From: Conor Dooley <conor@kernel.org>
To: "Björn Töpel" <bjorn@kernel.org>
Cc: "Paul Walmsley" <paul.walmsley@sifive.com>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Albert Ou" <aou@eecs.berkeley.edu>,
linux-riscv@lists.infradead.org, "Guo Ren" <guoren@kernel.org>,
"Björn Töpel" <bjorn@rivosinc.com>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH] riscv, kprobes: Stricter c.jr/c.jalr decoding
Date: Tue, 3 Jan 2023 10:33:20 +0000 [thread overview]
Message-ID: <Y7QEcDU0sMoKrpw4@spud> (raw)
In-Reply-To: <87sfgsp15q.fsf@all.your.base.are.belong.to.us>
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On Tue, Jan 03, 2023 at 07:44:49AM +0100, Björn Töpel wrote:
> Conor Dooley <conor@kernel.org> writes:
> > On Mon, Jan 02, 2023 at 05:07:48PM +0100, Björn Töpel wrote:
> >> From: Björn Töpel <bjorn@rivosinc.com>
> >> diff --git a/arch/riscv/kernel/probes/simulate-insn.h b/arch/riscv/kernel/probes/simulate-insn.h
> >> index cb6ff7dccb92..de8474146a9b 100644
> >> --- a/arch/riscv/kernel/probes/simulate-insn.h
> >> +++ b/arch/riscv/kernel/probes/simulate-insn.h
> >> @@ -31,9 +31,9 @@ __RISCV_INSN_FUNCS(fence, 0x7f, 0x0f);
> >> } while (0)
> >>
> >> __RISCV_INSN_FUNCS(c_j, 0xe003, 0xa001);
> >> -__RISCV_INSN_FUNCS(c_jr, 0xf007, 0x8002);
> >
> > Hmm, I wonder where the mask originally came from!
>
> I think it's just a simple bug -- missing that "rs2" must be zero.
>
> > I had a look at the compressed spec, of which the version google gave to
> > me was v1.9 [1], and Table 1.6 in that (Instruction listing for RVC,
> > Quadrant 2) seems to list them all together.
> > [1] -
> > https://riscv.org/wp-content/uploads/2015/11/riscv-compressed-spec-v1.9.pdf
>
> C-ext is part of the unpriv spec:
> https://github.com/riscv/riscv-isa-manual/releases
Yah, I was trying to see if there was some period piece which was
misleading that would have explained the mask. I looked again & the v1.7
spec doesn't have that table, but also has no reason to suggest the
current mask either. Guess it was just a mistake :)
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next prev parent reply other threads:[~2023-01-03 10:34 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-02 16:07 [PATCH] riscv, kprobes: Stricter c.jr/c.jalr decoding Björn Töpel
2023-01-02 20:31 ` Conor Dooley
2023-01-03 6:44 ` Björn Töpel
2023-01-03 10:33 ` Conor Dooley [this message]
2023-01-03 9:59 ` Guo Ren
2023-01-05 23:00 ` patchwork-bot+linux-riscv
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