2023-07-25 06:14:46

by Nam Cao

[permalink] [raw]
Subject: [PATCH] riscv: remove redundant mv instructions

Some mv instructions were useful when first introduced to preserve a0 and
a1 before function calls. However the code has changed and they are now
redundant. Remove them.

Signed-off-by: Nam Cao <[email protected]>
---
arch/riscv/kernel/head.S | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 11c3b94c4534..3710ea5d160f 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -289,10 +289,6 @@ clear_bss:
blt a3, a4, clear_bss
clear_bss_done:
#endif
- /* Save hart ID and DTB physical address */
- mv s0, a0
- mv s1, a1
-
la a2, boot_cpu_hartid
XIP_FIXUP_OFFSET a2
REG_S a0, (a2)
@@ -306,7 +302,7 @@ clear_bss_done:
la a0, __dtb_start
XIP_FIXUP_OFFSET a0
#else
- mv a0, s1
+ mv a0, a1
#endif /* CONFIG_BUILTIN_DTB */
call setup_vm
#ifdef CONFIG_MMU
--
2.34.1



2023-07-25 08:38:38

by Alexandre Ghiti

[permalink] [raw]
Subject: Re: [PATCH] riscv: remove redundant mv instructions

Hi Nam,


On 25/07/2023 07:38, Nam Cao wrote:
> Some mv instructions were useful when first introduced to preserve a0 and
> a1 before function calls. However the code has changed and they are now
> redundant. Remove them.
>
> Signed-off-by: Nam Cao <[email protected]>
> ---
> arch/riscv/kernel/head.S | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
> index 11c3b94c4534..3710ea5d160f 100644
> --- a/arch/riscv/kernel/head.S
> +++ b/arch/riscv/kernel/head.S
> @@ -289,10 +289,6 @@ clear_bss:
> blt a3, a4, clear_bss
> clear_bss_done:
> #endif
> - /* Save hart ID and DTB physical address */
> - mv s0, a0
> - mv s1, a1
> -
> la a2, boot_cpu_hartid
> XIP_FIXUP_OFFSET a2
> REG_S a0, (a2)
> @@ -306,7 +302,7 @@ clear_bss_done:
> la a0, __dtb_start
> XIP_FIXUP_OFFSET a0
> #else
> - mv a0, s1
> + mv a0, a1
> #endif /* CONFIG_BUILTIN_DTB */
> call setup_vm
> #ifdef CONFIG_MMU


You can add:

Reviewed-by: Alexandre Ghiti <[email protected]>

Thanks,

Alex


Subject: Re: [PATCH] riscv: remove redundant mv instructions

Hello:

This patch was applied to riscv/linux.git (for-next)
by Palmer Dabbelt <[email protected]>:

On Tue, 25 Jul 2023 07:38:35 +0200 you wrote:
> Some mv instructions were useful when first introduced to preserve a0 and
> a1 before function calls. However the code has changed and they are now
> redundant. Remove them.
>
> Signed-off-by: Nam Cao <[email protected]>
> ---
> arch/riscv/kernel/head.S | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)

Here is the summary with links:
- riscv: remove redundant mv instructions
https://git.kernel.org/riscv/c/10f763532d58

You are awesome, thank you!
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