From eafd7836a0a1ea135cda26739358959f5e92e42b Mon Sep 17 00:00:00 2001 From: Vivian Wang Date: Thu, 21 Aug 2025 17:16:31 +0800 Subject: [PATCH 1/5] riscv: pgtable: Use __riscv_has_extension_unlikely Use __riscv_has_extension_unlikely() to check for RISCV_ISA_EXT_SVVPTC, replacing the use of asm goto with ALTERNATIVE. The "unlikely" variant is used to match the behavior of the original implementation using ALTERNATIVE("nop", "j %l[svvptc]", ...). Signed-off-by: Vivian Wang Signed-off-by: Linux RISC-V bot --- arch/riscv/include/asm/pgtable.h | 15 +++++++-------- arch/riscv/mm/pgtable.c | 22 ++++++++++------------ 2 files changed, 17 insertions(+), 20 deletions(-) diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h index 91697fbf1f9013..f37a0c3dab8a8c 100644 --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -495,8 +495,13 @@ static inline void update_mmu_cache_range(struct vm_fault *vmf, struct vm_area_struct *vma, unsigned long address, pte_t *ptep, unsigned int nr) { - asm goto(ALTERNATIVE("nop", "j %l[svvptc]", 0, RISCV_ISA_EXT_SVVPTC, 1) - : : : : svvptc); + /* + * Svvptc guarantees that the new valid pte will be visible within + * a bounded timeframe, so when the uarch does not cache invalid + * entries, we don't have to do anything. + */ + if (__riscv_has_extension_unlikely(0, RISCV_ISA_EXT_SVVPTC)) + return; /* * The kernel assumes that TLBs don't cache invalid entries, but @@ -508,12 +513,6 @@ static inline void update_mmu_cache_range(struct vm_fault *vmf, while (nr--) local_flush_tlb_page(address + nr * PAGE_SIZE); -svvptc:; - /* - * Svvptc guarantees that the new valid pte will be visible within - * a bounded timeframe, so when the uarch does not cache invalid - * entries, we don't have to do anything. - */ } #define update_mmu_cache(vma, addr, ptep) \ update_mmu_cache_range(NULL, vma, addr, ptep, 1) diff --git a/arch/riscv/mm/pgtable.c b/arch/riscv/mm/pgtable.c index 8b6c0a112a8db4..289ca6fa6b4de8 100644 --- a/arch/riscv/mm/pgtable.c +++ b/arch/riscv/mm/pgtable.c @@ -9,8 +9,16 @@ int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address, pte_t *ptep, pte_t entry, int dirty) { - asm goto(ALTERNATIVE("nop", "j %l[svvptc]", 0, RISCV_ISA_EXT_SVVPTC, 1) - : : : : svvptc); + if (__riscv_has_extension_unlikely(0, RISCV_ISA_EXT_SVVPTC)) { + if (!pte_same(ptep_get(ptep), entry)) { + __set_pte_at(vma->vm_mm, ptep, entry); + /* Here only not svadu is impacted */ + flush_tlb_page(vma, address); + return true; + } + + return false; + } if (!pte_same(ptep_get(ptep), entry)) __set_pte_at(vma->vm_mm, ptep, entry); @@ -19,16 +27,6 @@ int ptep_set_access_flags(struct vm_area_struct *vma, * the case that the PTE changed and the spurious fault case. */ return true; - -svvptc: - if (!pte_same(ptep_get(ptep), entry)) { - __set_pte_at(vma->vm_mm, ptep, entry); - /* Here only not svadu is impacted */ - flush_tlb_page(vma, address); - return true; - } - - return false; } int ptep_test_and_clear_young(struct vm_area_struct *vma, From 0fdfbcea06f1ec7413952e5635368ea7a5bc6504 Mon Sep 17 00:00:00 2001 From: Vivian Wang Date: Thu, 21 Aug 2025 17:16:32 +0800 Subject: [PATCH 2/5] riscv: checksum: 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[no_zbb]", "nop", ...). While we're at it, also remove bogus comment about Zbb being likely available. We have to choose between "likely" and "unlikely" due to limitations of the asm goto feature, but that does not mean we should put a bad comment on why we pick "likely" over "unlikely". Signed-off-by: Vivian Wang Signed-off-by: Linux RISC-V bot --- arch/riscv/include/asm/checksum.h | 13 +++----- arch/riscv/lib/csum.c | 53 +++++++------------------------ 2 files changed, 16 insertions(+), 50 deletions(-) diff --git a/arch/riscv/include/asm/checksum.h b/arch/riscv/include/asm/checksum.h index da378856f1d590..70eb50173fb6ab 100644 --- a/arch/riscv/include/asm/checksum.h +++ b/arch/riscv/include/asm/checksum.h @@ -49,16 +49,11 @@ static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl) * ZBB only saves three instructions on 32-bit and five on 64-bit so not * worth checking if supported without Alternatives. */ - if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB)) { + if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && + IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB) && + __riscv_has_extension_likely(0, RISCV_ISA_EXT_ZBB)) { unsigned long fold_temp; - asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0, - RISCV_ISA_EXT_ZBB, 1) - : - : - : - : no_zbb); - if (IS_ENABLED(CONFIG_32BIT)) { asm(".option push \n\ .option arch,+zbb \n\ @@ -81,7 +76,7 @@ static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl) } return (__force __sum16)(csum >> 16); } -no_zbb: + #ifndef CONFIG_32BIT csum += ror64(csum, 32); csum >>= 32; diff --git a/arch/riscv/lib/csum.c b/arch/riscv/lib/csum.c index 9408f50ca59a89..420e9eb93e8531 100644 --- a/arch/riscv/lib/csum.c +++ b/arch/riscv/lib/csum.c @@ -40,20 +40,11 @@ __sum16 csum_ipv6_magic(const struct in6_addr *saddr, uproto = (__force unsigned int)htonl(proto); sum += uproto; - if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB)) { + if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && + IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB) && + __riscv_has_extension_likely(0, RISCV_ISA_EXT_ZBB)) { unsigned long fold_temp; - /* - * Zbb is likely available when the kernel is compiled with Zbb - * support, so nop when Zbb is available and jump when Zbb is - * not available. - */ - asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0, - RISCV_ISA_EXT_ZBB, 1) - : - : - : - : no_zbb); asm(".option push \n\ .option arch,+zbb \n\ rori %[fold_temp], %[sum], 32 \n\ @@ -66,7 +57,7 @@ __sum16 csum_ipv6_magic(const struct in6_addr *saddr, : [sum] "+r" (sum), [fold_temp] "=&r" (fold_temp)); return (__force __sum16)(sum >> 16); } -no_zbb: + sum += ror64(sum, 32); sum >>= 32; return csum_fold((__force __wsum)sum); @@ -152,21 +143,11 @@ do_csum_with_alignment(const unsigned char *buff, int len) csum = do_csum_common(ptr, end, data); #ifdef CC_HAS_ASM_GOTO_TIED_OUTPUT - if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB)) { + if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && + IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB) && + __riscv_has_extension_likely(0, RISCV_ISA_EXT_ZBB)) { unsigned long fold_temp; - /* - * Zbb is likely available when the kernel is compiled with Zbb - * support, so nop when Zbb is available and jump when Zbb is - * not available. - */ - asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0, - RISCV_ISA_EXT_ZBB, 1) - : - : - : - : no_zbb); - #ifdef CONFIG_32BIT asm_goto_output(".option push \n\ .option arch,+zbb \n\ @@ -204,7 +185,7 @@ do_csum_with_alignment(const unsigned char *buff, int len) end: return csum >> 16; } -no_zbb: + #endif /* CC_HAS_ASM_GOTO_TIED_OUTPUT */ #ifndef CONFIG_32BIT csum += ror64(csum, 32); @@ -234,21 +215,11 @@ do_csum_no_alignment(const unsigned char *buff, int len) end = (const unsigned long *)(buff + len); csum = do_csum_common(ptr, end, data); - if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB)) { + if (IS_ENABLED(CONFIG_RISCV_ISA_ZBB) && + IS_ENABLED(CONFIG_TOOLCHAIN_HAS_ZBB) && + __riscv_has_extension_likely(0, RISCV_ISA_EXT_ZBB)) { unsigned long fold_temp; - /* - * Zbb is likely available when the kernel is compiled with Zbb - * support, so nop when Zbb is available and jump when Zbb is - * not available. - */ - asm goto(ALTERNATIVE("j %l[no_zbb]", "nop", 0, - RISCV_ISA_EXT_ZBB, 1) - : - : - : - : no_zbb); - #ifdef CONFIG_32BIT asm (".option push \n\ .option arch,+zbb \n\ @@ -274,7 +245,7 @@ do_csum_no_alignment(const unsigned char *buff, int len) #endif /* !CONFIG_32BIT */ return csum >> 16; } -no_zbb: + #ifndef CONFIG_32BIT csum += ror64(csum, 32); csum >>= 32; From 85f9dae1000df6f111d2ed534627f2b907b97e3c Mon Sep 17 00:00:00 