEP, "single_step", regs, 5,
5, SIGTRAP) == NOTIFY_STOP)
goto bail;
@ -1179,6 +1183,9 @@ void program_check_exception(struct pt_regs *regs)
if (debugger_bpt(regs))
goto bail;
if (kprobe_handler(regs))
goto bail;
/* trap exception */
if (notify_die(DIE_BPT, "breakpoint", regs, 5, 5, SIGTRAP)
== NOTIFY_STOP)
@ -1747,6 +1754,9 @@ void DebugException(struct pt_regs *regs, unsigned long debug_status)
return;
}
if (kprobe_post_handler(regs))
return;
if (notify_die(DIE_SSTEP, "block_step", regs, 5,
5, SIGTRAP) == NOTIFY_STOP) {
return;
@ -1761,6 +1771,9 @@ void DebugException(struct pt_regs *regs, unsigned long debug_status)
/* Clear the instruction completion event */
mtspr(SPRN_DBSR, DBSR_IC);
if (kprobe_post_handler(regs))
return;
if (notify_die(DIE_SSTEP, "single_step", regs, 5,
5, SIGTRAP) == NOTIFY_STOP) {
return;