plat/kvm/x86: Use position independent code for lxboot

This should make it easier in the future to extend the entry point to
support proper boot loaders such as the one in QEMU.

Signed-off-by: Marco Schlumpp <marco@unikraft.io>
Reviewed-by: Sergiu Moga <sergiu.moga@protonmail.com>
Approved-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io>
Tested-by: Unikraft CI <monkey@unikraft.io>
GitHub-Closes: #760

diff --git a/plat/kvm/x86/lxboot.S b/plat/kvm/x86/lxboot.S
index 8d0a34f393c237b6add0658d486652ca9e458ab9..41e71063948996c33ec05a7e3525c59d7c626e1c 100644 (file)
--- a/plat/kvm/x86/lxboot.S
+++ b/plat/kvm/x86/lxboot.S
@@ -6,6 +6,7 @@
 
 #include <uk/config.h>
 #include <uk/asm.h>
+#include <uk/plat/common/lcpu.h>
 
 #include <kvm-x86/lxboot.h>
 
@@ -16,10 +17,9 @@
 .space 4096
 lcpu_bootstack:
 
-.section .rodata
 lcpu_boot_startup_args:
-       .quad   lxboot_entry
-       .quad   lcpu_bootstack
+       .quad   0
+       .quad   0
 
 /**
  * 64-bit Linux Boot Protocol entry function
@@ -35,9 +35,14 @@ ENTRY(_lxboot_entry)
        cmpl    $LXBOOT_HDR_HEADER_MAGIC, LXBOOT_HDR_HEADER_OFFSET(%rsi)
        jne     no_lxboot
 
-       movq    $lcpu_boot_startup_args, %rdi   /* startup args for boot CPU */
+       /* startup args for boot CPU */
+       leaq    lcpu_boot_startup_args(%rip), %rdi
+       leaq    lxboot_entry(%rip), %rax
+       movq    %rax, LCPU_SARGS_ENTRY_OFFSET(%rdi)
+       leaq    lcpu_bootstack(%rip), %rax
+       movq    %rax, LCPU_SARGS_STACKP_OFFSET(%rdi)
 
-       movq    $x86_bpt_pml4, %rax
+       leaq    x86_bpt_pml4(%rip), %rax
        movq    %rax, %cr3
 
        jmp     lcpu_start64