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[71.212.39.66]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-21de32eb9f1sm62403605ad.115.2025.02.02.13.57.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 02 Feb 2025 13:57:59 -0800 (PST) Message-ID: <6208a701-0338-4e1f-b0e2-28bf50d81f86@linaro.org> Date: Sun, 2 Feb 2025 13:57:57 -0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] target/sparc: fake UltraSPARC T1 PCR and PIC registers From: Richard Henderson To: Artyom Tarasenko , qemu-devel@nongnu.org Cc: Mark Cave-Ayland References: <20250131214528.117846-1-atar4qemu@gmail.com> <99ea71e8-b978-41c6-8ba5-f056935ea39e@linaro.org> Content-Language: en-US In-Reply-To: <99ea71e8-b978-41c6-8ba5-f056935ea39e@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::102e; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x102e.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 2/2/25 13:46, Richard Henderson wrote: > On 1/31/25 13:44, Artyom Tarasenko wrote: >> fake access to >> PCR Performance Control Register >> and >> PIC Performance Instrumentation Counter. >> >> Ignore writes in privileged mode, and return 0 on reads. >> >> This allows booting Tribblix, MilaX and v9os under Niagara target. >> >> Signed-off-by: Artyom Tarasenko >> --- >>   target/sparc/insns.decode |  7 ++++++- >>   target/sparc/translate.c  | 20 ++++++++++++++++++++ >>   2 files changed, 26 insertions(+), 1 deletion(-) >> >> diff --git a/target/sparc/insns.decode b/target/sparc/insns.decode >> index 989c20b44a..504147563c 100644 >> --- a/target/sparc/insns.decode >> +++ b/target/sparc/insns.decode >> @@ -96,7 +96,10 @@ CALL    01 i:s30 >>       RDTICK          10 rd:5  101000 00100 0 0000000000000 >>       RDPC            10 rd:5  101000 00101 0 0000000000000 >>       RDFPRS          10 rd:5  101000 00110 0 0000000000000 >> -    RDASR17         10 rd:5  101000 10001 0 0000000000000 >> +    { >> +      RDASR17       10 rd:5  101000 10001 0 0000000000000 >> +      RDPIC         10 rd:5  101000 10001 0 0000000000000 >> +    } >>       RDGSR           10 rd:5  101000 10011 0 0000000000000 >>       RDSOFTINT       10 rd:5  101000 10110 0 0000000000000 >>       RDTICK_CMPR     10 rd:5  101000 10111 0 0000000000000 >> @@ -114,6 +117,8 @@ CALL    01 i:s30 >>       WRCCR           10 00010 110000 ..... . .............  @n_r_ri >>       WRASI           10 00011 110000 ..... . .............  @n_r_ri >>       WRFPRS          10 00110 110000 ..... . .............  @n_r_ri >> +    WRPCR           10 10000 110000 01000 0 0000000000000 >> +    WRPIC           10 10001 110000 01000 0 0000000000000 >>       { >>         WRGSR         10 10011 110000 ..... . .............  @n_r_ri >>         WRPOWERDOWN   10 10011 110000 ..... . .............  @n_r_ri >> diff --git a/target/sparc/translate.c b/target/sparc/translate.c >> index 7e5c7351cb..285c9b0a59 100644 >> --- a/target/sparc/translate.c >> +++ b/target/sparc/translate.c >> @@ -2882,6 +2882,15 @@ static TCGv do_rd_leon3_config(DisasContext *dc, TCGv dst) >>   TRANS(RDASR17, ASR17, do_rd_special, true, a->rd, do_rd_leon3_config) >> +static TCGv do_rdpic(DisasContext *dc, TCGv dst) >> +{ >> +    tcg_gen_movi_tl(dst, 0UL); >> +    return dst; >> +} > > return tcg_constant_tl(0); > >> + >> +TRANS(RDPIC, HYPV, do_rd_special, true, a->rd, do_rdpic) > > Surely reads are not allowed in user mode. You might as well implement RDPCR as well, which *is* privileged. Since PCR=0, then RDPCR is allowed. It might be worthwhile to implement PCR, or at least PCR.PRIV. r~ r~