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target-arm: Break the TB after ISB to execute self-modified code correctly

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If any store instruction writes the code inside the same TB
after this store insn, the execution of the TB must be stopped
to execute new code correctly.
As described in ARMv8 manual D3.4.6 self-modifying code must do an
IC invalidation to be valid, and an ISB after it. So it's enough to end
the TB after ISB instruction on the code translation.
Also this TB break is necessary to take any pending interrupts immediately
after an ISB (as required by ARMv8 ARM D1.14.4).

Backports commit 6df99dec9e81838423d723996e96236693fa31fe from qemu
This commit is contained in:
Sergey Sorokin 2018-02-16 14:34:12 -05:00 committed by Lioncash
parent d1bba24d86
commit 04992f0fb3
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GPG key ID: 4E3C3CC1031BA9C7
3 changed files with 29 additions and 5 deletions
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9
qemu/target-arm/helper.c
View file

@ -545,8 +545,13 @@ static const ARMCPRegInfo v6_cp_reginfo[] = {
/* prefetch by MVA in v6, NOP in v7 */
{ "MVA_prefetch", 15,7,13, 0,0,1, 0,
ARM_CP_NOP, PL1_W, },
{ "ISB", 15,7,5, 0,0,4, 0,
ARM_CP_NOP, PL0_W, },
/* We need to break the TB after ISB to execute self-modifying code
* correctly and also to take any pending interrupts immediately.
* So use arm_cp_write_ignore() function instead of ARM_CP_NOP flag.
*/
{ "ISB", 15,7,5, 0,0,4, 0, ARM_CP_NO_RAW,
PL0_W, 0, NULL, 0, 0, {0, 0},
NULL, NULL, arm_cp_write_ignore },
{ "DSB", 15,7,10, 0,0,4, 0,
ARM_CP_NOP, PL0_W, },
{ "DMB", 15,7,10, 0,0,5, 0,

8
qemu/target-arm/translate-a64.c
View file

@ -1270,9 +1270,15 @@ static void handle_sync(DisasContext *s, uint32_t insn,
return;
case 4: /* DSB */
case 5: /* DMB */
case 6: /* ISB */
/* We don't emulate caches so barriers are no-ops */
return;
case 6: /* ISB */
/* We need to break the TB after this insn to execute
* a self-modified code correctly and also to take
* any pending interrupts immediately.
*/
s->is_jmp = DISAS_UPDATE;
return;
default:
unallocated_encoding(s);
return;

17
qemu/target-arm/translate.c
View file

@ -7860,10 +7860,16 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn) // qq
return;
case 4: /* dsb */
case 5: /* dmb */
case 6: /* isb */
ARCH(7);
/* We don't emulate caches so these are a no-op. */
return;
case 6: /* isb */
/* We need to break the TB after this insn to execute
* self-modifying code correctly and also to take
* any pending interrupts immediately.
*/
gen_lookup_tb(s);
return;
default:
goto illegal_op;
}
@ -10172,9 +10178,16 @@ static int disas_thumb2_insn(CPUARMState *env, DisasContext *s, uint16_t insn_hw
break;
case 4: /* dsb */
case 5: /* dmb */
case 6: /* isb */
/* These execute as NOPs. */
break;
case 6: /* isb */
/* We need to break the TB after this insn
* to execute self-modifying code correctly
* and also to take any pending interrupts
* immediately.
*/
gen_lookup_tb(s);
break;
default:
goto illegal_op;
}