[PATCH v3] riscv, bpf: Optimize zextw insn with Zba extension

[PATCH v3] riscv, bpf: Optimize zextw insn with Zba extension

[Xiao Wang]

The Zba extension provides add.uw insn which can be used to implement
zext.w with rs2 set as ZERO.

Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
---
v3:
* Remove the Kconfig dependencies on TOOLCHAIN_HAS_ZBA and
  RISCV_ALTERNATIVE. (Andrew)
v2:
* Add Zba description in the Kconfig. (Lehui)
* Reword the Kconfig help message to make it clearer. (Conor)
---
 arch/riscv/Kconfig       | 12 ++++++++++++
 arch/riscv/net/bpf_jit.h | 18 ++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 6bec1bce6586..b64d55dc929f 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -601,6 +601,18 @@ config TOOLCHAIN_HAS_VECTOR_CRYPTO
 	def_bool $(as-instr, .option arch$(comma) +v$(comma) +zvkb)
 	depends on AS_HAS_OPTION_ARCH
 
+config RISCV_ISA_ZBA
+	bool "Zba extension support for bit manipulation instructions"
+	default y
+	help
+	   Add support for enabling optimisations in the kernel when the Zba
+	   extension is detected at boot.
+
+	   The Zba extension provides instructions to accelerate the generation
+	   of addresses that index into arrays of basic data types.
+
+	   If you don't know what to do here, say Y.
+
 config RISCV_ISA_ZBB
 	bool "Zbb extension support for bit manipulation instructions"
 	depends on TOOLCHAIN_HAS_ZBB
diff --git a/arch/riscv/net/bpf_jit.h b/arch/riscv/net/bpf_jit.h
index f4b6b3b9edda..18a7885ba95e 100644
--- a/arch/riscv/net/bpf_jit.h
+++ b/arch/riscv/net/bpf_jit.h
@@ -18,6 +18,11 @@ static inline bool rvc_enabled(void)
 	return IS_ENABLED(CONFIG_RISCV_ISA_C);
 }
 
+static inline bool rvzba_enabled(void)
+{
+	return IS_ENABLED(CONFIG_RISCV_ISA_ZBA) && riscv_has_extension_likely(RISCV_ISA_EXT_ZBA);
+}
+
 static inline bool rvzbb_enabled(void)
 {
 	return IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && riscv_has_extension_likely(RISCV_ISA_EXT_ZBB);
@@ -937,6 +942,14 @@ static inline u16 rvc_sdsp(u32 imm9, u8 rs2)
 	return rv_css_insn(0x7, imm, rs2, 0x2);
 }
 
+/* RV64-only ZBA instructions. */
+
+static inline u32 rvzba_zextw(u8 rd, u8 rs1)
+{
+	/* add.uw rd, rs1, ZERO */
+	return rv_r_insn(0x04, RV_REG_ZERO, rs1, 0, rd, 0x3b);
+}
+
 #endif /* __riscv_xlen == 64 */
 
 /* Helper functions that emit RVC instructions when possible. */
@@ -1159,6 +1172,11 @@ static inline void emit_zexth(u8 rd, u8 rs, struct rv_jit_context *ctx)
 
 static inline void emit_zextw(u8 rd, u8 rs, struct rv_jit_context *ctx)
 {
+	if (rvzba_enabled()) {
+		emit(rvzba_zextw(rd, rs), ctx);
+		return;
+	}
+
 	emit_slli(rd, rs, 32, ctx);
 	emit_srli(rd, rd, 32, ctx);
 }
-- 
2.25.1

Re: [PATCH v3] riscv, bpf: Optimize zextw insn with Zba extension

[Andrew Jones]

On Thu, May 16, 2024 at 05:04:30PM GMT, Xiao Wang wrote:
> The Zba extension provides add.uw insn which can be used to implement
> zext.w with rs2 set as ZERO.
> 
> Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
> ---
> v3:
> * Remove the Kconfig dependencies on TOOLCHAIN_HAS_ZBA and
>   RISCV_ALTERNATIVE. (Andrew)
> v2:
> * Add Zba description in the Kconfig. (Lehui)
> * Reword the Kconfig help message to make it clearer. (Conor)
> ---
>  arch/riscv/Kconfig       | 12 ++++++++++++
>  arch/riscv/net/bpf_jit.h | 18 ++++++++++++++++++
>  2 files changed, 30 insertions(+)
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

Re: [PATCH v3] riscv, bpf: Optimize zextw insn with Zba extension

[Pu Lehui]

