From: Conor Dooley <conor@kernel.org>
To: Charlie Jenkins <charlie@rivosinc.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>,
linux-kernel@vger.kernel.org, Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
linux-riscv@lists.infradead.org
Subject: Re: [PATCH v2 2/5] riscv: Add checksum library
Date: Thu, 7 Sep 2023 10:52:35 +0100 [thread overview]
Message-ID: <20230907-9d5d2e7ef2a20edd75514470@fedora> (raw)
In-Reply-To: <20230905-optimize_checksum-v2-2-ccd658db743b@rivosinc.com>
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On Tue, Sep 05, 2023 at 09:46:51PM -0700, Charlie Jenkins wrote:
> +#ifdef CONFIG_RISCV_ISA_ZBB
> + if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) {
> + /*
> + * Zbb is likely available when the kernel is compiled with Zbb
> + * support, so nop when Zbb is available and jump when Zbb is
> + * not available.
> + */
> + asm_volatile_goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0,
> + RISCV_ISA_EXT_ZBB, 1)
> + :
> + :
> + :
> + : no_zbb);
> + } else {
> + if (!__riscv_isa_extension_available(NULL, RISCV_ISA_EXT_ZBB))
> + goto no_zbb;
> + }
Again, do these constructs have an appreciable benefit over doing
if (!riscv_has_extension_likely(<ZBB>)
goto no_zbb;
?
That encaspulates the fallback to a non-alternative mechanism for you,
in case you had not noticed.
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next prev parent reply other threads:[~2023-09-07 9:52 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-06 4:46 [PATCH v2 0/5] riscv: Add fine-tuned checksum functions Charlie Jenkins
2023-09-06 4:46 ` [PATCH v2 1/5] riscv: Checksum header Charlie Jenkins
2023-09-07 9:40 ` Conor Dooley
2023-09-07 17:44 ` Charlie Jenkins
2023-09-10 21:20 ` David Laight
2023-09-11 18:16 ` Charlie Jenkins
2023-09-06 4:46 ` [PATCH v2 2/5] riscv: Add checksum library Charlie Jenkins
2023-09-07 9:52 ` Conor Dooley [this message]
2023-09-07 17:47 ` Charlie Jenkins
2023-09-06 4:46 ` [PATCH v2 3/5] riscv: Vector checksum header Charlie Jenkins
2023-09-07 9:47 ` Conor Dooley
2023-09-07 17:43 ` Charlie Jenkins
2023-09-07 9:58 ` Conor Dooley
2023-09-07 17:41 ` Charlie Jenkins
2023-09-06 4:46 ` [PATCH v2 4/5] riscv: Vector checksum library Charlie Jenkins
2023-09-06 4:46 ` [PATCH v2 5/5] riscv: Test checksum functions Charlie Jenkins
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