[PATCH 05/13] kexec: Make kexec_segment user buffer pointer a union

Vivek Goyal
2014-06-03T13:08:19Z

So far kexec_segment->buf was always a user space pointer as user space
passed the array of kexec_segment structures and kernel copied it.

But with new system call, list of kexec segments will be prepared by
kernel and kexec_segment->buf will point to a kernel memory.

So while I was adding code where I made assumption that ->buf is pointing
to kernel memory, sparse started giving warning.

Make ->buf a union. And where a user space pointer is expected, access
it using ->buf and where a kernel space pointer is expected, access it
using ->kbuf. That takes care of sparse warnings.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
include/linux/kexec.h | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index a756419..d0285cc 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -69,7 +69,18 @@ typedef unsigned long kimage_entry_t;
#define IND_SOURCE 0x8

struct kexec_segment {
- void __user *buf;
+ /*
+ * This pointer can point to user memory if kexec_load() system
+ * call is used or will point to kernel memory if
+ * kexec_file_load() system call is used.
+ *
+ * Use ->buf when expecting to deal with user memory and use ->kbuf
+ * when expecting to deal with kernel memory.
+ */
+ union {
+ void __user *buf;
+ void *kbuf;
+ };
size_t bufsz;
unsigned long mem;
size_t memsz;
--
1.9.0