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[74.87.59.234]) by smtp.gmail.com with ESMTPSA id e14-20020a62aa0e000000b005a816b7c3e8sm89655pff.24.2023.02.15.18.58.17 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Feb 2023 18:58:17 -0800 (PST) From: Richard Henderson To: qemu-devel@nongnu.org Subject: [PATCH v2 27/30] tcg/i386: Examine MemOp for atomicity and alignment Date: Wed, 15 Feb 2023 16:57:36 -1000 Message-Id: <20230216025739.1211680-28-richard.henderson@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230216025739.1211680-1-richard.henderson@linaro.org> References: <20230216025739.1211680-1-richard.henderson@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::430; envelope-from=richard.henderson@linaro.org; helo=mail-pf1-x430.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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org No change to the ultimate load/store routines yet, so some atomicity conditions not yet honored, but plumbs the change to alignment through the adjacent functions. Signed-off-by: Richard Henderson --- tcg/i386/tcg-target.c.inc | 128 ++++++++++++++++++++++++++++++-------- 1 file changed, 101 insertions(+), 27 deletions(-) diff --git a/tcg/i386/tcg-target.c.inc b/tcg/i386/tcg-target.c.inc index 21442c9339..6ee7bc5a9a 100644 --- a/tcg/i386/tcg-target.c.inc +++ b/tcg/i386/tcg-target.c.inc @@ -1746,6 +1746,83 @@ tcg_out_testi(TCGContext *s, TCGReg r, uint32_t i) } } +/* + * Return the alignment and atomicity to use for the inline fast path + * for the given memory operation. The alignment may be larger than + * that specified in @opc, and the correct alignment will be diagnosed + * by the slow path helper. + */ +static MemOp atom_and_align_for_opc(TCGContext *s, MemOp opc, MemOp *out_al) +{ + MemOp align = get_alignment_bits(opc); + MemOp atom, atmax, atsub, size = opc & MO_SIZE; + + /* When serialized, no further atomicity required. */ + if (s->gen_tb->cflags & CF_PARALLEL) { + atom = opc & MO_ATOM_MASK; + } else { + atom = MO_ATOM_NONE; + } + + atmax = opc & MO_ATMAX_MASK; + if (atmax == MO_ATMAX_SIZE) { + atmax = size; + } else { + atmax = atmax >> MO_ATMAX_SHIFT; + } + + switch (atom) { + case MO_ATOM_NONE: + /* The operation requires no specific atomicity. */ + atmax = MO_8; + atsub = MO_8; + break; + case MO_ATOM_IFALIGN: + /* If unaligned, the subobjects are bytes. */ + atsub = MO_8; + break; + case MO_ATOM_WITHIN16: + /* If unaligned, there are subobjects if atmax < size. */ + atsub = (atmax < size ? atmax : MO_8); + atmax = size; + break; + case MO_ATOM_SUBALIGN: + /* If unaligned but not odd, there are subobjects up to atmax - 1. */ + atsub = (atmax == MO_8 ? MO_8 : atmax - 1); + break; + default: + g_assert_not_reached(); + } + + /* + * Per Intel Architecture SDM, Volume 3 Section 8.1.1, + * - Pentium family guarantees atomicity of aligned <= 64-bit. + * - P6 family guarantees atomicity of unaligned <= 64-bit + * which fit within a cache line. + * - AVX guarantees atomicity of aligned 128-bit VMOVDQA (et al). + * + * There is no language in the Intel manual specifying what happens + * with the partial memory operations when crossing a cache line. + * When there is required atomicity of subobjects, we must perform + * an additional runtime test for alignment and then perform either + * the full operation, or two half-sized operations. + * + * For x86_64, and MO_64, we do not have a scratch register with + * which to do this. Only allow splitting for MO_64 on i386, + * where the data is already separated, or MO_128. + * Otherwise, require full alignment and fall back to the helper + * for the misaligned case. + */ + if (align < atmax + && atsub != MO_8 + && size != (TCG_TARGET_REG_BITS == 64 ? MO_128 : MO_64)) { + align = size; + } + + *out_al = align; + return atmax; +} + /* * helper signature: helper_ld*_mmu(CPUState *env, target_ulong addr, * int mmu_idx, uintptr_t ra) @@ -1987,7 +2064,7 @@ static bool tcg_out_qemu_st_slow_path(TCGContext *s, TCGLabelQemuLdst *l) * First argument register is clobbered. */ static void tcg_out_tlb_load(TCGContext *s, TCGReg addrlo, TCGReg addrhi, - int mem_index, MemOp opc, + int mem_index, MemOp a_bits, MemOp s_bits, tcg_insn_unit **label_ptr, int which) { const TCGReg r0 = TCG_REG_L0; @@ -1995,8 +2072,6 @@ static void tcg_out_tlb_load(TCGContext *s, TCGReg addrlo, TCGReg addrhi, TCGType ttype = TCG_TYPE_I32; TCGType tlbtype = TCG_TYPE_I32; int trexw = 0, hrexw = 0, tlbrexw = 0; - unsigned a_bits = get_alignment_bits(opc); - unsigned s_bits = opc & MO_SIZE; unsigned a_mask = (1 << a_bits) - 1; unsigned s_mask = (1 << s_bits) - 1; target_ulong tlb_mask; @@ -2124,7 +2199,8 @@ static inline int setup_guest_base_seg(void) static void tcg_out_qemu_ld_direct(TCGContext *s, TCGReg datalo, TCGReg datahi, TCGReg base, int index, intptr_t ofs, - int seg, TCGType type, MemOp memop) + int seg, TCGType type, MemOp memop, + MemOp atom, MemOp align) { bool use_movbe = false; int rexw = (type == TCG_TYPE_I32 ? 0 : P_REXW); @@ -2225,11 +2301,8 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, TCGType type) TCGReg datalo, datahi, addrlo; TCGReg addrhi __attribute__((unused)); MemOpIdx oi; - MemOp opc; + MemOp opc, atom, align; tcg_insn_unit *label_ptr[2] = { }; -#ifndef CONFIG_SOFTMMU - unsigned a_bits; -#endif datalo = *args++; switch (type) { @@ -2246,26 +2319,27 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, TCGType type) addrhi = (TARGET_LONG_BITS > TCG_TARGET_REG_BITS ? *args++ : 0); oi = *args++; opc = get_memop(oi); + atom = atom_and_align_for_opc(s, opc, &align); #if defined(CONFIG_SOFTMMU) - tcg_out_tlb_load(s, addrlo, addrhi, get_mmuidx(oi), opc, + tcg_out_tlb_load(s, addrlo, addrhi, get_mmuidx(oi), align, opc & MO_SIZE, label_ptr, offsetof(CPUTLBEntry, addr_read)); /* TLB Hit. */ - tcg_out_qemu_ld_direct(s, datalo, datahi, TCG_REG_L1, -1, 0, 0, type, opc); + tcg_out_qemu_ld_direct(s, datalo, datahi, TCG_REG_L1, -1, 0, 0, type, + opc, atom, align); /* Record the current context of a load into ldst label */ add_qemu_ldst_label(s, true, type, oi, datalo, datahi, TCG_REG_L1, addrhi, s->code_ptr, label_ptr); #else - a_bits = get_alignment_bits(opc); - if (a_bits) { - tcg_out_test_alignment(s, addrlo, a_bits, label_ptr); + if (align) { + tcg_out_test_alignment(s, addrlo, align, label_ptr); } tcg_out_qemu_ld_direct(s, datalo, datahi, addrlo, x86_guest_base_index, x86_guest_base_offset, x86_guest_base_seg, - type, opc); - if (a_bits) { + type, opc, atom, align); + if (align) { add_qemu_ldst_label(s, true, type, oi, datalo, datahi, addrlo, addrhi, s->code_ptr, label_ptr); } @@ -2274,7 +2348,8 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, TCGType type) static void tcg_out_qemu_st_direct(TCGContext *s, TCGReg datalo, TCGReg datahi, TCGReg base, int index, intptr_t ofs, - int seg, MemOp memop) + int seg, MemOp memop, + MemOp atom, MemOp align) { bool use_movbe = false; int movop = OPC_MOVL_EvGv; @@ -2329,11 +2404,8 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, TCGType type) TCGReg datalo, datahi, addrlo; TCGReg addrhi __attribute__((unused)); MemOpIdx oi; - MemOp opc; + MemOp opc, atom, align; tcg_insn_unit *label_ptr[2] = { }; -#ifndef CONFIG_SOFTMMU - unsigned a_bits; -#endif datalo = *args++; switch (type) { @@ -2350,25 +2422,27 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, TCGType type) addrhi = (TARGET_LONG_BITS > TCG_TARGET_REG_BITS ? *args++ : 0); oi = *args++; opc = get_memop(oi); + atom = atom_and_align_for_opc(s, opc, &align); #if defined(CONFIG_SOFTMMU) - tcg_out_tlb_load(s, addrlo, addrhi, get_mmuidx(oi), opc, + tcg_out_tlb_load(s, addrlo, addrhi, get_mmuidx(oi), align, opc & MO_SIZE, label_ptr, offsetof(CPUTLBEntry, addr_write)); /* TLB Hit. */ - tcg_out_qemu_st_direct(s, datalo, datahi, TCG_REG_L1, -1, 0, 0, opc); + tcg_out_qemu_st_direct(s, datalo, datahi, TCG_REG_L1, -1, 0, 0, + opc, atom, align); /* Record the current context of a store into ldst label */ add_qemu_ldst_label(s, false, type, oi, datalo, datahi, TCG_REG_L1, addrhi, s->code_ptr, label_ptr); #else - a_bits = get_alignment_bits(opc); - if (a_bits) { - tcg_out_test_alignment(s, addrlo, a_bits, label_ptr); + if (align) { + tcg_out_test_alignment(s, addrlo, align, label_ptr); } tcg_out_qemu_st_direct(s, datalo, datahi, addrlo, x86_guest_base_index, - x86_guest_base_offset, x86_guest_base_seg, opc); - if (a_bits) { + x86_guest_base_offset, x86_guest_base_seg, + opc, atom, align); + if (align) { add_qemu_ldst_label(s, false, type, oi, datalo, datahi, addrlo, addrhi, s->code_ptr, label_ptr); }