Re: [Qemu-devel] [PATCH] e500, book3s: mfspr 259: Register mapped/aliased SPRG3 user read

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Apr 19, 2017 at 06:48:22PM +0200, Bernhard Kaindl wrote:
> This patch registers mfspr 259 for Book3S and e500 family cores
> following this research:
> 
> mfspr 259 provides read-only mapped user access to SPRG3(SPR 275) according to:
> 
> - PowerISA 2.02, Book III (documents implementation starting with POWER4+ @ p20)
> - IBM PowerPC 970MP RISC Microprocessor User's Manual v2.1, page 48
> - Amit Singh: "Mac OS X Internals: A Systems Approach" on 970 and 970FX cores:
>   He demonstrates mfspr 259 reading TLS data from Mac OS X on G5 on page 588
> - NXP documents it in the Core Reference Manuals of: e500, e500mc and e5500
> - getcpu() of the 32 & 64-bit Book3S Linux vDSOs use it to read the core number
> 
> mfspr 259 does not appear to be implemented in these cores according to:
> 
> - 74xx series: MPC7410/MPC7400 and MPC7450 RISC Microprocessor Reference Manuals
> - 4xx series:  PPC440 Processor User's Manual, Revision 1.09 by AMCC
> - 750 series:  IBM PowerPC 750CL RISC Microprocessor User's Manual
> - e200 series: e200z4 Power Architectureâ Core Reference Manual
> 
> Implementation: gen_spr_usprg3() is called from init_proc_book3s_common()
> (covers the 970 and POWER cores) and init_proc_e500() (covers the e500 family)
> to register spr_read_ureg() in the same way which it already provides
> the mapped SPR access for SPR_USPRG4-7 in gen_spr_usprgh() for cores
> which have the same read-only mapped SPRG register access for SPRG4-7.
> 
> Verified using Linux by pinning a thread to a core and checking sched_getcpu()
> using qemu-system-ppc64 -M pseries -cpu POWER8 using MTTCG on a x86_64 host.
> 
> Signed-off-by: Bernhard Kaindl <bernhard.kaindl@thalesgroup.com>
> Reviewed-by: Stefan Resch <stefan.resch@thalesgroup.com>

Applied to ppc-for-2.10. thanks.

> ---
>  target/ppc/translate_init.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/target/ppc/translate_init.c b/target/ppc/translate_init.c
> index 77e5463..0ecf541 100644
> --- a/target/ppc/translate_init.c
> +++ b/target/ppc/translate_init.c
> @@ -1640,6 +1640,14 @@ static void spr_write_booke_pid (DisasContext *ctx, int sprn, int gprn)
>  }
>  #endif
>  
> +static void gen_spr_usprg3 (CPUPPCState *env)
> +{
> +    spr_register(env, SPR_USPRG3, "USPRG3",
> +                 &spr_read_ureg, SPR_NOACCESS,
> +                 &spr_read_ureg, SPR_NOACCESS,
> +                 0x00000000);
> +}
> +
>  static void gen_spr_usprgh (CPUPPCState *env)
>  {
>      spr_register(env, SPR_USPRG4, "USPRG4",
> @@ -4914,6 +4922,7 @@ static void init_proc_e500 (CPUPPCState *env, int version)
>              break;
>      }
>      gen_spr_BookE(env, ivor_mask);
> +    gen_spr_usprg3(env);
>      /* Processor identification */
>      spr_register(env, SPR_BOOKE_PIR, "PIR",
>                   SPR_NOACCESS, SPR_NOACCESS,
> @@ -8245,6 +8254,7 @@ static void init_proc_book3s_common(CPUPPCState *env)
>  {
>      gen_spr_ne_601(env);
>      gen_tbl(env);
> +    gen_spr_usprg3(env);
>      gen_spr_book3s_altivec(env);
>      gen_spr_book3s_pmu_sup(env);
>      gen_spr_book3s_pmu_user(env);

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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