parisc: Increase KERNEL_INITIAL_SIZE for 32-bit SMP kernels

Increase the initial kernel default page mapping size for SMP kernels to 32MB
and add a runtime check which panics early if the kernel is bigger than the
initial mapping size.

This fixes boot crashes of 32bit SMP kernels. Due to the introduction of huge
page support in kernel 4.4 and it's required initial kernel layout in memory, a
32bit SMP kernel usually got bigger (in layout, not size) than 16MB.

Cc: stable@vger.kernel.org #4.4+
Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/include/asm/pgtable.h b/arch/parisc/include/asm/pgtable.h
index 291cee28ccb60da84576ba1d9e103a0dc6e78ba5..e44bdb9078a56d15c5e5eea1ba027d0bb8f52d2b 100644 (file)
--- a/arch/parisc/include/asm/pgtable.h
+++ b/arch/parisc/include/asm/pgtable.h
@@ -83,7 +83,7 @@ static inline void purge_tlb_entries(struct mm_struct *mm, unsigned long addr)
        printk("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, (unsigned long)pgd_val(e))
 
 /* This is the size of the initially mapped kernel memory */
-#ifdef CONFIG_64BIT
+#if defined(CONFIG_64BIT) || defined(CONFIG_SMP)
 #define KERNEL_INITIAL_ORDER   25      /* 1<<25 = 32MB */
 #else
 #define KERNEL_INITIAL_ORDER   24      /* 1<<24 = 16MB */

diff --git a/arch/parisc/kernel/setup.c b/arch/parisc/kernel/setup.c
index f7ea626e29c9b3bce80d28062cbf802ab2313785..81d6f639194478fa96b33a7f30ba4d612c9cfa8f 100644 (file)
--- a/arch/parisc/kernel/setup.c
+++ b/arch/parisc/kernel/setup.c
@@ -38,6 +38,7 @@
 #include <linux/export.h>
 
 #include <asm/processor.h>
+#include <asm/sections.h>
 #include <asm/pdc.h>
 #include <asm/led.h>
 #include <asm/machdep.h>       /* for pa7300lc_init() proto */
@@ -140,6 +141,13 @@ void __init setup_arch(char **cmdline_p)
 #endif
        printk(KERN_CONT ".\n");
 
+       /*
+        * Check if initial kernel page mappings are sufficient.
+        * panic early if not, else we may access kernel functions
+        * and variables which can't be reached.
+        */
+       if (__pa((unsigned long) &_end) >= KERNEL_INITIAL_SIZE)
+               panic("KERNEL_INITIAL_ORDER too small!");
 
        pdc_console_init();