Re: [PATCH] RISC-V: Add STACKLEAK erasing the kernel stack at the end of syscalls

From: Guo Ren <guoren@kernel.org>
To: Conor.Dooley@microchip.com
Cc: oleg@redhat.com, vgupta@kernel.org, linux@armlinux.org.uk,
	 monstr@monstr.eu, dinguyen@kernel.org, palmer@dabbelt.com,
	 davem@davemloft.net, arnd@arndb.de, shorne@gmail.com,
	 paul.walmsley@sifive.com, aou@eecs.berkeley.edu,
	ardb@kernel.org,  heiko@sntech.de, daolu@rivosinc.com,
	linux-arch@vger.kernel.org,  linux-kernel@vger.kernel.org,
	linux-riscv@lists.infradead.org,
	 linux-arm-kernel@lists.infradead.org,
	linux-snps-arc@lists.infradead.org,  sparclinux@vger.kernel.org,
	openrisc@lists.librecores.org,  xianting.tian@linux.alibaba.com,
	linux-efi@vger.kernel.org
Subject: Re: [PATCH] RISC-V: Add STACKLEAK erasing the kernel stack at the end of syscalls
Date: Wed, 7 Sep 2022 09:51:36 +0800	[thread overview]
Message-ID: <CAJF2gTQvPpXwrfS_fTo+Pn=nufeCWE_tCcmPB-YZAZjdt9GbvA@mail.gmail.com> (raw)
In-Reply-To: <6c48657c-04df-132d-6167-49ed293dea44@microchip.com>

Hi all,

How about the generic_entry version:

https://lore.kernel.org/lkml/20220907014809.919979-1-guoren@kernel.org/

On Wed, Sep 7, 2022 at 1:35 AM <Conor.Dooley@microchip.com> wrote:
>
> On 03/09/2022 17:23, guoren@kernel.org wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> >
> > From: Xianting Tian <xianting.tian@linux.alibaba.com>
> >
> > This adds support for the STACKLEAK gcc plugin to RISC-V and disables
> > the plugin in EFI stub code, which is out of scope for the protection.
> >
> > For the benefits of STACKLEAK feature, please check the commit
> > afaef01c0015 ("x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls")
> >
> > Performance impact (tested on qemu env with 1 riscv64 hart, 1GB mem)
> >     hackbench -s 512 -l 200 -g 15 -f 25 -P
> >     2.0% slowdown
> >
> > Signed-off-by: Xianting Tian <xianting.tian@linux.alibaba.com>
>
> What changed since Xianting posted it himself a week ago:
> https://lore.kernel.org/linux-riscv/20220828135407.3897717-1-xianting.tian@linux.alibaba.com/
>
> There's an older patch from Du Lao adding STACKLEAK too:
> https://lore.kernel.org/linux-riscv/20220615213834.3116135-1-daolu@rivosinc.com/
>
> But since there's been no activity there since June...
>
> > ---
> >  arch/riscv/Kconfig                    | 1 +
> >  arch/riscv/include/asm/processor.h    | 4 ++++
> >  arch/riscv/kernel/entry.S             | 3 +++
> >  drivers/firmware/efi/libstub/Makefile | 2 +-
> >  4 files changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index ed66c31e4655..61fd0dad4463 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -85,6 +85,7 @@ config RISCV
> >         select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
> >         select HAVE_ARCH_THREAD_STRUCT_WHITELIST
> >         select HAVE_ARCH_VMAP_STACK if MMU && 64BIT
> > +       select HAVE_ARCH_STACKLEAK
> >         select HAVE_ASM_MODVERSIONS
> >         select HAVE_CONTEXT_TRACKING_USER
> >         select HAVE_DEBUG_KMEMLEAK
> > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
> > index d0537573501e..5e1fc4f82883 100644
> > --- a/drivers/firmware/efi/libstub/Makefile
> > +++ b/drivers/firmware/efi/libstub/Makefile
> > @@ -25,7 +25,7 @@ cflags-$(CONFIG_ARM)          := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> >                                    -fno-builtin -fpic \
> >                                    $(call cc-option,-mno-single-pic-base)
> >  cflags-$(CONFIG_RISCV)         := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > -                                  -fpic
> > +                                  -fpic $(DISABLE_STACKLEAK_PLUGIN)
> >
> >  cflags-$(CONFIG_EFI_GENERIC_STUB) += -I$(srctree)/scripts/dtc/libfdt
> >
> > --
> > 2.17.1
> >
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
>

-- 
Best Regards
 Guo Ren

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