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[50.113.46.110]) by smtp.gmail.com with ESMTPSA id p125-20020a622983000000b004f6c5d58225sm13790899pfp.90.2022.03.07.23.20.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Mar 2022 23:20:35 -0800 (PST) From: Richard Henderson To: qemu-devel@nongnu.org Subject: [PATCH v4 17/33] target/nios2: Prevent writes to read-only or reserved control fields Date: Mon, 7 Mar 2022 21:19:49 -1000 Message-Id: <20220308072005.307955-18-richard.henderson@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220308072005.307955-1-richard.henderson@linaro.org> References: <20220308072005.307955-1-richard.henderson@linaro.org> MIME-Version: 1.0 X-Host-Lookup-Failed: Reverse DNS lookup failed for 2607:f8b0:4864:20::102a (failed) Received-SPF: pass client-ip=2607:f8b0:4864:20::102a; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x102a.google.com X-Spam_score_int: -6 X-Spam_score: -0.7 X-Spam_bar: / X-Spam_report: (-0.7 / 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, PDS_HP_HELO_NORDNS=0.659, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no 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: , Cc: marex@denx.de, peter.maydell@linaro.org, amir.gonnen@neuroblade.ai Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: "Qemu-devel" Create an array of masks which detail the writable and readonly bits for each control register. Apply them when writing to control registers. Signed-off-by: Richard Henderson --- target/nios2/cpu.h | 13 ++++++ target/nios2/cpu.c | 90 +++++++++++++++++++++++++++++++++------- target/nios2/translate.c | 80 ++++++++++++++++++++++++++++------- 3 files changed, 152 insertions(+), 31 deletions(-) diff --git a/target/nios2/cpu.h b/target/nios2/cpu.h index 927c4aaa80..7faec97d77 100644 --- a/target/nios2/cpu.h +++ b/target/nios2/cpu.h @@ -207,6 +207,11 @@ struct CPUNios2State { int error_code; }; +typedef struct { + uint32_t writable; + uint32_t readonly; +} ControlRegState; + /** * Nios2CPU: * @env: #CPUNios2State @@ -230,9 +235,17 @@ struct Nios2CPU { uint32_t reset_addr; uint32_t exception_addr; uint32_t fast_tlb_miss_addr; + + /* Bits within each control register which are reserved or readonly. */ + ControlRegState cr_state[NUM_CR_REGS]; }; +static inline bool nios2_cr_reserved(const ControlRegState *s) +{ + return (s->writable | s->readonly) == 0; +} + void nios2_tcg_init(void); void nios2_cpu_do_interrupt(CPUState *cs); void dump_mmu(CPUNios2State *env); diff --git a/target/nios2/cpu.c b/target/nios2/cpu.c index f2813d3b47..189adf111c 100644 --- a/target/nios2/cpu.c +++ b/target/nios2/cpu.c @@ -88,6 +88,55 @@ static void nios2_cpu_initfn(Object *obj) cpu_set_cpustate_pointers(cpu); + /* Begin with all fields of all registers are reserved. */ + memset(cpu->cr_state, 0, sizeof(cpu->cr_state)); + + /* + * The combination of writable and readonly is the set of all + * non-reserved fields. We apply writable as a mask to bits, + * and merge in existing readonly bits, before storing. + */ +#define WR_REG(C) cpu->cr_state[C].writable = -1 +#define RO_REG(C) cpu->cr_state[C].readonly = -1 +#define WR_FIELD(C, F) cpu->cr_state[C].writable |= R_##C##_##F##_MASK +#define RO_FIELD(C, F) cpu->cr_state[C].readonly |= R_##C##_##F##_MASK + + WR_FIELD(CR_STATUS, PIE); + WR_REG(CR_ESTATUS); + WR_REG(CR_BSTATUS); + RO_REG(CR_CPUID); + WR_FIELD(CR_EXCEPTION, CAUSE); + WR_REG(CR_BADADDR); + + /* TODO: These control registers are not present with the EIC. */ + WR_REG(CR_IENABLE); + RO_REG(CR_IPENDING); + + if (cpu->mmu_present) { + WR_FIELD(CR_STATUS, U); + WR_FIELD(CR_STATUS, EH); + + WR_FIELD(CR_PTEADDR, VPN); + WR_FIELD(CR_PTEADDR, PTBASE); + + RO_FIELD(CR_TLBMISC, D); + RO_FIELD(CR_TLBMISC, PERM); + RO_FIELD(CR_TLBMISC, BAD); + RO_FIELD(CR_TLBMISC, DBL); + WR_FIELD(CR_TLBMISC, WR); + WR_FIELD(CR_TLBMISC, RD); + WR_FIELD(CR_TLBMISC, WAY); + + WR_REG(CR_TLBACC); + } + + /* TODO: ECC and MPU not implemented. */ + +#undef WR_REG +#undef RO_REG +#undef WR_FIELD +#undef RO_FIELD + #if !defined(CONFIG_USER_ONLY) mmu_init(&cpu->env); @@ -152,23 +201,26 @@ static void nios2_cpu_disas_set_info(CPUState *cpu, disassemble_info *info) static int nios2_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n) { Nios2CPU *cpu = NIOS2_CPU(cs); - CPUClass *cc = CPU_GET_CLASS(cs); CPUNios2State *env = &cpu->env; + uint32_t val; - if (n > cc->gdb_num_core_regs) { + if (n < 32) { /* GP regs */ + val = env->regs[n]; + } else if (n == 32) { /* PC */ + val = env->pc; + } else if (n < 49) { /* Status regs */ + unsigned cr = n - 33; + if (nios2_cr_reserved(&cpu->cr_state[cr])) { + val = 0; + } else { + val = env->ctrl[n - 33]; + } + } else { + /* Invalid regs */ return 0; } - if (n < 32) { /* GP regs */ - return gdb_get_reg32(mem_buf, env->regs[n]); - } else if (n == 32) { /* PC */ - return gdb_get_reg32(mem_buf, env->pc); - } else if (n < 49) { /* Status regs */ - return gdb_get_reg32(mem_buf, env->ctrl[n - 33]); - } - - /* Invalid regs */ - return 0; + return gdb_get_reg32(mem_buf, val); } static int nios2_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n) @@ -176,17 +228,25 @@ static int nios2_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n) Nios2CPU *cpu = NIOS2_CPU(cs); CPUClass *cc = CPU_GET_CLASS(cs); CPUNios2State *env = &cpu->env; + uint32_t val; if (n > cc->gdb_num_core_regs) { return 0; } + val = ldl_p(mem_buf); if (n < 32) { /* GP regs */ - env->regs[n] = ldl_p(mem_buf); + env->regs[n] = val; } else if (n == 32) { /* PC */ - env->pc = ldl_p(mem_buf); + env->pc = val; } else if (n < 49) { /* Status regs */ - env->ctrl[n - 33] = ldl_p(mem_buf); + unsigned cr = n - 33; + /* ??? Maybe allow the debugger to write to readonly fields. */ + val &= cpu->cr_state[cr].writable; + val |= cpu->cr_state[cr].readonly & env->ctrl[cr]; + env->ctrl[cr] = val; + } else { + g_assert_not_reached(); } return 4; diff --git a/target/nios2/translate.c b/target/nios2/translate.c index 77b3bf05f3..38e16df459 100644 --- a/target/nios2/translate.c +++ b/target/nios2/translate.c @@ -101,6 +101,7 @@ typedef struct DisasContext { TCGv_i32 zero; target_ulong pc; int mem_idx; + const ControlRegState *cr_state; } DisasContext; static TCGv cpu_R[NUM_GP_REGS]; @@ -452,17 +453,26 @@ static void callr(DisasContext *dc, uint32_t code, uint32_t flags) /* rC <- ctlN */ static void rdctl(DisasContext *dc, uint32_t code, uint32_t flags) { - R_TYPE(instr, code); - TCGv t1, t2; - if (!gen_check_supervisor(dc)) { return; } +#ifdef CONFIG_USER_ONLY + g_assert_not_reached(); +#else + R_TYPE(instr, code); + TCGv t1, t2; + if (unlikely(instr.c == R_ZERO)) { return; } + /* Reserved registers read as zero. */ + if (nios2_cr_reserved(&dc->cr_state[instr.imm5])) { + tcg_gen_movi_tl(cpu_R[instr.c], 0); + return; + } + switch (instr.imm5) { case CR_IPENDING: /* @@ -486,6 +496,7 @@ static void rdctl(DisasContext *dc, uint32_t code, uint32_t flags) offsetof(CPUNios2State, ctrl[instr.imm5])); break; } +#endif } /* ctlN <- rA */ @@ -500,6 +511,14 @@ static void wrctl(DisasContext *dc, uint32_t code, uint32_t flags) #else R_TYPE(instr, code); TCGv v = load_gpr(dc, instr.a); + uint32_t ofs = offsetof(CPUNios2State, ctrl[instr.imm5]); + uint32_t wr = dc->cr_state[instr.imm5].writable; + uint32_t ro = dc->cr_state[instr.imm5].readonly; + + /* Skip reserved or readonly registers. */ + if (wr == 0) { + return; + } switch (instr.imm5) { case CR_PTEADDR: @@ -511,17 +530,35 @@ static void wrctl(DisasContext *dc, uint32_t code, uint32_t flags) case CR_TLBMISC: gen_helper_mmu_write_tlbmisc(cpu_env, v); break; - case CR_IPENDING: - /* ipending is read only, writes ignored. */ - break; case CR_STATUS: case CR_IENABLE: /* If interrupts were enabled using WRCTL, trigger them. */ dc->base.is_jmp = DISAS_UPDATE; /* fall through */ default: - tcg_gen_st_tl(v, cpu_env, - offsetof(CPUNios2State, ctrl[instr.imm5])); + if (wr == -1) { + /* The register is entirely writable. */ + tcg_gen_st_tl(v, cpu_env, ofs); + } else { + /* + * The register is partially read-only or reserved: + * merge the value. + */ + TCGv n = tcg_temp_new(); + + tcg_gen_andi_tl(n, v, wr); + + if (ro != 0) { + TCGv o = tcg_temp_new(); + tcg_gen_ld_tl(o, cpu_env, ofs); + tcg_gen_andi_tl(o, o, ro); + tcg_gen_or_tl(n, n, o); + tcg_temp_free(o); + } + + tcg_gen_st_tl(n, cpu_env, ofs); + tcg_temp_free(n); + } break; } #endif @@ -785,9 +822,11 @@ static void nios2_tr_init_disas_context(DisasContextBase *dcbase, CPUState *cs) { DisasContext *dc = container_of(dcbase, DisasContext, base); CPUNios2State *env = cs->env_ptr; + Nios2CPU *cpu = env_archcpu(env); int page_insns; dc->mem_idx = cpu_mmu_index(env, false); + dc->cr_state = cpu->cr_state; /* Bound the number of insns to execute to those left on the page. */ page_insns = -(dc->base.pc_first | TARGET_PAGE_MASK) / 4; @@ -902,16 +941,25 @@ void nios2_cpu_dump_state(CPUState *cs, FILE *f, int flags) } #if !defined(CONFIG_USER_ONLY) - for (i = 0; i < NUM_CR_REGS; i++) { - qemu_fprintf(f, "%9s=%8.8x ", cr_regnames[i], env->ctrl[i]); - if ((i + 1) % 4 == 0) { - qemu_fprintf(f, "\n"); + int j; + + for (i = j = 0; i < NUM_CR_REGS; i++) { + if (!nios2_cr_reserved(&cpu->cr_state[i])) { + qemu_fprintf(f, "%9s=%8.8x ", cr_regnames[i], env->ctrl[i]); + if (++j % 4 == 0) { + qemu_fprintf(f, "\n"); + } } } - qemu_fprintf(f, " mmu write: VPN=%05X PID %02X TLBACC %08X\n", - env->mmu.pteaddr_wr & R_CR_PTEADDR_VPN_MASK, - FIELD_EX32(env->mmu.tlbmisc_wr, CR_TLBMISC, PID), - env->mmu.tlbacc_wr); + if (j % 4 != 0) { + qemu_fprintf(f, "\n"); + } + if (cpu->mmu_present) { + qemu_fprintf(f, " mmu write: VPN=%05X PID %02X TLBACC %08X\n", + env->mmu.pteaddr_wr & R_CR_PTEADDR_VPN_MASK, + FIELD_EX32(env->mmu.tlbmisc_wr, CR_TLBMISC, PID), + env->mmu.tlbacc_wr); + } #endif qemu_fprintf(f, "\n\n"); }