linux-kernel - [PATCH v5 06/13] riscv: mm: Combine the SMP and UP TLB flush code

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Message-ID: <20240229232211.161961-7-samuel.holland@sifive.com>
Date: Thu, 29 Feb 2024 15:21:47 -0800
From: Samuel Holland <samuel.holland@...ive.com>
To: Palmer Dabbelt <palmer@...belt.com>,
	linux-riscv@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	Alexandre Ghiti <alexghiti@...osinc.com>,
	Jisheng Zhang <jszhang@...nel.org>,
	Yunhui Cui <cuiyunhui@...edance.com>,
	Samuel Holland <samuel.holland@...ive.com>
Subject: [PATCH v5 06/13] riscv: mm: Combine the SMP and UP TLB flush code

In SMP configurations, all TLB flushing narrower than flush_tlb_all()
goes through __flush_tlb_range(). Do the same in UP configurations.

This allows UP configurations to take advantage of recent improvements
to the code in tlbflush.c, such as support for huge pages and flushing
multiple-page ranges.

Reviewed-by: Alexandre Ghiti <alexghiti@...osinc.com>
Signed-off-by: Samuel Holland <samuel.holland@...ive.com>
---

(no changes since v4)

Changes in v4:
 - Merge the two copies of __flush_tlb_range() and rely on the compiler
   to optimize out the broadcast path (both clang and gcc do this)
 - Merge the two copies of flush_tlb_all() and rely on constant folding

Changes in v2:
 - Move the SMP/UP merge earlier in the series to avoid build issues
 - Make a copy of __flush_tlb_range() instead of adding ifdefs inside
 - local_flush_tlb_all() is the only function used on !MMU (smpboot.c)

 arch/riscv/Kconfig                |  2 +-
 arch/riscv/include/asm/tlbflush.h | 30 +++---------------------------
 arch/riscv/mm/Makefile            |  5 +----
 3 files changed, 5 insertions(+), 32 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 0bfcfec67ed5..de9b6f2279ff 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -60,7 +60,7 @@ config RISCV
 	select ARCH_USE_MEMTEST
 	select ARCH_USE_QUEUED_RWLOCKS
 	select ARCH_USES_CFI_TRAPS if CFI_CLANG
-	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP && MMU
+	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if MMU
 	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
 	select ARCH_WANT_FRAME_POINTERS
 	select ARCH_WANT_GENERAL_HUGETLB if !RISCV_ISA_SVNAPOT
diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
index 928f096dca21..4f86424b1ba5 100644
--- a/arch/riscv/include/asm/tlbflush.h
+++ b/arch/riscv/include/asm/tlbflush.h
@@ -27,12 +27,7 @@ static inline void local_flush_tlb_page(unsigned long addr)
 {
 	ALT_FLUSH_TLB_PAGE(__asm__ __volatile__ ("sfence.vma %0" : : "r" (addr) : "memory"));
 }
-#else /* CONFIG_MMU */
-#define local_flush_tlb_all()			do { } while (0)
-#define local_flush_tlb_page(addr)		do { } while (0)
-#endif /* CONFIG_MMU */
 
-#if defined(CONFIG_SMP) && defined(CONFIG_MMU)
 void flush_tlb_all(void);
 void flush_tlb_mm(struct mm_struct *mm);
 void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
@@ -54,27 +49,8 @@ void arch_tlbbatch_add_pending(struct arch_tlbflush_unmap_batch *batch,
 			       unsigned long uaddr);
 void arch_flush_tlb_batched_pending(struct mm_struct *mm);
 void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch);
-
-#else /* CONFIG_SMP && CONFIG_MMU */
-
-#define flush_tlb_all() local_flush_tlb_all()
-#define flush_tlb_page(vma, addr) local_flush_tlb_page(addr)
-
-static inline void flush_tlb_range(struct vm_area_struct *vma,
-		unsigned long start, unsigned long end)
-{
-	local_flush_tlb_all();
-}
-
-/* Flush a range of kernel pages */
-static inline void flush_tlb_kernel_range(unsigned long start,
-	unsigned long end)
-{
-	local_flush_tlb_all();
-}
-
-#define flush_tlb_mm(mm) flush_tlb_all()
-#define flush_tlb_mm_range(mm, start, end, page_size) flush_tlb_all()
-#endif /* !CONFIG_SMP || !CONFIG_MMU */
+#else /* CONFIG_MMU */
+#define local_flush_tlb_all()			do { } while (0)
+#endif /* CONFIG_MMU */
 
 #endif /* _ASM_RISCV_TLBFLUSH_H */
diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile
index 2c869f8026a8..cbe4d775ef56 100644
--- a/arch/riscv/mm/Makefile
+++ b/arch/riscv/mm/Makefile
@@ -13,14 +13,11 @@ endif
 KCOV_INSTRUMENT_init.o := n
 
 obj-y += init.o
-obj-$(CONFIG_MMU) += extable.o fault.o pageattr.o pgtable.o
+obj-$(CONFIG_MMU) += extable.o fault.o pageattr.o pgtable.o tlbflush.o
 obj-y += cacheflush.o
 obj-y += context.o
 obj-y += pmem.o
 
-ifeq ($(CONFIG_MMU),y)
-obj-$(CONFIG_SMP) += tlbflush.o
-endif
 obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
 obj-$(CONFIG_PTDUMP_CORE) += ptdump.o
 obj-$(CONFIG_KASAN)   += kasan_init.o
-- 
2.43.1