Messages in this thread Patch in this message | | | Subject | Re: [PATCH v2 1/3] powerpc: Don't force ENOSYS as error on syscall fail | From | Michael Ellerman <> | Date | Thu, 12 Feb 2015 16:24:39 +1100 |
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On Wed, 2015-02-11 at 08:36 +0000, Bogdan Purcareata wrote: > In certain scenarios - e.g. seccomp filtering with ERRNO as default action - > the system call fails for other reasons than the syscall not being available. > The seccomp filter can be configured to store a user-defined error code on > return from a blacklisted syscall. Don't always set ENOSYS on > do_syscall_trace_enter failure. > > v2: > - move setting ENOSYS as errno from the syscall entry assembly to > do_syscall_trace_enter, only in the specific case
> diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S > index 194e46d..0111e04 100644 > --- a/arch/powerpc/kernel/entry_64.S > +++ b/arch/powerpc/kernel/entry_64.S > @@ -269,7 +269,6 @@ syscall_dotrace: > b .Lsyscall_dotrace_cont > > syscall_enosys: > - li r3,-ENOSYS > b syscall_exit
This still looks wrong to me.
On 64 bit we do:
CURRENT_THREAD_INFO(r11, r1) ld r10,TI_FLAGS(r11) andi. r11,r10,_TIF_SYSCALL_DOTRACE bne syscall_dotrace .Lsyscall_dotrace_cont: cmpldi 0,r0,NR_syscalls bge- syscall_enosys ...
syscall_enosys: li r3,-ENOSYS b .Lsyscall_exit
Your patch removes the load of ENOSYS. Which means if we're not doing syscall tracing, and we get an out-of-bounds syscall number, we'll return with something random on r3. Won't we?
The 32-bit code looks more or less similar, although the label has a different name.
cheers
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