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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /arch/x86/realmode/rm/trampoline_32.S
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/x86/realmode/rm/trampoline_32.S')
-rw-r--r--arch/x86/realmode/rm/trampoline_32.S73
1 files changed, 73 insertions, 0 deletions
diff --git a/arch/x86/realmode/rm/trampoline_32.S b/arch/x86/realmode/rm/trampoline_32.S
new file mode 100644
index 000000000..3fad907a1
--- /dev/null
+++ b/arch/x86/realmode/rm/trampoline_32.S
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+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *
+ * 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
+SYM_CODE_START(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
+
+ /*
+ * 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
+SYM_CODE_END(trampoline_start)
+
+ .section ".text32","ax"
+ .code32
+SYM_CODE_START(startup_32) # note: also used from wakeup_asm.S
+ jmp *%eax
+SYM_CODE_END(startup_32)
+
+ .bss
+ .balign 8
+SYM_DATA_START(trampoline_header)
+ SYM_DATA_LOCAL(tr_start, .space 4)
+ SYM_DATA_LOCAL(tr_gdt_pad, .space 2)
+ SYM_DATA_LOCAL(tr_gdt, .space 6)
+SYM_DATA_END(trampoline_header)
+
+#include "trampoline_common.S"