[POWERPC] Reworking machine check handling and Fix 440/440A

This adds a cputable function pointer for the CPU-side machine
check handling. The semantic is still the same as the old one,
the one in ppc_md. overrides the one in cputable, though
ultimately we'll want to change that so the CPU gets first.

This removes CONFIG_440A which was a problem for multiplatform
kernels and instead fixes up the IVOR at runtime from a setup_cpu
function. The "A" version of the machine check also tweaks the
regs->trap value to differenciate the 2 versions at the C level.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>

arch/powerpc/kernel/cpu_setup_44x.S

@@ -23,11 +23,20 @@ _GLOBAL(__setup_cpu_440epx)
 	mflr	r4
 	bl	__init_fpu_44x
 	bl	__plb_disable_wrp
+	bl	__fixup_440A_mcheck
 	mtlr	r4
 	blr
 _GLOBAL(__setup_cpu_440grx)
 	b	__plb_disable_wrp
+_GLOBAL(__setup_cpu_440gx)
+_GLOBAL(__setup_cpu_440spe)
+	b	__fixup_440A_mcheck
 
+ /* Temporary fixup for arch/ppc until we kill the whole thing */
+#ifndef CONFIG_PPC_MERGE
+_GLOBAL(__fixup_440A_mcheck)
+	blr
+#endif
 
 /* enable APU between CPU and FPU */
 _GLOBAL(__init_fpu_44x)

arch/powerpc/kernel/head_44x.S

@@ -289,11 +289,8 @@ interrupt_base:
 	CRITICAL_EXCEPTION(0x0100, CriticalInput, unknown_exception)
 
 	/* Machine Check Interrupt */
-#ifdef CONFIG_440A
-	MCHECK_EXCEPTION(0x0200, MachineCheck, machine_check_exception)
-#else
 	CRITICAL_EXCEPTION(0x0200, MachineCheck, machine_check_exception)
-#endif
+	MCHECK_EXCEPTION(0x0210, MachineCheckA, machine_check_exception)
 
 	/* Data Storage Interrupt */
 	START_EXCEPTION(DataStorage)
@@ -673,6 +670,15 @@ finish_tlb_load:
  * Global functions
  */
 
+/*
+ * Adjust the machine check IVOR on 440A cores
+ */
+_GLOBAL(__fixup_440A_mcheck)
+	li	r3,MachineCheckA@l
+	mtspr	SPRN_IVOR1,r3
+	sync
+	blr
+
 /*
  * extern void giveup_altivec(struct task_struct *prev)
  *

arch/powerpc/kernel/head_booke.h

@@ -166,7 +166,7 @@
 	mfspr	r5,SPRN_ESR;					\
 	stw	r5,_ESR(r11);					\
 	addi	r3,r1,STACK_FRAME_OVERHEAD;			\
-	EXC_XFER_TEMPLATE(hdlr, n+2, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \
+	EXC_XFER_TEMPLATE(hdlr, n+4, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \
 			  NOCOPY, mcheck_transfer_to_handler,   \
 			  ret_from_mcheck_exc)
 

arch/powerpc/kernel/traps.c

@@ -334,18 +334,25 @@ static inline int check_io_access(struct pt_regs *regs)
 #define clear_single_step(regs)	((regs)->msr &= ~MSR_SE)
 #endif
 
-static int generic_machine_check_exception(struct pt_regs *regs)
+#if defined(CONFIG_4xx)
+int machine_check_4xx(struct pt_regs *regs)
 {
 	unsigned long reason = get_mc_reason(regs);
 
-#if defined(CONFIG_4xx) && !defined(CONFIG_440A)
 	if (reason & ESR_IMCP) {
 		printk("Instruction");
 		mtspr(SPRN_ESR, reason & ~ESR_IMCP);
 	} else
 		printk("Data");
 	printk(" machine check in kernel mode.\n");
-#elif defined(CONFIG_440A)
+
+	return 0;
+}
+
+int machine_check_440A(struct pt_regs *regs)
+{
+	unsigned long reason = get_mc_reason(regs);
+
 	printk("Machine check in kernel mode.\n");
 	if (reason & ESR_IMCP){
 		printk("Instruction Synchronous Machine Check exception\n");
@@ -375,7 +382,13 @@ static int generic_machine_check_exception(struct pt_regs *regs)
 		/* Clear MCSR */
 		mtspr(SPRN_MCSR, mcsr);
 	}
-#elif defined (CONFIG_E500)
+	return 0;
+}
+#elif defined(CONFIG_E500)
+int machine_check_e500(struct pt_regs *regs)
+{
+	unsigned long reason = get_mc_reason(regs);
+
 	printk("Machine check in kernel mode.\n");
 	printk("Caused by (from MCSR=%lx): ", reason);
 
