[PATCH ARM v6 08/14] mini-os: arm: memory management

[Thomas Leonard <talex5@gmail.com>]

Based on an initial patch by Karim Raslan.

Signed-off-by: Karim Allah Ahmed <karim.allah.ahmed@gmail.com>
Signed-off-by: Thomas Leonard <talex5@gmail.com>

---

Changes since v5:

- Require only minimum property lengths (requested by Ian Campbell).

Addressed Julien Grall's comments:
- Added comments explaining the lengths when checking FDT properties.
- Use paddr_t type to represent physical addresses.
---
 extras/mini-os/arch/arm/mm.c | 138 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 138 insertions(+)
 create mode 100644 extras/mini-os/arch/arm/mm.c

diff --git a/extras/mini-os/arch/arm/mm.c b/extras/mini-os/arch/arm/mm.c
new file mode 100644
index 0000000..ec1f821
--- /dev/null
+++ b/extras/mini-os/arch/arm/mm.c
@@ -0,0 +1,138 @@
+#include <mini-os/console.h>
+#include <xen/memory.h>
+#include <arch_mm.h>
+#include <mini-os/hypervisor.h>
+#include <libfdt.h>
+#include <lib.h>
+
+int physical_address_offset;
+
+unsigned long allocate_ondemand(unsigned long n, unsigned long alignment)
+{
+    // FIXME
+    BUG();
+}
+
+void arch_init_mm(unsigned long *start_pfn_p, unsigned long *max_pfn_p)
+{
+    int memory;
+    int prop_len = 0;
+    const uint64_t *regs;
+
+    printk("    _text: %p(VA)\n", &_text);
+    printk("    _etext: %p(VA)\n", &_etext);
+    printk("    _erodata: %p(VA)\n", &_erodata);
+    printk("    _edata: %p(VA)\n", &_edata);
+    printk("    stack start: %p(VA)\n", _boot_stack);
+    printk("    _end: %p(VA)\n", &_end);
+
+    if (fdt_num_mem_rsv(device_tree) != 0)
+        printk("WARNING: reserved memory not supported!\n");
+
+    memory = fdt_node_offset_by_prop_value(device_tree, -1, "device_type", "memory", sizeof("memory"));
+    if (memory < 0) {
+        printk("No memory found in FDT!\n");
+        BUG();
+    }
+
+    /* Xen will always provide us at least one bank of memory.
+     * Mini-OS will use the first bank for the time-being. */
+    regs = fdt_getprop(device_tree, memory, "reg", &prop_len);
+
+    /* The property must contain at least the start address
+     * and size, each of which is 8-bytes. */
+    if (regs == NULL || prop_len < 16) {
+        printk("Bad 'reg' property: %p %d\n", regs, prop_len);
+        BUG();
+    }
+
+    unsigned int end = (unsigned int) &_end;
+    paddr_t mem_base = fdt64_to_cpu(regs[0]);
+    unsigned int mem_size = fdt64_to_cpu(regs[1]);
+    printk("Found memory at %p (len 0x%x)\n", mem_base, mem_size);
+
+    BUG_ON(to_virt(mem_base) > (void *) &_text);          /* Our image isn't in our RAM! */
+    *start_pfn_p = PFN_UP(to_phys(end));
+    int heap_len = mem_size - (PFN_PHYS(*start_pfn_p) - mem_base);
+    *max_pfn_p = *start_pfn_p + PFN_DOWN(heap_len);
+
+    printk("Using pages %d to %d as free space for heap.\n", *start_pfn_p, *max_pfn_p);
+
+    /* The device tree is probably in memory that we're about to hand over to the page
+     * allocator, so move it to the end and reserve that space.
+     */
+    int fdt_size = fdt_totalsize(device_tree);
+    void *new_device_tree = to_virt(((*max_pfn_p << PAGE_SHIFT) - fdt_size) & PAGE_MASK);
+    if (new_device_tree != device_tree) {
+        memmove(new_device_tree, device_tree, fdt_size);
+    }
+    device_tree = new_device_tree;
+    *max_pfn_p = to_phys(new_device_tree) >> PAGE_SHIFT;
+}
+
+void arch_init_p2m(unsigned long max_pfn)
+{
+}
+
+void arch_init_demand_mapping_area(unsigned long cur_pfn)
+{
+}
+
+/* Get Xen's suggested physical page assignments for the grant table. */
+static paddr_t get_gnttab_base(void)
+{
+    int hypervisor;
+    int len = 0;
+    const uint64_t *regs;
+    paddr_t gnttab_base;
+
+    hypervisor = fdt_node_offset_by_compatible(device_tree, -1, "xen,xen");
+    BUG_ON(hypervisor < 0);
+
+    regs = fdt_getprop(device_tree, hypervisor, "reg", &len);
+    /* The property contains the address and size, 8-bytes each. */
+    if (regs == NULL || len < 16) {
+        printk("Bad 'reg' property: %p %d\n", regs, len);
+        BUG();
+    }
+
+    gnttab_base = fdt64_to_cpu(regs[0]);
+
+    printk("FDT suggests grant table base %lx\n", gnttab_base);
+
+    return gnttab_base;
+}
+
+grant_entry_t *arch_init_gnttab(int nr_grant_frames)
+{
+    struct xen_add_to_physmap xatp;
+    struct gnttab_setup_table setup;
+    xen_pfn_t frames[nr_grant_frames];
+    paddr_t gnttab_table;
+    int i, rc;
+
+    gnttab_table = get_gnttab_base();
+
+    for (i = 0; i < nr_grant_frames; i++)
+    {
+        xatp.domid = DOMID_SELF;
+        xatp.size = 0;      /* Seems to be unused */
+        xatp.space = XENMAPSPACE_grant_table;
+        xatp.idx = i;
+        xatp.gpfn = (gnttab_table >> PAGE_SHIFT) + i;
+        rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
+        BUG_ON(rc != 0);
+    }
+
+    setup.dom = DOMID_SELF;
+    setup.nr_frames = nr_grant_frames;
+    set_xen_guest_handle(setup.frame_list, frames);
+    HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
+    if (setup.status != 0)
+    {
+        printk("GNTTABOP_setup_table failed; status = %d\n", setup.status);
+        BUG();
+    }
+
+    return to_virt(gnttab_table);
+}
-- 
2.0.1