Re: [RFC PATCH 1/2] RISC-V: Mark existing SBI as legacy SBI.

From: Palmer Dabbelt
Date: Wed Aug 28 2019 - 17:37:36 EST

On Tue, 27 Aug 2019 01:37:00 PDT (-0700), rppt@xxxxxxxxxxxxx wrote:
On Tue, Aug 27, 2019 at 01:58:03PM +0530, Anup Patel wrote:
On Tue, Aug 27, 2019 at 1:21 PM Mike Rapoport <rppt@xxxxxxxxxxxxx> wrote:
>
> On Mon, Aug 26, 2019 at 04:32:55PM -0700, Atish Patra wrote:
> > As per the new SBI specification, current SBI implementation is
> > defined as legacy and will be removed/replaced in future.
> >
> > Rename existing implementation to reflect that. This patch is just
> > a preparatory patch for SBI v0.2 and doesn't introduce any functional
> > changes.
> >
> > Signed-off-by: Atish Patra <atish.patra@xxxxxxx>
> > ---
> > arch/riscv/include/asm/sbi.h | 61 +++++++++++++++++++-----------------
> > 1 file changed, 33 insertions(+), 28 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> > index 21134b3ef404..7f5ecaaaa0d7 100644
> > --- a/arch/riscv/include/asm/sbi.h
> > +++ b/arch/riscv/include/asm/sbi.h
> > @@ -8,17 +8,18 @@
> >
> > #include <linux/types.h>
> >
> > -#define SBI_SET_TIMER 0
> > -#define SBI_CONSOLE_PUTCHAR 1
> > -#define SBI_CONSOLE_GETCHAR 2
> > -#define SBI_CLEAR_IPI 3
> > -#define SBI_SEND_IPI 4
> > -#define SBI_REMOTE_FENCE_I 5
> > -#define SBI_REMOTE_SFENCE_VMA 6
> > -#define SBI_REMOTE_SFENCE_VMA_ASID 7
> > -#define SBI_SHUTDOWN 8
> > -
> > -#define SBI_CALL(which, arg0, arg1, arg2, arg3) ({ \
> > +
> > +#define SBI_EXT_LEGACY_SET_TIMER 0x0
> > +#define SBI_EXT_LEGACY_CONSOLE_PUTCHAR 0x1
> > +#define SBI_EXT_LEGACY_CONSOLE_GETCHAR 0x2
> > +#define SBI_EXT_LEGACY_CLEAR_IPI 0x3
> > +#define SBI_EXT_LEGACY_SEND_IPI 0x4
> > +#define SBI_EXT_LEGACY_REMOTE_FENCE_I 0x5
> > +#define SBI_EXT_LEGACY_REMOTE_SFENCE_VMA 0x6
> > +#define SBI_EXT_LEGACY_REMOTE_SFENCE_VMA_ASID 0x7
> > +#define SBI_EXT_LEGACY_SHUTDOWN 0x8
>
> I can't say I'm closely following RISC-V development, but what will happen
> when SBI v0.3 will come out and will render v0.2 legacy?
> Won't we need another similar renaming then?

Going forward with SBI v0.3 and higher, we won't see any calling
convention changes.

The SBI spec will be maintained and improved by RISC-V UNIX
platform spec working group.

My best guess is that, all future SBI releases (v0.3 or higher) will
include more optional SBI extensions (hart hotplug, power management, etc).

Thanks for the clarification!

Specifically the issue is that 0.1 didn't include any mechanism for probing the existence of a function, but since that has been added in 0.2 it's possible to maintain compatible with future versions.


