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diff --git a/sys/amd64/amd64/xen-locore.S b/sys/amd64/amd64/xen-locore.S
--- a/sys/amd64/amd64/xen-locore.S
+++ b/sys/amd64/amd64/xen-locore.S
@@ -61,7 +61,7 @@
ELFNOTE(Xen, XEN_ELFNOTE_SUSPEND_CANCEL, .long, 0)
ELFNOTE(Xen, XEN_ELFNOTE_BSD_SYMTAB, .asciz, "yes")
/* For PVHv2 support. */
- ELFNOTE(Xen, XEN_ELFNOTE_PHYS32_ENTRY, .long, VTOP(xen_start32))
+ ELFNOTE(Xen, XEN_ELFNOTE_PHYS32_ENTRY, .long, xen_start32)
.text
.p2align PAGE_SHIFT, 0x90 /* Hypercall_page needs to be PAGE aligned */
@@ -71,12 +71,13 @@
/* PVH entry point. */
.code32
+ .pushsection .text.init32
ENTRY(xen_start32)
/* Load flat GDT */
- movl $VTOP(gdtdesc32), %eax
+ movl $gdt32desc, %eax
lgdt (%eax)
- jmp $GDT_CODE, $VTOP(reload_cs)
+ jmp $GDT_CODE, $reload_cs
reload_cs:
movw $GDT_DATA, %ax
@@ -90,38 +91,6 @@
pushl $PSL_KERNEL
popfl
- /*
- * Create the page tables.
- * The first 1GB is mapped using 2MB entries.
- */
- movl $0, %eax
-pgbuild:
- cmp $(PAGE_SIZE/ENTRY_SIZE), %eax
- jae pgbuild_done
-
- /* PT4[i] = VTOP(&PT3[0]) | PG_V | PG_RW | PG_U */
- movl $VTOP(PT4), %ecx
- movl $VTOP(PT3), %edx
- orl $(PG_V | PG_RW | PG_U), %edx
- movl %edx, (%ecx,%eax,ENTRY_SIZE)
-
- /* PT3[i] = VTOP(&PT2[0]) | PG_V | PG_RW | PG_U */
- movl $VTOP(PT3), %ecx
- movl $VTOP(PT2), %edx
- orl $(PG_V | PG_RW | PG_U), %edx
- movl %edx, (%ecx,%eax,ENTRY_SIZE)
-
- /* PT2[i] = i * 2MiB | PG_V | PG_RW | PG_PS | PG_U */
- movl $VTOP(PT2), %ecx
- movl %eax, %edx
- shll $PDRSHIFT, %edx
- orl $(PG_V | PG_RW | PG_PS | PG_U), %edx
- movl %edx, (%ecx,%eax,ENTRY_SIZE)
-
- inc %eax
- jmp pgbuild
-
-pgbuild_done:
/* Turn on EFER.LME */
movl $MSR_EFER, %ecx
rdmsr
@@ -134,7 +103,7 @@
movl %eax, %cr4
/* Set %cr3 for PT4 */
- movl $VTOP(PT4), %eax
+ call xen_start_pgtable
movl %eax, %cr3
/* Turn on paging (implicitly sets EFER.LMA) */
@@ -143,9 +112,9 @@
movl %eax, %cr0
/* Now we're in compatibility mode. Set %cs for long mode */
- movl $VTOP(gdtdesc), %eax
+ movl $gdt64desc, %eax
lgdt (%eax)
- ljmp $GDT_CODE, $VTOP(longmode)
+ ljmp $GDT_CODE, $longmode
.code64
longmode:
@@ -155,6 +124,7 @@
pushq %rax
ret
+ .popsection
start_kernel:
/*
* Pass %ebx as the argument to hammer_time_xen, it contains
@@ -168,41 +138,3 @@
/* NOTREACHED */
0: hlt
jmp 0b
-
-/* Space for initial page tables */
- .data
- .p2align 12,0x40
-PT4:
- .space 0x1000
-PT3:
- .space 0x1000
-PT2:
- .space 0x1000
-
-/* 64bit GDT */
-gdtdesc:
- .word gdtend - gdt - 1
- .long VTOP(gdt) # low
- .long 0 # high
-gdt:
- .long 0 # null descriptor
- .long 0
- .long 0x00000000 # %cs
- .long 0x00209800
- .long 0x00000000 # %ds
- .long 0x00008000
-gdtend:
-
-/* 32bit GDT */
-gdtdesc32:
- .word gdt32end - gdt32 - 1
- .long VTOP(gdt32)
- .long 0
-gdt32:
- .long 0 # null descriptor
- .long 0
- .long 0x0000ffff # %cs
- .long 0x00cf9a00
- .long 0x0000ffff # %ds, %es, %ss
- .long 0x00cf9200
-gdt32end:
diff --git a/sys/amd64/amd64/xen-start.c b/sys/amd64/amd64/xen-start.c
new file mode 100644
--- /dev/null
+++ b/sys/amd64/amd64/xen-start.c
@@ -0,0 +1,92 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+#include <sys/cdefs.h>
+#include <sys/param.h>
+
+#include <machine/_inttypes.h>
+
+#include <x86/segments.h>
+
+/*
+ * This code is compiled in 32bit mode, so it can be called from the PVH entry
+ * point as part of the bootstrap sequence to transition to long mode. Care
+ * should be taken to avoid calling any external functions, as that will not
+ * work. Also only the .text, .data, .rodata and .bss sections are handled
+ * specially so that VMA == LMA.
