From: Vivian Wang <wangruikang@iscas.ac.cn>
Date: Tue, 18 Nov 2025 04:19:22 +0000 (-0700)
Subject: riscv: hweight: Use riscv_has_extension_likely
X-Git-Tag: v6.19-rc1~105^2~13
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8261a9d167e8b3007c0e830a1f7ab8c8b8c24b79;p=thirdparty%2Fkernel%2Flinux.git

riscv: hweight: Use riscv_has_extension_likely

Use riscv_has_extension_likely() to check for RISCV_ISA_EXT_ZBB,
replacing the use of asm goto with ALTERNATIVE.

The "likely" variant is used to match the behavior of the original
implementation using ALTERNATIVE("j %l[legacy]", "nop", ...).

Signed-off-by: Vivian Wang <wangruikang@iscas.ac.cn>
Link: https://patch.msgid.link/20251020-riscv-altn-helper-wip-v4-3-ef941c87669a@iscas.ac.cn
Signed-off-by: Paul Walmsley <pjw@kernel.org>
---

diff --git a/arch/riscv/include/asm/arch_hweight.h b/arch/riscv/include/asm/arch_hweight.h
index 0e7cdbbec8efd..f3c0831beefc6 100644
--- a/arch/riscv/include/asm/arch_hweight.h
+++ b/arch/riscv/include/asm/arch_hweight.h
@@ -19,10 +19,10 @@
 
 static __always_inline unsigned int __arch_hweight32(unsigned int w)
 {
-#if defined(CONFIG_RISCV_ISA_ZBB) && defined(CONFIG_TOOLCHAIN_HAS_ZBB)
-	asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
-				      RISCV_ISA_EXT_ZBB, 1)
-			  : : : : legacy);
+	if (!(IS_ENABLED(CONFIG_RISCV_ISA_ZBB) &&
+	      IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB) &&
+	      riscv_has_extension_likely(RISCV_ISA_EXT_ZBB)))
+		return __sw_hweight32(w);
 
 	asm (".option push\n"
 	     ".option arch,+zbb\n"
@@ -31,10 +31,6 @@ static __always_inline unsigned int __arch_hweight32(unsigned int w)
 	     : "=r" (w) : "r" (w) :);
 
 	return w;
-
-legacy:
-#endif
-	return __sw_hweight32(w);
 }
 
 static inline unsigned int __arch_hweight16(unsigned int w)
@@ -50,10 +46,10 @@ static inline unsigned int __arch_hweight8(unsigned int w)
 #if BITS_PER_LONG == 64
 static __always_inline unsigned long __arch_hweight64(__u64 w)
 {
-#if defined(CONFIG_RISCV_ISA_ZBB) && defined(CONFIG_TOOLCHAIN_HAS_ZBB)
-	asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
-				      RISCV_ISA_EXT_ZBB, 1)
-			  : : : : legacy);
+	if (!(IS_ENABLED(CONFIG_RISCV_ISA_ZBB) &&
+	      IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB) &&
+	      riscv_has_extension_likely(RISCV_ISA_EXT_ZBB)))
+		return __sw_hweight64(w);
 
 	asm (".option push\n"
 	     ".option arch,+zbb\n"
@@ -62,10 +58,6 @@ static __always_inline unsigned long __arch_hweight64(__u64 w)
 	     : "=r" (w) : "r" (w) :);
 
 	return w;
-
-legacy:
-#endif
-	return __sw_hweight64(w);
 }
 #else /* BITS_PER_LONG == 64 */
 static inline unsigned long __arch_hweight64(__u64 w)