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x86, realmode: Move not-common bits out of trampoline_common.S
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Move the bits that aren't actually common out of trampoline_common.S
and into the arch-specific files.  Furthermore, make sure the page
directory is first in the .bss section for trampoline_64.S in order to
not waste an entire page of memory.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
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H. Peter Anvin committed May 16, 2012
1 parent 7960387 commit 51edbe6
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Showing 3 changed files with 33 additions and 35 deletions.
8 changes: 8 additions & 0 deletions arch/x86/realmode/rm/trampoline_32.S
Original file line number Diff line number Diff line change
Expand Up @@ -63,4 +63,12 @@ ENTRY(trampoline_start)
ENTRY(startup_32) # note: also used from wakeup_asm.S
jmp *%eax

.bss
.balign 8
GLOBAL(trampoline_header)
tr_start: .space 4
tr_gdt_pad: .space 2
tr_gdt: .space 6
END(trampoline_header)

#include "trampoline_common.S"
25 changes: 25 additions & 0 deletions arch/x86/realmode/rm/trampoline_64.S
Original file line number Diff line number Diff line change
Expand Up @@ -125,4 +125,29 @@ ENTRY(startup_64)
# Now jump into the kernel using virtual addresses
jmpq *tr_start(%rip)

.section ".rodata","a"
# Duplicate the global descriptor table
# so the kernel can live anywhere
.balign 16
.globl tr_gdt
tr_gdt:
.short tr_gdt_end - tr_gdt - 1 # gdt limit
.long pa_tr_gdt
.short 0
.quad 0x00cf9b000000ffff # __KERNEL32_CS
.quad 0x00af9b000000ffff # __KERNEL_CS
.quad 0x00cf93000000ffff # __KERNEL_DS
tr_gdt_end:

.bss
.balign PAGE_SIZE
GLOBAL(trampoline_pgd) .space PAGE_SIZE

.balign 8
GLOBAL(trampoline_header)
tr_start: .space 8
GLOBAL(tr_cr4) .space 4
GLOBAL(tr_efer) .space 8
END(trampoline_header)

#include "trampoline_common.S"
35 changes: 0 additions & 35 deletions arch/x86/realmode/rm/trampoline_common.S
Original file line number Diff line number Diff line change
@@ -1,42 +1,7 @@
.section ".rodata","a"

#ifdef CONFIG_X86_64
# Duplicate the global descriptor table
# so the kernel can live anywhere
.balign 16
.globl tr_gdt
tr_gdt:
.short tr_gdt_end - tr_gdt - 1 # gdt limit
.long pa_tr_gdt
.short 0
.quad 0x00cf9b000000ffff # __KERNEL32_CS
.quad 0x00af9b000000ffff # __KERNEL_CS
.quad 0x00cf93000000ffff # __KERNEL_DS
tr_gdt_end:
#endif

.balign 4
tr_idt: .fill 1, 6, 0

.bss

.balign 4
GLOBAL(trampoline_status) .space 4

.balign 8
GLOBAL(trampoline_header)
#ifdef CONFIG_X86_32
tr_start: .space 4
tr_gdt_pad: .space 2
tr_gdt: .space 6
#else
tr_start: .space 8
GLOBAL(tr_cr4) .space 4
GLOBAL(tr_efer) .space 8
#endif
END(trampoline_header)

#ifdef CONFIG_X86_64
.balign PAGE_SIZE
GLOBAL(trampoline_pgd) .space PAGE_SIZE
#endif

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