[Xen-devel] [PATCH for-4.13 v4 06/19] xen/arm64: entry: Avoid open-coding interrupt flags

[Julien Grall <julien.grall@arm.com>]

At the moment, the interrupts to mask/unmask are hardcoded in the code
making more difficult to find out what's going on.

A new series of short-hand specific to the file entry.S is now added.

The name of the short-hands should tell which interrupts will be
changed by the msr daif{set, clr} instructions.

Take the opportunity to replace the hardcoded values with the new
short-hands.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

---
    Changes in v3:
        - Add Stefano's reviewed-by

    Changes in v2:
        - Patch added
---
 xen/arch/arm/arm64/entry.S | 36 +++++++++++++++++++++++++++---------
 1 file changed, 27 insertions(+), 9 deletions(-)

diff --git a/xen/arch/arm/arm64/entry.S b/xen/arch/arm/arm64/entry.S
index 3e41ba65b6..fac4655bb9 100644
--- a/xen/arch/arm/arm64/entry.S
+++ b/xen/arch/arm/arm64/entry.S
@@ -6,6 +6,24 @@
 #include <asm/smccc.h>
 #include <public/xen.h>
 
+#define IFLAGS_D_BIT    8
+#define IFLAGS_A_BIT    4
+#define IFLAGS_I_BIT    2
+#define IFLAGS_F_BIT    1
+
+/*
+ * Short-hands to define the interrupts (D, A, I, F)
+ *
+ * _ means the interrupt state will not change
+ * X means the state of interrupt X will change
+ *
+ * To be used with msr daif{set, clr} only.
+ *
+ */
+#define IFLAGS__AI_     IFLAGS_A_BIT | IFLAGS_I_BIT
+#define IFLAGS__A__     IFLAGS_A_BIT
+#define IFLAGS___I_     IFLAGS_I_BIT
+
 /*
  * Stack pushing/popping (register pairs only). Equivalent to store decrement
  * before, load increment after.
@@ -338,7 +356,7 @@ guest_sync_slowpath:
         ALTERNATIVE("bl check_pending_vserror; cbnz x0, 1f",
                     "nop; nop",
                     SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT)
-        msr     daifclr, #6
+        msr     daifclr, #IFLAGS__AI_
         mov     x0, sp
         bl      do_trap_guest_sync
 1:
@@ -354,7 +372,7 @@ guest_irq:
         ALTERNATIVE("bl check_pending_vserror; cbnz x0, 1f",
                     "nop; nop",
                     SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT)
-        msr     daifclr, #4
+        msr     daifclr, #IFLAGS__A__
         mov     x0, sp
         bl      do_trap_irq
 1:
@@ -366,7 +384,7 @@ guest_fiq_invalid:
 
 guest_error:
         entry   hyp=0, compat=0
-        msr     daifclr, #6
+        msr     daifclr, #IFLAGS__AI_
         mov     x0, sp
         bl      do_trap_guest_serror
         exit    hyp=0, compat=0
@@ -381,7 +399,7 @@ guest_sync_compat:
         ALTERNATIVE("bl check_pending_vserror; cbnz x0, 1f",
                     "nop; nop",
                     SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT)
-        msr     daifclr, #6
+        msr     daifclr, #IFLAGS__AI_
         mov     x0, sp
         bl      do_trap_guest_sync
 1:
@@ -397,7 +415,7 @@ guest_irq_compat:
         ALTERNATIVE("bl check_pending_vserror; cbnz x0, 1f",
                     "nop; nop",
                     SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT)
-        msr     daifclr, #4
+        msr     daifclr, #IFLAGS__A__
         mov     x0, sp
         bl      do_trap_irq
 1:
@@ -409,7 +427,7 @@ guest_fiq_invalid_compat:
 
 guest_error_compat:
         entry   hyp=0, compat=1
-        msr     daifclr, #6
+        msr     daifclr, #IFLAGS__AI_
         mov     x0, sp
         bl      do_trap_guest_serror
         exit    hyp=0, compat=1
@@ -420,7 +438,7 @@ ENTRY(return_to_new_vcpu64)
         exit    hyp=0, compat=0
 
 return_from_trap:
-        msr     daifset, #2 /* Mask interrupts */
+        msr     daifset, #IFLAGS___I_ /* Mask interrupts */
 
         ldr     x21, [sp, #UREGS_PC]            /* load ELR */
         ldr     w22, [sp, #UREGS_CPSR]          /* load SPSR */
@@ -471,7 +489,7 @@ check_pending_vserror:
          * SError, the EL2 error exception will happen after PSTATE.A
          * is cleared.
          */
-        msr     daifclr, #4
+        msr     daifclr, #IFLAGS__A__
 
         /*
          * This is our single instruction exception window. A pending
@@ -490,7 +508,7 @@ abort_guest_exit_start:
         .global abort_guest_exit_end
 abort_guest_exit_end:
         /* Mask PSTATE asynchronous abort bit, close the checking window. */
-        msr     daifset, #4
+        msr     daifset, #IFLAGS__A__
 
         /*
          * Compare elr_el2 and the saved value to check whether we are
-- 
2.11.0


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