Larger kernel binary: increase virtual address mappings at boot

KTF kernel binary is usually less than 2M and thus single l1 boot page table mapping 2M VA range works out. Upcoming PMU changes increase binary size to 4.5 M and we'll need additional mapping at boto tables. Increasing boot l1 tables to map initial 6M range. Signed-off-by: Deepak Gupta <[email protected]>
KernelTestFramework · Nov 25, 2020 · 04845d6 · 04845d6
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commit 04845d6
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Showing 2 changed files with 44 additions and 6 deletions.
diff --git a/arch/x86/boot/pagetables.S b/arch/x86/boot/pagetables.S
@@ -28,27 +28,63 @@
 
 /* Initial identity map page tables */
 SECTION(.data.init, "aw", PAGE_SIZE)
-GLOBAL(l1_pt_entries)
+
+/* Each single l1_pt_entry covers a 4K of virtual addr range */
+
+/* First 2M range 0-2M */
+GLOBAL(l1_pt_entries1)
+    .rept L1_PT_ENTRIES
+    .long PT_PADDR(l1_pt_entries1, L1_PT_SHIFT) + L1_PROT, 0
+    .endr
+END_OBJECT(l1_pt_entries1)
+
+/* Second 2M range 2M-4M */
+GLOBAL(l1_pt_entries2)
     .rept L1_PT_ENTRIES
-    .long PT_PADDR(l1_pt_entries, L1_PT_SHIFT) + L1_PROT, 0
+    .long PT_PADDR(l1_pt_entries1, L1_PT_SHIFT) + L1_PROT, 0
     .endr
-END_OBJECT(l1_pt_entries)
+END_OBJECT(l1_pt_entries2)
 
+/* Third 2M range 4M-6M */
+GLOBAL(l1_pt_entries3)
+    .rept L1_PT_ENTRIES
+    .long PT_PADDR(l1_pt_entries1, L1_PT_SHIFT) + L1_PROT, 0
+    .endr
+END_OBJECT(l1_pt_entries3)
+
+/* 
+ * Each single l2_pt_entry points to l1_pt_entry table and 
+ * thus a single l2_pt_entry covers a 2M of virtual addr range 
+ */
 GLOBAL(l2_pt_entries)
-    .long l1_pt_entries + L2_PROT, 0
-    .fill (L2_PT_ENTRIES - 1), PTE_SIZE, 0
+    .long l1_pt_entries1 + L2_PROT, 0           /* Covers 0-2M */
+    .long l1_pt_entries2 + L2_PROT, 0           /* Covers 2M-4M */
+    .long l1_pt_entries3 + L2_PROT, 0           /* Covers 4M-6M */
+    .fill (L2_PT_ENTRIES - 3), PTE_SIZE, 0      /* 3 entries used, rests all are zeroed */
 END_OBJECT(l2_pt_entries)
 
+/* 
+ * Each single l3_pt_entry points to a l2_pt_entry table and 
+ * thus a single l3_pt_entry covers a 1G of virtual addr range 
+ */
 #if defined(__i386__)
 .align PAGE_SIZE
 #endif
 GLOBAL(l3_pt_entries)
+    /* Should cover identity and user addresses */
     .long l2_pt_entries + L3_PROT, 0
 
     .fill (L3_PT_ENTRIES - 3), PTE_SIZE, 0
 
+    /* 
+    * Kernel range starts at 0xffffffff80000000. 
+    * That makes l3 index = 0x1fe.
+    */
     .long l2_pt_entries + L3_PROT, 0
 
+    /* 
+    * Don't expect to spill over 0x1fe at boot time. So 1ff is zeroed
+    */
     .quad 0
 END_OBJECT(l3_pt_entries)
 

diff --git a/include/arch/x86/pagetable.h b/include/arch/x86/pagetable.h
@@ -245,7 +245,9 @@ static inline void set_pgentry(pgentry_t *e, mfn_t mfn, unsigned long flags) {
 
 /* External declarations */
 
-extern pte_t l1_pt_entries[L1_PT_ENTRIES];
+extern pte_t l1_pt_entries1[L1_PT_ENTRIES];
+extern pte_t l1_pt_entries2[L1_PT_ENTRIES];
+extern pte_t l1_pt_entries3[L1_PT_ENTRIES];
 extern pde_t l2_pt_entries[L2_PT_ENTRIES];
 extern pdpe_t l3_pt_entries[L3_PT_ENTRIES];
 #if defined(__x86_64__)