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From: Nam Cao <namcao@linutronix.de>
To: Rui Qi <qirui.001@bytedance.com>,
	palmer@dabbelt.com, pjw@kernel.org, aou@eecs.berkeley.edu,
	alex@ghiti.fr
Cc: Rui Qi <qirui.001@bytedance.com>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] riscv: fix frame pointer in call_on_irq_stack for RV32
Date: Mon, 22 Jun 2026 20:08:31 +0200	[thread overview]
Message-ID: <87h5muv468.fsf@yellow.woof> (raw)
In-Reply-To: <20260603035305.564823-1-qirui.001@bytedance.com>

"Rui Qi" <qirui.001@bytedance.com> writes:
> --- a/arch/riscv/kernel/entry.S
> +++ b/arch/riscv/kernel/entry.S
> @@ -383,7 +383,7 @@ SYM_FUNC_START(call_on_irq_stack)
>  	addi	sp, sp, -STACKFRAME_SIZE_ON_STACK
>  	REG_S	ra, STACKFRAME_RA(sp)
>  	REG_S	s0, STACKFRAME_FP(sp)
> -	addi	s0, sp, STACKFRAME_SIZE_ON_STACK
> +	addi	s0, sp, STACKFRAME_SIZE

Doesn't this break the calling convention? The ABI specifies that "After
the prologue, the frame pointer register will point to [...] the stack
pointer value on entry to the current procedure". The frame pointer is
already correct here.

It is the storage locations of ra and fp that are broken. The ABI says
"This puts the return address at fp - XLEN/8, and the previous frame
pointer at fp - 2 * XLEN/8".

Or am I confused?

Nam

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WARNING: multiple messages have this Message-ID (diff)
From: Nam Cao <namcao@linutronix.de>
To: Rui Qi <qirui.001@bytedance.com>,
	palmer@dabbelt.com, pjw@kernel.org, aou@eecs.berkeley.edu,
	alex@ghiti.fr
Cc: Rui Qi <qirui.001@bytedance.com>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] riscv: fix frame pointer in call_on_irq_stack for RV32
Date: Mon, 22 Jun 2026 20:08:31 +0200	[thread overview]
Message-ID: <87h5muv468.fsf@yellow.woof> (raw)
In-Reply-To: <20260603035305.564823-1-qirui.001@bytedance.com>

"Rui Qi" <qirui.001@bytedance.com> writes:
> --- a/arch/riscv/kernel/entry.S
> +++ b/arch/riscv/kernel/entry.S
> @@ -383,7 +383,7 @@ SYM_FUNC_START(call_on_irq_stack)
>  	addi	sp, sp, -STACKFRAME_SIZE_ON_STACK
>  	REG_S	ra, STACKFRAME_RA(sp)
>  	REG_S	s0, STACKFRAME_FP(sp)
> -	addi	s0, sp, STACKFRAME_SIZE_ON_STACK
> +	addi	s0, sp, STACKFRAME_SIZE

Doesn't this break the calling convention? The ABI specifies that "After
the prologue, the frame pointer register will point to [...] the stack
pointer value on entry to the current procedure". The frame pointer is
already correct here.

It is the storage locations of ra and fp that are broken. The ABI says
"This puts the return address at fp - XLEN/8, and the previous frame
pointer at fp - 2 * XLEN/8".

Or am I confused?

Nam

  parent reply	other threads:[~2026-06-22 18:08 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-03  3:53 [PATCH] riscv: fix frame pointer in call_on_irq_stack for RV32 Rui Qi
2026-06-03  3:53 ` Rui Qi
2026-06-22  2:54 ` Rui Qi
2026-06-22  2:54   ` Rui Qi
2026-06-22 18:08 ` Nam Cao [this message]
2026-06-22 18:08   ` Nam Cao

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