- Split out fill_page() from xol_get_insn_slot().
- Allocate trampoline page, as the very first one in uprobed
task xol area, and fill it with breakpoint opcode.
- Also introduce get_trampoline_vaddr() helper, to wrap the
trampoline address extraction from area->vaddr. That removes
confusion and eases the debug experience in case ->vaddr
notion will be changed.
Signed-off-by: Anton Arapov <an...@redhat.com>
---
kernel/events/uprobes.c | 35 ++++++++++++++++++++++++++---------
1 file changed, 26 insertions(+), 9 deletions(-)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 3205a2e..86706d1 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1080,6 +1080,21 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned
long start, unsigned lon
set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags);
}
+static void fill_page(struct page *page, unsigned long offset, uprobe_opcode_t
*insn)
+{
+ void *vaddr;
+
+ vaddr = kmap_atomic(page);
+ memcpy(vaddr + offset, insn, MAX_UINSN_BYTES);
+ kunmap_atomic(vaddr);
+
+ /*
+ * We probably need flush_icache_user_range() but it needs vma.
+ * This should work on supported architectures too.
+ */
+ flush_dcache_page(page);
+}
+
/* Slot allocation for XOL */
static int xol_add_vma(struct xol_area *area)
{
@@ -1122,6 +1137,7 @@ static struct xol_area *get_xol_area(void)
{
struct mm_struct *mm = current->mm;
struct xol_area *area;
+ uprobe_opcode_t insn = UPROBE_SWBP_INSN;
area = mm->uprobes_state.xol_area;
if (area)
@@ -1139,6 +1155,10 @@ static struct xol_area *get_xol_area(void)
if (!area->page)
goto free_bitmap;
+ /* pre-allocate for return probes */
+ set_bit(0, area->bitmap);
+ fill_page(area->page, 0, &insn);
+
init_waitqueue_head(&area->wq);
if (!xol_add_vma(area))
return area;
@@ -1226,7 +1246,6 @@ static unsigned long xol_get_insn_slot(struct uprobe
*uprobe)
struct xol_area *area;
unsigned long offset;
unsigned long xol_vaddr;
- void *vaddr;
area = get_xol_area();
if (!area)
@@ -1238,14 +1257,7 @@ static unsigned long xol_get_insn_slot(struct uprobe
*uprobe)
/* Initialize the slot */
offset = xol_vaddr & ~PAGE_MASK;
- vaddr = kmap_atomic(area->page);
- memcpy(vaddr + offset, uprobe->arch.insn, MAX_UINSN_BYTES);
- kunmap_atomic(vaddr);
- /*
- * We probably need flush_icache_user_range() but it needs vma.
- * This should work on supported architectures too.
- */
- flush_dcache_page(area->page);
+ fill_page(area->page, offset, uprobe->arch.insn);
return xol_vaddr;
}
@@ -1341,6 +1353,11 @@ static struct uprobe_task *get_utask(void)
return current->utask;
}
+static unsigned long get_trampoline_vaddr(struct xol_area *area)
+{
+ return area->vaddr;
+}
+
/* Prepare to single-step probed instruction out of line. */
static int
pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr)
--
1.8.1.4
--
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