4 files changed, 46 insertions, 12 deletions

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 75b91bb772bd..dd647c919a66 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -119,13 +119,12 @@ static inline int is_zero_pfn(unsigned long pfn)
 
 #ifndef __ASSEMBLY__
 /*
- * The vmalloc area will always be on the topmost area of the kernel
- * mapping. We reserve 96MB (31bit) / 128GB (64bit) for vmalloc,
- * which should be enough for any sane case.
- * By putting vmalloc at the top, we maximise the gap between physical
- * memory and vmalloc to catch misplaced memory accesses. As a side
- * effect, this also makes sure that 64 bit module code cannot be used
- * as system call address.
+ * The vmalloc and module area will always be on the topmost area of the kernel
+ * mapping. We reserve 96MB (31bit) / 128GB (64bit) for vmalloc and modules.
+ * On 64 bit kernels we have a 2GB area at the top of the vmalloc area where
+ * modules will reside. That makes sure that inter module branches always
+ * happen without trampolines and in addition the placement within a 2GB frame
+ * is branch prediction unit friendly.
  */
 extern unsigned long VMALLOC_START;
 extern unsigned long VMALLOC_END;
@@ -133,6 +132,14 @@ extern struct page *vmemmap;
 
 #define VMEM_MAX_PHYS ((unsigned long) vmemmap)
 
+#ifdef CONFIG_64BIT
+extern unsigned long MODULES_VADDR;
+extern unsigned long MODULES_END;
+#define MODULES_VADDR   MODULES_VADDR
+#define MODULES_END     MODULES_END
+#define MODULES_LEN     (1UL << 31)
+#endif
+
 /*
  * A 31 bit pagetable entry of S390 has following format:
  *  |   PFRA          |    |  OS  |
diff --git a/arch/s390/kernel/module.c b/arch/s390/kernel/module.c
index 46412b1d7e1e..4610deafd953 100644
--- a/arch/s390/kernel/module.c
+++ b/arch/s390/kernel/module.c
@@ -44,6 +44,17 @@
 #define PLT_ENTRY_SIZE 20
 #endif /* CONFIG_64BIT */
 
+#ifdef CONFIG_64BIT
+void *module_alloc(unsigned long size)
+{
+        if (PAGE_ALIGN(size) > MODULES_LEN)
+                return NULL;
+        return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
+                                    GFP_KERNEL, PAGE_KERNEL, -1,
+                                    __builtin_return_address(0));
+}
+#endif
+
 /* Free memory returned from module_alloc */
 void module_free(struct module *mod, void *module_region)
 {
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index bfb48f18169c..b1f2be9aaaad 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -105,6 +105,11 @@ EXPORT_SYMBOL(VMALLOC_END);
 struct page *vmemmap;
 EXPORT_SYMBOL(vmemmap);
 
+#ifdef CONFIG_64BIT
+unsigned long MODULES_VADDR;
+unsigned long MODULES_END;
+#endif
+
 /* An array with a pointer to the lowcore of every CPU. */
 struct _lowcore *lowcore_ptr[NR_CPUS];
 EXPORT_SYMBOL(lowcore_ptr);
@@ -544,19 +549,23 @@ static void __init setup_memory_end(void)
 
         /* Choose kernel address space layout: 2, 3, or 4 levels. */
 #ifdef CONFIG_64BIT
-        vmalloc_size = VMALLOC_END ?: 128UL << 30;
+        vmalloc_size = VMALLOC_END ?: (128UL << 30) - MODULES_LEN;
         tmp = (memory_end ?: real_memory_size) / PAGE_SIZE;
         tmp = tmp * (sizeof(struct page) + PAGE_SIZE) + vmalloc_size;
         if (tmp <= (1UL << 42))
                 vmax = 1UL << 42;       /* 3-level kernel page table */
         else
                 vmax = 1UL << 53;       /* 4-level kernel page table */
+        /* module area is at the end of the kernel address space. */
+        MODULES_END = vmax;
+        MODULES_VADDR = MODULES_END - MODULES_LEN;
+        VMALLOC_END = MODULES_VADDR;
 #else
         vmalloc_size = VMALLOC_END ?: 96UL << 20;
         vmax = 1UL << 31;               /* 2-level kernel page table */
-#endif
         /* vmalloc area is at the end of the kernel address space. */
         VMALLOC_END = vmax;
+#endif
         VMALLOC_START = vmax - vmalloc_size;
 
         /* Split remaining virtual space between 1:1 mapping & vmemmap array */
diff --git a/arch/s390/mm/dump_pagetables.c b/arch/s390/mm/dump_pagetables.c
index cd1c62d160ed..cbc6668acb85 100644
--- a/arch/s390/mm/dump_pagetables.c
+++ b/arch/s390/mm/dump_pagetables.c
@@ -18,6 +18,9 @@ enum address_markers_idx {
         KERNEL_END_NR,
         VMEMMAP_NR,
         VMALLOC_NR,
+#ifdef CONFIG_64BIT
+        MODULES_NR,
+#endif
 };
 
 static struct addr_marker address_markers[] = {
@@ -26,6 +29,9 @@ static struct addr_marker address_markers[] = {
         [KERNEL_END_NR]   = {(unsigned long)&_end, "Kernel Image End"},
         [VMEMMAP_NR]      = {0, "vmemmap Area"},
         [VMALLOC_NR]      = {0, "vmalloc Area"},
+#ifdef CONFIG_64BIT
+        [MODULES_NR]      = {0, "Modules Area"},
+#endif
         { -1, NULL }
 };
 
@@ -205,11 +211,12 @@ static int pt_dump_init(void)
          * kernel ASCE. We need this to keep the page table walker functions
          * from accessing non-existent entries.
          */
-#ifdef CONFIG_64BIT
+#ifdef CONFIG_32BIT
+        max_addr = 1UL << 31;
+#else
         max_addr = (S390_lowcore.kernel_asce & _REGION_ENTRY_TYPE_MASK) >> 2;
         max_addr = 1UL << (max_addr * 11 + 31);
-#else
-        max_addr = 1UL << 31;
+        address_markers[MODULES_NR].start_address = MODULES_VADDR;
 #endif
         address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
         address_markers[VMALLOC_NR].start_address = VMALLOC_START;