@@ -403,7 +416,14 @@ static int generic_machine_check_exception(struct pt_regs *regs)
 		printk("Bus - Instruction Parity Error\n");
 	if (reason & MCSR_BUS_RPERR)
 		printk("Bus - Read Parity Error\n");
-#elif defined (CONFIG_E200)
+
+	return 0;
+}
+#elif defined(CONFIG_E200)
+int machine_check_e200(struct pt_regs *regs)
+{
+	unsigned long reason = get_mc_reason(regs);
+
 	printk("Machine check in kernel mode.\n");
 	printk("Caused by (from MCSR=%lx): ", reason);
 
@@ -421,7 +441,14 @@ static int generic_machine_check_exception(struct pt_regs *regs)
 		printk("Bus - Read Bus Error on data load\n");
 	if (reason & MCSR_BUS_WRERR)
 		printk("Bus - Write Bus Error on buffered store or cache line push\n");
-#else /* !CONFIG_4xx && !CONFIG_E500 && !CONFIG_E200 */
+
+	return 0;
+}
+#else
+int machine_check_generic(struct pt_regs *regs)
+{
+	unsigned long reason = get_mc_reason(regs);
+
 	printk("Machine check in kernel mode.\n");
 	printk("Caused by (from SRR1=%lx): ", reason);
 	switch (reason & 0x601F0000) {
@@ -451,22 +478,26 @@ static int generic_machine_check_exception(struct pt_regs *regs)
 	default:
 		printk("Unknown values in msr\n");
 	}
-#endif /* CONFIG_4xx */
-
 	return 0;
 }
+#endif /* everything else */
 
 void machine_check_exception(struct pt_regs *regs)
 {
 	int recover = 0;
 
-	/* See if any machine dependent calls */
+	/* See if any machine dependent calls. In theory, we would want
+	 * to call the CPU first, and call the ppc_md. one if the CPU
+	 * one returns a positive number. However there is existing code
+	 * that assumes the board gets a first chance, so let's keep it
+	 * that way for now and fix things later. --BenH.
+	 */
 	if (ppc_md.machine_check_exception)
 		recover = ppc_md.machine_check_exception(regs);
-	else
-		recover = generic_machine_check_exception(regs);
+	else if (cur_cpu_spec->machine_check)
+		recover = cur_cpu_spec->machine_check(regs);
 
-	if (recover)
+	if (recover > 0)
 		return;
 
 	if (user_mode(regs)) {
@@ -476,7 +507,12 @@ void machine_check_exception(struct pt_regs *regs)
 	}
 
 #if defined(CONFIG_8xx) && defined(CONFIG_PCI)
-	/* the qspan pci read routines can cause machine checks -- Cort */
+	/* the qspan pci read routines can cause machine checks -- Cort
+	 *
+	 * yuck !!! that totally needs to go away ! There are better ways
+	 * to deal with that than having a wart in the mcheck handler.
+	 * -- BenH
+	 */
 	bad_page_fault(regs, regs->dar, SIGBUS);
 	return;
 #endif

arch/powerpc/platforms/44x/Kconfig

@@ -62,11 +62,6 @@ config 440GX
 config 440SP
 	bool
 
-config 440A
-	bool
-	depends on 440GX || 440EPX
-	default y
-
 # 44x errata/workaround config symbols, selected by the CPU models above
 config IBM440EP_ERR42
 	bool

arch/ppc/kernel/traps.c

@@ -231,39 +231,25 @@ platform_machine_check(struct pt_regs *regs)
 {
 }
 
-void machine_check_exception(struct pt_regs *regs)
+#if defined(CONFIG_4xx)
+int machine_check_4xx(struct pt_regs *regs)
 {
 	unsigned long reason = get_mc_reason(regs);
 
