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target/arm: Allow ARMv6-M Thumb2 instructions

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ARMv6-M supports 6 Thumb2 instructions. This patch checks for these
instructions and allows their execution.
Like Thumb2 cores, ARMv6-M always interprets BL instruction as 32-bit.

This patch is required for future Cortex-M0 support.

Backports commit 14120108f87b3f9e1beacdf0a6096e464e62bb65 from qemu
This commit is contained in:
Julia Suvorova 2018-06-15 14:12:12 -04:00 committed by Lioncash
parent d81cc5f5cd
commit f447a6f668
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GPG key ID: 4E3C3CC1031BA9C7
1 changed files with 38 additions and 5 deletions
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43
qemu/target/arm/translate.c
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@ -10134,7 +10134,8 @@ static bool thumb_insn_is_16bit(DisasContext *s, uint32_t insn)
* end up actually treating this as two 16-bit insns, though,
* if it's half of a bl/blx pair that might span a page boundary.
*/
if (arm_dc_feature(s, ARM_FEATURE_THUMB2)) {
if (arm_dc_feature(s, ARM_FEATURE_THUMB2) ||
arm_dc_feature(s, ARM_FEATURE_M)) {
/* Thumb2 cores (including all M profile ones) always treat
* 32-bit insns as 32-bit.
*/
@ -10256,10 +10257,38 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
int conds;
int logic_cc;
/* The only 32 bit insn that's allowed for Thumb1 is the combined
* BL/BLX prefix and suffix.
/*
* ARMv6-M supports a limited subset of Thumb2 instructions.
* Other Thumb1 architectures allow only 32-bit
* combined BL/BLX prefix and suffix.
*/
if ((insn & 0xf800e800) != 0xf000e800) {
if (arm_dc_feature(s, ARM_FEATURE_M) &&
!arm_dc_feature(s, ARM_FEATURE_V7)) {
int i;
bool found = false;
const uint32_t armv6m_insn[] = {0xf3808000 /* msr */,
0xf3b08040 /* dsb */,
0xf3b08050 /* dmb */,
0xf3b08060 /* isb */,
0xf3e08000 /* mrs */,
0xf000d000 /* bl */};
const uint32_t armv6m_mask[] = {0xffe0d000,
0xfff0d0f0,
0xfff0d0f0,
0xfff0d0f0,
0xffe0d000,
0xf800d000};
for (i = 0; i < ARRAY_SIZE(armv6m_insn); i++) {
if ((insn & armv6m_mask[i]) == armv6m_insn[i]) {
found = true;
break;
}
}
if (!found) {
goto illegal_op;
}
} else if ((insn & 0xf800e800) != 0xf000e800) {
ARCH(6T2);
}
@ -11180,7 +11209,11 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
}
break;
case 3: /* Special control operations. */
ARCH(7);
if (!arm_dc_feature(s, ARM_FEATURE_V7) &&
!(arm_dc_feature(s, ARM_FEATURE_V6) &&
arm_dc_feature(s, ARM_FEATURE_M))) {
goto illegal_op;
}
op = (insn >> 4) & 0xf;
switch (op) {
case 2: /* clrex */