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

From: Vincent Chen
Date: Mon Mar 04 2019 - 19:22:06 EST


On Tue, Mar 05, 2019 at 04:35:08AM +0800, Palmer Dabbelt wrote:
> 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?


OK, I will improve it and submit a v2 patch.