From: Vivian Wang <wangruikang@iscas.ac.cn>
Date: Tue, 18 Nov 2025 04:19:22 +0000 (-0700)
Subject: riscv: bitops: Use riscv_has_extension_likely
X-Git-Tag: v6.19-rc1~105^2~12
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6b85e9ac4a25c5e69f8121e95eea14da6e3df2fa;p=thirdparty%2Flinux.git

riscv: bitops: 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-v4-4-ef941c87669a@iscas.ac.cn
Signed-off-by: Paul Walmsley <pjw@kernel.org>
---

diff --git a/arch/riscv/include/asm/bitops.h b/arch/riscv/include/asm/bitops.h
index 77880677b06e0..238092125c118 100644
--- a/arch/riscv/include/asm/bitops.h
+++ b/arch/riscv/include/asm/bitops.h
@@ -47,9 +47,8 @@
 
 static __always_inline __attribute_const__ unsigned long variable__ffs(unsigned long word)
 {
-	asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
-				      RISCV_ISA_EXT_ZBB, 1)
-			  : : : : legacy);
+	if (!riscv_has_extension_likely(RISCV_ISA_EXT_ZBB))
+		return generic___ffs(word);
 
 	asm volatile (".option push\n"
 		      ".option arch,+zbb\n"
@@ -58,9 +57,6 @@ static __always_inline __attribute_const__ unsigned long variable__ffs(unsigned
 		      : "=r" (word) : "r" (word) :);
 
 	return word;
-
-legacy:
-	return generic___ffs(word);
 }
 
 /**
@@ -76,9 +72,8 @@ legacy:
 
 static __always_inline __attribute_const__ unsigned long variable__fls(unsigned long word)
 {
-	asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
-				      RISCV_ISA_EXT_ZBB, 1)
-			  : : : : legacy);
+	if (!riscv_has_extension_likely(RISCV_ISA_EXT_ZBB))
+		return generic___fls(word);
 
 	asm volatile (".option push\n"
 		      ".option arch,+zbb\n"
@@ -87,9 +82,6 @@ static __always_inline __attribute_const__ unsigned long variable__fls(unsigned
 		      : "=r" (word) : "r" (word) :);
 
 	return BITS_PER_LONG - 1 - word;
-
-legacy:
-	return generic___fls(word);
 }
 
 /**
@@ -105,9 +97,8 @@ legacy:
 
 static __always_inline __attribute_const__ int variable_ffs(int x)
 {
-	asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
-				      RISCV_ISA_EXT_ZBB, 1)
-			  : : : : legacy);
+	if (!riscv_has_extension_likely(RISCV_ISA_EXT_ZBB))
+		return generic_ffs(x);
 
 	if (!x)
 		return 0;
@@ -119,9 +110,6 @@ static __always_inline __attribute_const__ int variable_ffs(int x)
 		      : "=r" (x) : "r" (x) :);
 
 	return x + 1;
-
-legacy:
-	return generic_ffs(x);
 }
 
 /**
@@ -137,9 +125,8 @@ legacy:
 
 static __always_inline int variable_fls(unsigned int x)
 {
-	asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
-				      RISCV_ISA_EXT_ZBB, 1)
-			  : : : : legacy);
+	if (!riscv_has_extension_likely(RISCV_ISA_EXT_ZBB))
+		return generic_fls(x);
 
 	if (!x)
 		return 0;
@@ -151,9 +138,6 @@ static __always_inline int variable_fls(unsigned int x)
 		      : "=r" (x) : "r" (x) :);
 
 	return 32 - x;
-
-legacy:
-	return generic_fls(x);
 }
 
 /**