[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>

1 files changed, 49 insertions, 13 deletions

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index cad64840fce4..848a20475db8 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/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