diff options
Diffstat (limited to 'kernel/arch/x86/realmode/rm/trampoline_32.S')
| -rw-r--r-- | kernel/arch/x86/realmode/rm/trampoline_32.S | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/kernel/arch/x86/realmode/rm/trampoline_32.S b/kernel/arch/x86/realmode/rm/trampoline_32.S new file mode 100644 index 000000000..48ddd76bc --- /dev/null +++ b/kernel/arch/x86/realmode/rm/trampoline_32.S @@ -0,0 +1,73 @@ +/* + * + * Trampoline.S Derived from Setup.S by Linus Torvalds + * + * 4 Jan 1997 Michael Chastain: changed to gnu as. + * + * This is only used for booting secondary CPUs in SMP machine + * + * Entry: CS:IP point to the start of our code, we are + * in real mode with no stack, but the rest of the + * trampoline page to make our stack and everything else + * is a mystery. + * + * We jump into arch/x86/kernel/head_32.S. + * + * On entry to trampoline_start, the processor is in real mode + * with 16-bit addressing and 16-bit data. CS has some value + * and IP is zero. Thus, we load CS to the physical segment + * of the real mode code before doing anything further. + */ + +#include <linux/linkage.h> +#include <asm/segment.h> +#include <asm/page_types.h> +#include "realmode.h" + + .text + .code16 + + .balign PAGE_SIZE +ENTRY(trampoline_start) + wbinvd # Needed for NUMA-Q should be harmless for others + + LJMPW_RM(1f) +1: + mov %cs, %ax # Code and data in the same place + mov %ax, %ds + + cli # We should be safe anyway + + movl tr_start, %eax # where we need to go + + movl $0xA5A5A5A5, trampoline_status + # write marker for master knows we're running + + /* + * GDT tables in non default location kernel can be beyond 16MB and + * lgdt will not be able to load the address as in real mode default + * operand size is 16bit. Use lgdtl instead to force operand size + * to 32 bit. + */ + lidtl tr_idt # load idt with 0, 0 + lgdtl tr_gdt # load gdt with whatever is appropriate + + movw $1, %dx # protected mode (PE) bit + lmsw %dx # into protected mode + + ljmpl $__BOOT_CS, $pa_startup_32 + + .section ".text32","ax" + .code32 +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" |