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SubjectRe: [tip:x86/x32] x32: Fix alignment fail in struct compat_siginfo
On 04/18/2012 11:15 AM, H.J. Lu wrote:
>
> In x32 glibc, I have
>
> # if compile for X32
> /* si_utime and si_stime must be 4 byte aligned for x32 to match the
> kernel. We align siginfo_t to 8 bytes so that si_utime and si_stime
> are actually aligned to 8 bytes since their offsets are multiple of
> 8 bytes. */
> typedef __clock_t __attribute__ ((__aligned__ (4))) __sigchld_clock_t;
> # define __SI_ALIGNMENT __attribute__ ((__aligned__ (8)))
> # else
> typedef __clock_t __sigchld_clock_t;
> # define __SI_ALIGNMENT
> # endif
>
> typedef struct siginfo
> {
> ...
> /* SIGCHLD. */
> struct
> {
> __pid_t si_pid; /* Which child. */
> __uid_t si_uid; /* Real user ID of sending process. */
> int si_status; /* Exit value or signal. */
> __sigchld_clock_t si_utime;
> __sigchld_clock_t si_stime;
> } _sigchld;
> ...
> } siginfo_t __SI_ALIGNMENT;
>

So in other words, a separate type just for this. However, the question
still holds: could we simply change __kernel_clock_t for x32 and be done
with it? It would affect the alignment of struct tms, I guess; it
wouldn't really affect the kernel directly since the kernel gets a
pointer straight from userspace for times(2), but it would kind of mess
up a userspace which uses __kernel_clock_t directly.

Urk, okay...

-hpa


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