[Xen-devel] [PATCH 2/2] x86: trampoline cleanup

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

To make future changes less error prone, and to slightly simplify a
possible future conversion to a relocatable trampoline even for the
multiboot path (pretty desirable given that we had to change the
trampoline base a number of times to escape collisions with firmware
placed data),
- remove final uses of bootsym_phys() from trampoline.S, allowing the
  symbol to be undefined before including this file (to make sure no
  new references get added)
- replace two easy to deal with uses of bootsym_phys() in head.S
- remove an easy to replace reference to BOOT_TRAMPOLINE

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -202,11 +202,11 @@ __start:
 
         /* Copy bootstrap trampoline to low memory, below 1MB. */
         mov     $sym_phys(trampoline_start),%esi
-        mov     $bootsym_phys(trampoline_start),%edi
+        mov     %edx,%edi
         mov     $trampoline_end - trampoline_start,%ecx
         rep     movsb
 
-        mov     $bootsym_phys(early_stack),%esp
+        lea     early_stack-trampoline_start(%edx),%esp
         call    cmdline_parse_early
 
         /* Jump into the relocated trampoline. */
@@ -214,6 +214,8 @@ __start:
 
 #include "cmdline.S"
 
+#undef bootsym_phys
+
 reloc:
 #include "reloc.S"
 
--- a/xen/arch/x86/boot/trampoline.S
+++ b/xen/arch/x86/boot/trampoline.S
@@ -132,7 +132,7 @@ high_start:
 
         .code32
 trampoline_boot_cpu_entry:
-        cmpb    $0,bootsym_phys(skip_realmode)
+        cmpb    $0,bootsym_rel(skip_realmode,5)
         jnz     .Lskip_realmode
 
         /* Load pseudo-real-mode segments. */
@@ -152,7 +152,7 @@ trampoline_boot_cpu_entry:
 
         /* Load proper real-mode values into %cs, %ds, %es and %ss. */
         ljmp    $(BOOT_TRAMPOLINE>>4),$bootsym(1f)
-1:      mov     $(BOOT_TRAMPOLINE>>4),%ax
+1:      mov     %cs,%ax
         mov     %ax,%ds
         mov     %ax,%es
         mov     %ax,%ss
@@ -195,7 +195,7 @@ trampoline_boot_cpu_entry:
         lmsw    %ax                       # CR0.PE = 1 (enter protected mode)
 
         /* Load proper protected-mode values into all segment registers. */
-        ljmpl   $BOOT_CS32,$bootsym_phys(1f)
+        ljmpl   $BOOT_CS32,$bootsym_rel(1f,6)
         .code32
 1:      mov     $BOOT_DS,%eax
         mov     %eax,%ds

Attachment: x86-trampoline-cleanup.patch
Description: Text document

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