Regards,
Anup

>
> > +#define SBI_CALL_LEGACY(which, arg0, arg1, arg2, arg3) ({ \
> > register uintptr_t a0 asm ("a0") = (uintptr_t)(arg0); \
> > register uintptr_t a1 asm ("a1") = (uintptr_t)(arg1); \
> > register uintptr_t a2 asm ("a2") = (uintptr_t)(arg2); \
> > @@ -32,58 +33,61 @@
> > })
> >
> > /* Lazy implementations until SBI is finalized */
> > -#define SBI_CALL_0(which) SBI_CALL(which, 0, 0, 0, 0)
> > -#define SBI_CALL_1(which, arg0) SBI_CALL(which, arg0, 0, 0, 0)
> > -#define SBI_CALL_2(which, arg0, arg1) SBI_CALL(which, arg0, arg1, 0, 0)
> > -#define SBI_CALL_3(which, arg0, arg1, arg2) \
> > - SBI_CALL(which, arg0, arg1, arg2, 0)
> > -#define SBI_CALL_4(which, arg0, arg1, arg2, arg3) \
> > - SBI_CALL(which, arg0, arg1, arg2, arg3)
> > +#define SBI_CALL_LEGACY_0(which) SBI_CALL_LEGACY(which, 0, 0, 0, 0)
> > +#define SBI_CALL_LEGACY_1(which, arg0) SBI_CALL_LEGACY(which, arg0, 0, 0, 0)
> > +#define SBI_CALL_LEGACY_2(which, arg0, arg1) \
> > + SBI_CALL_LEGACY(which, arg0, arg1, 0, 0)
> > +#define SBI_CALL_LEGACY_3(which, arg0, arg1, arg2) \
> > + SBI_CALL_LEGACY(which, arg0, arg1, arg2, 0)
> > +#define SBI_CALL_LEGACY_4(which, arg0, arg1, arg2, arg3) \
> > + SBI_CALL_LEGACY(which, arg0, arg1, arg2, arg3)
> >
> > static inline void sbi_console_putchar(int ch)
> > {
> > - SBI_CALL_1(SBI_CONSOLE_PUTCHAR, ch);
> > + SBI_CALL_LEGACY_1(SBI_EXT_LEGACY_CONSOLE_PUTCHAR, ch);
> > }
> >
> > static inline int sbi_console_getchar(void)
> > {
> > - return SBI_CALL_0(SBI_CONSOLE_GETCHAR);
> > + return SBI_CALL_LEGACY_0(SBI_EXT_LEGACY_CONSOLE_GETCHAR);
> > }
> >
> > static inline void sbi_set_timer(uint64_t stime_value)
> > {
> > #if __riscv_xlen == 32
> > - SBI_CALL_2(SBI_SET_TIMER, stime_value, stime_value >> 32);
> > + SBI_CALL_LEGACY_2(SBI_EXT_LEGACY_SET_TIMER, stime_value,
> > + stime_value >> 32);
> > #else
> > - SBI_CALL_1(SBI_SET_TIMER, stime_value);
> > + SBI_CALL_LEGACY_1(SBI_EXT_LEGACY_SET_TIMER, stime_value);
> > #endif
> > }
> >
> > static inline void sbi_shutdown(void)
> > {
> > - SBI_CALL_0(SBI_SHUTDOWN);
> > + SBI_CALL_LEGACY_0(SBI_EXT_LEGACY_SHUTDOWN);
> > }
> >
> > static inline void sbi_clear_ipi(void)
> > {
> > - SBI_CALL_0(SBI_CLEAR_IPI);
> > + SBI_CALL_LEGACY_0(SBI_EXT_LEGACY_CLEAR_IPI);
> > }
> >
> > static inline void sbi_send_ipi(const unsigned long *hart_mask)
> > {
> > - SBI_CALL_1(SBI_SEND_IPI, hart_mask);
> > + SBI_CALL_LEGACY_1(SBI_EXT_LEGACY_SEND_IPI, hart_mask);
> > }
> >
> > static inline void sbi_remote_fence_i(const unsigned long *hart_mask)
> > {
> > - SBI_CALL_1(SBI_REMOTE_FENCE_I, hart_mask);
> > + SBI_CALL_LEGACY_1(SBI_EXT_LEGACY_REMOTE_FENCE_I, hart_mask);
> > }
> >
> > static inline void sbi_remote_sfence_vma(const unsigned long *hart_mask,
> > unsigned long start,
> > unsigned long size)
> > {
> > - SBI_CALL_3(SBI_REMOTE_SFENCE_VMA, hart_mask, start, size);
> > + SBI_CALL_LEGACY_3(SBI_EXT_LEGACY_REMOTE_SFENCE_VMA, hart_mask,
> > + start, size);
> > }
> >
> > static inline void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
> > @@ -91,7 +95,8 @@ static inline void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
> > unsigned long size,
> > unsigned long asid)
> > {
> > - SBI_CALL_4(SBI_REMOTE_SFENCE_VMA_ASID, hart_mask, start, size, asid);
> > + SBI_CALL_LEGACY_4(SBI_EXT_LEGACY_REMOTE_SFENCE_VMA_ASID, hart_mask,
> > + start, size, asid);
> > }
> >
> > #endif
> > --
> > 2.21.0
> >
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@xxxxxxxxxxxxxxxxxxx
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
> >
>
> --
> Sincerely yours,
> Mike.
>
>
> _______________________________________________
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> linux-riscv@xxxxxxxxxxxxxxxxxxx
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