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[PULL,10/20] target/arm: Warn about restoring to unaligned stack

Message ID 1507305585-20608-11-git-send-email-peter.maydell@linaro.org
State New
Headers show
Series [PULL,01/20] arm: Fix SMC reporting to EL2 when QEMU provides PSCI | expand

Commit Message

Peter Maydell Oct. 6, 2017, 3:59 p.m. UTC 
Attempting to do an exception return with an exception frame that
is not 8-aligned is UNPREDICTABLE in v8M; warn about this.
(It is not UNPREDICTABLE in v7M, and our implementation can
handle the merely-4-aligned case fine, so we don't need to
do anything except warn.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 1506092407-26985-8-git-send-email-peter.maydell@linaro.org
---
 target/arm/helper.c | 7 +++++++
 1 file changed, 7 insertions(+)
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Patch

diff --git a/target/arm/helper.c b/target/arm/helper.c
index bee0f5d..bb57be7 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6413,6 +6413,13 @@  static void do_v7m_exception_exit(ARMCPU *cpu)
                                               return_to_sp_process);
         uint32_t frameptr = *frame_sp_p;
 
+        if (!QEMU_IS_ALIGNED(frameptr, 8) &&
+            arm_feature(env, ARM_FEATURE_V8)) {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "M profile exception return with non-8-aligned SP "
+                          "for destination state is UNPREDICTABLE\n");
+        }
+
         /* Pop registers. TODO: make these accesses use the correct
          * attributes and address space (S/NS, priv/unpriv) and handle
          * memory transaction failures.