xen/arm32: entry: Split __DEFINE_ENTRY_TRAP in two

The preprocessing macro __DEFINE_ENTRY_TRAP is used to generate trap
entry function. While the macro is fairly small today, follow-up patches
will increase the size signicantly.

In general, assembly macros are more readable as they allow you to name
parameters and avoid '\'. So the actual implementation of the trap is
now switched to an assembly macro.

This is part of XSA-303.

Reported-by: Julien Grall <Julien.Grall@arm.com>
Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
master commit: 6eeef7ecaeec002bb1da7e20c9cfaec5549bd940
master date: 2019-10-31 16:20:58 +0100

diff --git a/xen/arch/arm/arm32/entry.S b/xen/arch/arm/arm32/entry.S
index f6908e3f165845c78bafaa0cc83bf22f988ffd40..525ec26e83c37e6ffadd3afb7dcccb3212c6d8f1 100644 (file)
--- a/xen/arch/arm/arm32/entry.S
+++ b/xen/arch/arm/arm32/entry.S
@@ -125,24 +125,28 @@ abort_guest_exit_end:
 skip_check:
         mov pc, lr
 
-/*
- * Macro to define trap entry. The iflags corresponds to the list of
- * interrupts (Asynchronous Abort, IRQ, FIQ) to unmask.
- */
+        /*
+         * Macro to define trap entry. The iflags corresponds to the list of
+         * interrupts (Asynchronous Abort, IRQ, FIQ) to unmask.
+         */
+        .macro vector trap, iflags
+        SAVE_ALL
+        cpsie   \iflags
+        adr     lr, return_from_trap
+        mov     r0, sp
+        /*
+         * Save the stack pointer in r11. It will be restored after the
+         * trap has been handled (see return_from_trap).
+         */
+        mov     r11, sp
+        bic     sp, #7      /* Align the stack pointer (noop on guest trap) */
+        b       do_trap_\trap
+        .endm
+
 #define __DEFINE_TRAP_ENTRY(trap, iflags)                               \
         ALIGN;                                                          \
 trap_##trap:                                                            \
-        SAVE_ALL;                                                       \
-        cpsie iflags;                                                   \
-        adr lr, return_from_trap;                                       \
-        mov r0, sp;                                                     \
-        /*                                                              \
-         * Save the stack pointer in r11. It will be restored after the \
-         * trap has been handled (see return_from_trap).                \
-         */                                                             \
-        mov r11, sp;                                                    \
-        bic sp, #7; /* Align the stack pointer (noop on guest trap) */  \
-        b do_trap_##trap
+        vector trap, iflags
 
 /* Trap handler which unmask IRQ/Abort, keep FIQ masked */
 #define DEFINE_TRAP_ENTRY(trap) __DEFINE_TRAP_ENTRY(trap, ai)