2001 From: Vivian Wang Date: Thu, 21 Aug 2025 17:16:33 +0800 Subject: [PATCH 3/5] 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 Signed-off-by: Linux RISC-V bot --- arch/riscv/include/asm/arch_hweight.h | 24 ++++++++---------------- 1 file changed, 8 insertions(+), 16 deletions(-) diff --git a/arch/riscv/include/asm/arch_hweight.h b/arch/riscv/include/asm/arch_hweight.h index 0e7cdbbec8efd3..021bc671de299d 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(0, 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(0, 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) From 677212121c226f80215cae7d8a88bca7aaa2efa9 Mon Sep 17 00:00:00 2001 From: Vivian Wang Date: Thu, 21 Aug 2025 17:16:34 +0800 Subject: [PATCH 4/5] 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 Signed-off-by: Linux RISC-V bot --- arch/riscv/include/asm/bitops.h | 32 ++++++++------------------------ 1 file changed, 8 insertions(+), 24 deletions(-) diff --git a/arch/riscv/include/asm/bitops.h b/arch/riscv/include/asm/bitops.h index d59310f74c2ba7..f70ccc0c2ffb86 100644 --- a/arch/riscv/include/asm/bitops.h +++ b/arch/riscv/include/asm/bitops.h @@ -47,9 +47,8 @@ static __always_inline 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(0, RISCV_ISA_EXT_ZBB)) + return generic___ffs(word); asm volatile (".option push\n" ".option arch,+zbb\n" @@ -58,9 +57,6 @@ static __always_inline unsigned long variable__ffs(unsigned long word) : "=r" (word) : "r" (word) :); return word; - -legacy: - return generic___ffs(word); } /** @@ -76,9 +72,8 @@ static __always_inline unsigned long variable__ffs(unsigned long word) static __always_inline 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(0, RISCV_ISA_EXT_ZBB)) + return generic___fls(word); asm volatile (".option push\n" ".option arch,+zbb\n" @@ -87,9 +82,6 @@ static __always_inline unsigned long variable__fls(unsigned long word) : "=r" (word) : "r" (word) :); return BITS_PER_LONG - 1 - word; - -legacy: - return generic___fls(word); } /** @@ -105,9 +97,8 @@ static __always_inline unsigned long variable__fls(unsigned long word) static __always_inline int variable_ffs(int x) { - asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0, - RISCV_ISA_EXT_ZBB, 1) - : : : : legacy); + if (!__riscv_has_extension_likely(0, RISCV_ISA_EXT_ZBB)) + return generic_ffs(x); if (!x) return 0; @@ -119,9 +110,6 @@ static __always_inline int variable_ffs(int x) : "=r" (x) : "r" (x) :); return x + 1; - -legacy: - return generic_ffs(x); } /** @@ -137,9 +125,8 @@ static __always_inline int variable_ffs(int x) 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(0, 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); } /** From ab7f12d69db5ec3de301dea866aa613ec74debef Mon Sep 17 00:00:00 2001 From: Vivian Wang Date: Thu, 21 Aug 2025 17:16:35 +0800 Subject: [PATCH 5/5] riscv: cmpxchg: Use __riscv_has_extension_likely Use __riscv_has_extension_likely() to check for RISCV_ISA_EXT_ZAWRS, 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[no_zawrs]", "nop", ...). Signed-off-by: Vivian Wang Signed-off-by: Linux RISC-V bot --- arch/riscv/include/asm/cmpxchg.h | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/arch/riscv/include/asm/cmpxchg.h b/arch/riscv/include/asm/cmpxchg.h index 0b749e71021624..6a372ab9bcf68b 100644 --- a/arch/riscv/include/asm/cmpxchg.h +++ b/arch/riscv/include/asm/cmpxchg.h @@ -370,9 +370,10 @@ static __always_inline void __cmpwait(volatile void *ptr, u32 *__ptr32b; ulong __s, __val, __mask; - asm goto(ALTERNATIVE("j %l[no_zawrs]", "nop", - 0, RISCV_ISA_EXT_ZAWRS, 1) - : : : : no_zawrs); + if (!__riscv_has_extension_likely(0, RISCV_ISA_EXT_ZAWRS)) { + asm volatile(RISCV_PAUSE : : : "memory"); + return; + } switch (size) { case 1: @@ -434,11 +435,6 @@ static __always_inline void __cmpwait(volatile void *ptr, default: BUILD_BUG(); } - - return; - -no_zawrs: - asm volatile(RISCV_PAUSE : : : "memory"); } #define __cmpwait_relaxed(ptr, val) \