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Date: Mon, 18 Oct 2021 22:17:11 -0700
From: Max Filippov <jcmvbkbc@...il.com>
To: linux-xtensa@...ux-xtensa.org
Cc: Chris Zankel <chris@...kel.net>, linux-kernel@...r.kernel.org,
Max Filippov <jcmvbkbc@...il.com>
Subject: [PATCH 05/10] 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@...il.com>
---
arch/xtensa/include/asm/asmmacro.h | 65 +++++++++++++++++++++++++++++
arch/xtensa/include/asm/core.h | 11 +++++
arch/xtensa/include/asm/processor.h | 32 +++++++++++---
3 files changed, 102 insertions(+), 6 deletions(-)
diff --git a/arch/xtensa/include/asm/asmmacro.h b/arch/xtensa/include/asm/asmmacro.h
index bfc89e11f469..809c507d1825 100644
--- a/arch/xtensa/include/asm/asmmacro.h
+++ b/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 */
diff --git a/arch/xtensa/include/asm/core.h b/arch/xtensa/include/asm/core.h
index 5590b0f68837..9138077e567d 100644
--- a/arch/xtensa/include/asm/core.h
+++ b/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
diff --git a/arch/xtensa/include/asm/processor.h b/arch/xtensa/include/asm/processor.h
index 7f63aca6a0d3..aeec2916030c 100644
--- a/arch/xtensa/include/asm/processor.h
+++ b/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).
*/
--
2.20.1
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