Re: [PATCH bpf-next] riscv, bpf: Fix RV32 broken build, and silence RV64 warning

On 11/3/21 2:35 PM, Björn Töpel wrote:

On Wed, 3 Nov 2021 at 14:15, Daniel Borkmann [off-list ref] wrote:

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On 11/3/21 12:54 PM, Björn Töpel wrote:

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Commit 252c765bd764 ("riscv, bpf: Add BPF exception tables") only
addressed RV64, and broke the RV32 build [1]. Fix by gating the exception
tables code with CONFIG_ARCH_RV64I.

Further, silence a "-Wmissing-prototypes" warning [2] in the RV64 BPF
JIT.

[1] https://lore.kernel.org/llvm/202111020610.9oy9Rr0G-lkp@intel.com/ (local)
[2] https://lore.kernel.org/llvm/202110290334.2zdMyRq4-lkp@intel.com/ (local)

Fixes: 252c765bd764 ("riscv, bpf: Add BPF exception tables")
Signed-off-by: Björn Töpel <bjorn@kernel.org>
---
Tong/Daniel: The RV32 build has been broken since Thursday. I'll try
to fast-track a bit, and commit a quick-fix for it. Hope that's OK
with you, Tong!

I've verified the build on my machine using riscv32 GCC 9.3.0 and
riscv64 GCC 11.2.0.

Thanks for the fix Bjorn!

[...]

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+int rv_bpf_fixup_exception(const struct exception_table_entry *ex,
+                             struct pt_regs *regs);

I'm okay to take this as a quick fix, but if its not too much hassle, could we add a
arch/riscv/include/asm/extable.h in similar fashion like arm64 or x86 where we move
the ex_handler_bpf() signature there, did you have a chance to check?

OK! I've not looked into it yet!

There's a patch out from Jisheng on the RV list, which is starting
some consolidation work [1].

@Jisheng What do you think about adding type/handlers [2,3] as
arm64/x86 recently did, to your series?

Fyi, Bjorn, took your fix into bpf so we can move forward wrt broken build & warning
given its small anyway and I'm doing bpf PR very soon today. Either way, Jisheng, you
or Tong can follow-up looking into the extable streamlining wrt arm64/x86. Thanks!

[1] https://lore.kernel.org/linux-riscv/20211022001957.1eba8f04@xhacker/ (local)
[2] https://lore.kernel.org/linux-arm-kernel/20211019160219.5202-11-mark.rutland@arm.com/ (local)
[3] https://lore.kernel.org/lkml/20210908132525.211958725@linutronix.de/ (local)