-	if (user_mode(regs)) {
-		regs->msr |= MSR_RI;
-		_exception(SIGBUS, regs, BUS_ADRERR, regs->nip);
-		return;
-	}
-
-#if defined(CONFIG_8xx) && defined(CONFIG_PCI)
-	/* the qspan pci read routines can cause machine checks -- Cort */
-	bad_page_fault(regs, regs->dar, SIGBUS);
-	return;
-#endif
-
-	if (debugger_fault_handler) {
-		debugger_fault_handler(regs);
-		regs->msr |= MSR_RI;
-		return;
-	}
-
-	if (check_io_access(regs))
-		return;
-
-#if defined(CONFIG_4xx) && !defined(CONFIG_440A)
 	if (reason & ESR_IMCP) {
 		printk("Instruction");
 		mtspr(SPRN_ESR, reason & ~ESR_IMCP);
 	} else
 		printk("Data");
 	printk(" machine check in kernel mode.\n");
-#elif defined(CONFIG_440A)
+
+	return 0;
+}
+
+int machine_check_440A(struct pt_regs *regs)
+{
+	unsigned long reason = get_mc_reason(regs);
+
 	printk("Machine check in kernel mode.\n");
 	if (reason & ESR_IMCP){
 		printk("Instruction Synchronous Machine Check exception\n");
@@ -293,7 +279,13 @@ void machine_check_exception(struct pt_regs *regs)
 		/* Clear MCSR */
 		mtspr(SPRN_MCSR, mcsr);
 	}
-#elif defined (CONFIG_E500)
+	return 0;
+}
+#elif defined(CONFIG_E500)
+int machine_check_e500(struct pt_regs *regs)
+{
+	unsigned long reason = get_mc_reason(regs);
+
 	printk("Machine check in kernel mode.\n");
 	printk("Caused by (from MCSR=%lx): ", reason);
 
@@ -305,8 +297,6 @@ void machine_check_exception(struct pt_regs *regs)
 		printk("Data Cache Push Parity Error\n");
 	if (reason & MCSR_DCPERR)
 		printk("Data Cache Parity Error\n");
-	if (reason & MCSR_GL_CI)
-		printk("Guarded Load or Cache-Inhibited stwcx.\n");
 	if (reason & MCSR_BUS_IAERR)
 		printk("Bus - Instruction Address Error\n");
 	if (reason & MCSR_BUS_RAERR)
@@ -318,12 +308,19 @@ void machine_check_exception(struct pt_regs *regs)
 	if (reason & MCSR_BUS_RBERR)
 		printk("Bus - Read Data Bus Error\n");
 	if (reason & MCSR_BUS_WBERR)
-		printk("Bus - Write Data Bus Error\n");
+		printk("Bus - Read Data Bus Error\n");
 	if (reason & MCSR_BUS_IPERR)
 		printk("Bus - Instruction Parity Error\n");
 	if (reason & MCSR_BUS_RPERR)
 		printk("Bus - Read Parity Error\n");
-#elif defined (CONFIG_E200)
+
+	return 0;
+}
+#elif defined(CONFIG_E200)
+int machine_check_e200(struct pt_regs *regs)
+{
+	unsigned long reason = get_mc_reason(regs);
+
 	printk("Machine check in kernel mode.\n");
 	printk("Caused by (from MCSR=%lx): ", reason);
 
@@ -341,7 +338,14 @@ void machine_check_exception(struct pt_regs *regs)
 		printk("Bus - Read Bus Error on data load\n");
 	if (reason & MCSR_BUS_WRERR)
 		printk("Bus - Write Bus Error on buffered store or cache line push\n");
-#else /* !CONFIG_4xx && !CONFIG_E500 && !CONFIG_E200 */
+
+	return 0;
+}
+#else
+int machine_check_generic(struct pt_regs *regs)
+{
+	unsigned long reason = get_mc_reason(regs);
+
 	printk("Machine check in kernel mode.\n");
 	printk("Caused by (from SRR1=%lx): ", reason);
 	switch (reason & 0x601F0000) {
@@ -371,7 +375,39 @@ void machine_check_exception(struct pt_regs *regs)
 	default:
 		printk("Unknown values in msr\n");
 	}
-#endif /* CONFIG_4xx */
+	return 0;
+}
+#endif /* everything else */
+
+void machine_check_exception(struct pt_regs *regs)
+{
+	int recover = 0;
+
+	if (cur_cpu_spec->machine_check)
+		recover = cur_cpu_spec->machine_check(regs);
+	if (recover > 0)
+		return;
+
+	if (user_mode(regs)) {
+		regs->msr |= MSR_RI;
+		_exception(SIGBUS, regs, BUS_ADRERR, regs->nip);
+		return;
+	}
+
+#if defined(CONFIG_8xx) && defined(CONFIG_PCI)
+	/* the qspan pci read routines can cause machine checks -- Cort */
+	bad_page_fault(regs, regs->dar, SIGBUS);
+	return;
+#endif
+
+	if (debugger_fault_handler) {
+		debugger_fault_handler(regs);
+		regs->msr |= MSR_RI;
+		return;
+	}
+
+	if (check_io_access(regs))
+		return;
 
