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Index: head/sys/amd64/amd64/mp_machdep.c
===================================================================
--- head/sys/amd64/amd64/mp_machdep.c
+++ head/sys/amd64/amd64/mp_machdep.c
@@ -86,6 +86,8 @@
#define GiB(v) (v ## ULL << 30)
+#define AP_BOOTPT_SZ (PAGE_SIZE * 3)
+
extern struct pcpu __pcpu[];
/* Temporary variables for init_secondary() */
@@ -100,45 +102,79 @@
static int start_ap(int apic_id);
+static bool
+is_kernel_paddr(vm_paddr_t pa)
+{
+
+ return (pa >= trunc_2mpage(btext - KERNBASE) &&
+ pa < round_page(_end - KERNBASE));
+}
+
+static bool
+is_mpboot_good(vm_paddr_t start, vm_paddr_t end)
+{
+
+ return (start + AP_BOOTPT_SZ <= GiB(4) && atop(end) < Maxmem);
+}
+
/*
* Calculate usable address in base memory for AP trampoline code.
*/
void
mp_bootaddress(vm_paddr_t *physmap, unsigned int *physmap_idx)
{
+ vm_paddr_t start, end;
unsigned int i;
bool allocated;
alloc_ap_trampoline(physmap, physmap_idx);
+ /*
+ * Find a memory region big enough below the 4GB boundary to
+ * store the initial page tables. Region must be mapped by
+ * the direct map.
+ *
+ * Note that it needs to be aligned to a page boundary.
+ */
allocated = false;
for (i = *physmap_idx; i <= *physmap_idx; i -= 2) {
/*
- * Find a memory region big enough below the 4GB
- * boundary to store the initial page tables. Region
- * must be mapped by the direct map.
- *
- * Note that it needs to be aligned to a page
- * boundary.
+ * First, try to chomp at the start of the physmap region.
+ * Kernel binary might claim it already.
*/
- if (physmap[i] >= GiB(4) || physmap[i + 1] -
- round_page(physmap[i]) < PAGE_SIZE * 3 ||
- atop(physmap[i + 1]) > Maxmem)
- continue;
+ start = round_page(physmap[i]);
+ end = start + AP_BOOTPT_SZ;
+ if (start < end && end <= physmap[i + 1] &&
+ is_mpboot_good(start, end) &&
+ !is_kernel_paddr(start) && !is_kernel_paddr(end - 1)) {
+ allocated = true;
+ physmap[i] = end;
+ break;
+ }
- allocated = true;
- mptramp_pagetables = round_page(physmap[i]);
- physmap[i] = round_page(physmap[i]) + (PAGE_SIZE * 3);
+ /*
+ * Second, try to chomp at the end. Again, check
+ * against kernel.
+ */
+ end = trunc_page(physmap[i + 1]);
+ start = end - AP_BOOTPT_SZ;
+ if (start < end && start >= physmap[i] &&
+ is_mpboot_good(start, end) &&
+ !is_kernel_paddr(start) && !is_kernel_paddr(end - 1)) {
+ allocated = true;
+ physmap[i + 1] = start;
+ break;
+ }
+ }
+ if (allocated) {
+ mptramp_pagetables = start;
if (physmap[i] == physmap[i + 1] && *physmap_idx != 0) {
memmove(&physmap[i], &physmap[i + 2],
sizeof(*physmap) * (*physmap_idx - i + 2));
*physmap_idx -= 2;
}
- break;
- }
-
- if (!allocated) {
- mptramp_pagetables = trunc_page(boot_address) - (PAGE_SIZE * 3);
+ } else {
+ mptramp_pagetables = trunc_page(boot_address) - AP_BOOTPT_SZ;
if (bootverbose)
printf(
"Cannot find enough space for the initial AP page tables, placing them at %#x",

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