linux-kernel - Re: [PATCH] powerpc: Fix 'intra_function

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Message-ID: <934be33f-ba7d-4363-a1c8-e9e7c381646a@linux.ibm.com>
Date: Wed, 5 Mar 2025 09:34:17 +0530
From: Venkat Rao Bagalkote <venkat88@...ux.ibm.com>
To: Christophe Leroy <christophe.leroy@...roup.eu>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>, Naveen N Rao <naveen@...nel.org>,
        Madhavan Srinivasan <maddy@...ux.ibm.com>
Cc: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH] powerpc: Fix 'intra_function_call not a direct call'
 warning

Hello Christophe,

On 05/03/25 4:30 am, Christophe Leroy wrote:
> The following build warning have been reported:
>
>    arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0xe84: intra_function_call not a direct call
>    arch/powerpc/kernel/switch.o: warning: objtool: .text+0x4: intra_function_call not a direct call
>
> This happens due to commit bb7f054f4de2 ("objtool/powerpc: Add support
> for decoding all types of uncond branches") because that commit decodes
> 'bl .+4' as a normal instruction because that instruction is used by
> clang instead of 'bcl 20,31,+.4' for relocatable code.
>
> The solution is simply to remove the ANNOTATE_INTRA_FUNCTION_CALL
> annotation now that the instruction is not seen as a function call
> anymore.
>
> Reported-by: Venkat Rao Bagalkote <venkat88@...ux.ibm.com>
> Closes: https://lore.kernel.org/all/8c4c3fc2-2bd7-4148-af68-2f504d6119e0@linux.ibm.com
> Fixes: bb7f054f4de2 ("objtool/powerpc: Add support for decoding all types of uncond branches")
> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
> ---
>   arch/powerpc/kernel/switch.S            | 1 -
>   arch/powerpc/kvm/book3s_hv_rmhandlers.S | 2 --
>   2 files changed, 3 deletions(-)
>
> diff --git a/arch/powerpc/kernel/switch.S b/arch/powerpc/kernel/switch.S
> index 608c0ce7cec6..59e3ee99db0e 100644
> --- a/arch/powerpc/kernel/switch.S
> +++ b/arch/powerpc/kernel/switch.S
> @@ -39,7 +39,6 @@ flush_branch_caches:
>   
>   	// Flush the link stack
>   	.rept 64
> -	ANNOTATE_INTRA_FUNCTION_CALL
>   	bl	.+4
>   	.endr
>   	b	1f
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index ea7ad200b330..83f7504349d2 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -1524,14 +1524,12 @@ kvm_flush_link_stack:
>   
>   	/* Flush the link stack. On Power8 it's up to 32 entries in size. */
>   	.rept 32
> -	ANNOTATE_INTRA_FUNCTION_CALL
>   	bl	.+4
>   	.endr
>   
>   	/* And on Power9 it's up to 64. */
>   BEGIN_FTR_SECTION
>   	.rept 32
> -	ANNOTATE_INTRA_FUNCTION_CALL
>   	bl	.+4
>   	.endr
>   END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)


Applied this patch on top of linux-next 20250303, and it fixes the below 
reported warning.

arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0xe84: intra_function_call not a direct call
arch/powerpc/kernel/switch.o: warning: objtool: .text+0x4: intra_function_call not a direct call



Please add below tag:

Tested-By: Venkat Rao Bagalkote <venkat88@...ux.ibm.com>

Regards,
Venkat.