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[PULL,28/33] target/arm: Add v8M stack checks for Thumb2 LDM/STM

Message ID 20181008140004.12612-29-peter.maydell@linaro.org
State Accepted
Commit 7c0ed88e7d6bee3e55c3d8935c46226cb544191a
Headers show
Series target-arm queue | expand

Commit Message

Peter Maydell Oct. 8, 2018, 1:59 p.m. UTC 
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: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

Message-id: 20181002163556.10279-10-peter.maydell@linaro.org
---
 target/arm/translate.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

-- 
2.19.0
diff mbox series

Patch

diff --git a/target/arm/translate.c b/target/arm/translate.c
index c16d6075d94..3fb378a492d 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -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);