From: "Nicholas Piggin" <npiggin@gmail.com>
To: "Rohan McLure" <rmclure@linux.ibm.com>, <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH 21/23] powerpc/64: Add INTERRUPT_SANITIZE_REGISTERS Kconfig
Date: Tue, 20 Sep 2022 12:10:49 +1000 [thread overview]
Message-ID: <CN0V3W8CZZU1.3K5F733ERJOK0@bobo> (raw)
In-Reply-To: <20220916053300.786330-22-rmclure@linux.ibm.com>
On Fri Sep 16, 2022 at 3:32 PM AEST, Rohan McLure wrote:
> Add Kconfig option for enabling clearing of registers on arrival in an
> interrupt handler. This reduces the speculation influence of registers
> on kernel internals. The option will be consumed by 64-bit systems that
> feature speculation and wish to implement this mitigation.
>
> This patch only introduces the Kconfig option, no actual mitigations.
>
> The primary overhead of this mitigation lies in an increased number of
> registers that must be saved and restored by interrupt handlers on
> Book3S systems. Enable by default on Book3E systems, which prior to
> this patch eagerly save and restore register state, meaning that the
> mitigation when implemented will have minimal overhead.
>
> Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Thanks for adding this. Maybe I'm being sentimental and we might end
up just simplifying code by always doing it... for now I'm happier to
have the option.
Acked-by: Nicholas Piggin <npiggin@gmail.com>
> ---
> V4 -> V5: New patch
> ---
> arch/powerpc/Kconfig | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index ef6c83e79c9b..a643ebd83349 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -528,6 +528,15 @@ config HOTPLUG_CPU
>
> Say N if you are unsure.
>
> +config INTERRUPT_SANITIZE_REGISTERS
> + bool "Clear gprs on interrupt arrival"
> + depends on PPC64 && ARCH_HAS_SYSCALL_WRAPPER
> + default PPC_BOOK3E_64
> + help
> + Reduce the influence of user register state on interrupt handlers and
> + syscalls through clearing user state from registers before handling
> + the exception.
> +
> config PPC_QUEUED_SPINLOCKS
> bool "Queued spinlocks" if EXPERT
> depends on SMP
> --
> 2.34.1
next prev parent reply other threads:[~2022-09-20 2:11 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-16 5:32 [PATCH 00/23] powerpc: Syscall wrapper and register clearing Rohan McLure
2022-09-16 5:32 ` [PATCH 01/23] powerpc: Remove asmlinkage from syscall handler definitions Rohan McLure
2022-09-16 5:32 ` [PATCH 02/23] powerpc: Save caller r3 prior to system_call_exception Rohan McLure
2022-09-16 5:32 ` [PATCH 03/23] powerpc: Add ZEROIZE_GPRS macros for register clears Rohan McLure
2022-09-16 5:32 ` [PATCH 04/23] powerpc/64s: Use {ZEROIZE,SAVE,REST}_GPRS macros in sc, scv 0 handlers Rohan McLure
2022-09-16 5:32 ` [PATCH 05/23] powerpc/32: Clarify interrupt restores with REST_GPR macro in entry_32.S Rohan McLure
2022-09-20 0:51 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 06/23] powerpc/64e: Clarify register saves and clears with {SAVE,ZEROIZE}_GPRS Rohan McLure
2022-09-20 0:55 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 07/23] powerpc/64s: Fix comment on interrupt handler prologue Rohan McLure
2022-09-20 0:55 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 08/23] powerpc: Fix fallocate and fadvise64_64 compat parameter combination Rohan McLure
2022-09-16 6:54 ` Arnd Bergmann
2022-09-20 1:01 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 09/23] asm-generic: compat: Support BE for long long args in 32-bit ABIs Rohan McLure
2022-09-20 1:06 ` Nicholas Piggin
2022-09-20 7:09 ` Arnd Bergmann
2022-09-16 5:32 ` [PATCH 10/23] powerpc: Use generic fallocate compatibility syscall Rohan McLure
2022-09-16 6:56 ` Arnd Bergmann
2022-09-16 5:32 ` [PATCH 11/23] powerpc/32: Remove powerpc select specialisation Rohan McLure
2022-09-16 5:32 ` [PATCH 12/23] powerpc: Remove direct call to personality syscall handler Rohan McLure
2022-09-16 5:32 ` [PATCH 13/23] powerpc: Remove direct call to mmap2 syscall handlers Rohan McLure
2022-09-16 5:32 ` [PATCH 14/23] powerpc: Provide do_ppc64_personality helper Rohan McLure
2022-09-16 5:32 ` [PATCH 15/23] powerpc: Adopt SYSCALL_DEFINE for arch-specific syscall handlers Rohan McLure
2022-09-16 5:48 ` Rohan McLure
2022-09-20 1:24 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 16/23] powerpc: Include all arch-specific syscall prototypes Rohan McLure
2022-09-20 1:27 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 17/23] powerpc: Enable compile-time check for syscall handlers Rohan McLure
2022-09-20 1:30 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 18/23] powerpc: Use common syscall handler type Rohan McLure
2022-09-20 1:39 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 19/23] powerpc: Provide syscall wrapper Rohan McLure
2022-09-20 1:59 ` Nicholas Piggin
2022-09-21 3:44 ` Rohan McLure
2022-09-16 5:32 ` [PATCH 20/23] powerpc/64s: Clear/restore caller gprs in syscall interrupt/return Rohan McLure
2022-09-20 2:03 ` Nicholas Piggin
2022-09-20 4:54 ` Rohan McLure
2022-09-21 5:33 ` Rohan McLure
2022-09-20 2:07 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 21/23] powerpc/64: Add INTERRUPT_SANITIZE_REGISTERS Kconfig Rohan McLure
2022-09-20 2:10 ` Nicholas Piggin [this message]
2022-09-16 5:32 ` [PATCH 22/23] powerpc/64s: Clear gprs on interrupt routine entry in Book3S Rohan McLure
2022-09-20 2:27 ` Nicholas Piggin
2022-09-16 5:33 ` [PATCH 23/23] powerpc/64e: Clear gprs on interrupt routine entry on Book3E Rohan McLure
2022-09-16 5:58 ` [PATCH 00/23] powerpc: Syscall wrapper and register clearing Rohan McLure
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