 	/*
 	 * Optional platform-provided routine to print out

include/asm-powerpc/cputable.h

@@ -57,6 +57,14 @@ enum powerpc_pmc_type {
 	PPC_PMC_PA6T = 2,
 };
 
+struct pt_regs;
+
+extern int machine_check_generic(struct pt_regs *regs);
+extern int machine_check_4xx(struct pt_regs *regs);
+extern int machine_check_440A(struct pt_regs *regs);
+extern int machine_check_e500(struct pt_regs *regs);
+extern int machine_check_e200(struct pt_regs *regs);
+
 /* NOTE WELL: Update identify_cpu() if fields are added or removed! */
 struct cpu_spec {
 	/* CPU is matched via (PVR & pvr_mask) == pvr_value */
@@ -97,6 +105,11 @@ struct cpu_spec {
 
 	/* Name of processor class, for the ELF AT_PLATFORM entry */
 	char		*platform;
+
+	/* Processor specific machine check handling. Return negative
+	 * if the error is fatal, 1 if it was fully recovered and 0 to
+	 * pass up (not CPU originated) */
+	int		(*machine_check)(struct pt_regs *regs);
 };
 
 extern struct cpu_spec		*cur_cpu_spec;

include/asm-powerpc/ptrace.h

@@ -106,7 +106,8 @@ extern int ptrace_put_reg(struct task_struct *task, int regno,
  */
 #define FULL_REGS(regs)		(((regs)->trap & 1) == 0)
 #ifndef __powerpc64__
-#define IS_CRITICAL_EXC(regs)	(((regs)->trap & 2) == 0)
+#define IS_CRITICAL_EXC(regs)	(((regs)->trap & 2) != 0)
+#define IS_MCHECK_EXC(regs)	(((regs)->trap & 4) != 0)
 #endif /* ! __powerpc64__ */
 #define TRAP(regs)		((regs)->trap & ~0xF)
 #ifdef __powerpc64__

include/asm-powerpc/reg_booke.h

@@ -218,7 +218,6 @@
 #define	CCR1_TCS	0x00000080 /* Timer Clock Select */
 
 /* Bit definitions for the MCSR. */
-#ifdef CONFIG_440A
 #define MCSR_MCS	0x80000000 /* Machine Check Summary */
 #define MCSR_IB		0x40000000 /* Instruction PLB Error */
 #define MCSR_DRB	0x20000000 /* Data Read PLB Error */
@@ -228,7 +227,7 @@
 #define MCSR_DCSP	0x02000000 /* D-Cache Search Parity Error */
 #define MCSR_DCFP	0x01000000 /* D-Cache Flush Parity Error */
 #define MCSR_IMPE	0x00800000 /* Imprecise Machine Check Exception */
-#endif
+
 #ifdef CONFIG_E500
 #define MCSR_MCP 	0x80000000UL /* Machine Check Input Pin */
 #define MCSR_ICPERR 	0x40000000UL /* I-Cache Parity Error */

include/asm-ppc/reg_booke.h

@@ -207,7 +207,7 @@
 #define	CCR1_TCS	0x00000080 /* Timer Clock Select */
 
 /* Bit definitions for the MCSR. */
-#ifdef CONFIG_440A
+#ifdef CONFIG_4xx
 #define MCSR_MCS	0x80000000 /* Machine Check Summary */
 #define MCSR_IB		0x40000000 /* Instruction PLB Error */
 #define MCSR_DRB	0x20000000 /* Data Read PLB Error */