From: Palmer Dabbelt <palmer@dabbelt.com>
To: greentime.hu@sifive.com
Cc: greentime.hu@sifive.com, linux-riscv@lists.infradead.org,
aou@eecs.berkeley.edu, linux-kernel@vger.kernel.org,
Paul Walmsley <paul.walmsley@sifive.com>
Subject: Re: [PATCH 2/2] riscv: Simplify the checking for SR_PP
Date: Tue, 21 Jul 2020 19:59:00 -0700 (PDT) [thread overview]
Message-ID: <mhng-94c29866-a954-4eaf-916a-9ed87b560d19@palmerdabbelt-glaptop1> (raw)
In-Reply-To: <4bac52941700cd7b714a41606df7b53f4cf24824.1594629047.git.greentime.hu@sifive.com>
On Mon, 13 Jul 2020 01:32:16 PDT (-0700), greentime.hu@sifive.com wrote:
> This patch simplifies the checking for SR_MPP and SR_SPP. It uses SR_PP in the
> code flow for both m-mode and s-mode then we can remove the ifdef here.
>
> Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
> ---
> arch/riscv/kernel/entry.S | 7 +------
> 1 file changed, 1 insertion(+), 6 deletions(-)
>
> diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
> index 000984695cd6..597beae0d238 100644
> --- a/arch/riscv/kernel/entry.S
> +++ b/arch/riscv/kernel/entry.S
> @@ -210,13 +210,8 @@ ret_from_syscall_rejected:
> ret_from_exception:
> REG_L s0, PT_STATUS(sp)
> csrc CSR_STATUS, SR_IE
> -#ifdef CONFIG_RISCV_M_MODE
> - /* the MPP value is too large to be used as an immediate arg for addi */
> - li t0, SR_MPP
> + li t0, SR_PP
> and s0, s0, t0
> -#else
> - andi s0, s0, SR_SPP
> -#endif
> bnez s0, resume_kernel
>
> resume_userspace:
This one is actually on a fairly fast path, so I can buy it's worth saving the
cycle.
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next prev parent reply other threads:[~2020-07-22 2:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-13 8:32 [PATCH 1/2] riscv: Fix building error in entry.S when CONFIG_RISCV_M_MODE is enabled Greentime Hu
2020-07-13 8:32 ` [PATCH 2/2] riscv: Simplify the checking for SR_PP Greentime Hu
2020-07-22 2:59 ` Palmer Dabbelt [this message]
2020-07-13 20:11 ` [PATCH 1/2] riscv: Fix building error in entry.S when CONFIG_RISCV_M_MODE is enabled Palmer Dabbelt
2020-07-22 2:58 ` Palmer Dabbelt
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