powerpc: Add transactional memory paca scratch register to show_regs

Add transactional memory paca scratch register to show_regs. This is useful
for debugging.

Signed-off-by: Matt Evans <[e-mail]>
Signed-off-by: Michael Neuling <[e-mail]>
Signed-off-by: Benjamin Herrenschmidt <[e-mail]>

arch/powerpc/include/asm/paca.h

···
 	u8 irq_work_pending;		/* IRQ_WORK interrupt while soft-disable */
 	u8 nap_state_lost;		/* NV GPR values lost in power7_idle */
 	u64 sprg3;			/* Saved user-visible sprg */
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+	u64 tm_scratch;                 /* TM scratch area for reclaim */
+#endif
 
 #ifdef CONFIG_PPC_POWERNV
 	/* Pointer to OPAL machine check event structure set by the

arch/powerpc/kernel/asm-offsets.c

···
 	DEFINE(THREAD_TAR, offsetof(struct thread_struct, tar));
 #endif
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+	DEFINE(PACATMSCRATCH, offsetof(struct paca_struct, tm_scratch));
 	DEFINE(THREAD_TM_TFHAR, offsetof(struct thread_struct, tm_tfhar));
 	DEFINE(THREAD_TM_TEXASR, offsetof(struct thread_struct, tm_texasr));
 	DEFINE(THREAD_TM_TFIAR, offsetof(struct thread_struct, tm_tfiar));

arch/powerpc/kernel/entry_64.S

···
 	andc	r4,r4,r0	 /* r0 contains MSR_RI here */
 	mtmsrd	r4,1
 
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+	/* TM debug */
+	std	r3, PACATMSCRATCH(r13) /* Stash returned-to MSR */
+#endif
 	/*
 	 * r13 is our per cpu area, only restore it if we are returning to
 	 * userspace the value stored in the stack frame may belong to

arch/powerpc/kernel/process.c

···
 	printk("NIP ["REG"] %pS\n", regs->nip, (void *)regs->nip);
 	printk("LR ["REG"] %pS\n", regs->link, (void *)regs->link);
 #endif
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+	printk("PACATMSCRATCH [%llx]\n", get_paca()->tm_scratch);
+#endif
 	show_stack(current, (unsigned long *) regs->gpr[1]);
 	if (!user_mode(regs))
 		show_instructions(regs);