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([2602:ae:1598:4c01:ec81:440e:33a4:40b9]) by smtp.gmail.com with ESMTPSA id z21-20020aa791d5000000b006260526cf0csm13771165pfa.116.2023.05.16.12.42.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 May 2023 12:42:14 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Cc: LIU Zhiwei Subject: [PULL 31/80] tcg/riscv: Support softmmu unaligned accesses Date: Tue, 16 May 2023 12:40:56 -0700 Message-Id: <20230516194145.1749305-32-richard.henderson@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230516194145.1749305-1-richard.henderson@linaro.org> References: <20230516194145.1749305-1-richard.henderson@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::533; envelope-from=richard.henderson@linaro.org; helo=mail-pg1-x533.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, T_SCC_BODY_TEXT_LINE=-0.01 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 The system is required to emulate unaligned accesses, even if the hardware does not support it. The resulting trap may or may not be more efficient than the qemu slow path. There are linux kernel patches in flight to allow userspace to query hardware support; we can re-evaluate whether to enable this by default after that. In the meantime, softmmu now matches useronly, where we already assumed that unaligned accesses are supported. Reviewed-by: LIU Zhiwei Signed-off-by: Richard Henderson --- tcg/riscv/tcg-target.c.inc | 48 ++++++++++++++++++++++---------------- 1 file changed, 28 insertions(+), 20 deletions(-) diff --git a/tcg/riscv/tcg-target.c.inc b/tcg/riscv/tcg-target.c.inc index 19cd4507fb..415e6c6e15 100644 --- a/tcg/riscv/tcg-target.c.inc +++ b/tcg/riscv/tcg-target.c.inc @@ -910,12 +910,13 @@ static TCGLabelQemuLdst *prepare_host_addr(TCGContext *s, TCGReg *pbase, #ifdef CONFIG_SOFTMMU unsigned s_bits = opc & MO_SIZE; + unsigned s_mask = (1u << s_bits) - 1; int mem_index = get_mmuidx(oi); int fast_ofs = TLB_MASK_TABLE_OFS(mem_index); int mask_ofs = fast_ofs + offsetof(CPUTLBDescFast, mask); int table_ofs = fast_ofs + offsetof(CPUTLBDescFast, table); - TCGReg mask_base = TCG_AREG0, table_base = TCG_AREG0; - tcg_target_long compare_mask; + int compare_mask; + TCGReg addr_adj; ldst = new_ldst_label(s); ldst->is_ld = is_ld; @@ -924,14 +925,33 @@ static TCGLabelQemuLdst *prepare_host_addr(TCGContext *s, TCGReg *pbase, QEMU_BUILD_BUG_ON(TLB_MASK_TABLE_OFS(0) > 0); QEMU_BUILD_BUG_ON(TLB_MASK_TABLE_OFS(0) < -(1 << 11)); - tcg_out_ld(s, TCG_TYPE_PTR, TCG_REG_TMP0, mask_base, mask_ofs); - tcg_out_ld(s, TCG_TYPE_PTR, TCG_REG_TMP1, table_base, table_ofs); + tcg_out_ld(s, TCG_TYPE_PTR, TCG_REG_TMP0, TCG_AREG0, mask_ofs); + tcg_out_ld(s, TCG_TYPE_PTR, TCG_REG_TMP1, TCG_AREG0, table_ofs); tcg_out_opc_imm(s, OPC_SRLI, TCG_REG_TMP2, addr_reg, TARGET_PAGE_BITS - CPU_TLB_ENTRY_BITS); tcg_out_opc_reg(s, OPC_AND, TCG_REG_TMP2, TCG_REG_TMP2, TCG_REG_TMP0); tcg_out_opc_reg(s, OPC_ADD, TCG_REG_TMP2, TCG_REG_TMP2, TCG_REG_TMP1); + /* + * For aligned accesses, we check the first byte and include the alignment + * bits within the address. For unaligned access, we check that we don't + * cross pages using the address of the last byte of the access. + */ + addr_adj = addr_reg; + if (a_bits < s_bits) { + addr_adj = TCG_REG_TMP0; + tcg_out_opc_imm(s, TARGET_LONG_BITS == 32 ? OPC_ADDIW : OPC_ADDI, + addr_adj, addr_reg, s_mask - a_mask); + } + compare_mask = TARGET_PAGE_MASK | a_mask; + if (compare_mask == sextreg(compare_mask, 0, 12)) { + tcg_out_opc_imm(s, OPC_ANDI, TCG_REG_TMP1, addr_adj, compare_mask); + } else { + tcg_out_movi(s, TCG_TYPE_TL, TCG_REG_TMP1, compare_mask); + tcg_out_opc_reg(s, OPC_AND, TCG_REG_TMP1, TCG_REG_TMP1, addr_adj); + } + /* Load the tlb comparator and the addend. */ tcg_out_ld(s, TCG_TYPE_TL, TCG_REG_TMP0, TCG_REG_TMP2, is_ld ? offsetof(CPUTLBEntry, addr_read) @@ -939,29 +959,17 @@ static TCGLabelQemuLdst *prepare_host_addr(TCGContext *s, TCGReg *pbase, tcg_out_ld(s, TCG_TYPE_PTR, TCG_REG_TMP2, TCG_REG_TMP2, offsetof(CPUTLBEntry, addend)); - /* We don't support unaligned accesses. */ - if (a_bits < s_bits) { - a_bits = s_bits; - } - /* Clear the non-page, non-alignment bits from the address. */ - compare_mask = (tcg_target_long)TARGET_PAGE_MASK | a_mask; - if (compare_mask == sextreg(compare_mask, 0, 12)) { - tcg_out_opc_imm(s, OPC_ANDI, TCG_REG_TMP1, addr_reg, compare_mask); - } else { - tcg_out_movi(s, TCG_TYPE_TL, TCG_REG_TMP1, compare_mask); - tcg_out_opc_reg(s, OPC_AND, TCG_REG_TMP1, TCG_REG_TMP1, addr_reg); - } - /* Compare masked address with the TLB entry. */ ldst->label_ptr[0] = s->code_ptr; tcg_out_opc_branch(s, OPC_BNE, TCG_REG_TMP0, TCG_REG_TMP1, 0); /* TLB Hit - translate address using addend. */ + addr_adj = addr_reg; if (TARGET_LONG_BITS == 32) { - tcg_out_ext32u(s, TCG_REG_TMP0, addr_reg); - addr_reg = TCG_REG_TMP0; + addr_adj = TCG_REG_TMP0; + tcg_out_ext32u(s, addr_adj, addr_reg); } - tcg_out_opc_reg(s, OPC_ADD, TCG_REG_TMP0, TCG_REG_TMP2, addr_reg); + tcg_out_opc_reg(s, OPC_ADD, TCG_REG_TMP0, TCG_REG_TMP2, addr_adj); *pbase = TCG_REG_TMP0; #else if (a_mask) { -- 2.34.1