target/arm: Correct condition for v8M callee stack push

[Qemu-devel] [PATCH] target/arm: Correct condition for v8M callee stack push

Peter Maydell posted 1 patch 5 years, 6 months ago

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git fetch https://github.com/patchew-project/qemu tags/patchew/20181002145940.30931-1-peter.maydell@linaro.org

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target/arm/helper.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

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[Qemu-devel] [PATCH] target/arm: Correct condition for v8M callee stack push

Posted by Peter Maydell 5 years, 6 months ago

In v7m_exception_taken() we were incorrectly using a
"LR bit EXCRET.ES is 1" check when it should be 0
(compare the pseudocode ExceptionTaken() function).
This meant we didn't stack the callee-saved registers
when tailchaining from a NonSecure to a Secure exception.

Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 64b15645944..073fb3c5cb0 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6938,7 +6938,7 @@ static void v7m_exception_taken(ARMCPU *cpu, uint32_t lr, bool dotailchain,
                  * not already saved.
                  */
                 if (lr & R_V7M_EXCRET_DCRS_MASK &&
-                    !(dotailchain && (lr & R_V7M_EXCRET_ES_MASK))) {
+                    !(dotailchain && !(lr & R_V7M_EXCRET_ES_MASK))) {
                     push_failed = v7m_push_callee_stack(cpu, lr, dotailchain,
                                                         ignore_stackfaults);
                 }
-- 
2.19.0

Re: [Qemu-devel] [PATCH] target/arm: Correct condition for v8M callee stack push

Posted by Richard Henderson 5 years, 6 months ago

On 10/2/18 9:59 AM, Peter Maydell wrote:
> In v7m_exception_taken() we were incorrectly using a
> "LR bit EXCRET.ES is 1" check when it should be 0
> (compare the pseudocode ExceptionTaken() function).
> This meant we didn't stack the callee-saved registers
> when tailchaining from a NonSecure to a Secure exception.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  target/arm/helper.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~