> Date: Thu, 4 Jun 2020 20:33:00 +0200
> From: Christian Weisgerber <na...@mips.inka.de>
>
> Here's a proposal for implementing cpu_rnd_messybits() as a read of
> the cycle counter on alpha, powerpc, and sparc64. Since I don't have
> those archs, the diff is not even compile-tested.
>
> * alpha: RPCC is a 32-bit counter (in a 64-bit register)
> * powerpc: TB is a 64-bit counter split into two registers
> * sparc64: TICK is a(n implementation-defined, up to) 63-bit counter
powerpc and sparc64 bits are ok kettenis@
> Index: sys/arch/alpha/alpha/machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/alpha/alpha/machdep.c,v
> retrieving revision 1.191
> diff -u -p -r1.191 machdep.c
> --- sys/arch/alpha/alpha/machdep.c 31 May 2020 06:23:56 -0000 1.191
> +++ sys/arch/alpha/alpha/machdep.c 4 Jun 2020 17:57:45 -0000
> @@ -1854,12 +1854,3 @@ alpha_XXX_dmamap(v)
> /* XXX */
> return (vtophys(v) | alpha_XXX_dmamap_or); /* XXX */
> } /* XXX */
> /* XXX XXX END XXX XXX */
> -
> -unsigned int
> -cpu_rnd_messybits(void)
> -{
> - struct timespec ts;
> -
> - nanotime(&ts);
> - return (ts.tv_nsec ^ (ts.tv_sec << 20));
> -}
> Index: sys/arch/alpha/include/cpu.h
> ===================================================================
> RCS file: /cvs/src/sys/arch/alpha/include/cpu.h,v
> retrieving revision 1.62
> diff -u -p -r1.62 cpu.h
> --- sys/arch/alpha/include/cpu.h 31 May 2020 06:23:56 -0000 1.62
> +++ sys/arch/alpha/include/cpu.h 4 Jun 2020 17:59:25 -0000
> @@ -288,7 +288,11 @@ do {
> \
> */
> #define cpu_number() alpha_pal_whami()
>
> -unsigned int cpu_rnd_messybits(void);
> +static inline unsigned int
> +cpu_rnd_messybits(void)
> +{
> + return alpha_rpcc();
> +}
>
> /*
> * Arguments to hardclock and gatherstats encapsulate the previous
> Index: sys/arch/macppc/macppc/machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/macppc/macppc/machdep.c,v
> retrieving revision 1.191
> diff -u -p -r1.191 machdep.c
> --- sys/arch/macppc/macppc/machdep.c 31 May 2020 06:23:57 -0000 1.191
> +++ sys/arch/macppc/macppc/machdep.c 4 Jun 2020 18:07:31 -0000
> @@ -913,12 +913,3 @@ cpu_switchto(struct proc *oldproc, struc
>
> cpu_switchto_asm(oldproc, newproc);
> }
> -
> -unsigned int
> -cpu_rnd_messybits(void)
> -{
> - struct timespec ts;
> -
> - nanotime(&ts);
> - return (ts.tv_nsec ^ (ts.tv_sec << 20));
> -}
> Index: sys/arch/powerpc/include/cpu.h
> ===================================================================
> RCS file: /cvs/src/sys/arch/powerpc/include/cpu.h,v
> retrieving revision 1.67
> diff -u -p -r1.67 cpu.h
> --- sys/arch/powerpc/include/cpu.h 31 May 2020 06:23:58 -0000 1.67
> +++ sys/arch/powerpc/include/cpu.h 4 Jun 2020 18:13:07 -0000
> @@ -161,7 +161,15 @@ extern int ppc_nobat;
>
> void cpu_bootstrap(void);
>
> -unsigned int cpu_rnd_messybits(void);
> +static inline unsigned int
> +cpu_rnd_messybits(void)
> +{
> + unsigned int hi, lo;
> +
> + __asm volatile("mftbu %0; mftb %1" : "=r" (hi), "=r" (lo));
> +
> + return (hi ^ lo);
> +}
>
> /*
> * This is used during profiling to integrate system time.
> Index: sys/arch/sparc64/include/cpu.h
> ===================================================================
> RCS file: /cvs/src/sys/arch/sparc64/include/cpu.h,v
> retrieving revision 1.94
> diff -u -p -r1.94 cpu.h
> --- sys/arch/sparc64/include/cpu.h 31 May 2020 06:23:58 -0000 1.94
> +++ sys/arch/sparc64/include/cpu.h 4 Jun 2020 18:05:18 -0000
> @@ -211,7 +211,15 @@ void cpu_unidle(struct cpu_info *);
> #define curpcb __curcpu->ci_cpcb
> #define fpproc __curcpu->ci_fpproc
>
> -unsigned int cpu_rnd_messybits(void);
> +static inline unsigned int
> +cpu_rnd_messybits(void)
> +{
> + u_int64_t tick;
> +
> + __asm volatile("rd %%tick, %0" : "=r" (tick) :);
> +
> + return ((tick >> 32) ^ tick);
> +}
>
> /*
> * On processors with multiple threads we force a thread switch.
> Index: sys/arch/sparc64/sparc64/machdep.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/sparc64/sparc64/machdep.c,v
> retrieving revision 1.196
> diff -u -p -r1.196 machdep.c
> --- sys/arch/sparc64/sparc64/machdep.c 31 May 2020 06:23:58 -0000
> 1.196
> +++ sys/arch/sparc64/sparc64/machdep.c 4 Jun 2020 18:01:16 -0000
> @@ -2114,12 +2114,3 @@ blink_led_timeout(void *vsc)
> t = (((averunnable.ldavg[0] + FSCALE) * hz) >> (FSHIFT + 1));
> timeout_add(&sc->bls_to, t);
> }
> -
> -unsigned int
> -cpu_rnd_messybits(void)
> -{
> - struct timespec ts;
> -
> - nanotime(&ts);
> - return (ts.tv_nsec ^ (ts.tv_sec << 20));
> -}
> --
> Christian "naddy" Weisgerber na...@mips.inka.de
>
>
