Re: [RESEND PATCH] MIPS: head: Reorder instructions missing a delay slot
On Tue, Jun 27, 2017 at 07:22:16PM +, Karl Beldan wrote: > In this sequence the 'move' is assumed in the delay slot of the 'beq', > but head.S is in reorder mode and the former gets pushed one 'nop' > farther by the assembler. > > The corrected behavior made booting with an UHI supplied dtb erratic. Excellent catch, patch applied! Thanks Karl, Ralf
Re: [RESEND PATCH] MIPS: head: Reorder instructions missing a delay slot
On Tue, Jun 27, 2017 at 07:22:16PM +, Karl Beldan wrote:
> In this sequence the 'move' is assumed in the delay slot of the 'beq',
> but head.S is in reorder mode and the former gets pushed one 'nop'
> farther by the assembler.
>
> The corrected behavior made booting with an UHI supplied dtb erratic.
>
> Fixes: 15f37e158892 ("MIPS: store the appended dtb address in a variable")
> Cc:
> Cc: Ralf Baechle
> Cc: Jonas Gorski
> Signed-off-by: Karl Beldan
Ouch, nice catch.
Reviewed-by: James Hogan
Cheers
James
> ---
> arch/mips/kernel/head.S | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S
> index cf05220..d1bb506 100644
> --- a/arch/mips/kernel/head.S
> +++ b/arch/mips/kernel/head.S
> @@ -106,8 +106,8 @@ NESTED(kernel_entry, 16, sp) #
> kernel entry point
> beq t0, t1, dtb_found
> #endif
> li t1, -2
> - beq a0, t1, dtb_found
> movet2, a1
> + beq a0, t1, dtb_found
>
> li t2, 0
> dtb_found:
> --
> 2.10.1
>
>
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[RESEND PATCH] MIPS: head: Reorder instructions missing a delay slot
In this sequence the 'move' is assumed in the delay slot of the 'beq',
but head.S is in reorder mode and the former gets pushed one 'nop'
farther by the assembler.
The corrected behavior made booting with an UHI supplied dtb erratic.
Fixes: 15f37e158892 ("MIPS: store the appended dtb address in a variable")
Cc:
Cc: Ralf Baechle
Cc: Jonas Gorski
Signed-off-by: Karl Beldan
---
arch/mips/kernel/head.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S
index cf05220..d1bb506 100644
--- a/arch/mips/kernel/head.S
+++ b/arch/mips/kernel/head.S
@@ -106,8 +106,8 @@ NESTED(kernel_entry, 16, sp)#
kernel entry point
beq t0, t1, dtb_found
#endif
li t1, -2
- beq a0, t1, dtb_found
movet2, a1
+ beq a0, t1, dtb_found
li t2, 0
dtb_found:
--
2.10.1
