linux-kernel - Re: [PATCH] arm64: Fix PIE_E1 mapping for _PAGE_READONLY

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Message-ID:
 <GV1PR08MB105210D9BD328C2446CA8C551FBB1A@GV1PR08MB10521.eurprd08.prod.outlook.com>
Date: Sat, 27 Dec 2025 15:46:58 +0000
From: Yeo Reum Yun <YeoReum.Yun@....com>
To: Seongsu Park <sgsu.park@...sung.com>, Catalin Marinas
	<Catalin.Marinas@....com>, "will@...nel.org" <will@...nel.org>
CC: "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arm64: Fix PIE_E1 mapping for _PAGE_READONLY_EXEC

Hi Seongsu, 

> diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h
> index 161e8660eddd..ca14f61dee81 100644
> --- a/arch/arm64/include/asm/pgtable-prot.h
> +++ b/arch/arm64/include/asm/pgtable-prot.h
> @@ -180,7 +180,7 @@ static inline bool __pure lpa2_is_enabled(void)
>       PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_GCS),           PIE_NONE_O) | \
>       PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_GCS_RO),        PIE_NONE_O) | \
>        PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_EXECONLY),      PIE_NONE_O) | \
> -       PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_READONLY_EXEC), PIE_R)      | \
> +       PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_READONLY_EXEC), PIE_RX)     | \
>        PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_SHARED_EXEC),   PIE_RW)     | \
>       PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_READONLY),      PIE_R)      | \
>        PIRx_ELx_PERM_PREP(pte_pi_index(_PAGE_SHARED),        PIE_RW)     | \


NIT: This looks like it allows executing user code from the kernel.
Why is this necessary?


--  
Sincerely,
Yeoreum Yun