For -M These should always be thumb mode.
Log a message if this is seen.
Signed-off-by: Michael Davidsaver <[email protected]>
---
target-arm/helper.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/target-arm/helper.c b/target-arm/helper.c
index 4408100..4178400 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -5396,7 +5396,8 @@ static void do_v7m_exception_exit(CPUARMState *env)
qemu_log_mask(LOG_GUEST_ERROR,
"M profile return from interrupt with misaligned "
"PC is UNPREDICTABLE\n");
- /* Actual hardware seems to ignore the lsbit, and there are several
+ /* The ARM calls for UsageFault when the T bit isn't set, but
+ * actual hardware seems to ignore the lsbit, and there are several
* RTOSes out there which incorrectly assume the r15 in the stack
* frame should be a Thumb-style "lsbit indicates ARM/Thumb" value.
*/
@@ -5498,6 +5499,12 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
addr = ldl_phys(cs->as, env->v7m.vecbase + env->v7m.exception * 4);
env->regs[15] = addr & 0xfffffffe;
env->thumb = addr & 1;
+ if (!env->thumb) {
+ qemu_log_mask(LOG_GUEST_ERROR,
+ "M profile interrupt handler %d with incorrect "
+ "instruction mode in PC is UNPREDICTABLE\n",
+ env->v7m.exception);
+ }
}
/* Function used to synchronize QEMU's AArch64 register set with AArch32
--
2.1.4
