+/*
+ * Exception prolog for machine check exceptions. This is similar to
+ * the critical exception prolog, except that machine check exceptions
+ * have their own save area. For Book E processors, we also have a
+ * reserved register (SPRG6) that is only used in machine check exceptions
+ * so we can free up a GPR to use as the base for indirect access to the
+ * machine check exception save area. This is necessary since the MMU
+ * is always on and the save area is offset from KERNELBASE.
+ */
+#define MCHECK_EXCEPTION_PROLOG \
+ mtspr SPRG6W,r8; /* SPRG6 used in machine checks */ \
+ lis r8,mcheck_save@ha; \
+ stw r10,mcheck_r10@l(r8); \
+ stw r11,mcheck_r11@l(r8); \
+ mfspr r10,SPRG0; \
+ stw r10,mcheck_sprg0@l(r8); \
+ mfspr r10,SPRG1; \
+ stw r10,mcheck_sprg1@l(r8); \
+ mfspr r10,SPRG4R; \
+ stw r10,mcheck_sprg4@l(r8); \
+ mfspr r10,SPRG5R; \
+ stw r10,mcheck_sprg5@l(r8); \
+ mfspr r10,SPRG7R; \
+ stw r10,mcheck_sprg7@l(r8); \
+ mfspr r10,SPRN_PID; \
+ stw r10,mcheck_pid@l(r8); \
+ mfspr r10,SRR0; \
+ stw r10,mcheck_srr0@l(r8); \
+ mfspr r10,SRR1; \
+ stw r10,mcheck_srr1@l(r8); \
+ mfspr r10,CSRR0; \
+ stw r10,mcheck_csrr0@l(r8); \
+ mfspr r10,CSRR1; \
+ stw r10,mcheck_csrr1@l(r8); \
+ mfspr r8,SPRG6R; /* SPRG6 used in machine checks */ \
+ mfcr r10; /* save CR in r10 for now */\
+ mfspr r11,SPRN_MCSRR1; /* check whether user or kernel */\
+ andi. r11,r11,MSR_PR; \
+ lis r11,mcheck_stack_top@h; \
+ ori r11,r11,mcheck_stack_top@l; \
+ beq 1f; \
+ /* COMING FROM USER MODE */ \
+ mfspr r11,SPRG3; /* if from user, start at top of */\
+ lwz r11,THREAD_INFO-THREAD(r11); /* this thread's kernel stack */\
+ addi r11,r11,THREAD_SIZE; \
+1: subi r11,r11,INT_FRAME_SIZE; /* Allocate an exception frame */\
+ stw r10,_CCR(r11); /* save various registers */\
+ stw r12,GPR12(r11); \
+ stw r9,GPR9(r11); \
+ mflr r10; \
+ stw r10,_LINK(r11); \
+ mfspr r12,SPRN_DEAR; /* save DEAR and ESR in the frame */\
+ stw r12,_DEAR(r11); /* since they may have had stuff */\
+ mfspr r9,SPRN_ESR; /* in them at the point where the */\
+ stw r9,_ESR(r11); /* exception was taken */\
+ mfspr r12,MCSRR0; \
+ stw r1,GPR1(r11); \
+ mfspr r9,MCSRR1; \
+ stw r1,0(r11); \
+ tovirt(r1,r11); \
+ rlwinm r9,r9,0,14,12; /* clear MSR_WE (necessary?) */\
+ stw r0,GPR0(r11); \
+ SAVE_4GPRS(3, r11); \
+ SAVE_2GPRS(7, r11)
+