From: Rabin Vincent rabin@rab.in

Allow arches to customize how the instruction is filled into the xol slot. ARM will use this to insert an undefined instruction after the real instruction in order to simulate a single step of the instruction without hardware support.

Signed-off-by: Rabin Vincent rabin@rab.in Signed-off-by: David A. Long dave.long@linaro.org --- include/linux/uprobes.h | 1 + kernel/events/uprobes.c | 10 +++++++++- 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index eca5bd5..2a0aa10 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -134,6 +134,7 @@ extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk); extern int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data); extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs); extern bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs); +extern void __weak arch_uprobe_xol_copy(struct arch_uprobe *auprobe, void *vaddr); #else /* !CONFIG_UPROBES */ struct uprobes_state { }; diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 2f3a4cb..64471bd 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1238,6 +1238,11 @@ static unsigned long xol_take_insn_slot(struct xol_area *area) return slot_addr; }

+void __weak arch_uprobe_xol_copy(struct arch_uprobe *auprobe, void *vaddr) +{ + memcpy(vaddr, auprobe->insn, MAX_UINSN_BYTES); +} + /* * xol_get_insn_slot - allocate a slot for xol. * Returns the allocated slot address or 0. @@ -1246,6 +1251,7 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe) { struct xol_area *area; unsigned long xol_vaddr; + void *kaddr;

area = get_xol_area(); if (!area) @@ -1256,7 +1262,9 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe) return 0;

/* Initialize the slot */ - copy_to_page(area->page, xol_vaddr, uprobe->arch.insn, MAX_UINSN_BYTES); + kaddr = kmap_atomic(area->page); + arch_uprobe_xol_copy(&uprobe->arch, kaddr + (xol_vaddr & ~PAGE_MASK)); + kunmap_atomic(kaddr); /* * We probably need flush_icache_user_range() but it needs vma. * This should work on supported architectures too.