On 2024/5/16 17:04, Xiao Wang wrote:
> The Zba extension provides add.uw insn which can be used to implement
> zext.w with rs2 set as ZERO.
> 
> Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
> ---
> v3:
> * Remove the Kconfig dependencies on TOOLCHAIN_HAS_ZBA and
>    RISCV_ALTERNATIVE. (Andrew)
> v2:
> * Add Zba description in the Kconfig. (Lehui)
> * Reword the Kconfig help message to make it clearer. (Conor)
> ---
>   arch/riscv/Kconfig       | 12 ++++++++++++
>   arch/riscv/net/bpf_jit.h | 18 ++++++++++++++++++
>   2 files changed, 30 insertions(+)
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 6bec1bce6586..b64d55dc929f 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -601,6 +601,18 @@ config TOOLCHAIN_HAS_VECTOR_CRYPTO
>   	def_bool $(as-instr, .option arch$(comma) +v$(comma) +zvkb)
>   	depends on AS_HAS_OPTION_ARCH
>   
> +config RISCV_ISA_ZBA
> +	bool "Zba extension support for bit manipulation instructions"
> +	default y
> +	help
> +	   Add support for enabling optimisations in the kernel when the Zba
> +	   extension is detected at boot.
> +
> +	   The Zba extension provides instructions to accelerate the generation
> +	   of addresses that index into arrays of basic data types.
> +
> +	   If you don't know what to do here, say Y.
> +
>   config RISCV_ISA_ZBB
>   	bool "Zbb extension support for bit manipulation instructions"
>   	depends on TOOLCHAIN_HAS_ZBB
> diff --git a/arch/riscv/net/bpf_jit.h b/arch/riscv/net/bpf_jit.h
> index f4b6b3b9edda..18a7885ba95e 100644
> --- a/arch/riscv/net/bpf_jit.h
> +++ b/arch/riscv/net/bpf_jit.h
> @@ -18,6 +18,11 @@ static inline bool rvc_enabled(void)
>   	return IS_ENABLED(CONFIG_RISCV_ISA_C);
>   }
>   
> +static inline bool rvzba_enabled(void)
> +{
> +	return IS_ENABLED(CONFIG_RISCV_ISA_ZBA) && riscv_has_extension_likely(RISCV_ISA_EXT_ZBA);
> +}
> +
>   static inline bool rvzbb_enabled(void)
>   {
>   	return IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && riscv_has_extension_likely(RISCV_ISA_EXT_ZBB);
> @@ -937,6 +942,14 @@ static inline u16 rvc_sdsp(u32 imm9, u8 rs2)
>   	return rv_css_insn(0x7, imm, rs2, 0x2);
>   }
>   
> +/* RV64-only ZBA instructions. */
> +
> +static inline u32 rvzba_zextw(u8 rd, u8 rs1)
> +{
> +	/* add.uw rd, rs1, ZERO */
> +	return rv_r_insn(0x04, RV_REG_ZERO, rs1, 0, rd, 0x3b);
> +}
> +
>   #endif /* __riscv_xlen == 64 */
>   
>   /* Helper functions that emit RVC instructions when possible. */
> @@ -1159,6 +1172,11 @@ static inline void emit_zexth(u8 rd, u8 rs, struct rv_jit_context *ctx)
>   
>   static inline void emit_zextw(u8 rd, u8 rs, struct rv_jit_context *ctx)
>   {
> +	if (rvzba_enabled()) {
> +		emit(rvzba_zextw(rd, rs), ctx);
> +		return;
> +	}
> +
>   	emit_slli(rd, rs, 32, ctx);
>   	emit_srli(rd, rd, 32, ctx);
>   }
Reviewed-by: Pu Lehui <pulehui@huawei.com>
Tested-by: Pu Lehui <pulehui@huawei.com>

Re: [PATCH v3] riscv, bpf: Optimize zextw insn with Zba extension

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Daniel Borkmann <daniel@iogearbox.net>:

On Thu, 16 May 2024 17:04:30 +0800 you wrote:
> The Zba extension provides add.uw insn which can be used to implement
> zext.w with rs2 set as ZERO.
> 
> Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
> ---
> v3:
> * Remove the Kconfig dependencies on TOOLCHAIN_HAS_ZBA and
>   RISCV_ALTERNATIVE. (Andrew)
> v2:
> * Add Zba description in the Kconfig. (Lehui)
> * Reword the Kconfig help message to make it clearer. (Conor)
> 
> [...]

Here is the summary with links:
  - [v3] riscv, bpf: Optimize zextw insn with Zba extension
    https://git.kernel.org/bpf/bpf-next/c/c12603e76ef6

You are awesome, thank you!
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