On Tuesday 03 November 2015 02:30:30 Yury Norov wrote:
> From: Philipp Tomsich
>
> Based on Andrew Pinski's original patch-series and adapted with changes
> to reduce the duplication of code-paths and resolve issue found during
> LTP testing.
>
> Signed-off-by: Philipp Tomsich
> Signed-off-by: Christoph Muellner
> Signed-off-by: Yury Norov
> Signed-off-by: Andrew Pinski
> Reviewed-by: David Daney
Thanks for the updated version, I'm much happier with this, and only have
some comments on a few details to the later patches.
> +This document describes the ILP32 syscall ABI and where it differs
> +from the generic linux syscall interface.
> +
> +Some structures are changed to reduce the difference in the code path
> +for both ILP32 and LP64 ABIs for signal handling.
> +
> +The following structures have been changed so the layout of the
> +structures are the same between ILP32 and LP64 ABIs, including:
> + * sigval_tcontains pointers
> + * sigeventUses sigval_t which causes it to be the same. Special
> + handing is needed for reading; in the mq_notify syscall
> + * sigaction Conversion is handled in the userland (glibc), as the
> + userland data structures are defined in glibc anyway.
Right, makes sense.
> +A number of structures differ between ILP32 and LP64, including:
> + * timespecuses time_t and suseconds_t
> + * timeval uses time_t and suseconds_t
> + * statuses timespec/time_t
As I commented, we might want to change this for 'stat', which doesn't
really time_t anyway.
> + * semid64_ds uses time_t.
> + * msqid64_ds uses time_t.
> + * shmid64_ds uses time_t.
These use the arm32 layout, right? That's good for consistency.
Fixing these for y2038 will be a bit ugly, but that code can be
shared across all architectures.
> + * rt_sigframe uses siginfo and ucontext.
> + * siginfo_t uses clock_t and sigval_t
> + * ucontextuses stack_t and sigset_t
> + * fd_set This is done to avoid endian issues between ILP32 and
> +LP64. Syscalls consuming fd_set use timespec.
> + * struct msgbuf The specification of 'struct msgbuf' defines the 'mtype'
> + field as a 'long' (i.e. 32bit for ILP32, but 64bit for
> +LP64). Functions that operate on 'struct msgbuf' need
> +to be passed through the compat-syscalls to resolve
> +this.
> + * stack_t contains pointers (handled in the compatibility layer)
> +
> +Also the syscalls which normally would pass 64bit values as two arguments;
> +now pass the 64bit value as one argument. Also they have been renamed
> +(removing the 64 from the name) to avoid confusion.
> +The list of these LP64 syscalls reused by ILP32 clients is:
> + * fcntl
> + * statfs
> + * fstatfs
Did you forget to edit this list? I see fcntl and {f,}statfs use the compat
implementation, not the native one in your patches.
> + * truncate
> + * ftruncate
> + * lseek
> + * sendfile
> + * fadvise64
Makes sense. I think using the normal compat syscalls would have been
just as good here, to save a few lines in the syscall table, but I
agree that the calling conventions are rather silly when you pass
a 64-bit number in two registers.
> + * newfstatat
> + * fstat
This contradicts what you write above regarding separate 'struct stat'.
> + * mmap
Not direct reuse because of the wrapper to check the page size I guess.
Aside from the wrapper, the 32-bit and 64-bit system calls are basically
identical.
Arnd
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