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Date: Thu, 31 Dec 2020 23:38:52 +0800
From: WANG Xuerui <kernel@...0n.name>
To: Jiaxun Yang <jiaxun.yang@...goat.com>,
"open list:MIPS" <linux-mips@...r.kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Serge Semin <Sergey.Semin@...kalelectronics.ru>,
Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
周琰杰 (Zhou Yanjie)
<zhouyanjie@...yeetech.com>, Paul Burton <paulburton@...nel.org>,
Paul Cercueil <paul@...pouillou.net>,
Tiezhu Yang <yangtiezhu@...ngson.cn>,
Huacai Chen <chenhc@...ote.com>, YunQiang Su <syq@...ian.org>,
Liangliang Huang <huanglllzu@...il.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] MIPS: Add vulnerabilities infrastructure
Hi Jiaxun,
Overall a nice step towards a more conformant arch/mips! Some nits below
though.
On 12/30/20 11:23 AM, Jiaxun Yang wrote:
> Add infrastructure to display CPU vulnerabilities.
> As most MIPS CPU vendors are dead today and we can't confirm
> vulnerabilities states with them, we'll display vulnerabilities
> as "Unknown" by default and override them in cpu-probe.c
Add trailing period.
>
> Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
> ---
> arch/mips/Kconfig | 1 +
> arch/mips/include/asm/cpu-info.h | 5 ++++
> arch/mips/include/asm/cpu.h | 7 +++++
> arch/mips/kernel/Makefile | 2 +-
> arch/mips/kernel/vulnbl.c | 46 ++++++++++++++++++++++++++++++++
> 5 files changed, 60 insertions(+), 1 deletion(-)
> create mode 100644 arch/mips/kernel/vulnbl.c
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index ef5b2a177b1b..524053b8f769 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -24,6 +24,7 @@ config MIPS
> select GENERIC_CLOCKEVENTS
> select GENERIC_CMOS_UPDATE
> select GENERIC_CPU_AUTOPROBE
> + select GENERIC_CPU_VULNERABILITIES
> select GENERIC_GETTIMEOFDAY
> select GENERIC_IOMAP
> select GENERIC_IRQ_PROBE
> diff --git a/arch/mips/include/asm/cpu-info.h b/arch/mips/include/asm/cpu-info.h
> index a600670d00e9..1a964dbfc0a8 100644
> --- a/arch/mips/include/asm/cpu-info.h
> +++ b/arch/mips/include/asm/cpu-info.h
> @@ -106,6 +106,11 @@ struct cpuinfo_mips {
> unsigned int guestid_mask;
> unsigned int guestid_cache;
>
> + /* Vulnerabilities */
> + unsigned int vulnerabilities; /* Vulnerabilities states that we known */
> + unsigned int vulnerable; /* Vulnerabilities affated */
> + unsigned int mitigations; /* Mitigations */
Could you make the field names a little clearer? Like "known_mask",
"affected_mask" and "mitigated_mask"?
Also I wonder if removing the first mask is okay, since if a bit is
neither "affected" nor "mitigated" then it must belong to the "unknown"
case.
> +
> #ifdef CONFIG_CPU_LOONGSON3_CPUCFG_EMULATION
> /* CPUCFG data for this CPU, synthesized at probe time.
> *
> diff --git a/arch/mips/include/asm/cpu.h b/arch/mips/include/asm/cpu.h
> index f5b04e8f6061..3414c9f5464e 100644
> --- a/arch/mips/include/asm/cpu.h
> +++ b/arch/mips/include/asm/cpu.h
> @@ -447,4 +447,11 @@ enum cpu_type_enum {
> #define MIPS_ASE_LOONGSON_EXT 0x00002000 /* Loongson EXTensions */
> #define MIPS_ASE_LOONGSON_EXT2 0x00004000 /* Loongson EXTensions R2 */
>
> +/*
> + * CPU security vulnerabilities
> + */
> +#define MIPS_VULNBL_MELTDOWN BIT(0)
> +#define MIPS_VULNBL_SPECTRE_V1 BIT(1)
> +#define MIPS_VULNBL_SPECTRE_V2 BIT(2)
Looking at the arch/x86 vulnerabilities code, I tend to think that
"VULNBL" is not (rather ugly) shorthand for "vulnerability", but
"vulnerability blacklist" (!), because they have "VULNWL" for apparently
"whitelist". So I suggest writing out "VULNERABILITY" fully for clarity.
> +
> #endif /* _ASM_CPU_H */
> diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
> index 13a26d254829..39abc8ead5e0 100644
> --- a/arch/mips/kernel/Makefile
> +++ b/arch/mips/kernel/Makefile
> @@ -8,7 +8,7 @@ extra-y := head.o vmlinux.lds
> obj-y += cmpxchg.o cpu-probe.o branch.o elf.o entry.o genex.o idle.o irq.o \
> process.o prom.o ptrace.o reset.o setup.o signal.o \
> syscall.o time.o topology.o traps.o unaligned.o watch.o \
> - vdso.o cacheinfo.o
> + vdso.o cacheinfo.o vulnbl.o
>
> ifdef CONFIG_FUNCTION_TRACER
> CFLAGS_REMOVE_ftrace.o = -pg
> diff --git a/arch/mips/kernel/vulnbl.c b/arch/mips/kernel/vulnbl.c
> new file mode 100644
> index 000000000000..fc73da6214fe
> --- /dev/null
> +++ b/arch/mips/kernel/vulnbl.c
Same with this filename.
> @@ -0,0 +1,46 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020, Jiaxun Yang <jiaxun.yang@...goat.com>
> + * MIPS CPU vulnerabilities
> + */
> +
> +#include <linux/device.h>
> +
> +#include <asm/cpu-info.h>
> +#include <asm/cpu.h>
> +
> +ssize_t cpu_show_meltdown(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + if (!(boot_cpu_data.vulnerabilities & MIPS_VULNBL_MELTDOWN))
> + return sprintf(buf, "Unknown\n");
> +
> + if (!(boot_cpu_data.vulnerable & MIPS_VULNBL_MELTDOWN))
> + return sprintf(buf, "Not affected\n");
> +
> + return sprintf(buf, "Affected\n");
Be consistent with other arches and use "Vulnerable"?
> +}
> +
> +ssize_t cpu_show_spectre_v1(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + if (!(boot_cpu_data.vulnerabilities & MIPS_VULNBL_SPECTRE_V1))
> + return sprintf(buf, "Unknown\n");
> +
> + if (!(boot_cpu_data.vulnerable & MIPS_VULNBL_SPECTRE_V1))
> + return sprintf(buf, "Not affected\n");
> +
> + return sprintf(buf, "Affected\n");
Same as above.
> +}
> +
> +ssize_t cpu_show_spectre_v2(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + if (!(boot_cpu_data.vulnerabilities & MIPS_VULNBL_SPECTRE_V2))
> + return sprintf(buf, "Unknown\n");
> +
> + if (!(boot_cpu_data.vulnerable & MIPS_VULNBL_SPECTRE_V2))
> + return sprintf(buf, "Not affected\n");
> +
> + return sprintf(buf, "Affected\n");
Same as above.
> +}
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