powerpc: DebugException remove args

Like other interrupt handler conversions, switch to getting registers
from the pt_regs argument.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210130130852.2952424-10-npiggin@gmail.com

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

@@ -791,7 +791,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
 	EXCEPTION_COMMON_CRIT(0xd00)
 	std	r14,_DSISR(r1)
 	addi	r3,r1,STACK_FRAME_OVERHEAD
-	mr	r4,r14
 	ld	r14,PACA_EXCRIT+EX_R14(r13)
 	ld	r15,PACA_EXCRIT+EX_R15(r13)
 	bl	save_nvgprs
@@ -864,7 +863,6 @@ kernel_dbg_exc:
 	INTS_DISABLE
 	std	r14,_DSISR(r1)
 	addi	r3,r1,STACK_FRAME_OVERHEAD
-	mr	r4,r14
 	ld	r14,PACA_EXDBG+EX_R14(r13)
 	ld	r15,PACA_EXDBG+EX_R15(r13)
 	bl	save_nvgprs

arch/powerpc/kernel/head_40x.S

@@ -476,6 +476,7 @@ _ENTRY(saved_ksp_limit)
 
 	/* continue normal handling for a critical exception... */
 2:	mfspr	r4,SPRN_DBSR
+	stw	r4,_ESR(r11)		/* DebugException takes DBSR in _ESR */
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	EXC_XFER_TEMPLATE(DebugException, 0x2002, \
 		(MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \

arch/powerpc/kernel/head_booke.h

@@ -406,6 +406,7 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
 									      \
 	/* continue normal handling for a debug exception... */		      \
 2:	mfspr	r4,SPRN_DBSR;						      \
+	stw	r4,_ESR(r11);		/* DebugException takes DBSR in _ESR */\
 	addi	r3,r1,STACK_FRAME_OVERHEAD;				      \
 	EXC_XFER_TEMPLATE(DebugException, 0x2008, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), debug_transfer_to_handler, ret_from_debug_exc)
 
@@ -459,6 +460,7 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
 									      \
 	/* continue normal handling for a critical exception... */	      \
 2:	mfspr	r4,SPRN_DBSR;						      \
+	stw	r4,_ESR(r11);		/* DebugException takes DBSR in _ESR */\
 	addi	r3,r1,STACK_FRAME_OVERHEAD;				      \
 	EXC_XFER_TEMPLATE(DebugException, 0x2002, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), crit_transfer_to_handler, ret_from_crit_exc)
 

arch/powerpc/kernel/traps.c

@@ -1957,8 +1957,10 @@ static void handle_debug(struct pt_regs *regs, unsigned long debug_status)
 		mtspr(SPRN_DBCR0, current->thread.debug.dbcr0);
 }
 
-void DebugException(struct pt_regs *regs, unsigned long debug_status)
+void DebugException(struct pt_regs *regs)
 {
+	unsigned long debug_status = regs->dsisr;
+
 	current->thread.debug.dbsr = debug_status;
 
 	/* Hack alert: On BookE, Branch Taken stops on the branch itself, while