Re: [RFC v2 PATCH 4/7] arm64: tlbflush.h: add __tlbi() macro

Christoffer Dall
2016-09-06T10:37:02Z

On Tue, Sep 06, 2016 at 11:05:17AM +0100, Punit Agrawal wrote:
> Christoffer Dall <christoffer.dall@linaro.org> writes:
>
> > On Mon, Sep 05, 2016 at 05:31:34PM +0100, Punit Agrawal wrote:
> >> From: Mark Rutland <mark.rutland@arm.com>
> >>
> >> As with dsb() and isb(), add a __tlbi() helper so that we can avoid
> >> distracting asm boilerplate every time we want a TLBI. As some TLBI
> >> operations take an argument while others do not, some pre-processor is
> >> used to handle these two cases with different assembly blocks.
> >>
> >> The existing tlbflush.h code is moved over to use the helper.
> >>
> >> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> >> Cc: Catalin Marinas <catalin.marinas@arm.com>
> >> Cc: Marc Zyngier <marc.zyngier@arm.com>
> >> Cc: Will Deacon <will.deacon@arm.com>
> >> [ rename helper to __tlbi, update commit log ]
> >> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> >> ---
> >> arch/arm64/include/asm/tlbflush.h | 31 +++++++++++++++++++++++--------
> >> 1 file changed, 23 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> >> index b460ae2..e9e42a7 100644
> >> --- a/arch/arm64/include/asm/tlbflush.h
> >> +++ b/arch/arm64/include/asm/tlbflush.h
> >> @@ -25,6 +25,21 @@
> >> #include <asm/cputype.h>
> >>
> >> /*
> >> + * Raw TLBI operations. Drivers and most kernel code should use the TLB
> >> + * management routines below in preference to these. Where necessary, these can
> >
> > in preference to these?
> >
> >> + * be used to avoid asm() boilerplate.
> >
> > 'these' seem to be a bit overloaded in this commentary.
> >
>
> I've locally updated the comment to -
>
> "Raw TLBI operations.
>
> Where necessary, use the __tlbi macro to avoid asm()
> boilerplate. *Note:* Drivers and most kernel code should use the
> TLB management routines in preference to the macros."
>
> Is that better?

Yes. I would get rid of the *Note:* part, but that's really
nit-picking.

Thanks,
-Christoffer

>
> >> + *
> >> + * Can be used as __tlbi(op) or __tlbi(op, arg), depending on whether a
> >> + * particular TLBI op takes an argument or not. The macros below handle invoking
> >> + * the asm with or without the register argument as appropriate.
> >> + */
> >> +#define __TLBI_0(op, arg) asm ("tlbi " #op)
> >> +#define __TLBI_1(op, arg) asm ("tlbi " #op ", %0" : : "r" (arg))
> >> +#define __TLBI_N(op, arg, n, ...) __TLBI_##n(op, arg)
> >> +
> >> +#define __tlbi(op, ...) __TLBI_N(op, ##__VA_ARGS__, 1, 0)
> >> +
> >> +/*
> >> * TLB Management
> >> * ==============
> >> *
> >> @@ -66,7 +81,7 @@
> >> static inline void local_flush_tlb_all(void)
> >> {
> >> dsb(nshst);
> >> - asm("tlbi vmalle1");
> >> + __tlbi(vmalle1);
> >> dsb(nsh);
> >> isb();
> >> }
> >> @@ -74,7 +89,7 @@ static inline void local_flush_tlb_all(void)
> >> static inline void flush_tlb_all(void)
> >> {
> >> dsb(ishst);
> >> - asm("tlbi vmalle1is");
> >> + __tlbi(vmalle1is);
> >> dsb(ish);
> >> isb();
> >> }
> >> @@ -84,7 +99,7 @@ static inline void flush_tlb_mm(struct mm_struct *mm)
> >> unsigned long asid = ASID(mm) << 48;
> >>
> >> dsb(ishst);
> >> - asm("tlbi aside1is, %0" : : "r" (asid));
> >> + __tlbi(aside1is, asid);
> >> dsb(ish);
> >> }
> >>
> >> @@ -94,7 +109,7 @@ static inline void flush_tlb_page(struct vm_area_struct *vma,
> >> unsigned long addr = uaddr >> 12 | (ASID(vma->vm_mm) << 48);
> >>
> >> dsb(ishst);
> >> - asm("tlbi vale1is, %0" : : "r" (addr));
> >> + __tlbi(vale1is, addr);
> >> dsb(ish);
> >> }
> >>
> >> @@ -122,9 +137,9 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
> >> dsb(ishst);
> >> for (addr = start; addr < end; addr += 1 << (PAGE_SHIFT - 12)) {
> >> if (last_level)
> >> - asm("tlbi vale1is, %0" : : "r"(addr));
> >> + __tlbi(vale1is, addr);
> >> else
> >> - asm("tlbi vae1is, %0" : : "r"(addr));
> >> + __tlbi(vae1is, addr);
> >> }
> >> dsb(ish);
> >> }
> >> @@ -149,7 +164,7 @@ static inline void flush_tlb_kernel_range(unsigned long start, unsigned long end
> >>
> >> dsb(ishst);
> >> for (addr = start; addr < end; addr += 1 << (PAGE_SHIFT - 12))
> >> - asm("tlbi vaae1is, %0" : : "r"(addr));
> >> + __tlbi(vaae1is, addr);
> >> dsb(ish);
> >> isb();
> >> }
> >> @@ -163,7 +178,7 @@ static inline void __flush_tlb_pgtable(struct mm_struct *mm,
> >> {
> >> unsigned long addr = uaddr >> 12 | (ASID(mm) << 48);
> >>
> >> - asm("tlbi vae1is, %0" : : "r" (addr));
> >> + __tlbi(vae1is, addr);
> >> dsb(ish);
> >> }
> >>
> >> --
> >> 2.8.1
> >>
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