[PATCH v9 2/6] arch: move SA_* definitions to generic headers

[Peter Collingbourne]

On Wed, Aug 19, 2020 at 3:30 AM Dave Martin <Dave.Martin at arm.com> wrote:
>
> On Mon, Aug 17, 2020 at 08:33:47PM -0700, Peter Collingbourne wrote:
> > Most architectures with the exception of alpha, mips, parisc and
> > sparc use the same values for these flags. Move their definitions into
> > asm-generic/signal-defs.h and allow the architectures with non-standard
> > values to override them. Also, document the non-standard flag values
> > in order to make it easier to add new generic flags in the future.
> >
> > Signed-off-by: Peter Collingbourne <pcc at google.com>
> > ---
> > View this change in Gerrit: https://linux-review.googlesource.com/q/Ia3849f18b8009bf41faca374e701cdca36974528
> >
> >  arch/alpha/include/uapi/asm/signal.h   | 14 --------
> >  arch/arm/include/uapi/asm/signal.h     | 28 ++-------------
> >  arch/h8300/include/uapi/asm/signal.h   | 24 -------------
> >  arch/ia64/include/uapi/asm/signal.h    | 24 -------------
> >  arch/m68k/include/uapi/asm/signal.h    | 24 -------------
> >  arch/mips/include/uapi/asm/signal.h    | 12 -------
> >  arch/parisc/include/uapi/asm/signal.h  | 13 -------
> >  arch/powerpc/include/uapi/asm/signal.h | 24 -------------
> >  arch/s390/include/uapi/asm/signal.h    | 24 -------------
> >  arch/sparc/include/uapi/asm/signal.h   |  4 +--
> >  arch/x86/include/uapi/asm/signal.h     | 24 -------------
> >  arch/xtensa/include/uapi/asm/signal.h  | 24 -------------
> >  include/uapi/asm-generic/signal-defs.h | 47 ++++++++++++++++++++++++++
> >  include/uapi/asm-generic/signal.h      | 29 ----------------
> >  14 files changed, 51 insertions(+), 264 deletions(-)
>
> Nice diffstat!
>
> >
> > diff --git a/arch/alpha/include/uapi/asm/signal.h b/arch/alpha/include/uapi/asm/signal.h
> > index 74c750bf1c1a..a69dd8d080a8 100644
> > --- a/arch/alpha/include/uapi/asm/signal.h
> > +++ b/arch/alpha/include/uapi/asm/signal.h
> > @@ -60,20 +60,6 @@ typedef unsigned long sigset_t;
> >  #define SIGRTMIN     32
> >  #define SIGRTMAX     _NSIG
> >
> > -/*
> > - * SA_FLAGS values:
> > - *
> > - * SA_ONSTACK indicates that a registered stack_t will be used.
> > - * SA_RESTART flag to get restarting signals (which were the default long ago)
> > - * SA_NOCLDSTOP flag to turn off SIGCHLD when children stop.
> > - * SA_RESETHAND clears the handler when the signal is delivered.
> > - * SA_NOCLDWAIT flag on SIGCHLD to inhibit zombies.
> > - * SA_NODEFER prevents the current signal from being masked in the handler.
> > - *
> > - * SA_ONESHOT and SA_NOMASK are the historical Linux names for the Single
> > - * Unix names RESETHAND and NODEFER respectively.
> > - */
> > -
> >  #define SA_ONSTACK   0x00000001
> >  #define SA_RESTART   0x00000002
> >  #define SA_NOCLDSTOP 0x00000004
> > diff --git a/arch/arm/include/uapi/asm/signal.h b/arch/arm/include/uapi/asm/signal.h
> > index 9b4185ba4f8a..7727f0984d26 100644
> > --- a/arch/arm/include/uapi/asm/signal.h
> > +++ b/arch/arm/include/uapi/asm/signal.h
> > @@ -60,33 +60,11 @@ typedef unsigned long sigset_t;
> >  #define SIGSWI               32
> >
> >  /*
> > - * SA_FLAGS values:
> > - *
> > - * SA_NOCLDSTOP              flag to turn off SIGCHLD when children stop.
> > - * SA_NOCLDWAIT              flag on SIGCHLD to inhibit zombies.
> > - * SA_SIGINFO                deliver the signal with SIGINFO structs
> > - * SA_THIRTYTWO              delivers the signal in 32-bit mode, even if the task
> > - *                   is running in 26-bit.
> > - * SA_ONSTACK                allows alternate signal stacks (see sigaltstack(2)).
> > - * SA_RESTART                flag to get restarting signals (which were the default long ago)
> > - * SA_NODEFER                prevents the current signal from being masked in the handler.
> > - * SA_RESETHAND              clears the handler when the signal is delivered.
> > - *
> > - * SA_ONESHOT and SA_NOMASK are the historical Linux names for the Single
> > - * Unix names RESETHAND and NODEFER respectively.
> > + * SA_THIRTYTWO historically meant deliver the signal in 32-bit mode, even if
> > + * the task is running in 26-bit. But since the kernel no longer supports
> > + * 26-bit mode, the flag has no effect.
> >   */
> > -#define SA_NOCLDSTOP 0x00000001
> > -#define SA_NOCLDWAIT 0x00000002
> > -#define SA_SIGINFO   0x00000004
> >  #define SA_THIRTYTWO 0x02000000
>
> Can we add a placeholder for this in the common header?  We don't want
> people accidentally defining a new generic flag that clashes with this.

This flag (bit 25) is covered by the comment in
include/uapi/asm-generic/signal-defs.h that reads:

/*
 * The following bits are used in architecture-specific SA_* definitions and
 * should be avoided for new generic flags: 3, 4, 5, 6, 7, 8, 9, 16, 24, 25, 26.
 */

Peter