powerpc: add a definition for the marker offset within the interrupt frame

Define a constant rather than open-code the offset for the
"regs" marker.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-9-npiggin@gmail.com

arch/powerpc/include/asm/ptrace.h

@@ -125,6 +125,7 @@ struct pt_regs
 #define STACK_INT_FRAME_SIZE	(sizeof(struct pt_regs) + \
 				 STACK_FRAME_OVERHEAD + KERNEL_REDZONE_SIZE)
 #define STACK_INT_FRAME_REGS	STACK_FRAME_OVERHEAD
+#define STACK_INT_FRAME_MARKER	(STACK_FRAME_OVERHEAD - 16)
 #define STACK_FRAME_MARKER	12
 
 #ifdef CONFIG_PPC64_ELF_ABI_V2
@@ -145,6 +146,7 @@ struct pt_regs
 #define STACK_FRAME_LR_SAVE	1	/* Location of LR in stack frame */
 #define STACK_INT_FRAME_SIZE	(sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD)
 #define STACK_INT_FRAME_REGS	STACK_FRAME_OVERHEAD
+#define STACK_INT_FRAME_MARKER	(STACK_FRAME_OVERHEAD - 8)
 #define STACK_FRAME_MARKER	2
 #define STACK_FRAME_MIN_SIZE	STACK_FRAME_OVERHEAD
 

arch/powerpc/kernel/entry_32.S

@@ -114,7 +114,7 @@ transfer_to_syscall:
 	addi	r12,r12,STACK_FRAME_REGS_MARKER@l
 	stw	r9,_MSR(r1)
 	li	r2, INTERRUPT_SYSCALL
-	stw	r12,8(r1)
+	stw	r12,STACK_INT_FRAME_MARKER(r1)
 	stw	r2,_TRAP(r1)
 	SAVE_GPR(0, r1)
 	SAVE_GPRS(3, 8, r1)

arch/powerpc/kernel/exceptions-64e.S

@@ -391,7 +391,7 @@ exc_##n##_common:							    \
 	std	r10,_CCR(r1);		/* store orig CR in stackframe */   \
 	std	r9,GPR1(r1);		/* store stack frame back link */   \
 	std	r11,SOFTE(r1);		/* and save it to stackframe */     \
-	std	r12,STACK_FRAME_OVERHEAD-16(r1); /* mark the frame */	    \
+	std	r12,STACK_INT_FRAME_MARKER(r1); /* mark the frame */	    \
 	std	r3,_TRAP(r1);		/* set trap number		*/  \
 	std	r0,RESULT(r1);		/* clear regs->result */	    \
 	SAVE_NVGPRS(r1);

arch/powerpc/kernel/exceptions-64s.S

@@ -591,7 +591,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
 	li	r10,0
 	LOAD_REG_IMMEDIATE(r11, STACK_FRAME_REGS_MARKER)
 	std	r10,RESULT(r1)		/* clear regs->result		*/
-	std	r11,STACK_FRAME_OVERHEAD-16(r1) /* mark the frame	*/
+	std	r11,STACK_INT_FRAME_MARKER(r1) /* mark the frame	*/
 .endm
 
 /*

arch/powerpc/kernel/head_32.h

@@ -112,7 +112,7 @@ _ASM_NOKPROBE_SYMBOL(\name\()_virt)
 	stw	r0,GPR0(r1)
 	lis	r10,STACK_FRAME_REGS_MARKER@ha /* exception frame marker */
 	addi	r10,r10,STACK_FRAME_REGS_MARKER@l
-	stw	r10,8(r1)
+	stw	r10,STACK_INT_FRAME_MARKER(r1)
 	li	r10, \trapno
 	stw	r10,_TRAP(r1)
 	SAVE_GPRS(3, 8, r1)

arch/powerpc/kernel/head_booke.h

@@ -84,7 +84,7 @@ END_BTB_FLUSH_SECTION
 	stw	r0,GPR0(r1)
 	lis	r10, STACK_FRAME_REGS_MARKER@ha	/* exception frame marker */
 	addi	r10, r10, STACK_FRAME_REGS_MARKER@l
-	stw	r10, 8(r1)
+	stw	r10, STACK_INT_FRAME_MARKER(r1)
 	li	r10, \trapno
 	stw	r10,_TRAP(r1)
 	SAVE_GPRS(3, 8, r1)

arch/powerpc/kernel/interrupt_64.S

@@ -77,11 +77,11 @@ _ASM_NOKPROBE_SYMBOL(system_call_vectored_\name)
 	std	r11,_TRAP(r1)
 	std	r12,_CCR(r1)
 	std	r3,ORIG_GPR3(r1)
+	LOAD_REG_IMMEDIATE(r11, STACK_FRAME_REGS_MARKER)
+	std	r11,STACK_INT_FRAME_MARKER(r1)		/* "regs" marker */
 	/* Calling convention has r3 = regs, r4 = orig r0 */
 	addi	r3,r1,STACK_INT_FRAME_REGS
 	mr	r4,r0
-	LOAD_REG_IMMEDIATE(r11, STACK_FRAME_REGS_MARKER)
-	std	r11,-16(r3)		/* "regshere" marker */
 
 BEGIN_FTR_SECTION
 	HMT_MEDIUM
@@ -250,11 +250,11 @@ END_BTB_FLUSH_SECTION
 	std	r11,_TRAP(r1)
 	std	r12,_CCR(r1)
 	std	r3,ORIG_GPR3(r1)
+	LOAD_REG_IMMEDIATE(r11, STACK_FRAME_REGS_MARKER)
+	std	r11,STACK_INT_FRAME_MARKER(r1)		/* "regs" marker */
 	/* Calling convention has r3 = regs, r4 = orig r0 */
 	addi	r3,r1,STACK_INT_FRAME_REGS
 	mr	r4,r0
-	LOAD_REG_IMMEDIATE(r11, STACK_FRAME_REGS_MARKER)
-	std	r11,-16(r3)		/* "regshere" marker */
 
 #ifdef CONFIG_PPC_BOOK3S
 	li	r11,1
@@ -637,7 +637,7 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
 	 * Leaving a stale STACK_FRAME_REGS_MARKER on the stack can confuse
 	 * the reliable stack unwinder later on. Clear it.
 	 */
-	std	r0,STACK_FRAME_OVERHEAD-16(r1)
+	std	r0,STACK_INT_FRAME_MARKER(r1)
 
 	REST_GPRS(2, 5, r1)
 

arch/powerpc/kvm/book3s_hv_rmhandlers.S

@@ -2729,7 +2729,7 @@ kvmppc_bad_host_intr:
 	std	r6, SOFTE(r1)
 	LOAD_PACA_TOC()
 	LOAD_REG_IMMEDIATE(3, STACK_FRAME_REGS_MARKER)
-	std	r3, STACK_FRAME_OVERHEAD-16(r1)
+	std	r3, STACK_INT_FRAME_MARKER(r1)
 
 	/*
 	 * XXX On POWER7 and POWER8, we just spin here since we don't