+ */
+
+/* GDT descriptors for the PVH entry point trampoline. */
+const static struct segment_descriptor gdt64[] = {
+ { }, /* NULL descriptor */
+ {
+ .sd_type = SDT_MEMERA,
+ .sd_p = 1,
+ .sd_xx = 0x2 /* Longmode bit. */
+ }, /* %cs */
+ { .sd_p = 1 }, /* %ds */
+};
+const struct {
+ uint64_t limit:16;
+ const struct segment_descriptor *base;
+ uint32_t pad;
+} __packed gdt64desc = {
+ .limit = sizeof(gdt64) - 1,
+ .base = gdt64,
+};
+
+const static struct segment_descriptor gdt32[] = {
+ { }, /* NULL descriptor */
+ {
+ .sd_lolimit = 0xffff,
+ .sd_type = SDT_MEMERA,
+ .sd_p = 1,
+ .sd_hilimit = 0xf,
+ .sd_def32 = 1,
+ .sd_gran = 1,
+ }, /* %cs */
+ {
+ .sd_lolimit = 0xffff,
+ .sd_type = SDT_MEMRWA,
+ .sd_p = 1,
+ .sd_hilimit = 0xf,
+ .sd_def32 = 1,
+ .sd_gran = 1,
+ }, /* %ds, %es, %ss */
+};
+const struct {
+ unsigned int limit:16;
+ const struct segment_descriptor *base;
+} __packed gdt32desc = {
+ .limit = sizeof(gdt32) - 1,
+ .base = gdt32,
+};
+
+/* Called from assembly only. */
+uint32_t xen_start_pgtable(void);
+
+#define PG_V 0x001
+#define PG_RW 0x002
+#define PG_PS 0x080
+
+uint32_t xen_start_pgtable(void)
+{
+ static uint64_t PT4[PAGE_SIZE/sizeof(uint64_t)] __aligned(PAGE_SIZE);
+ static uint64_t PT3[PAGE_SIZE/sizeof(uint64_t)] __aligned(PAGE_SIZE);
+ static uint64_t PT2[PAGE_SIZE/sizeof(uint64_t)] __aligned(PAGE_SIZE);
+ unsigned int i;
+
+ for (i = 0; i < nitems(PT4); i++) {
+ /* Each slot of the level 4 pages points to the same level 3 page */
+ PT4[i] = (uint64_t)&PT3[0];
+ PT4[i] |= PG_V | PG_RW;
+
+ /* Each slot of the level 3 pages points to the same level 2 page */
+ PT3[i] = (uint64_t)&PT2[0];
+ PT3[i] |= PG_V | PG_RW;
+
+ /* The level 2 page slots are mapped with 2MB pages for 1GB. */
+ PT2[i] = i * (2 * 1024 * 1024);
+ PT2[i] |= PG_V | PG_RW | PG_PS;
+ }
+
+ return (uint32_t)&PT4[0];
+}
diff --git a/sys/conf/files.amd64 b/sys/conf/files.amd64
--- a/sys/conf/files.amd64
+++ b/sys/conf/files.amd64
@@ -78,6 +78,8 @@
amd64/amd64/initcpu.c standard
amd64/amd64/io.c optional io
amd64/amd64/locore.S standard no-obj
+amd64/amd64/xen-start.c optional xenhvm \
+ compile-with "${NORMAL_C} -m32 -g0 && ${OBJCOPY} -I elf32-i386 -O elf64-x86-64 --rename-section .text=.text.init32 --rename-section .data=.data.init32 --rename-section .rodata=.rodata.init32 --rename-section .bss=.bss.init32 ${.TARGET} ${.TARGET}"
amd64/amd64/xen-locore.S optional xenhvm \
compile-with "${NORMAL_S} -g0" \
no-ctfconvert
diff --git a/sys/conf/ldscript.amd64 b/sys/conf/ldscript.amd64
--- a/sys/conf/ldscript.amd64
+++ b/sys/conf/ldscript.amd64
@@ -4,14 +4,26 @@
SEARCH_DIR("/usr/lib");
SECTIONS
{
+ /* PVH 32bit protected mode init code.
+ *
+ * Force VMA == LMA, as that code runs with paging disabled or with identity
+ * page tables.
+ */
+ . = kernload + SIZEOF_HEADERS;
+ /*
+ * Merge all sections into a single .text section, either we run with paging
+ * disabled and flat segments, or with identity page tables with all entries
+ * having AWX permissions. Trying to keep sections separated is useless.
+ */
+ .text.init32 : AT (.) { *(.text.init32 .data.init32 .rodata.init32 .bss.init32) }
/* Read-only sections, merged into text segment: */
- . = kernbase + kernload + SIZEOF_HEADERS;
+ . = . + kernbase;
/*
* Use the AT keyword in order to set the right LMA that contains
* the physical address where the section should be loaded. This is
* needed for the Xen loader which honours the LMA.
*/
- .interp : AT (kernload + SIZEOF_HEADERS) { *(.interp) }
+ .interp : AT (. - kernbase) { *(.interp) }
.hash : { *(.hash) }
.gnu.hash : { *(.gnu.hash) }
.dynsym : { *(.dynsym) }

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