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powerpc/kprobes: Clean up jprobe detection in livepatch handler

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In commit c05b8c4474 ("powerpc/kprobes: Skip livepatch_handler() for
jprobes"), we added a helper is_current_kprobe_addr() to help detect if
the modified regs->nip was due to a jprobe or livepatch. Masami felt
that the function name was not quite clear. To that end, this patch
renames is_current_kprobe_addr() to __is_active_jprobe() and adds a
comment to (hopefully) better clarify the purpose of this helper. The
helper has also now been moved to kprobes-ftrace.c so that it is only
available for KPROBES_ON_FTRACE.

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 2017-09-22 14:40:45 +05:30 committed by Michael Ellerman
parent a7b440383f
commit bf3a912517
4 changed files with 14 additions and 9 deletions
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2
arch/powerpc/include/asm/kprobes.h
View File

@ -103,8 +103,8 @@ extern int kprobe_exceptions_notify(struct notifier_block *self,
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);
extern int is_current_kprobe_addr(unsigned long addr);
#ifdef CONFIG_KPROBES_ON_FTRACE
extern int __is_active_jprobe(unsigned long addr);
extern int skip_singlestep(struct kprobe *p, struct pt_regs *regs,
struct kprobe_ctlblk *kcb);
#else

11
arch/powerpc/kernel/kprobes-ftrace.c
View File

@ -25,6 +25,17 @@
#include <linux/preempt.h>
#include <linux/ftrace.h>
/*
* This is called from ftrace code after invoking registered handlers to
* disambiguate regs->nip changes done by jprobes and livepatch. We check if
* there is an active jprobe at the provided address (mcount location).
*/
int __is_active_jprobe(unsigned long addr)
{
struct kprobe *p = kprobe_running();
return (p && (unsigned long)p->addr == addr) ? 1 : 0;
}
static nokprobe_inline
int __skip_singlestep(struct kprobe *p, struct pt_regs *regs,
struct kprobe_ctlblk *kcb, unsigned long orig_nip)

6
arch/powerpc/kernel/kprobes.c
View File

@ -43,12 +43,6 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
int is_current_kprobe_addr(unsigned long addr)
{
struct kprobe *p = kprobe_running();
return (p && (unsigned long)p->addr == addr) ? 1 : 0;
}
bool arch_within_kprobe_blacklist(unsigned long addr)
{
return (addr >= (unsigned long)__kprobes_text_start &&

4
arch/powerpc/kernel/trace/ftrace_64_mprofile.S
View File

@ -110,9 +110,9 @@ ftrace_call:
/* NIP has not been altered, skip over further checks */
beq 1f
/* Check if there is an active kprobe on us */
/* Check if there is an active jprobe on us */
subi r3, r14, 4
bl is_current_kprobe_addr
bl __is_active_jprobe
nop
/*