sh: handle early calls to return_address() when using dwarf unwinder.
The dwarf unwinder ties in to an early initcall, but it's possible that
return_address() calls will be made prior to that. This implements some
additional error handling in to the dwarf unwinder as well as an exit
path in the return_address() case to bail out if the unwinder hasn't come
up yet.
This fixes a NULL pointer deref in early boot when mempool_alloc() blows
up on the not-yet-ready mempool via dwarf_unwind_stack().
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/kernel/dwarf.c b/arch/sh/kernel/dwarf.c
index 886d7d8..49c09c7 100644
--- a/arch/sh/kernel/dwarf.c
+++ b/arch/sh/kernel/dwarf.c
@@ -49,6 +49,8 @@
static struct dwarf_cie *cached_cie;
+static unsigned int dwarf_unwinder_ready;
+
/**
* dwarf_frame_alloc_reg - allocate memory for a DWARF register
* @frame: the DWARF frame whose list of registers we insert on
@@ -582,6 +584,13 @@
unsigned long addr;
/*
+ * If we've been called in to before initialization has
+ * completed, bail out immediately.
+ */
+ if (!dwarf_unwinder_ready)
+ return NULL;
+
+ /*
* If we're starting at the top of the stack we need get the
* contents of a physical register to get the CFA in order to
* begin the virtual unwinding of the stack.
@@ -1167,7 +1176,7 @@
*/
static int __init dwarf_unwinder_init(void)
{
- int err;
+ int err = -ENOMEM;
dwarf_frame_cachep = kmem_cache_create("dwarf_frames",
sizeof(struct dwarf_frame), 0,
@@ -1181,11 +1190,15 @@
mempool_alloc_slab,
mempool_free_slab,
dwarf_frame_cachep);
+ if (!dwarf_frame_pool)
+ goto out;
dwarf_reg_pool = mempool_create(DWARF_REG_MIN_REQ,
mempool_alloc_slab,
mempool_free_slab,
dwarf_reg_cachep);
+ if (!dwarf_reg_pool)
+ goto out;
err = dwarf_parse_section(__start_eh_frame, __stop_eh_frame, NULL);
if (err)
@@ -1195,11 +1208,13 @@
if (err)
goto out;
+ dwarf_unwinder_ready = 1;
+
return 0;
out:
printk(KERN_ERR "Failed to initialise DWARF unwinder: %d\n", err);
dwarf_unwinder_cleanup();
- return -EINVAL;
+ return err;
}
early_initcall(dwarf_unwinder_init);
diff --git a/arch/sh/kernel/return_address.c b/arch/sh/kernel/return_address.c
index cbf1dd5..5124aeb 100644
--- a/arch/sh/kernel/return_address.c
+++ b/arch/sh/kernel/return_address.c
@@ -24,6 +24,8 @@
struct dwarf_frame *tmp;
tmp = dwarf_unwind_stack(ra, frame);
+ if (!tmp)
+ return NULL;
if (frame)
dwarf_free_frame(frame);