[Xen-devel] [PATCH v4 1/3] arm: processor: add new struct hsr_smc32 into hsr union

[Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>]

On ARMv8, one of conditional exceptions (SMC that originates
from AArch32 state) has extra field in HSR.ISS encoding:

CCKNOWNPASS, bit [19]
Indicates whether the instruction might have failed its condition
code check.
   0 - The instruction was unconditional, or was conditional and
   passed  its condition code check.
   1 - The instruction was conditional, and might have failed its
   condition code check.
(ARM DDI 0487B.a page D7-2272)

This is an instruction specific field, so better to add new structure
to union hsr. This structure describes ISS encoding for an exception
from SMC instruction executing in AArch32 state. But we define this
struct for both ARMv7 and ARMv8, because ARMv8 encoding is backwards
compatible with ARMv7.

Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>
---
 xen/include/asm-arm/processor.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/xen/include/asm-arm/processor.h b/xen/include/asm-arm/processor.h
index 855ded1..926ae68 100644
--- a/xen/include/asm-arm/processor.h
+++ b/xen/include/asm-arm/processor.h
@@ -488,6 +488,23 @@ union hsr {
         unsigned long ec:6;     /* Exception Class */
     } cp; /* HSR_EC_CP */
 
+    /*
+     * This encoding is valid only for ARMv8 (ARM DDI 0487B.a, pages D7-2271 
and
+     * G6-4957). On ARMv7, encoding ISS for EC=0x13 is defined as UNK/SBZP
+     * (ARM DDI 0406C.c page B3-1431). UNK/SBZP means that hardware implements
+     * this field as Read-As-Zero. ARMv8 is backwards compatible with ARMv7:
+     * reading CCKNOWNPASS on ARMv7 will return 0, which means that condition
+     * check was passed or instruction was unconditional.
+     */
+    struct hsr_smc32 {
+        unsigned long res0:19;  /* Reserved */
+        unsigned long ccknownpass:1; /* Instruction passed conditional check */
+        unsigned long cc:4;    /* Condition Code */
+        unsigned long ccvalid:1;/* CC Valid */
+        unsigned long len:1;   /* Instruction length */
+        unsigned long ec:6;    /* Exception Class */
+    } smc32; /* HSR_EC_SMC32 */
+
 #ifdef CONFIG_ARM_64
     struct hsr_sysreg {
         unsigned long read:1;   /* Direction */
-- 
2.7.4


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