zicfiss has following instructions
- sspopchk: pops a value from shadow stack and compares with x1/x5.
If they dont match, reports a sw check exception with tval = 3.
- sspush: pushes value in x1/x5 on shadow stack
- ssrdp: reads current shadow stack
- ssamoswap: swaps contents of shadow stack atomically
sspopchk/sspush/ssrdp default to zimop if zimop implemented and SSE=0
If SSE=0, ssamoswap is illegal instruction exception.
This patch implements shadow stack operations for qemu-user and shadow
stack is not protected.
Signed-off-by: Deepak Gupta <debug@rivosinc.com>
Co-developed-by: Jim Shu <jim.shu@sifive.com>
Co-developed-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
---
target/riscv/cpu_bits.h | 2 +
target/riscv/insn32.decode | 21 +++-
target/riscv/insn_trans/trans_rvzicfiss.c.inc | 114 ++++++++++++++++++
target/riscv/translate.c | 5 +
4 files changed, 140 insertions(+), 2 deletions(-)
create mode 100644 target/riscv/insn_trans/trans_rvzicfiss.c.inc
diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
index 8223beaceb..385a2c67c2 100644
--- a/target/riscv/cpu_bits.h
+++ b/target/riscv/cpu_bits.h
@@ -697,6 +697,8 @@ typedef enum RISCVException {
/* zicfilp defines lp violation results in sw check with tval = 2*/
#define RISCV_EXCP_SW_CHECK_FCFI_TVAL 2
+/* zicfiss defines ss violation results in sw check with tval = 3*/
+#define RISCV_EXCP_SW_CHECK_BCFI_TVAL 3
#define RISCV_EXCP_INT_FLAG 0x80000000
#define RISCV_EXCP_INT_MASK 0x7fffffff
diff --git a/target/riscv/insn32.decode b/target/riscv/insn32.decode
index 27108b992b..e9139ec1b9 100644
--- a/target/riscv/insn32.decode
+++ b/target/riscv/insn32.decode
@@ -246,6 +246,7 @@ remud 0000001 ..... ..... 111 ..... 1111011 @r
lr_w 00010 . . 00000 ..... 010 ..... 0101111 @atom_ld
sc_w 00011 . . ..... ..... 010 ..... 0101111 @atom_st
amoswap_w 00001 . . ..... ..... 010 ..... 0101111 @atom_st
+ssamoswap_w 01001 . . ..... ..... 010 ..... 0101111 @atom_st
amoadd_w 00000 . . ..... ..... 010 ..... 0101111 @atom_st
amoxor_w 00100 . . ..... ..... 010 ..... 0101111 @atom_st
amoand_w 01100 . . ..... ..... 010 ..... 0101111 @atom_st
@@ -259,6 +260,7 @@ amomaxu_w 11100 . . ..... ..... 010 ..... 0101111 @atom_st
lr_d 00010 . . 00000 ..... 011 ..... 0101111 @atom_ld
sc_d 00011 . . ..... ..... 011 ..... 0101111 @atom_st
amoswap_d 00001 . . ..... ..... 011 ..... 0101111 @atom_st
+ssamoswap_d 01001 . . ..... ..... 011 ..... 0101111 @atom_st
amoadd_d 00000 . . ..... ..... 011 ..... 0101111 @atom_st
amoxor_d 00100 . . ..... ..... 011 ..... 0101111 @atom_st
amoand_d 01100 . . ..... ..... 011 ..... 0101111 @atom_st
@@ -1022,8 +1024,23 @@ amocas_d 00101 . . ..... ..... 011 ..... 0101111 @atom_st
amocas_q 00101 . . ..... ..... 100 ..... 0101111 @atom_st
# *** Zimop may-be-operation extension ***
-mop_r_n 1 . 00 .. 0111 .. ..... 100 ..... 1110011 @mop5
-mop_rr_n 1 . 00 .. 1 ..... ..... 100 ..... 1110011 @mop3
+{
+ # zicfiss instructions carved out of mop.r
+ [
+ ssrdp 1100110 11100 00000 100 rd:5 1110011
+ sspopchk 1100110 11100 00001 100 00000 1110011 &r2 rs1=1 rd=0
+ sspopchk 1100110 11100 00101 100 00000 1110011 &r2 rs1=5 rd=0
+ ]
+ mop_r_n 1 . 00 .. 0111 .. ..... 100 ..... 1110011 @mop5
+}
+{
+ # zicfiss instruction carved out of mop.rr
+ [
+ sspush 1100111 00001 00000 100 00000 1110011 &r2_s rs2=1 rs1=0
+ sspush 1100111 00101 00000 100 00000 1110011 &r2_s rs2=5 rs1=0
+ ]
+ mop_rr_n 1 . 00 .. 1 ..... ..... 100 ..... 1110011 @mop3
+}
# *** Zabhb Standard Extension ***
amoswap_b 00001 . . ..... ..... 000 ..... 0101111 @atom_st
diff --git a/target/riscv/insn_trans/trans_rvzicfiss.c.inc b/target/riscv/insn_trans/trans_rvzicfiss.c.inc
new file mode 100644
index 0000000000..e3ebc4977c
--- /dev/null
+++ b/target/riscv/insn_trans/trans_rvzicfiss.c.inc
@@ -0,0 +1,114 @@
+/*
+ * RISC-V translation routines for the Control-Flow Integrity Extension
+ *
+ * Copyright (c) 2024 Rivos Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2 or later, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+static bool trans_sspopchk(DisasContext *ctx, arg_sspopchk *a)
+{
+ if (!ctx->bcfi_enabled) {
+ return false;
+ }
+
+ TCGv addr = tcg_temp_new();
+ TCGLabel *skip = gen_new_label();
+ uint32_t tmp = (get_xl(ctx) == MXL_RV64) ? 8 : 4;
+ TCGv data = tcg_temp_new();
+ tcg_gen_ld_tl(addr, tcg_env, offsetof(CPURISCVState, ssp));
+ decode_save_opc(ctx, RISCV_UW2_ALWAYS_STORE_AMO);
+ tcg_gen_qemu_ld_tl(data, addr, SS_MMU_INDEX(ctx),
+ mxl_memop(ctx) | MO_ALIGN);
+ TCGv rs1 = get_gpr(ctx, a->rs1, EXT_NONE);
+ tcg_gen_brcond_tl(TCG_COND_EQ, data, rs1, skip);
+ tcg_gen_st_tl(tcg_constant_tl(RISCV_EXCP_SW_CHECK_BCFI_TVAL),
+ tcg_env, offsetof(CPURISCVState, sw_check_code));
+ gen_helper_raise_exception(tcg_env,
+ tcg_constant_i32(RISCV_EXCP_SW_CHECK));
+ gen_set_label(skip);
+ tcg_gen_addi_tl(addr, addr, tmp);
+ tcg_gen_st_tl(addr, tcg_env, offsetof(CPURISCVState, ssp));
+
+ return true;
+}
+
+static bool trans_sspush(DisasContext *ctx, arg_sspush *a)
+{
+ if (!ctx->bcfi_enabled) {
+ return false;
+ }
+
+ TCGv addr = tcg_temp_new();
+ int tmp = (get_xl(ctx) == MXL_RV64) ? -8 : -4;
+ TCGv data = get_gpr(ctx, a->rs2, EXT_NONE);
+ decode_save_opc(ctx, RISCV_UW2_ALWAYS_STORE_AMO);
+ tcg_gen_ld_tl(addr, tcg_env, offsetof(CPURISCVState, ssp));
+ tcg_gen_addi_tl(addr, addr, tmp);
+ tcg_gen_qemu_st_tl(data, addr, SS_MMU_INDEX(ctx),
+ mxl_memop(ctx) | MO_ALIGN);
+ tcg_gen_st_tl(addr, tcg_env, offsetof(CPURISCVState, ssp));
+
+ return true;
+}
+
+static bool trans_ssrdp(DisasContext *ctx, arg_ssrdp *a)
+{
+ if (!ctx->bcfi_enabled || a->rd == 0) {
+ return false;
+ }
+
+ TCGv dest = dest_gpr(ctx, a->rd);
+ tcg_gen_ld_tl(dest, tcg_env, offsetof(CPURISCVState, ssp));
+ gen_set_gpr(ctx, a->rd, dest);
+
+ return true;
+}
+
+static bool trans_ssamoswap_w(DisasContext *ctx, arg_amoswap_w *a)
+{
+ REQUIRE_A_OR_ZAAMO(ctx);
+ if (!ctx->bcfi_enabled) {
+ return false;
+ }
+
+ TCGv dest = dest_gpr(ctx, a->rd);
+ TCGv src1, src2 = get_gpr(ctx, a->rs2, EXT_NONE);
+
+ decode_save_opc(ctx, RISCV_UW2_ALWAYS_STORE_AMO);
+ src1 = get_address(ctx, a->rs1, 0);
+
+ tcg_gen_atomic_xchg_tl(dest, src1, src2, SS_MMU_INDEX(ctx),
+ (MO_ALIGN | MO_TESL));
+ gen_set_gpr(ctx, a->rd, dest);
+ return true;
+}
+
+static bool trans_ssamoswap_d(DisasContext *ctx, arg_amoswap_w *a)
+{
+ REQUIRE_64BIT(ctx);
+ REQUIRE_A_OR_ZAAMO(ctx);
+ if (!ctx->bcfi_enabled) {
+ return false;
+ }
+
+ TCGv dest = dest_gpr(ctx, a->rd);
+ TCGv src1, src2 = get_gpr(ctx, a->rs2, EXT_NONE);
+
+ decode_save_opc(ctx, RISCV_UW2_ALWAYS_STORE_AMO);
+ src1 = get_address(ctx, a->rs1, 0);
+
+ tcg_gen_atomic_xchg_tl(dest, src1, src2, SS_MMU_INDEX(ctx),
+ (MO_ALIGN | MO_TESQ));
+ gen_set_gpr(ctx, a->rd, dest);
+ return true;
+}
diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index 0ca10818f3..bccaf8e89a 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -144,6 +144,8 @@ static inline bool has_ext(DisasContext *ctx, uint32_t ext)
#define get_address_xl(ctx) ((ctx)->address_xl)
#endif
+#define mxl_memop(ctx) ((get_xl(ctx) + 1) | MO_TE)
+
/* The word size for this machine mode. */
static inline int __attribute__((unused)) get_xlen(DisasContext *ctx)
{
@@ -1127,6 +1129,8 @@ static uint32_t opcode_at(DisasContextBase *dcbase, target_ulong pc)
return translator_ldl(env, &ctx->base, pc);
}
+#define SS_MMU_INDEX(ctx) (ctx->mem_idx | MMU_IDX_SS_WRITE)
+
/* Include insn module translation function */
#include "insn_trans/trans_rvi.c.inc"
#include "insn_trans/trans_rvm.c.inc"
@@ -1157,6 +1161,7 @@ static uint32_t opcode_at(DisasContextBase *dcbase, target_ulong pc)
#include "decode-insn16.c.inc"
#include "insn_trans/trans_rvzce.c.inc"
#include "insn_trans/trans_rvzcmop.c.inc"
+#include "insn_trans/trans_rvzicfiss.c.inc"
/* Include decoders for factored-out extensions */
#include "decode-XVentanaCondOps.c.inc"
--
2.45.0