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From:   Vineet Gupta <vgupta@kernel.org>
To:     linux-snps-arc@lists.infradead.org
Cc:     linux-kernel@vger.kernel.org, Pavel.Kozlov@synopsys.com,
        Vineet Gupta <vgupta@kernel.org>
Subject: [PATCH 1/5] ARC: entry: SAVE_ABI_CALLEE_REG: ISA/ABI specific helper
Date:   Fri,  8 Dec 2023 16:33:03 -0800
Message-Id: <20231209003307.480051-2-vgupta@kernel.org>
In-Reply-To: <20231209003307.480051-1-vgupta@kernel.org>
References: <20231209003307.480051-1-vgupta@kernel.org>
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And for ARcompact variant replace the PUSH/POP macros with gas provided
push/pop pseudo-instructions

This allows ISA specific implementation

e.g. Current ARCv2 PUSH/POP could be replaced with STD/LDL to save 2
registers at a time (w/o bothering with SP update each time) or
perhaps use ENTER_S/LEAVE_S to reduce code size

For ARCv3 ABI changed so callee regs are now r14-r26 (vs. r13-r25)
thus would need a different implementation.

Signed-off-by: Vineet Gupta <vgupta@kernel.org>
---
 arch/arc/include/asm/entry-arcv2.h   | 32 ++++++++++++++++++++
 arch/arc/include/asm/entry-compact.h | 32 ++++++++++++++++++++
 arch/arc/include/asm/entry.h         | 44 +++-------------------------
 arch/arc/include/asm/ptrace.h        | 14 +++++----
 4 files changed, 76 insertions(+), 46 deletions(-)

diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index 4d13320e0c1b..3802a2daaf86 100644
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -291,4 +291,36 @@
 				/* M = 8-1  N = 8 */
 .endm
 
+.macro SAVE_ABI_CALLEE_REGS
+	push	r13
+	push	r14
+	push	r15
+	push	r16
+	push	r17
+	push	r18
+	push	r19
+	push	r20
+	push	r21
+	push	r22
+	push	r23
+	push	r24
+	push	r25
+.endm
+
+.macro RESTORE_ABI_CALLEE_REGS
+	pop	r25
+	pop	r24
+	pop	r23
+	pop	r22
+	pop	r21
+	pop	r20
+	pop	r19
+	pop	r18
+	pop	r17
+	pop	r16
+	pop	r15
+	pop	r14
+	pop	r13
+.endm
+
 #endif
diff --git a/arch/arc/include/asm/entry-compact.h b/arch/arc/include/asm/entry-compact.h
index a0e760eb35a8..9841f1186417 100644
--- a/arch/arc/include/asm/entry-compact.h
+++ b/arch/arc/include/asm/entry-compact.h
@@ -33,6 +33,38 @@
 #include <asm/irqflags-compact.h>
 #include <asm/thread_info.h>	/* For THREAD_SIZE */
 
+.macro SAVE_ABI_CALLEE_REGS
+	push	r13
+	push	r14
+	push	r15
+	push	r16
+	push	r17
+	push	r18
+	push	r19
+	push	r20
+	push	r21
+	push	r22
+	push	r23
+	push	r24
+	push	r25
+.endm
+
+.macro RESTORE_ABI_CALLEE_REGS
+	pop	r25
+	pop	r24
+	pop	r23
+	pop	r22
+	pop	r21
+	pop	r20
+	pop	r19
+	pop	r18
+	pop	r17
+	pop	r16
+	pop	r15
+	pop	r14
+	pop	r13
+.endm
+
 /*--------------------------------------------------------------
  * Switch to Kernel Mode stack if SP points to User Mode stack
  *
diff --git a/arch/arc/include/asm/entry.h b/arch/arc/include/asm/entry.h
index 49c2e090cb5c..8e4e40d2d54a 100644
--- a/arch/arc/include/asm/entry.h
+++ b/arch/arc/include/asm/entry.h
@@ -87,48 +87,12 @@
 
 .endm
 
-/*--------------------------------------------------------------
- * Helpers to save/restore callee-saved regs:
- * used by several macros below
- *-------------------------------------------------------------*/
-.macro SAVE_R13_TO_R25
-	PUSH	r13
-	PUSH	r14
-	PUSH	r15
-	PUSH	r16
-	PUSH	r17
-	PUSH	r18
-	PUSH	r19
-	PUSH	r20
-	PUSH	r21
-	PUSH	r22
-	PUSH	r23
-	PUSH	r24
-	PUSH	r25
-.endm
-
-.macro RESTORE_R25_TO_R13
-	POP	r25
-	POP	r24
-	POP	r23
-	POP	r22
-	POP	r21
-	POP	r20
-	POP	r19
-	POP	r18
-	POP	r17
-	POP	r16
-	POP	r15
-	POP	r14
-	POP	r13
-.endm
-
 /*
  * save user mode callee regs as struct callee_regs
  *  - needed by fork/do_signal/unaligned-access-emulation.
  */
 .macro SAVE_CALLEE_SAVED_USER
-	SAVE_R13_TO_R25
+	SAVE_ABI_CALLEE_REGS
 .endm
 
 /*
@@ -136,18 +100,18 @@
  *  - could have been changed by ptrace tracer or unaligned-access fixup
  */
 .macro RESTORE_CALLEE_SAVED_USER
-	RESTORE_R25_TO_R13
+	RESTORE_ABI_CALLEE_REGS
 .endm
 
 /*
  * save/restore kernel mode callee regs at the time of context switch
  */
 .macro SAVE_CALLEE_SAVED_KERNEL
-	SAVE_R13_TO_R25
+	SAVE_ABI_CALLEE_REGS
 .endm
 
 .macro RESTORE_CALLEE_SAVED_KERNEL
-	RESTORE_R25_TO_R13
+	RESTORE_ABI_CALLEE_REGS
 .endm
 
 /*--------------------------------------------------------------
diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h
index 4a2b30fb5a98..00b9318e551e 100644
--- a/arch/arc/include/asm/ptrace.h
+++ b/arch/arc/include/asm/ptrace.h
@@ -54,6 +54,10 @@ struct pt_regs {
 	ecr_reg ecr;
 };
 
+struct callee_regs {
+	unsigned long r25, r24, r23, r22, r21, r20, r19, r18, r17, r16, r15, r14, r13;
+};
+
 #define MAX_REG_OFFSET offsetof(struct pt_regs, ecr)
 
 #else
@@ -92,16 +96,14 @@ struct pt_regs {
 	unsigned long status32;
 };
 
-#define MAX_REG_OFFSET offsetof(struct pt_regs, status32)
-
-#endif
-
-/* Callee saved registers - need to be saved only when you are scheduled out */
-
 struct callee_regs {
 	unsigned long r25, r24, r23, r22, r21, r20, r19, r18, r17, r16, r15, r14, r13;
 };
 
+#define MAX_REG_OFFSET offsetof(struct pt_regs, status32)
+
+#endif
+
 #define instruction_pointer(regs)	((regs)->ret)
 #define profile_pc(regs)		instruction_pointer(regs)
 
-- 
2.34.1