From 577c0f6226fde54a0018a8ebe7ff0ddbd0e16207 Mon Sep 17 00:00:00 2001
From: tkchia <tkchia-cosmo@gmx.com>
Date: Sun, 11 Sep 2022 14:56:54 +0000
Subject: [PATCH] Bare metal: fix some issues in initial page table creation

hello4.com now works outside of an emulator.
---
 libc/intrin/mman.greg.c      | 10 ++++++++--
 libc/runtime/mman.internal.h |  3 ++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/libc/intrin/mman.greg.c b/libc/intrin/mman.greg.c
index fa0623e50..cf872aa22 100644
--- a/libc/intrin/mman.greg.c
+++ b/libc/intrin/mman.greg.c
@@ -74,6 +74,10 @@ noasan textreal uint64_t *__get_virtual(struct mman *mm, uint64_t *t,
     if (!(*e & PAGE_V)) {
       if (!maketables) return NULL;
       if (!(p = __new_page(mm))) return NULL;
+      if (mm->use_bane)
+        __clear_page(BANE + p);
+      else
+        __clear_page(p);
       *e = p | PAGE_V | PAGE_RW;
     }
     t = (uint64_t *)(BANE + (*e & PAGE_TA));
@@ -117,16 +121,18 @@ static noasan textreal void __invert_memory(struct mman *mm, uint64_t *pml4t) {
   uint64_t i, j, *m, p, pe;
   for (i = 0; i < mm->e820n; ++i) {
     for (p = mm->e820[i].addr, pe = mm->e820[i].addr + mm->e820[i].size;
-         p + 0x200000 < pe; p += 4096) {
+         p != pe + 0x200000; p += 4096) {
       m = __get_virtual(mm, pml4t, BANE + p, true);
       if (m && !(*m & PAGE_V)) {
         *m = p | PAGE_V | PAGE_RW;
       }
     }
+    mm->use_bane = 1;
   }
 }
 
 noasan textreal void __setup_mman(struct mman *mm, uint64_t *pml4t) {
+  mm->use_bane = 0;
   __normalize_e820(mm);
   __invert_memory(mm, pml4t);
 }
@@ -150,7 +156,7 @@ noasan textreal void __map_phdrs(struct mman *mm, uint64_t *pml4t, uint64_t b) {
           v = b + p->p_offset + i;
           m = MAX(m, v);
         } else {
-          v = __clear_page(__new_page(mm));
+          v = __clear_page(BANE + __new_page(mm));
         }
         *__get_virtual(mm, pml4t, p->p_vaddr + i, true) = (v & PAGE_TA) | f;
       }
diff --git a/libc/runtime/mman.internal.h b/libc/runtime/mman.internal.h
index 39d3acdcc..3b3a54777 100644
--- a/libc/runtime/mman.internal.h
+++ b/libc/runtime/mman.internal.h
@@ -7,7 +7,7 @@ COSMOPOLITAN_C_START_
 struct mman {
   int64_t pdp;                           /* 0x0500 */
   int32_t pdpi;                          /* 0x0508 */
-  int32_t e820n;                         /* 0x050a */
+  int32_t e820n;                         /* 0x050c */
   struct SmapEntry e820[256];            /* 0x0510 */
   char pc_drive_base_table[11];          /* 0x1d10 */
   unsigned char pc_drive_type;           /* 0x1d1b */
@@ -17,6 +17,7 @@ struct mman {
   unsigned char pc_drive_last_head;      /* 0x1d20 */
   unsigned char pc_drive;                /* 0x1d21 */
   char bad_idt[6];                       /* 0x1d22 */
+  unsigned use_bane : 1, : 31;           /* 0x1d28 */
 };
 
 COSMOPOLITAN_C_END_