ARC: mm: HIGHMEM: populate high memory from DT

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

2 files changed, 74 insertions, 8 deletions

diff --git a/arch/arc/boot/dts/nsim_hs.dts b/arch/arc/boot/dts/nsim_hs.dts
index 911f069e0540..b0eb0e7fe21d 100644
--- a/arch/arc/boot/dts/nsim_hs.dts
+++ b/arch/arc/boot/dts/nsim_hs.dts
@@ -11,8 +11,16 @@
 
 / {
         compatible = "snps,nsim_hs";
+        #address-cells = <2>;
+        #size-cells = <2>;
         interrupt-parent = <&core_intc>;
 
+        memory {
+                device_type = "memory";
+                reg = <0x0 0x80000000 0x0 0x40000000    /* 1 GB low mem */
+                       0x1 0x00000000 0x0 0x40000000>;  /* 1 GB highmem */
+        };
+
         chosen {
                 bootargs = "earlycon=arc_uart,mmio32,0xc0fc1000,115200n8 console=ttyARC0,115200n8";
         };
@@ -26,8 +34,8 @@
                 #address-cells = <1>;
                 #size-cells = <1>;
 
-                /* child and parent address space 1:1 mapped */
-                ranges;
+                /* only perip space at end of low mem accessible */
+                ranges = <0x80000000 0x0 0x80000000 0x80000000>;
 
                 core_intc: core-interrupt-controller {
                         compatible = "snps,archs-intc";
diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
index a726a229baf6..a9305b5a2cd4 100644
--- a/arch/arc/mm/init.c
+++ b/arch/arc/mm/init.c
@@ -15,6 +15,7 @@
 #endif
 #include <linux/swap.h>
 #include <linux/module.h>
+#include <linux/highmem.h>
 #include <asm/page.h>
 #include <asm/pgalloc.h>
 #include <asm/sections.h>
@@ -27,6 +28,12 @@ EXPORT_SYMBOL(empty_zero_page);
 static const unsigned long low_mem_start = CONFIG_LINUX_LINK_BASE;
 static unsigned long low_mem_sz;
 
+#ifdef CONFIG_HIGHMEM
+static unsigned long min_high_pfn;
+static u64 high_mem_start;
+static u64 high_mem_sz;
+#endif
+
 /* User can over-ride above with "mem=nnn[KkMm]" in cmdline */
 static int __init setup_mem_sz(char *str)
 {
@@ -41,10 +48,22 @@ early_param("mem", setup_mem_sz);
 
 void __init early_init_dt_add_memory_arch(u64 base, u64 size)
 {
-        low_mem_sz = size;
-        BUG_ON(base != low_mem_start);
+        int in_use = 0;
+
+        if (!low_mem_sz) {
+                BUG_ON(base != low_mem_start);
+                low_mem_sz = size;
+                in_use = 1;
+        } else {
+#ifdef CONFIG_HIGHMEM
+                high_mem_start = base;
+                high_mem_sz = size;
+                in_use = 1;
+#endif
+        }
 
-        pr_info("Memory @ %llx of %ldM\n", base, TO_MB(size));
+        pr_info("Memory @ %llx [%lldM] %s\n",
+                base, TO_MB(size), !in_use ? "Not used":"");
 }
 
 #ifdef CONFIG_BLK_DEV_INITRD
@@ -74,6 +93,7 @@ early_param("initrd", early_initrd);
 void __init setup_arch_memory(void)
 {
         unsigned long zones_size[MAX_NR_ZONES];
+        unsigned long zones_holes[MAX_NR_ZONES];
 
         init_mm.start_code = (unsigned long)_text;
         init_mm.end_code = (unsigned long)_etext;
@@ -86,9 +106,26 @@ void __init setup_arch_memory(void)
         /* Last usable page of low mem */
         max_low_pfn = max_pfn = PFN_DOWN(low_mem_start + low_mem_sz);
 
-        max_mapnr = max_low_pfn - min_low_pfn;
+#ifdef CONFIG_HIGHMEM
+        min_high_pfn = PFN_DOWN(high_mem_start);
+        max_pfn = PFN_DOWN(high_mem_start + high_mem_sz);
+#endif
+
+        max_mapnr = max_pfn - min_low_pfn;
 
         /*------------- bootmem allocator setup -----------------------*/
+
+        /*
+         * seed the bootmem allocator after any DT memory node parsing or
+         * "mem=xxx" cmdline overrides have potentially updated @arc_mem_sz
+         *
+         * Only low mem is added, otherwise we have crashes when allocating
+         * mem_map[] itself. NO_BOOTMEM allocates mem_map[] at the end of
+         * avail memory, ending in highmem with a > 32-bit address. However
+         * it then tries to memset it with a truncaed 32-bit handle, causing
+         * the crash
+         */
+
         memblock_add(low_mem_start, low_mem_sz);
         memblock_reserve(low_mem_start, __pa(_end) - low_mem_start);
 
@@ -101,7 +138,17 @@ void __init setup_arch_memory(void)
 
         /*----------------- node/zones setup --------------------------*/
         memset(zones_size, 0, sizeof(zones_size));
+        memset(zones_holes, 0, sizeof(zones_holes));
+
         zones_size[ZONE_NORMAL] = max_low_pfn - min_low_pfn;
+        zones_holes[ZONE_NORMAL] = 0;
+
+#ifdef CONFIG_HIGHMEM
+        zones_size[ZONE_HIGHMEM] = max_pfn - max_low_pfn;
+
+        /* This handles the peripheral address space hole */
+        zones_holes[ZONE_HIGHMEM] = min_high_pfn - max_low_pfn;
+#endif
 
         /*
          * We can't use the helper free_area_init(zones[]) because it uses
@@ -112,9 +159,12 @@ void __init setup_arch_memory(void)
         free_area_init_node(0,                  /* node-id */
                             zones_size,         /* num pages per zone */
                             min_low_pfn,        /* first pfn of node */
-                            NULL);              /* NO holes */
+                            zones_holes);       /* holes */
 
-        high_memory = (void *)end_mem;
+#ifdef CONFIG_HIGHMEM
+        high_memory = (void *)(min_high_pfn << PAGE_SHIFT);
+        kmap_init();
+#endif
 }
 
 /*
@@ -125,6 +175,14 @@ void __init setup_arch_memory(void)
  */
 void __init mem_init(void)
 {
+#ifdef CONFIG_HIGHMEM
+        unsigned long tmp;
+
+        reset_all_zones_managed_pages();
+        for (tmp = min_high_pfn; tmp < max_pfn; tmp++)
+                free_highmem_page(pfn_to_page(tmp));
+#endif
+
         free_all_bootmem();
         mem_init_print_info(NULL);
 }