On Fri, Mar 29, 2024, at 12:44 AM, Deepak Gupta wrote:
> Adds description in dt-bindings (extensions.yaml)
>
> This patch adds support for detecting zicfiss and zicfilp. zicfiss and zicfilp
> stands for unprivleged integer spec extension for shadow stack and branch
> tracking on indirect branches, respectively.
>
> This patch looks for zicfiss and zicfilp in device tree and accordinlgy lights
> up bit in cpu feature bitmap. Furthermore this patch adds detection utility
> functions to return whether shadow stack or landing pads are supported by
> cpu.
>
> Signed-off-by: Deepak Gupta <debug@xxxxxxxxxxxx>
> ---
> .../devicetree/bindings/riscv/extensions.yaml | 10 ++++++++++
> arch/riscv/include/asm/cpufeature.h | 13 +++++++++++++
> arch/riscv/include/asm/hwcap.h | 2 ++
> arch/riscv/include/asm/processor.h | 1 +
> arch/riscv/kernel/cpufeature.c | 2 ++
> 5 files changed, 28 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/riscv/extensions.yaml
> b/Documentation/devicetree/bindings/riscv/extensions.yaml
> index 63d81dc895e5..f8d78bf7400b 100644
> --- a/Documentation/devicetree/bindings/riscv/extensions.yaml
> +++ b/Documentation/devicetree/bindings/riscv/extensions.yaml
> @@ -317,6 +317,16 @@ properties:
> The standard Zicboz extension for cache-block zeroing as
> ratified
> in commit 3dd606f ("Create cmobase-v1.0.pdf") of
> riscv-CMOs.
>
> + - const: zicfilp
> + description:
> + The standard Zicfilp extension for enforcing forward edge
> control-flow
> + integrity as ratified in commit 0036ff2 of riscv-cfi.
> +
> + - const: zicfiss
> + description:
> + The standard Zicfiss extension for enforcing backward edge
> control-flow
> + integrity as ratified in commit 0036ff2 of riscv-cfi.
> +
Neither of these extensions is currently ratified (the public review
period started 15 hours ago) and the git hashes are unlikely to be
correct for the ratified version.
-s
> - const: zicntr
> description:
> The standard Zicntr extension for base counters and
> timers, as
> diff --git a/arch/riscv/include/asm/cpufeature.h
> b/arch/riscv/include/asm/cpufeature.h
> index 0bd11862b760..f0fb8d8ae273 100644
> --- a/arch/riscv/include/asm/cpufeature.h
> +++ b/arch/riscv/include/asm/cpufeature.h
> @@ -8,6 +8,7 @@
>
> #include <linux/bitmap.h>
> #include <linux/jump_label.h>
> +#include <linux/smp.h>
> #include <asm/hwcap.h>
> #include <asm/alternative-macros.h>
> #include <asm/errno.h>
> @@ -137,4 +138,16 @@ static __always_inline bool
> riscv_cpu_has_extension_unlikely(int cpu, const unsi
>
> DECLARE_STATIC_KEY_FALSE(fast_misaligned_access_speed_key);
>
> +static inline bool cpu_supports_shadow_stack(void)
> +{
> + return (IS_ENABLED(CONFIG_RISCV_USER_CFI) &&
> + riscv_cpu_has_extension_unlikely(smp_processor_id(),
> RISCV_ISA_EXT_ZICFISS));
> +}
> +
> +static inline bool cpu_supports_indirect_br_lp_instr(void)
> +{
> + return (IS_ENABLED(CONFIG_RISCV_USER_CFI) &&
> + riscv_cpu_has_extension_unlikely(smp_processor_id(),
> RISCV_ISA_EXT_ZICFILP));
> +}
> +
> #endif
> diff --git a/arch/riscv/include/asm/hwcap.h
> b/arch/riscv/include/asm/hwcap.h
> index 1f2d2599c655..74b6c727f545 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -80,6 +80,8 @@
> #define RISCV_ISA_EXT_ZFA 71
> #define RISCV_ISA_EXT_ZTSO 72
> #define RISCV_ISA_EXT_ZACAS 73
> +#define RISCV_ISA_EXT_ZICFILP 74
> +#define RISCV_ISA_EXT_ZICFISS 75
>
> #define RISCV_ISA_EXT_XLINUXENVCFG 127
>
> diff --git a/arch/riscv/include/asm/processor.h
> b/arch/riscv/include/asm/processor.h
> index a8509cc31ab2..6c5b3d928b12 100644
> --- a/arch/riscv/include/asm/processor.h
> +++ b/arch/riscv/include/asm/processor.h
> @@ -13,6 +13,7 @@
> #include <vdso/processor.h>
>
> #include <asm/ptrace.h>
> +#include <asm/hwcap.h>
>
> #ifdef CONFIG_64BIT
> #define DEFAULT_MAP_WINDOW (UL(1) << (MMAP_VA_BITS - 1))
> diff --git a/arch/riscv/kernel/cpufeature.c
> b/arch/riscv/kernel/cpufeature.c
> index 79a5a35fab96..d052cad5b82f 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -263,6 +263,8 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
> __RISCV_ISA_EXT_DATA(h, RISCV_ISA_EXT_h),
> __RISCV_ISA_EXT_SUPERSET(zicbom, RISCV_ISA_EXT_ZICBOM,
> riscv_xlinuxenvcfg_exts),
> __RISCV_ISA_EXT_SUPERSET(zicboz, RISCV_ISA_EXT_ZICBOZ,
> riscv_xlinuxenvcfg_exts),
> + __RISCV_ISA_EXT_SUPERSET(zicfilp, RISCV_ISA_EXT_ZICFILP,
> riscv_xlinuxenvcfg_exts),
> + __RISCV_ISA_EXT_SUPERSET(zicfiss, RISCV_ISA_EXT_ZICFISS,
> riscv_xlinuxenvcfg_exts),
> __RISCV_ISA_EXT_DATA(zicntr, RISCV_ISA_EXT_ZICNTR),
> __RISCV_ISA_EXT_DATA(zicond, RISCV_ISA_EXT_ZICOND),
> __RISCV_ISA_EXT_DATA(zicsr, RISCV_ISA_EXT_ZICSR),
> --
> 2.43.2
>
>
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