From: Jan Beulich Date: Thu, 6 Jun 2019 12:06:29 +0000 (+0200) Subject: trace: fix build with gcc9 X-Git-Tag: archive/raspbian/4.11.3+24-g14b62ab3e5-1+rpi1~1^2~55^2~12 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=45342cd88d564a7da2dfbbc921898805008b0b6c;p=xen.git trace: fix build with gcc9 While I've not observed this myself, gcc 9 (imo validly) reportedly may complain trace.c: In function '__trace_hypercall': trace.c:826:19: error: taking address of packed member of 'struct ' may result in an unaligned pointer value [-Werror=address-of-packed-member] 826 | uint32_t *a = d.args; and the fix is rather simple - remove the __packed attribute. Introduce a BUILD_BUG_ON() as replacement, for the unlikely case that Xen might get ported to an architecture where array alignment higher that that of its elements. Reported-by: Martin Liška Signed-off-by: Jan Beulich Acked-by: George Dunlap master commit: 3fd3b266d4198c06e8e421ca515d9ba09ccd5155 master date: 2019-05-13 09:51:23 +0200 --- diff --git a/xen/common/trace.c b/xen/common/trace.c index 8cdc17b731..1e4a8a5c95 100644 --- a/xen/common/trace.c +++ b/xen/common/trace.c @@ -819,12 +819,18 @@ unlock: void __trace_hypercall(uint32_t event, unsigned long op, const xen_ulong_t *args) { - struct __packed { + struct { uint32_t op; uint32_t args[6]; } d; uint32_t *a = d.args; + /* + * In lieu of using __packed above, which gcc9 legitimately doesn't + * like in combination with the address of d.args[] taken. + */ + BUILD_BUG_ON(offsetof(typeof(d), args) != sizeof(d.op)); + #define APPEND_ARG32(i) \ do { \ unsigned i_ = (i); \