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Thu, 25 Jul 2024 16:46:44 -0700 (PDT) From: Deepak Gupta To: qemu-riscv@nongnu.org, qemu-devel@nongnu.org, jim.shu@sifive.com, andy.chiu@sifive.com, jesse.huang@sifive.com, kito.cheng@sifive.com Cc: palmer@dabbelt.com, Alistair.Francis@wdc.com, laurent@vivier.eu, bmeng.cn@gmail.com, liwei1518@gmail.com, dbarboza@ventanamicro.com, zhiwei_liu@linux.alibaba.com, Deepak Gupta Subject: [PATCH 16/24] target/riscv: shadow stack mmu index for shadow stack instructions Date: Thu, 25 Jul 2024 16:46:05 -0700 Message-ID: <20240725234614.3850142-17-debug@rivosinc.com> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240725234614.3850142-1-debug@rivosinc.com> References: <20240725234614.3850142-1-debug@rivosinc.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::42a; envelope-from=debug@rivosinc.com; helo=mail-pf1-x42a.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Shadow stack instructions shadow stack mmu index for load/stores. `MMU_IDX_SS_ACCESS` at bit positon 3 is used as shadow stack index. Shadow stack mmu index depend on privilege and SUM bit. If shadow stack accesses happening in user mode, shadow stack mmu index = 0b1000. If shaodw stack access happening in supervisor mode mmu index = 0b1001. If shadow stack access happening in supervisor mode with SUM=1 then mmu index = 0b1010 Signed-off-by: Deepak Gupta --- target/riscv/cpu.h | 13 +++++++++++++ target/riscv/cpu_helper.c | 3 +++ target/riscv/insn_trans/trans_rva.c.inc | 8 ++++++++ target/riscv/internals.h | 1 + target/riscv/translate.c | 25 +++++++++++++++++++++++++ 5 files changed, 50 insertions(+) diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h index 0e0a9d2be1..82475490ab 100644 --- a/target/riscv/cpu.h +++ b/target/riscv/cpu.h @@ -614,6 +614,19 @@ FIELD(TB_FLAGS, AXL, 26, 2) FIELD(TB_FLAGS, FCFI_LP_EXPECTED, 28, 1) /* zicfiss needs a TB flag so that correct TB is located based on tb flags */ FIELD(TB_FLAGS, BCFI_ENABLED, 29, 1) +/* + * zicfiss shadow stack is special memory on which regular stores aren't + * allowed but shadow stack stores are allowed. Shadow stack stores can + * happen as `sspush` or `ssamoswap` instructions. `sspush` implicitly + * takes shadow stack address from CSR_SSP. But `ssamoswap` takes address + * from encoded input register and it will be used by supervisor software + * to access (read/write) user shadow stack for setting up rt_frame during + * signal delivery. Supervisor software will do so by setting SUM=1. Thus + * a TB flag is needed if SUM was 1 during TB generation to correctly + * reflect memory permissions to access shadow stack user memory from + * supervisor mode. + */ +FIELD(TB_FLAGS, SUM, 30, 1) #ifdef TARGET_RISCV32 #define riscv_cpu_mxl(env) ((void)(env), MXL_RV32) diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c index 7942587a56..b2bb1e4293 100644 --- a/target/riscv/cpu_helper.c +++ b/target/riscv/cpu_helper.c @@ -180,6 +180,9 @@ void cpu_get_tb_cpu_state(CPURISCVState *env, vaddr *pc, fs = EXT_STATUS_DIRTY; vs = EXT_STATUS_DIRTY; #else + flags = FIELD_DP32(flags, TB_FLAGS, SUM, + ((env->mstatus & MSTATUS_SUM) == MSTATUS_SUM)); + flags = FIELD_DP32(flags, TB_FLAGS, PRIV, env->priv); flags |= riscv_env_mmu_index(env, 0); diff --git a/target/riscv/insn_trans/trans_rva.c.inc b/target/riscv/insn_trans/trans_rva.c.inc index db6c03f6a8..68b71339a3 100644 --- a/target/riscv/insn_trans/trans_rva.c.inc +++ b/target/riscv/insn_trans/trans_rva.c.inc @@ -132,6 +132,10 @@ static bool trans_ssamoswap_w(DisasContext *ctx, arg_amoswap_w *a) decode_save_opc(ctx); src1 = get_address(ctx, a->rs1, 0); +#ifndef CONFIG_USER_ONLY + /* Shadow stack access and thus index is SS TLB index */ + ss_mmu_idx = get_ss_index(ctx); +#endif tcg_gen_atomic_xchg_tl(dest, src1, src2, ss_mmu_idx, (MO_ALIGN | MO_TESL)); gen_set_gpr(ctx, a->rd, dest); @@ -224,6 +228,10 @@ static bool trans_ssamoswap_d(DisasContext *ctx, arg_amoswap_w *a) decode_save_opc(ctx); src1 = get_address(ctx, a->rs1, 0); +#ifndef CONFIG_USER_ONLY + /* Shadow stack access and thus index is SS TLB index */ + ss_mmu_idx = get_ss_index(ctx); +#endif tcg_gen_atomic_xchg_tl(dest, src1, src2, ss_mmu_idx, (MO_ALIGN | MO_TESQ)); gen_set_gpr(ctx, a->rd, dest); diff --git a/target/riscv/internals.h b/target/riscv/internals.h index dad0657c80..5147d6bf90 100644 --- a/target/riscv/internals.h +++ b/target/riscv/internals.h @@ -32,6 +32,7 @@ * - S+SUM+2STAGE 0b110 * - Shadow stack+U 0b1000 * - Shadow stack+S 0b1001 + * - Shadow stack+SUM 0b1010 */ #define MMUIdx_U 0 #define MMUIdx_S 1 diff --git a/target/riscv/translate.c b/target/riscv/translate.c index 9152a963ee..ad0f841807 100644 --- a/target/riscv/translate.c +++ b/target/riscv/translate.c @@ -123,6 +123,8 @@ typedef struct DisasContext { bool fcfi_lp_expected; /* zicfiss extension, if shadow stack was enabled during TB gen */ bool bcfi_enabled; + /* SUM was on during tb translation? */ + bool sum; } DisasContext; static inline bool has_ext(DisasContext *ctx, uint32_t ext) @@ -1128,6 +1130,29 @@ static uint32_t opcode_at(DisasContextBase *dcbase, target_ulong pc) return translator_ldl(env, &ctx->base, pc); } +#ifndef CONFIG_USER_ONLY +static unsigned int get_ss_index(DisasContext *ctx) +{ + int ss_mmu_idx = MMU_IDX_SS_ACCESS; + + /* + * If priv mode is S then a separate index for supervisor + * shadow stack accesses + */ + if (ctx->priv == PRV_S) { + ss_mmu_idx |= MMUIdx_S; + } + + /* If SUM was set, SS index should have S cleared */ + if (ctx->sum) { + ss_mmu_idx &= ~(MMUIdx_S); + ss_mmu_idx |= MMUIdx_S_SUM; + } + + return ss_mmu_idx; +} +#endif + /* Include insn module translation function */ #include "insn_trans/trans_rvi.c.inc" #include "insn_trans/trans_rvm.c.inc"