linux-kernel - [PATCH -fixes] riscv: Implement flush_cache

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Message-Id: <20230725132246.817726-1-alexghiti@rivosinc.com>
Date:   Tue, 25 Jul 2023 15:22:46 +0200
From:   Alexandre Ghiti <alexghiti@...osinc.com>
To:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Björn Töpel <bjorn@...osinc.com>,
        Alexandre Ghiti <alexghiti@...osinc.com>,
        Guo Ren <guoren@...nel.org>, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH -fixes] riscv: Implement flush_cache_vmap()

The RISC-V kernel needs a sfence.vma after a page table modification: we
used to rely on the vmalloc fault handling to emit an sfence.vma, but
commit 7d3332be011e ("riscv: mm: Pre-allocate PGD entries for
vmalloc/modules area") got rid of this path for 64-bit kernels, so now we
need to explicitly emit a sfence.vma in flush_cache_vmap().

Note that we don't need to implement flush_cache_vunmap() as the generic
code should emit a flush tlb after unmapping a vmalloc region.

Fixes: 7d3332be011e ("riscv: mm: Pre-allocate PGD entries for vmalloc/modules area")
Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
---
 arch/riscv/include/asm/cacheflush.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/riscv/include/asm/cacheflush.h b/arch/riscv/include/asm/cacheflush.h
index 8091b8bf4883..b93ffddf8a61 100644
--- a/arch/riscv/include/asm/cacheflush.h
+++ b/arch/riscv/include/asm/cacheflush.h
@@ -37,6 +37,10 @@ static inline void flush_dcache_page(struct page *page)
 #define flush_icache_user_page(vma, pg, addr, len) \
 	flush_icache_mm(vma->vm_mm, 0)
 
+#ifdef CONFIG_64BIT
+#define flush_cache_vmap(start, end)	flush_tlb_kernel_range(start, end)
+#endif
+
 #ifndef CONFIG_SMP
 
 #define flush_icache_all() local_flush_icache_all()
-- 
2.39.2