Architectural Support: x86_64 (#37)

[lunaix-os.git] / lunaix-os / arch / x86 / boot / x86_64 / kremap64.c

diff --git a/lunaix-os/arch/x86/boot/x86_64/kremap64.c b/lunaix-os/arch/x86/boot/x86_64/kremap64.c
new file mode 100644 (file)
index 0000000..ee9d298
--- /dev/null
+++ b/lunaix-os/arch/x86/boot/x86_64/kremap64.c
@@ -0,0 +1,188 @@
+#define __BOOT_CODE__
+
+#include <lunaix/mm/pagetable.h>
+#include <lunaix/compiler.h>
+
+#include <sys/boot/bstage.h>
+#include <sys/mm/mm_defs.h>
+
+#define RSVD_PAGES 32
+
+bridge_farsym(__kexec_start);
+bridge_farsym(__kexec_end);
+bridge_farsym(__kexec_text_start);
+bridge_farsym(__kexec_text_end);
+
+// define the initial page table layout
+struct kernel_map;
+
+static struct kernel_map kpt __section(".kpg");
+export_symbol(debug, boot, kpt);
+
+struct kernel_map {
+    pte_t l0t[_PAGE_LEVEL_SIZE];        // root table
+    pte_t l1t_rsvd[_PAGE_LEVEL_SIZE];   // 0~4G reservation
+
+    struct {
+        pte_t _lft[_PAGE_LEVEL_SIZE];
+    } krsvd[RSVD_PAGES];
+} align(8);
+
+struct allocator
+{
+    struct kernel_map* kpt_pa;
+    int pt_usage;
+};
+
+static inline ptr_t
+alloc_rsvd_page(struct allocator* _alloc)
+{
+    if (_alloc->pt_usage >= KEXEC_RSVD) {
+        asm ("ud2");
+    }
+
+    return __ptr(&_alloc->kpt_pa->krsvd[_alloc->pt_usage++]);
+}
+
+static pte_t* boot_text
+prealloc_pt(struct allocator* _allc, ptr_t va, 
+            pte_attr_t prot, size_t to_gran) 
+{
+    int lvl_i;
+    pte_t *ptep, pte;
+    size_t gran = L0T_SIZE;
+
+    ptep = (pte_t*)&_allc->kpt_pa->l0t[0];
+
+    for (int i = 0; i < _PTW_LEVEL && gran > to_gran; i++)
+    {
+        lvl_i = va_level_index(va, gran);
+        ptep = &ptep[lvl_i];
+        pte  = pte_at(ptep);
+
+        gran = gran >> _PAGE_LEVEL_SHIFT;
+
+        if (pte_isnull(pte)) {
+            pte = mkpte(alloc_rsvd_page(_allc), KERNEL_DATA);
+            if (to_gran == gran) {
+                pte = pte_setprot(pte, prot);
+            }
+
+            set_pte(ptep, pte);
+        }
+        ptep = (pte_t*) pte_paddr(pte);
+    }
+
+    return ptep;
+}
+
+static void boot_text
+do_remap()
+{
+    struct kernel_map* kpt_pa = (struct kernel_map*)to_kphysical(&kpt);
+    
+    pte_t* boot_l0tep   = (pte_t*)  kpt_pa;
+    pte_t *klptep, pte;
+
+    // identity map the first 4G for legacy compatibility
+    pte_t* l1_rsvd = (pte_t*) kpt_pa->l1t_rsvd;
+    pte_t id_map   = pte_mkhuge(mkpte_prot(KERNEL_DATA));
+    
+    set_pte(boot_l0tep, mkpte((ptr_t)l1_rsvd, KERNEL_DATA));
+    
+    for (int i = 0; i < 4; i++, l1_rsvd++)
+    {
+        id_map = pte_setpaddr(id_map, (ptr_t)i << 30);
+        set_pte(l1_rsvd, id_map);
+    }
+
+    // Remap the kernel to -2GiB
+
+    int table_usage = 0;
+    unsigned int lvl_i = 0;
+    struct allocator alloc = {
+        .kpt_pa = kpt_pa,
+        .pt_usage = 0
+    };
+
+    prealloc_pt(&alloc, VMAP, KERNEL_DATA, L1T_SIZE);
+
+    prealloc_pt(&alloc, PG_MOUNT_1, KERNEL_DATA, LFT_SIZE);
+
+
+    ptr_t kstart = page_aligned(__far(__kexec_text_start));
+
+#if LnT_ENABLED(3)
+    size_t gran  = L3T_SIZE;
+#else
+    size_t gran  = L2T_SIZE;
+#endif
+
+    prealloc_pt(&alloc, PMAP, KERNEL_DATA, gran);
+    klptep = prealloc_pt(&alloc, kstart, KERNEL_DATA, gran);
+    klptep += va_level_index(kstart, gran);
+
+    pte = mkpte(0, KERNEL_DATA);
+    for (int i = alloc.pt_usage; i < KEXEC_RSVD; i++)
+    {
+        pte = pte_setpaddr(pte, (ptr_t)&kpt_pa->krsvd[i]);
+        set_pte(klptep++, pte);
+    }
+
+    // this is the first LFT we hooked on.
+    // all these LFT are contig in physical address
+    klptep = (pte_t*) &kpt_pa->krsvd[alloc.pt_usage];
+    
+    // Ensure the size of kernel is within the reservation
+    int remain = KEXEC_RSVD - table_usage;
+    pfn_t kimg_pagecount = 
+        pfn(__far(__kexec_end) - __far(__kexec_start));
+    if (kimg_pagecount > remain * _PAGE_LEVEL_SIZE) {
+        // ERROR: require more pages
+        //  here should do something else other than head into blocking
+        asm("ud2");
+    }
+
+    // kernel .text
+    pfn_t ktext_end = pfn(to_kphysical(__far(__kexec_text_end)));
+    pfn_t i = pfn(to_kphysical(kstart));
+
+    klptep += i;
+    pte = pte_setprot(pte, KERNEL_EXEC);
+    for (; i < ktext_end; i++) {
+        pte = pte_setpaddr(pte, page_addr(i));
+        set_pte(klptep, pte);
+
+        klptep++;
+    }
+    
+    pfn_t kimg_end = pfn(to_kphysical(__far(__kexec_end)));
+
+    // all remaining kernel sections
+    pte = pte_setprot(pte, KERNEL_DATA);
+    for (; i < kimg_end; i++) {
+        pte = pte_setpaddr(pte, page_addr(i));
+        set_pte(klptep, pte);
+
+        klptep++;
+    }
+
+    // Build up self-reference
+    lvl_i = va_level_index(VMS_SELF, L0T_SIZE);
+    pte   = mkpte_root(__ptr(kpt_pa), KERNEL_DATA);
+    set_pte(boot_l0tep + lvl_i, pte);
+}
+
+
+ptr_t boot_text
+remap_kernel()
+{
+    ptr_t kmap_pa = to_kphysical(&kpt);
+    for (size_t i = 0; i < sizeof(kpt); i++) {
+        ((u8_t*)kmap_pa)[i] = 0;
+    }
+
+    do_remap();
+
+    return kmap_pa;
+}
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