From: Will Deacon <will@kernel.org>
To: Daniel Kiss <daniel.kiss@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, Ard.Biesheuvel@arm.com,
Catalin.Marinas@arm.com, pcc@google.com
Subject: Re: [PATCH v3 2/2] arm64: Conditionally configure PTR_AUTH key of the kernel.
Date: Mon, 29 Mar 2021 15:51:38 +0100 [thread overview]
Message-ID: <20210329145137.GE4203@willie-the-truck> (raw)
In-Reply-To: <20210208145554.2164638-3-daniel.kiss@arm.com>
On Mon, Feb 08, 2021 at 03:55:54PM +0100, Daniel Kiss wrote:
> If the kernel is not compiled with CONFIG_ARM64_PTR_AUTH_KERNEL=y,
> then no PACI/AUTI instructions are expected while the kernel is running
> so the kernel's key will not be used. Write of a system regiters
> is expensive therefore avoid it not required.
What happens if somebody tries to load a module built with PAC into a kernel
where CONFIG_ARM64_PTR_AUTH_KERNEL=n? Do we reject the module?
I'm not sure how much we care, but I'm a bit worried that it might not go
"obviously" wrong.
> Signed-off-by: Daniel Kiss <daniel.kiss@arm.com>
> ---
> arch/arm64/include/asm/asm_pointer_auth.h | 63 +++++++++++++----------
> arch/arm64/include/asm/pointer_auth.h | 20 +++++--
> arch/arm64/include/asm/processor.h | 2 +
> arch/arm64/kernel/asm-offsets.c | 2 +
> 4 files changed, 54 insertions(+), 33 deletions(-)
[...]
> diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h
> index c6b4f0603024..b34aebb95757 100644
> --- a/arch/arm64/include/asm/pointer_auth.h
> +++ b/arch/arm64/include/asm/pointer_auth.h
> @@ -30,9 +30,11 @@ struct ptrauth_keys_user {
> struct ptrauth_key apga;
> };
>
> +#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
> struct ptrauth_keys_kernel {
> struct ptrauth_key apia;
> };
> +#endif
>
> static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
> {
> @@ -54,6 +56,8 @@ do { \
> write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \
> } while (0)
>
> +#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
> +
> static __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
> {
> if (system_supports_address_auth())
> @@ -69,6 +73,8 @@ static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kerne
> isb();
> }
>
> +#endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
Can you group this with the struct and avoid having two #ifdef blocks?
Will
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next prev parent reply other threads:[~2021-03-29 22:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-08 14:55 [PATCH v3 0/2] arm64: split ARM64_PTR_AUTH option to userspace and kernel Daniel Kiss
2021-02-08 14:55 ` [PATCH v3 1/2] arm64: Add ARM64_PTR_AUTH_KERNEL config option Daniel Kiss
2021-03-29 14:51 ` Will Deacon
2021-02-08 14:55 ` [PATCH v3 2/2] arm64: Conditionally configure PTR_AUTH key of the kernel Daniel Kiss
2021-03-29 14:51 ` Will Deacon [this message]
2021-04-12 20:17 ` Daniel Kiss
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