Re: [PATCH] ppc: Fix BPF JIT for ABIv2
From: Naveen N. Rao <hidden>
Date: 2016-06-21 10:36:06
Also in:
linuxppc-dev, lkml
On 2016/06/20 03:56PM, Thadeu Lima de Souza Cascardo wrote:
On Sun, Jun 19, 2016 at 11:19:14PM +0530, Naveen N. Rao wrote:quoted
On 2016/06/17 10:00AM, Thadeu Lima de Souza Cascardo wrote:quoted
Hi, Michael and Naveen. I noticed independently that there is a problem with BPF JIT and ABIv2, and worked out the patch below before I noticed Naveen's patchset and the latest changes in ppc tree for a better way to check for ABI versions. However, since the issue described below affect mainline and stable kernels, would you consider applying it before merging your two patchsets, so that we can more easily backport the fix?Hi Cascardo, Given that this has been broken on ABIv2 since forever, I didn't bother fixing it. But, I can see why this would be a good thing to have for -stable and existing distros. However, while your patch below may fix the crash you're seeing on ppc64le, it is not sufficient -- you'll need changes in bpf_jit_asm.S as well.Hi, Naveen. Any tips on how to exercise possible issues there? Or what changes you think would be sufficient?
The calling convention is different with ABIv2 and so we'll need changes in bpf_slow_path_common() and sk_negative_common(). However, rather than enabling classic JIT for ppc64le, are we better off just disabling it?
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig@@ -128,7 +128,7 @@ config PPC select IRQ_FORCED_THREADING select HAVE_RCU_TABLE_FREE if SMP select HAVE_SYSCALL_TRACEPOINTS - select HAVE_CBPF_JIT + select HAVE_CBPF_JIT if CPU_BIG_ENDIAN select HAVE_ARCH_JUMP_LABEL select ARCH_HAVE_NMI_SAFE_CMPXCHG select ARCH_HAS_GCOV_PROFILE_ALL
Michael, Let me know your thoughts on whether you intend to take this patch or Cascardo's patch for -stable before the eBPF patches. I can redo my patches accordingly. - Naveen _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev