Commit 7c0ed88e authored by Peter Maydell's avatar Peter Maydell
Browse files

target/arm: Add v8M stack checks for Thumb2 LDM/STM 



Add the v8M stack checks for:
 * LDM (T2 encoding)
 * STM (T2 encoding)

This includes the 32-bit encodings of the instructions listed
in v8M ARM ARM rule R_YVWT as
 * LDM, LDMIA, LDMFD
 * LDMDB, LDMEA
 * POP (multiple registers)
 * PUSH (muliple registers)
 * STM, STMIA, STMEA
 * STMDB, STMFD

We perform the stack limit before doing any other part
of the load or store.

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: default avatarPhilippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Message-id: 20181002163556.10279-10-peter.maydell@linaro.org
parent 910d7692

target/arm/translate.c

+18 −1
Original line number Diff line number Diff line
@@ -10524,6 +10524,7 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn) 
            } else {

                int i, loaded_base = 0;

                TCGv_i32 loaded_var;

                bool wback = extract32(insn, 21, 1);

                /* Load/store multiple.  */

                addr = load_reg(s, rn);

                offset = 0;
@@ -10531,10 +10532,26 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn) 
                    if (insn & (1 << i))

                        offset += 4;

                }



                if (insn & (1 << 24)) {

                    tcg_gen_addi_i32(addr, addr, -offset);

                }



                if (s->v8m_stackcheck && rn == 13 && wback) {

                    /*

                     * If the writeback is incrementing SP rather than

                     * decrementing it, and the initial SP is below the

                     * stack limit but the final written-back SP would

                     * be above, then then we must not perform any memory

                     * accesses, but it is IMPDEF whether we generate

                     * an exception. We choose to do so in this case.

                     * At this point 'addr' is the lowest address, so

                     * either the original SP (if incrementing) or our

                     * final SP (if decrementing), so that's what we check.

                     */

                    gen_helper_v8m_stackcheck(cpu_env, addr);

                }



                loaded_var = NULL;

                for (i = 0; i < 16; i++) {

                    if ((insn & (1 << i)) == 0)
@@ -10562,7 +10579,7 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn) 
                if (loaded_base) {

                    store_reg(s, rn, loaded_var);

                }

                if (insn & (1 << 21)) {

                if (wback) {

                    /* Base register writeback.  */

                    if (insn & (1 << 24)) {

                        tcg_gen_addi_i32(addr, addr, -offset);