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s390/signal: cleanup uapi struct sigaction

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The struct sigaction for user space in arch/s390/include/uapi/asm/signal.h
is ill defined. The kernel uses two structures 'struct sigaction' and
'struct old_sigaction', the correlation in the kernel for both 31 and
64 bit is as follows

    sys_sigaction -> struct old_sigaction
    sys_rt_sigaction -> struct sigaction

The correlation of the (single) uapi definition for 'struct sigaction'
under '#ifndef __KERNEL__':

    31-bit: sys_sigaction -> uapi struct sigaction
    31-bit: sys_rt_sigaction -> no structure available

    64-bit: sys_sigaction -> no structure available
    64-bit: sys_rt_sigaction -> uapi struct sigaction

This is quite confusing. To make it a bit less confusing make the
uapi definition of 'struct sigaction' usable for sys_rt_sigaction for
both 31-bit and 64-bit.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2018-04-12 13:48:25 +02:00
parent 49d23a851d
commit fae7649121
1 changed files with 16 additions and 7 deletions
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23
arch/s390/include/uapi/asm/signal.h
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@ -97,22 +97,31 @@ typedef unsigned long sigset_t;
#include <asm-generic/signal-defs.h>
#ifndef __KERNEL__
/* Here we must cater to libcs that poke about in kernel headers. */
/*
* There are two system calls in regard to sigaction, sys_rt_sigaction
* and sys_sigaction. Internally the kernel uses the struct old_sigaction
* for the older sys_sigaction system call, and the kernel version of the
* struct sigaction for the newer sys_rt_sigaction.
*
* The uapi definition for struct sigaction has made a strange distinction
* between 31-bit and 64-bit in the past. For 64-bit the uapi structure
* looks like the kernel struct sigaction, but for 31-bit it used to
* look like the kernel struct old_sigaction. That practically made the
* structure unusable for either system call. To get around this problem
* the glibc always had its own definitions for the sigaction structures.
*
* The current struct sigaction uapi definition below is suitable for the
* sys_rt_sigaction system call only.
*/
struct sigaction {
union {
__sighandler_t _sa_handler;
void (*_sa_sigaction)(int, struct siginfo *, void *);
} _u;
#ifndef __s390x__ /* lovely */
sigset_t sa_mask;
unsigned long sa_flags;
void (*sa_restorer)(void);
#else /* __s390x__ */
unsigned long sa_flags;
void (*sa_restorer)(void);
sigset_t sa_mask;
#endif /* __s390x__ */
};
#define sa_handler _u._sa_handler