Re: [PATCH v2] RISC-V: Allow long jumps to __syscall_error

[Andrew Waterman <andrew@sifive.com>]

Thank you for making my suggested change.  LGTM.  (I don't have commit
access, though.)

On Fri, Sep 16, 2022 at 12:32 PM Łukasz Stelmach <l.stelmach@samsung.com> wrote:
>
> __syscall_error may end up farther than 1MiB away from a caller,
> especially when linking statically large binaries. tail allows for
> 4GiB jumps and is reduced to j when a linked symbol is within range.
>
> Fixes: 36960f0c76 ("RISC-V: Linux Syscall Interface")
> Fixes: 7f33b09c65 ("RISC-V: Linux ABI")
> Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
> ---
> Changes in v2:
>   - use tail instead of la+jr as advised by Andrew Waterman
>
>  sysdeps/unix/sysv/linux/riscv/clone.S       | 2 +-
>  sysdeps/unix/sysv/linux/riscv/getcontext.S  | 2 +-
>  sysdeps/unix/sysv/linux/riscv/setcontext.S  | 2 +-
>  sysdeps/unix/sysv/linux/riscv/swapcontext.S | 2 +-
>  sysdeps/unix/sysv/linux/riscv/sysdep.h      | 2 +-
>  sysdeps/unix/sysv/linux/riscv/vfork.S       | 2 +-
>  6 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/sysdeps/unix/sysv/linux/riscv/clone.S b/sysdeps/unix/sysv/linux/riscv/clone.S
> index d7d2915e87..45ea8f184b 100644
> --- a/sysdeps/unix/sysv/linux/riscv/clone.S
> +++ b/sysdeps/unix/sysv/linux/riscv/clone.S
> @@ -63,7 +63,7 @@ L (invalid):
>         li              a0, -EINVAL
>         /* Something bad happened -- no child created.  */
>  L (error):
> -       j               __syscall_error
> +       tail            __syscall_error
>         END (__clone)
>
>  /* Load up the arguments to the function.  Put this block of code in
> diff --git a/sysdeps/unix/sysv/linux/riscv/getcontext.S b/sysdeps/unix/sysv/linux/riscv/getcontext.S
> index 499f70b65d..f4f828805c 100644
> --- a/sysdeps/unix/sysv/linux/riscv/getcontext.S
> +++ b/sysdeps/unix/sysv/linux/riscv/getcontext.S
> @@ -70,7 +70,7 @@ LEAF (__getcontext)
>
>         ret
>
> -99:    j       __syscall_error
> +99:    tail    __syscall_error
>
>  PSEUDO_END (__getcontext)
>
> diff --git a/sysdeps/unix/sysv/linux/riscv/setcontext.S b/sysdeps/unix/sysv/linux/riscv/setcontext.S
> index e3bc84a2e6..1e529b900c 100644
> --- a/sysdeps/unix/sysv/linux/riscv/setcontext.S
> +++ b/sysdeps/unix/sysv/linux/riscv/setcontext.S
> @@ -92,7 +92,7 @@ LEAF (__setcontext)
>
>         jr      t1
>
> -99:    j       __syscall_error
> +99:    tail    __syscall_error
>
>  END (__setcontext)
>  libc_hidden_def (__setcontext)
> diff --git a/sysdeps/unix/sysv/linux/riscv/swapcontext.S b/sysdeps/unix/sysv/linux/riscv/swapcontext.S
> index 4da615f6d4..287ba364cd 100644
> --- a/sysdeps/unix/sysv/linux/riscv/swapcontext.S
> +++ b/sysdeps/unix/sysv/linux/riscv/swapcontext.S
> @@ -118,7 +118,7 @@ LEAF (__swapcontext)
>         jr      t1
>
>
> -99:    j       __syscall_error
> +99:    tail    __syscall_error
>
>  PSEUDO_END (__swapcontext)
>
> diff --git a/sysdeps/unix/sysv/linux/riscv/sysdep.h b/sysdeps/unix/sysv/linux/riscv/sysdep.h
> index 37ff07a0d7..aff8d857c9 100644
> --- a/sysdeps/unix/sysv/linux/riscv/sysdep.h
> +++ b/sysdeps/unix/sysv/linux/riscv/sysdep.h
> @@ -102,7 +102,7 @@
>  # else
>  #  define SYSCALL_ERROR_HANDLER(name)                          \
>  .Lsyscall_error ## name:                                       \
> -        j       __syscall_error;
> +        tail    __syscall_error;
>  # endif
>
>  /* Performs a system call, not setting errno.  */
> diff --git a/sysdeps/unix/sysv/linux/riscv/vfork.S b/sysdeps/unix/sysv/linux/riscv/vfork.S
> index 0970543619..1482406e2d 100644
> --- a/sysdeps/unix/sysv/linux/riscv/vfork.S
> +++ b/sysdeps/unix/sysv/linux/riscv/vfork.S
> @@ -39,7 +39,7 @@ LEAF (__libc_vfork)
>         bltz    a0, 1f
>         ret
>
> -1:     j               __syscall_error
> +1:     tail    __syscall_error
>  END (__libc_vfork)
>
>  weak_alias (__libc_vfork, vfork)
> --
> 2.30.2
>