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

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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.

Backports commit 7c0ed88e7d6bee3e55c3d8935c46226cb544191a from qemu
This commit is contained in:
Peter Maydell 2018-10-08 14:19:11 -04:00 committed by Lioncash
parent bb97240df6
commit de30651f5e
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GPG Key ID: 4E3C3CC1031BA9C7
1 changed files with 17 additions and 0 deletions
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17
qemu/target/arm/translate.c
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@ -10712,6 +10712,7 @@ 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;
@ -10719,10 +10720,26 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
if (insn & (1 << i))
offset += 4;
}
if (insn & (1 << 24)) {
tcg_gen_addi_i32(tcg_ctx, addr, addr, 0-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(tcg_ctx, tcg_ctx->cpu_env, addr);
}
loaded_var = NULL;
for (i = 0; i < 16; i++) {
if ((insn & (1 << i)) == 0)