linux-kernel - [PATCH 2/2] Bug Fix for last patch

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Message-Id: <20210316015328.13516-1-liu@jiuyang.me>
Date:   Tue, 16 Mar 2021 01:53:25 +0000
From:   Jiuyang Liu <liu@...yang.me>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Andrew Waterman <waterman@...s.berkeley.edu>,
        Jiuyang Liu <liu@...yang.me>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Atish Patra <atish.patra@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Anup Patel <anup.patel@....com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Mike Rapoport <rppt@...nel.org>,
        Greentime Hu <greentime.hu@...ive.com>,
        Zong Li <zong.li@...ive.com>, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] Bug Fix for last patch

Sorry for the noise, Andrew gave me feedbacks, and pointed two bugs in
last patch.
1. asid should be thread safe, which is not the intent.
2. asid extracting logic was wrong.

This patch fixes these bugs.

Signed-off-by: Jiuyang Liu <liu@...yang.me>
---
 arch/riscv/include/asm/tlbflush.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
index 4b25f51f163d..1f9b62b3670b 100644
--- a/arch/riscv/include/asm/tlbflush.h
+++ b/arch/riscv/include/asm/tlbflush.h
@@ -22,10 +22,14 @@ static inline void local_flush_tlb_page(unsigned long addr)
 	__asm__ __volatile__ ("sfence.vma %0" : : "r" (addr) : "memory");
 }
 
-static unsigned long asid;
+static inline unsigned long get_current_asid(void)
+{
+	return (csr_read(CSR_SATP) >> SATP_ASID_SHIFT) & SATP_ASID_MASK;
+}
+
 static inline void local_flush_tlb_asid(void)
 {
-	asid = csr_read(CSR_SATP) | (SATP_ASID_MASK << SATP_ASID_SHIFT);
+	unsigned long asid = get_current_asid();
 	__asm__ __volatile__ ("sfence.vma x0, %0" : : "r" (asid) : "memory");
 }
 
-- 
2.30.2