Re: [PATCH 0/3] riscv: Fix debug instruction check and support trap-based WARN()

[Palmer Dabbelt]

On Thu, 28 Feb 2019 02:31:28 PST (-0800), vincentc@xxxxxxxxxxxxx wrote:
> The handler for the debug exception will call is_valid_bugaddr(bugaddr) to
> check if the instruction in bugaddr is a real debug instruction. However,
> the expected instruction, ebreak, is possibly translated to c.ebreak by
> assmebler when C extension is supported. This patchset will add c.ebreak
> into the check mechanism. In addition, BUG() is currently unable to work in
> the kernel module due to an inappropriated condition in is_valid_bugaddr().
> This issue will be fixed in this patchset. Finally, this patchset enables
> WARN() related functions to trap the code to help developers debug it.
>
>
>
>
>
> Vincent Chen (3):
>   riscv: Add the support for c.ebreak check in is_valid_bugaddr()
>   riscv: Support BUG() in kernel module
>   riscv: Make WARN() related functions able to trigger a trap exception

I'm finding this patch set a bit hard to follow, and I think it has more diff 
than is necessary.  For example, the first patch introduces a new die() only to 
have it removed by the third patch.  There's also some unnecessary 
non-functional diff, like

   @@ -149,12 +161,13 @@ int is_valid_bugaddr(unsigned long pc)
           if (probe_kernel_address((bug_insn_t *)pc, insn))
                   return 0;
           if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32)
   -               return insn == __BUG_INSN_32;
   +               return (insn == __BUG_INSN_32);
           else
   -               return (insn & __COMPRESSED_INSN_MASK) == __BUG_INSN_16;
   +               return ((insn & __COMPRESSED_INSN_MASK) == __BUG_INSN_16);
    }
    #endif /* CONFIG_GENERIC_BUG */
   
   +
    void __init trap_init(void)
    {
           /*

I like the idea of the patch set, though.  Do you have time to clean it up and 
submit a v2?