From a6c9c87a5d498008bb3b3dfe4640f8bb196fa1ba Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Sat, 21 Mar 2020 18:26:22 -0400 Subject: [PATCH] target/arm: Stop assuming DBGDIDR always exists The AArch32 DBGDIDR defines properties like the number of breakpoints, watchpoints and context-matching comparators. On an AArch64 CPU, the register may not even exist if AArch32 is not supported at EL1. Currently we hard-code use of DBGDIDR to identify the number of breakpoints etc; this works for all our TCG CPUs, but will break if we ever add an AArch64-only CPU. We also have an assert() that the AArch32 and AArch64 registers match, which currently works only by luck for KVM because we don't populate either of these ID registers from the KVM vCPU and so they are both zero. Clean this up so we have functions for finding the number of breakpoints, watchpoints and context comparators which look in the appropriate ID register. This allows us to drop the "check that AArch64 and AArch32 agree on the number of breakpoints etc" asserts: * we no longer look at the AArch32 versions unless that's the right place to be looking * it's valid to have a CPU (eg AArch64-only) where they don't match * we shouldn't have been asserting the validity of ID registers in a codepath used with KVM anyway Backports commit 88ce6c6ee85d902f59dc65afc3ca86b34f02b9ed from qemu --- qemu/target/arm/cpu.h | 7 ++++++ qemu/target/arm/debug_helper.c | 6 ++--- qemu/target/arm/helper.c | 21 ++++------------- qemu/target/arm/internals.h | 42 ++++++++++++++++++++++++++++++++++ 4 files changed, 57 insertions(+), 19 deletions(-) diff --git a/qemu/target/arm/cpu.h b/qemu/target/arm/cpu.h index f1b49cf2..9bec7a62 100644 --- a/qemu/target/arm/cpu.h +++ b/qemu/target/arm/cpu.h @@ -1725,6 +1725,13 @@ FIELD(ID_DFR0, MPROFDBG, 20, 4) FIELD(ID_DFR0, PERFMON, 24, 4) FIELD(ID_DFR0, TRACEFILT, 28, 4) +FIELD(DBGDIDR, SE_IMP, 12, 1) +FIELD(DBGDIDR, NSUHD_IMP, 14, 1) +FIELD(DBGDIDR, VERSION, 16, 4) +FIELD(DBGDIDR, CTX_CMPS, 20, 4) +FIELD(DBGDIDR, BRPS, 24, 4) +FIELD(DBGDIDR, WRPS, 28, 4) + FIELD(MVFR0, SIMDREG, 0, 4) FIELD(MVFR0, FPSP, 4, 4) FIELD(MVFR0, FPDP, 8, 4) diff --git a/qemu/target/arm/debug_helper.c b/qemu/target/arm/debug_helper.c index 19e548ba..6bb77ef1 100644 --- a/qemu/target/arm/debug_helper.c +++ b/qemu/target/arm/debug_helper.c @@ -16,8 +16,8 @@ static bool linked_bp_matches(ARMCPU *cpu, int lbn) { CPUARMState *env = &cpu->env; uint64_t bcr = env->cp15.dbgbcr[lbn]; - int brps = extract32(cpu->dbgdidr, 24, 4); - int ctx_cmps = extract32(cpu->dbgdidr, 20, 4); + int brps = arm_num_brps(cpu); + int ctx_cmps = arm_num_ctx_cmps(cpu); int bt; uint32_t contextidr; uint64_t hcr_el2; @@ -29,7 +29,7 @@ static bool linked_bp_matches(ARMCPU *cpu, int lbn) * case DBGWCR_EL1.LBN must indicate that breakpoint). * We choose the former. */ - if (lbn > brps || lbn < (brps - ctx_cmps)) { + if (lbn >= brps || lbn < (brps - ctx_cmps)) { return false; } diff --git a/qemu/target/arm/helper.c b/qemu/target/arm/helper.c index 7e0163a5..3780d528 100644 --- a/qemu/target/arm/helper.c +++ b/qemu/target/arm/helper.c @@ -6035,23 +6035,12 @@ static void define_debug_regs(ARMCPU *cpu) }; /* Note that all these register