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[2001:8b0:1d0::2]) by smtp.gmail.com with ESMTPSA id r3-20020a5d4983000000b00317ab75748bsm10079758wrq.49.2023.09.11.06.53.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 Sep 2023 06:53:46 -0700 (PDT) From: Peter Maydell To: qemu-arm@nongnu.org, qemu-devel@nongnu.org Subject: [PATCH 7/7] target/arm: Implement FEAT_HBC Date: Mon, 11 Sep 2023 14:53:40 +0100 Message-Id: <20230911135340.1139553-8-peter.maydell@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230911135340.1139553-1-peter.maydell@linaro.org> References: <20230911135340.1139553-1-peter.maydell@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::429; envelope-from=peter.maydell@linaro.org; helo=mail-wr1-x429.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=unavailable 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org FEAT_HBC (Hinted conditional branches) provides a new instruction BC.cond, which behaves exactly like the existing B.cond except that it provides a hint to the branch predictor about the likely behaviour of the branch. Since QEMU does not implement branch prediction, we can treat this identically to B.cond. Signed-off-by: Peter Maydell Reviewed-by: Philippe Mathieu-Daudé --- docs/system/arm/emulation.rst | 1 + target/arm/cpu.h | 5 +++++ target/arm/tcg/a64.decode | 3 ++- linux-user/elfload.c | 1 + target/arm/tcg/cpu64.c | 4 ++++ target/arm/tcg/translate-a64.c | 4 ++++ 6 files changed, 17 insertions(+), 1 deletion(-) diff --git a/docs/system/arm/emulation.rst b/docs/system/arm/emulation.rst index 2e6a7c8961e..34429054a3f 100644 --- a/docs/system/arm/emulation.rst +++ b/docs/system/arm/emulation.rst @@ -39,6 +39,7 @@ the following architecture extensions: - FEAT_FlagM2 (Enhancements to flag manipulation instructions) - FEAT_GTG (Guest translation granule size) - FEAT_HAFDBS (Hardware management of the access flag and dirty bit state) +- FEAT_HBC (Hinted conditional branches) - FEAT_HCX (Support for the HCRX_EL2 register) - FEAT_HPDS (Hierarchical permission disables) - FEAT_HPDS2 (Translation table page-based hardware attributes) diff --git a/target/arm/cpu.h b/target/arm/cpu.h index eddf2d3b72c..fc45f1fb9e2 100644 --- a/target/arm/cpu.h +++ b/target/arm/cpu.h @@ -4050,6 +4050,11 @@ static inline bool isar_feature_aa64_i8mm(const ARMISARegisters *id) return FIELD_EX64(id->id_aa64isar1, ID_AA64ISAR1, I8MM) != 0; } +static inline bool isar_feature_aa64_hbc(const ARMISARegisters *id) +{ + return FIELD_EX64(id->id_aa64isar2, ID_AA64ISAR2, BC) != 0; +} + static inline bool isar_feature_aa64_tgran4_lpa2(const ARMISARegisters *id) { return FIELD_SEX64(id->id_aa64mmfr0, ID_AA64MMFR0, TGRAN4) >= 1; diff --git a/target/arm/tcg/a64.decode b/target/arm/tcg/a64.decode index ef64a3f9cba..71113173020 100644 --- a/target/arm/tcg/a64.decode +++ b/target/arm/tcg/a64.decode @@ -126,7 +126,8 @@ CBZ sf:1 011010 nz:1 ................... rt:5 &cbz imm=%imm19 TBZ . 011011 nz:1 ..... .............. rt:5 &tbz imm=%imm14 bitpos=%imm31_19 -B_cond 0101010 0 ................... 0 cond:4 imm=%imm19 +# B.cond and BC.cond +B_cond 0101010 0 ................... c:1 cond:4 imm=%imm19 BR 1101011 0000 11111 000000 rn:5 00000 &r BLR 1101011 0001 11111 000000 rn:5 00000 &r diff --git a/linux-user/elfload.c b/linux-user/elfload.c index bbb4f08109c..203a2b790d5 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -815,6 +815,7 @@ uint32_t get_elf_hwcap2(void) GET_FEATURE_ID(aa64_sme_f64f64, ARM_HWCAP2_A64_SME_F64F64); GET_FEATURE_ID(aa64_sme_i16i64, ARM_HWCAP2_A64_SME_I16I64); GET_FEATURE_ID(aa64_sme_fa64, ARM_HWCAP2_A64_SME_FA64); + GET_FEATURE_ID(aa64_hbc, ARM_HWCAP2_A64_HBC); return hwcaps; } diff --git a/target/arm/tcg/cpu64.c b/target/arm/tcg/cpu64.c index 0f8972950d6..90e033bbc3a 100644 --- a/target/arm/tcg/cpu64.c +++ b/target/arm/tcg/cpu64.c @@ -814,6 +814,10 @@ void aarch64_max_tcg_initfn(Object *obj) t = FIELD_DP64(t, ID_AA64ISAR1, I8MM, 1); /* FEAT_I8MM */ cpu->isar.id_aa64isar1 = t; + t = cpu->isar.id_aa64isar2; + t = FIELD_DP64(t, ID_AA64ISAR2, BC, 1); /* FEAT_HBC */ + cpu->isar.id_aa64isar2 = t; + t = cpu->isar.id_aa64pfr0; t = FIELD_DP64(t, ID_AA64PFR0, FP, 1); /* FEAT_FP16 */ t = FIELD_DP64(t, ID_AA64PFR0, ADVSIMD, 1); /* FEAT_FP16 */ diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c index 0b77c92437f..15eca55fc75 100644 --- a/target/arm/tcg/translate-a64.c +++ b/target/arm/tcg/translate-a64.c @@ -1453,6 +1453,10 @@ static bool trans_TBZ(DisasContext *s, arg_tbz *a) static bool trans_B_cond(DisasContext *s, arg_B_cond *a) { + /* BC.cond is only present with FEAT_HBC */ + if (a->c && !dc_isar_feature(aa64_hbc, s)) { + return false; + } reset_btype(s); if (a->cond < 0x0e) { /* genuinely conditional branches */