xtensa: definitions for call0 ABI

Add assembly macros for calls, call arguments, preserved registers,
function entry and return for windowed and call0 ABIs.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/include/asm/asmmacro.h

@@ -194,6 +194,12 @@
 #define XTENSA_STACK_ALIGNMENT		16
 
 #if defined(__XTENSA_WINDOWED_ABI__)
+
+/* Assembly instructions for windowed kernel ABI. */
+#define KABI_W
+/* Assembly instructions for call0 kernel ABI (will be ignored). */
+#define KABI_C0 #
+
 #define XTENSA_FRAME_SIZE_RESERVE	16
 #define XTENSA_SPILL_STACK_RESERVE	32
 
@@ -206,8 +212,34 @@
 #define abi_ret(frame_size) retw
 #define abi_ret_default retw
 
+	/* direct call */
+#define abi_call call4
+	/* indirect call */
+#define abi_callx callx4
+	/* outgoing call argument registers */
+#define abi_arg0 a6
+#define abi_arg1 a7
+#define abi_arg2 a8
+#define abi_arg3 a9
+#define abi_arg4 a10
+#define abi_arg5 a11
+	/* return value */
+#define abi_rv a6
+	/* registers preserved across call */
+#define abi_saved0 a2
+#define abi_saved1 a3
+
+	/* none of the above */
+#define abi_tmp0 a4
+#define abi_tmp1 a5
+
 #elif defined(__XTENSA_CALL0_ABI__)
 
+/* Assembly instructions for windowed kernel ABI (will be ignored). */
+#define KABI_W #
+/* Assembly instructions for call0 kernel ABI. */
+#define KABI_C0
+
 #define XTENSA_SPILL_STACK_RESERVE	0
 
 #define abi_entry(frame_size) __abi_entry (frame_size)
@@ -233,10 +265,43 @@
 
 #define abi_ret_default ret
 
+	/* direct call */
+#define abi_call call0
+	/* indirect call */
+#define abi_callx callx0
+	/* outgoing call argument registers */
+#define abi_arg0 a2
+#define abi_arg1 a3
+#define abi_arg2 a4
+#define abi_arg3 a5
+#define abi_arg4 a6
+#define abi_arg5 a7
+	/* return value */
+#define abi_rv a2
+	/* registers preserved across call */
+#define abi_saved0 a12
+#define abi_saved1 a13
+
+	/* none of the above */
+#define abi_tmp0 a8
+#define abi_tmp1 a9
+
 #else
 #error Unsupported Xtensa ABI
 #endif
 
+#if defined(USER_SUPPORT_WINDOWED)
+/* Assembly instructions for windowed user ABI. */
+#define UABI_W
+/* Assembly instructions for call0 user ABI (will be ignored). */
+#define UABI_C0 #
+#else
+/* Assembly instructions for windowed user ABI (will be ignored). */
+#define UABI_W #
+/* Assembly instructions for call0 user ABI. */
+#define UABI_C0
+#endif
+
 #define __XTENSA_HANDLER	.section ".exception.text", "ax"
 
 #endif /* _XTENSA_ASMMACRO_H */

arch/xtensa/include/asm/core.h

@@ -26,4 +26,15 @@
 #define XCHAL_SPANNING_WAY 0
 #endif
 
+#if XCHAL_HAVE_WINDOWED
+#if defined(CONFIG_USER_ABI_DEFAULT) || defined(CONFIG_USER_ABI_CALL0_PROBE)
+/* Whether windowed ABI is supported in userspace. */
+#define USER_SUPPORT_WINDOWED
+#endif
+#if defined(__XTENSA_WINDOWED_ABI__) || defined(USER_SUPPORT_WINDOWED)
+/* Whether windowed ABI is supported either in userspace or in the kernel. */
+#define SUPPORT_WINDOWED
+#endif
+#endif
+
 #endif

arch/xtensa/include/asm/processor.h

@@ -18,12 +18,6 @@
 #include <asm/types.h>
 #include <asm/regs.h>
 
-/* Assertions. */
-
-#if (XCHAL_HAVE_WINDOWED != 1)
-# error Linux requires the Xtensa Windowed Registers Option.
-#endif
-
 /* Xtensa ABI requires stack alignment to be at least 16 */
 
 #define STACK_ALIGN (XCHAL_DATA_WIDTH > 16 ? XCHAL_DATA_WIDTH : 16)
@@ -105,8 +99,18 @@
 #define WSBITS  (XCHAL_NUM_AREGS / 4)      /* width of WINDOWSTART in bits */
 #define WBBITS  (XCHAL_NUM_AREGS_LOG2 - 2) /* width of WINDOWBASE in bits */
 
+#if defined(__XTENSA_WINDOWED_ABI__)
+#define KERNEL_PS_WOE_MASK PS_WOE_MASK
+#elif defined(__XTENSA_CALL0_ABI__)
+#define KERNEL_PS_WOE_MASK 0
+#else
+#error Unsupported xtensa ABI
+#endif
+
 #ifndef __ASSEMBLY__
 
+#if defined(__XTENSA_WINDOWED_ABI__)
+
 /* Build a valid return address for the specified call winsize.
  * winsize must be 1 (call4), 2 (call8), or 3 (call12)
  */
@@ -117,6 +121,22 @@
  */
 #define MAKE_PC_FROM_RA(ra,sp)    (((ra) & 0x3fffffff) | ((sp) & 0xc0000000))
 
+#elif defined(__XTENSA_CALL0_ABI__)
+
+/* Build a valid return address for the specified call winsize.
+ * winsize must be 1 (call4), 2 (call8), or 3 (call12)
+ */
+#define MAKE_RA_FOR_CALL(ra, ws)   (ra)
+
+/* Convert return address to a valid pc
+ * Note: We assume that the stack pointer is in the same 1GB ranges as the ra
+ */
+#define MAKE_PC_FROM_RA(ra, sp)    (ra)
+
+#else
+#error Unsupported Xtensa ABI
+#endif
+
 /* Spill slot location for the register reg in the spill area under the stack
  * pointer sp. reg must be in the range [0..4).
  */