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* [PATCH] xen/arm: Surround HSR_SYSREG macro value with ()
@ 2017-11-29 17:46 Julien Grall
  2017-12-08 15:18 ` Julien Grall
  0 siblings, 1 reply; 3+ messages in thread
From: Julien Grall @ 2017-11-29 17:46 UTC (permalink / raw)
  To: xen-devel; +Cc: sstabellini, Julien Grall, andre.przywara

The value of the macro HCR_SYSREG is not surrounded by (). This means
the behavior may change depend on how it is used.

Thanksfully recent GCC will issue a warning for that.

Signed-off-by: Julien Grall <julien.grall@linaro.org>

---

I am not aware of any "bad" usage today in Xen. This was found whilst
playing with sysreg emulation and GCC complaining about the missing ().
---
 xen/include/asm-arm/arm64/sysregs.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/xen/include/asm-arm/arm64/sysregs.h b/xen/include/asm-arm/arm64/sysregs.h
index 084d2a1e5d..1811234249 100644
--- a/xen/include/asm-arm/arm64/sysregs.h
+++ b/xen/include/asm-arm/arm64/sysregs.h
@@ -32,11 +32,11 @@
 
 /* These are used to decode traps with HSR.EC==HSR_EC_SYSREG */
 #define HSR_SYSREG(op0,op1,crn,crm,op2) \
-    ((__HSR_SYSREG_##op0) << HSR_SYSREG_OP0_SHIFT) | \
-    ((__HSR_SYSREG_##op1) << HSR_SYSREG_OP1_SHIFT) | \
-    ((__HSR_SYSREG_##crn) << HSR_SYSREG_CRN_SHIFT) | \
-    ((__HSR_SYSREG_##crm) << HSR_SYSREG_CRM_SHIFT) | \
-    ((__HSR_SYSREG_##op2) << HSR_SYSREG_OP2_SHIFT)
+    (((__HSR_SYSREG_##op0) << HSR_SYSREG_OP0_SHIFT) | \
+     ((__HSR_SYSREG_##op1) << HSR_SYSREG_OP1_SHIFT) | \
+     ((__HSR_SYSREG_##crn) << HSR_SYSREG_CRN_SHIFT) | \
+     ((__HSR_SYSREG_##crm) << HSR_SYSREG_CRM_SHIFT) | \
+     ((__HSR_SYSREG_##op2) << HSR_SYSREG_OP2_SHIFT))
 
 #define HSR_SYSREG_DCISW          HSR_SYSREG(1,0,c7,c6,2)
 #define HSR_SYSREG_DCCSW          HSR_SYSREG(1,0,c7,c10,2)
-- 
2.11.0


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2017-11-29 17:46 [PATCH] xen/arm: Surround HSR_SYSREG macro value with () Julien Grall
2017-12-08 15:18 ` Julien Grall
2017-12-08 21:18   ` Stefano Stabellini

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