From: David Drysdale <redacted>
Date: Thu, 20 Nov 2014 11:28:22 +0000

On Wed, Nov 19, 2014 at 11:42 PM, Stephen Rothwell [off-list ref] wrote:

quoted

Hi David,

On Wed, 19 Nov 2014 17:27:51 +0000 David Drysdale [off-list ref] wrote:

quoted

diff --git a/arch/sparc/kernel/systbls_64.S b/arch/sparc/kernel/systbls_64.S
index 580cde9370c9..15069cb35dac 100644
--- a/arch/sparc/kernel/systbls_64.S
+++ b/arch/sparc/kernel/systbls_64.S

@@ -88,6 +88,7 @@ sys_call_table32:
      .word sys_syncfs, compat_sys_sendmmsg, sys_setns, compat_sys_process_vm_readv, compat_sys_process_vm_writev
 /*340*/      .word sys_kern_features, sys_kcmp, sys_finit_module, sys_sched_setattr, sys_sched_getattr
      .word sys32_renameat2, sys_seccomp, sys_getrandom, sys_memfd_create, sys_bpf
+/*350*/      .word sys_execveat

Shouldn't this be compat_sys_execveat?

Yeah, that would make sense -- thanks for spotting.

Looking at this more closely, I also wonder if we need a pair of wrappers
analogous to sys(32|64)_execve -- they include a (pipeline-executed)
flushw instruction after the jmpl to [compat_]sys_execve, which I guess
might be needed.  So I could add something like the following to
arch/sparc/kernel/syscalls.S:

  sys64_execveat:
      set sys_execveat, %g1
      jmpl %g1, %g0
      flushw
  #ifdef CONFIG_COMPAT
  sys32_execveat:
      set compat_sys_execveat, %g1
      jmpl %g1, %g0
      flushw
  #endif

However, I don't speak SPARC and can't run the code -- any thoughts
out there from someone who does & can?

Or maybe I should stop trying to be helpful with speculative patches, and
just leave wiring up the sparc stuff to the experts...

You need wrappers for execve() like system calls yes, in order to flush all
of the user register windows to the stack before the kill the address space.

I think your code snippet above is fine, except that you should indent
the flushw by one space more because it is in the delay slot of a
control transfer instruction.

Thanks.