x32: Fix alignment fail in struct compat_siginfo
authorH. Peter Anvin <hpa@zytor.com>
Wed, 14 Mar 2012 21:27:52 +0000 (14:27 -0700)
committerH. Peter Anvin <hpa@zytor.com>
Wed, 14 Mar 2012 21:27:52 +0000 (14:27 -0700)
commit31796ac4e8f0e88f5c10f1ad6dab8f19bebe44a4
treec9ae9d50b327d9f5e56f689b8dea5fe6f9a2bfc1
parentbb6fa8b275e132b1e9319dbab94211543a0b7bd3
x32: Fix alignment fail in struct compat_siginfo

Adding struct _sigchld_x32 caused a misalignment cascade in struct
siginfo, because union _sifields is located on an 4-byte boundary
(8-byte misaligned.)

Adding new fields that are 8-byte aligned caused the intermediate
structures to also be aligned to 8 bytes, thereby adding padding in
unexpected places.

Thus, change s64 to compat_s64 here, which makes it "misaligned on
paper".  In reality these fields *are* actually aligned (there are 3
preceeding ints outside the union and 3 inside struct _sigchld_x32),
but because of the intervening union and struct it is not possible for
gcc to avoid padding without breaking the ABI.

Reported-and-tested-by: H. J. Lu <hjl.tools@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1329696488-16970-1-git-send-email-hpa@zytor.com
arch/x86/include/asm/ia32.h