linux-kernel - [PATCH] riscv: mm: Fixup spurious fault of kernel vaddr

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Message-Id: <20230721145121.1854104-1-guoren@kernel.org>
Date:   Fri, 21 Jul 2023 10:51:21 -0400
From:   guoren@...nel.org
To:     guoren@...nel.org, palmer@...osinc.com, paul.walmsley@...ive.com,
        falcon@...ylab.org, bjorn@...nel.org, conor.dooley@...rochip.com,
        alex@...ti.fr
Cc:     linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org, Guo Ren <guoren@...ux.alibaba.com>
Subject: [PATCH] riscv: mm: Fixup spurious fault of kernel vaddr

From: Guo Ren <guoren@...ux.alibaba.com>

RISC-V specification permits the caching of PTEs whose V (Valid)
bit is clear. Operating systems must be written to cope with this
possibility, but implementers are reminded that eagerly caching
invalid PTEs will reduce performance by causing additional page
faults.

So we must keep vmalloc_fault for the spurious page faults of kernel
virtual address from an OoO machine.

Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
Signed-off-by: Guo Ren <guoren@...nel.org>
---
 arch/riscv/mm/fault.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index 85165fe438d8..f662c9eae7d4 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -258,8 +258,7 @@ void handle_page_fault(struct pt_regs *regs)
 	 * only copy the information from the master page table,
 	 * nothing more.
 	 */
-	if ((!IS_ENABLED(CONFIG_MMU) || !IS_ENABLED(CONFIG_64BIT)) &&
-	    unlikely(addr >= VMALLOC_START && addr < VMALLOC_END)) {
+	if (unlikely(addr >= TASK_SIZE)) {
 		vmalloc_fault(regs, code, addr);
 		return;
 	}
-- 
2.36.1