linux-kernel - Re: [PATCH] riscv: fix flush_tlb_range() end address for flush_tlb

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Message-ID: <alpine.DEB.2.21.9999.1908131359280.19217@viisi.sifive.com>
Date:   Tue, 13 Aug 2019 14:03:20 -0700 (PDT)
From:   Paul Walmsley <paul.walmsley@...ive.com>
To:     Christoph Hellwig <hch@...radead.org>
cc:     linux-riscv@...ts.infradead.org, schwab@...e.de,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] riscv: fix flush_tlb_range() end address for
 flush_tlb_page()

On Mon, 12 Aug 2019, Christoph Hellwig wrote:

> >  #define flush_tlb_range(vma, start, end) \
> >  	remote_sfence_vma(mm_cpumask((vma)->vm_mm), start, (end) - (start))
> > -#define flush_tlb_mm(mm) \
> > +
> > +static inline void flush_tlb_page(struct vm_area_struct *vma,
> > +				  unsigned long addr) {
> > +	flush_tlb_range(vma, addr, addr + PAGE_SIZE);
> > +}
> 
> Please put the opening brace on a line of its own.
> 
> Otherwise looks fine:
> 
> Reviewed-by: Christoph Hellwig <hch@....de>

Thanks, updated patch below.

Looks like checkpatch.pl is no longer issuing warnings about this type of 
brace placement issue.

Queuing for v5.3-rc.


- Paul

From: Paul Walmsley <paul.walmsley@...ive.com>
Date: Wed, 7 Aug 2019 19:07:34 -0700
Subject: [PATCH] riscv: fix flush_tlb_range() end address for flush_tlb_page()

The RISC-V kernel implementation of flush_tlb_page() when CONFIG_SMP
is set is wrong.  It passes zero to flush_tlb_range() as the final
address to flush, but it should be at least 'addr'.

Some other Linux architecture ports use the beginning address to
flush, plus PAGE_SIZE, as the final address to flush.  This might
flush slightly more than what's needed, but it seems unlikely that
being more clever would improve anything.  So let's just take that
implementation for now.

While here, convert the macro into a static inline function, primarily
to avoid unintentional multiple evaluations of 'addr'.

This second version of the patch fixes a coding style issue found by
Christoph Hellwig <hch@....de>.

Reported-by: Andreas Schwab <schwab@...e.de>
Signed-off-by: Paul Walmsley <paul.walmsley@...ive.com>
Reviewed-by: Christoph Hellwig <hch@....de>
---
 arch/riscv/include/asm/tlbflush.h | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
index 687dd19735a7..4d9bbe8438bf 100644
--- a/arch/riscv/include/asm/tlbflush.h
+++ b/arch/riscv/include/asm/tlbflush.h
@@ -53,10 +53,17 @@ static inline void remote_sfence_vma(struct cpumask *cmask, unsigned long start,
 }
 
 #define flush_tlb_all() sbi_remote_sfence_vma(NULL, 0, -1)
-#define flush_tlb_page(vma, addr) flush_tlb_range(vma, addr, 0)
+
 #define flush_tlb_range(vma, start, end) \
 	remote_sfence_vma(mm_cpumask((vma)->vm_mm), start, (end) - (start))
-#define flush_tlb_mm(mm) \
+
+static inline void flush_tlb_page(struct vm_area_struct *vma,
+				  unsigned long addr)
+{
+	flush_tlb_range(vma, addr, addr + PAGE_SIZE);
+}
+
+#define flush_tlb_mm(mm)				\
 	remote_sfence_vma(mm_cpumask(mm), 0, -1)
 
 #endif /* CONFIG_SMP */
-- 
2.23.0.rc1