fields hold "number of Xs minus 1". */ - brps = extract32(cpu->dbgdidr, 24, 4); - wrps = extract32(cpu->dbgdidr, 28, 4); - ctx_cmps = extract32(cpu->dbgdidr, 20, 4); + brps = arm_num_brps(cpu); + wrps = arm_num_wrps(cpu); + ctx_cmps = arm_num_ctx_cmps(cpu); assert(ctx_cmps <= brps); - /* The DBGDIDR and ID_AA64DFR0_EL1 define various properties - * of the debug registers such as number of breakpoints; - * check that if they both exist then they agree. - */ - if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) { - assert(FIELD_EX64(cpu->isar.id_aa64dfr0, ID_AA64DFR0, BRPS) == brps); - assert(FIELD_EX64(cpu->isar.id_aa64dfr0, ID_AA64DFR0, WRPS) == wrps); - assert(FIELD_EX64(cpu->isar.id_aa64dfr0, ID_AA64DFR0, CTX_CMPS) - == ctx_cmps); - } - define_one_arm_cp_reg(cpu, &dbgdidr); define_arm_cp_regs(cpu, debug_cp_reginfo); @@ -6059,7 +6048,7 @@ static void define_debug_regs(ARMCPU *cpu) define_arm_cp_regs(cpu, debug_lpae_cp_reginfo); } - for (i = 0; i < brps + 1; i++) { + for (i = 0; i < brps; i++) { ARMCPRegInfo dbgregs[] = { { .name = "DBGBVR", .state = ARM_CP_STATE_BOTH, .cp = 14, .opc0 = 2, .opc1 = 0, .crn = 0, .crm = i, .opc2 = 4, @@ -6078,7 +6067,7 @@ static void define_debug_regs(ARMCPU *cpu) define_arm_cp_regs(cpu, dbgregs); } - for (i = 0; i < wrps + 1; i++) { + for (i = 0; i < wrps; i++) { ARMCPRegInfo dbgregs[] = { { .name = "DBGWVR", .state = ARM_CP_STATE_BOTH, .cp = 14, .opc0 = 2, .opc1 = 0, .crn = 0, .crm = i, .opc2 = 6, diff --git a/qemu/target/arm/internals.h b/qemu/target/arm/internals.h index bd386e85..a816cb08 100644 --- a/qemu/target/arm/internals.h +++ b/qemu/target/arm/internals.h @@ -933,6 +933,48 @@ static inline uint32_t arm_debug_exception_fsr(CPUARMState *env) } } +/** + * arm_num_brps: Return number of implemented breakpoints. + * Note that the ID register BRPS field is "number of bps - 1", + * and we return the actual number of breakpoints. + */ +static inline int arm_num_brps(ARMCPU *cpu) +{ + if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) { + return FIELD_EX64(cpu->isar.id_aa64dfr0, ID_AA64DFR0, BRPS) + 1; + } else { + return FIELD_EX32(cpu->dbgdidr, DBGDIDR, BRPS) + 1; + } +} + +/** + * arm_num_wrps: Return number of implemented watchpoints. + * Note that the ID register WRPS field is "number of wps - 1", + * and we return the actual number of watchpoints. + */ +static inline int arm_num_wrps(ARMCPU *cpu) +{ + if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) { + return FIELD_EX64(cpu->isar.id_aa64dfr0, ID_AA64DFR0, WRPS) + 1; + } else { + return FIELD_EX32(cpu->dbgdidr, DBGDIDR, WRPS) + 1; + } +} + +/** + * arm_num_ctx_cmps: Return number of implemented context comparators. + * Note that the ID register CTX_CMPS field is "number of cmps - 1", + * and we return the actual number of comparators. + */ +static inline int arm_num_ctx_cmps(ARMCPU *cpu) +{ + if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) { + return FIELD_EX64(cpu->isar.id_aa64dfr0, ID_AA64DFR0, CTX_CMPS) + 1; + } else { + return FIELD_EX32(cpu->dbgdidr, DBGDIDR, CTX_CMPS) + 1; + } +} + /* Note make_memop_idx reserves 4 bits for mmu_idx, and MO_BSWAP is bit 3. * Thus a TCGMemOpIdx, without any MO_ALIGN bits, fits in 8 bits. */