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authorAnanth N Mavinakayanahalli <ananth@in.ibm.com>2005-06-27 15:17:01 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-27 15:23:52 -0700
commit9ec4b1f356b3bad928ae8e2aa9caebfa737d52df (patch)
tree24d27ffed66595a9d864448ec53200ca1745f62c /arch/ppc64/kernel
parentd3b8a1a8496c83bc4a3cc76505c29255af15572c (diff)
[PATCH] kprobes: fix single-step out of line - take2
Now that PPC64 has no-execute support, here is a second try to fix the single step out of line during kprobe execution. Kprobes on x86_64 already solved this problem by allocating an executable page and using it as the scratch area for stepping out of line. Reuse that. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/ppc64/kernel')
-rw-r--r--arch/ppc64/kernel/kprobes.c26
1 files changed, 22 insertions, 4 deletions
diff --git a/arch/ppc64/kernel/kprobes.c b/arch/ppc64/kernel/kprobes.c
index 782ce3efa2c..86cc5496db9 100644
--- a/arch/ppc64/kernel/kprobes.c
+++ b/arch/ppc64/kernel/kprobes.c
@@ -36,6 +36,8 @@
#include <asm/kdebug.h>
#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;
@@ -54,6 +56,15 @@ int arch_prepare_kprobe(struct kprobe *p)
printk("Cannot register a kprobe on rfid or mtmsrd\n");
ret = -EINVAL;
}
+
+ /* insn must be on a special executable page on ppc64 */
+ if (!ret) {
+ up(&kprobe_mutex);
+ p->ainsn.insn = get_insn_slot();
+ down(&kprobe_mutex);
+ if (!p->ainsn.insn)
+ ret = -ENOMEM;
+ }
return ret;
}
@@ -79,16 +90,22 @@ void arch_disarm_kprobe(struct kprobe *p)
void arch_remove_kprobe(struct kprobe *p)
{
+ up(&kprobe_mutex);
+ free_insn_slot(p->ainsn.insn);
+ down(&kprobe_mutex);
}
static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
{
+ kprobe_opcode_t insn = *p->ainsn.insn;
+
regs->msr |= MSR_SE;
- /*single step inline if it a breakpoint instruction*/
- if (p->opcode == BREAKPOINT_INSTRUCTION)
+
+ /* single step inline if it is a trap variant */
+ if (IS_TW(insn) || IS_TD(insn) || IS_TWI(insn) || IS_TDI(insn))
regs->nip = (unsigned long)p->addr;
else
- regs->nip = (unsigned long)&p->ainsn.insn;
+ regs->nip = (unsigned long)p->ainsn.insn;
}
static inline void save_previous_kprobe(void)
@@ -205,9 +222,10 @@ no_kprobe:
static void resume_execution(struct kprobe *p, struct pt_regs *regs)
{
int ret;
+ unsigned int insn = *p->ainsn.insn;
regs->nip = (unsigned long)p->addr;
- ret = emulate_step(regs, p->ainsn.insn[0]);
+ ret = emulate_step(regs, insn);
if (ret == 0)
regs->nip = (unsigned long)p->addr + 4;
}