linux-kernel - Re: [PATCH v12 17/28] riscv/signal: save and restore of shadow stack for signal

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Message-Id: <D92TVG7AWGLG.1GO0C83SS7M9G@ventanamicro.com>
Date: Thu, 10 Apr 2025 10:49:32 +0200
From: Radim Krčmář <rkrcmar@...tanamicro.com>
To: "Deepak Gupta" <debug@...osinc.com>, "Thomas Gleixner"
 <tglx@...utronix.de>, "Ingo Molnar" <mingo@...hat.com>, "Borislav Petkov"
 <bp@...en8.de>, "Dave Hansen" <dave.hansen@...ux.intel.com>,
 <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>, "Andrew Morton"
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 "Vlastimil Babka" <vbabka@...e.cz>, "Lorenzo Stoakes"
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 "Conor Dooley" <conor@...nel.org>, "Rob Herring" <robh@...nel.org>,
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Cc: <linux-kernel@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>,
 <linux-mm@...ck.org>, <linux-riscv@...ts.infradead.org>,
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 <cleger@...osinc.com>, <alexghiti@...osinc.com>, <samitolvanen@...gle.com>,
 <broonie@...nel.org>, <rick.p.edgecombe@...el.com>, "linux-riscv"
 <linux-riscv-bounces@...ts.infradead.org>
Subject: Re: [PATCH v12 17/28] riscv/signal: save and restore of shadow
 stack for signal

2025-03-14T14:39:36-07:00, Deepak Gupta <debug@...osinc.com>:
> diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c
> @@ -140,6 +142,62 @@ static long __restore_v_state(struct pt_regs *regs, void __user *sc_vec)
>  	return copy_from_user(current->thread.vstate.datap, datap, riscv_v_vsize);
>  }
>  
> +static long save_cfiss_state(struct pt_regs *regs, void __user *sc_cfi)
> +{
> +	struct __sc_riscv_cfi_state __user *state = sc_cfi;
> +	unsigned long ss_ptr = 0;
> +	long err = 0;
> +
> +	if (!IS_ENABLED(CONFIG_RISCV_USER_CFI) || !is_shstk_enabled(current))

!is_shstk_enabled() should be enough here.

[The rest looks fine, but I'll need more time to think about it.
 I'll return to this patch in v13.]